|2||30||10||2||Use machines with high spindle rigidity. (Use this product for machining centers, CNC lathes, automatic lathes, or milling machines.)||M3 4-40 UNC,6-40 UNF,6 BA-4 BA||The extra negative shape increases the machining temperature and anneals the tap.||Repolishing Type||Cutting Oil Unnecessary||Suitable for dry processing|
|3||40||15||3||Use machines with high spindle rigidity. (Use this product for machining centers, CNC lathes, automatic lathes, or milling machines.)||M4,M5 8-32 UNC, 10-32 UNF, 3 BA-2 BA||The extra negative shape increases the machining temperature and anneals the tap.||Repolishing Type||Cutting Oil Unnecessary||Suitable for dry processing|
|4||45||20||4||Use machines with high spindle rigidity. (Use this product for machining centers, CNC lathes, automatic lathes, or milling machines.)||M6 1/4-5/16 UNC, 1/4-5/16 UNF, 1 BA-0 BA||The extra negative shape increases the machining temperature and anneals the tap.||Repolishing Type||Suitable for dry processing|
|5||50||25||5||5/16-3/8 UNC, 5/16-3/8 UNF||The extra negative shape increases the machining temperature and anneals the tap.||Repolishing Type||Cutting Oil Unnecessary||Suitable for dry processing|
|6||60||30||6||3/8-1/2 UNC,3/8-1/2 UNF||The extra negative shape increases the machining temperature and anneals the tap.||Repolishing Type||Cutting Oil Unnecessary||Suitable for dry processing|
Drilling Hard Material
Tools should have a physical vapor deposition coating, which acts as a barrier between the carbide and the material being cut.
Drilling is a mainstream, economical choice for hole creation in a workpiece, and manufacturers have many tool options to choose from.
High-speed steel (HSS), solid-carbide, indexable, CBN, diamond-tipped, and interchangeable-head drills all have their place in manufacturing. Choosing the correct tool for the job depends on several factors, but workpiece material typically is the driver.
Like any other chipping operation, successful holemaking requires a stable machine tool, with toolholding, workholding, and coolant all playing major roles.
However, when the material being machined exceeds 50 HRC, heat—the common enemy in all chipmaking operations—becomes even more oppressive.
“Getting good tool life is the main challenge when cutting hard material because of the amount of heat being generated,” explained David Vetrecin, rotating tools product manager for Iscar Tools Canada.
When the heat stays in the drill, the tool itself will begin to break down. In solid-carbide drills, the common tool for drilling hard materials, microcracks can form on the cutting edges, which will eventually cause the drill to fail. A reinforced edge preparation becomes necessary to combat the stresses created.
“Hard material naturally is hard on the cutting edge, so edge prep is critical,” said Vetrecin.
In addition to cutting edge reinforcement, solid-carbide drills designed for hard materials often have straight flutes, which adds some rigidity to the tool. A harder grade of carbide also is used.
Because the amount of heat generated is high, a coated tool is the correct choice.
“Our tools have a PVD [physical vapor deposition] titanium aluminum coating, which acts as a barrier between the carbide and the material being cut, essentially acting as a shield so the heat doesn’t get into the tool,” said Vetrecin. “If you can control heat, you can control tool life.”
The ICM exchangeable drill head was developed for cutting stainless steel, but works well with hard materials because it has a T-land on the cutting edge.
Cutting conditions such as speeds and feeds must be taken into consideration when drilling holes in hard materials.
“As hardness goes up, speeds and feeds must come down dramatically,” said Vetrecin.
While finding the machining “sweet spot” can be a process of trial and error, establishing the correct cutting conditions is paramount. On hardened steel, speeds and feeds often need to be reduced by half or more compared to those used for drilling mild steel.
“If you have a tool with a reinforced cutting edge and use the proper cutting conditions, drilling hard material poses fewer challenges than many other difficult-to-chip materials,” said Vetrecin.
In fact, chip evacuation from holes typically is not a problem in hardened steels because the chips produced are relatively small, making them flow easily up the flutes. High-pressure coolant (1,000 PSI) still is recommended, however, to break the vapor barrier between the cutting edge and the chip.
Rethink the Process
Sending the material out for heat-treating before machining is a foreign concept to some companies, but one that should be explored.
“Shops that think a little outside the box typically are the ones that are willing to try this type of machining,” said Vetrecin.
A traditional method for machining a hard part looks like this:
Step 1—Perform the roughing stage.
Step 2—Send part for heat-treating.
In this situation, manufacturers often are at the mercy of a third-party heat-treating facility and the possible delivery delays that are all too common. This has meant that more and more companies are hardening the material prior to any machining.
“A major benefit of prehardening the material is that there is only one setup now,” said Vetrecin. “Because the part is loaded into the machine only once, there is less chance of creating scrap caused by moving the part around too much.
Also, the chance that the part is scrapped because it comes back warped is eliminated because the potential for this defect can be corrected for during machining.
Other benefits include:
- Less WIP parts.
- Reduced shipping costs.
- Reduced front-office costs.
Drawbacks to prehardening can include higher tool costs because more tooling must be used to machine the hardened material. Also, if the part includes a turning or milling operation, CBN tooling often is used.
“The part usually takes more time to machine when the material has been hardened, but you are no longer dependent on a supplier,” said Vetrecin. “You have to weigh the good and the bad.”
A manufacturer should not be limited to solid-carbide tooling only. Even in hardened material, as the hole size gets larger, other options should be considered. Drilling holes with larger diameters (greater than 1 in.) typically means using indexable tools.
“For these larger diameters it makes sense to use an indexable tool. These tools obviously have less carbide in them, and that makes them a more economical choice when a larger hole has to be drilled,” said Vetrecin. “We also have found that the ICM exchangeable drill head we developed for cutting stainless steel works well with hard materials because it has a T-land on the cutting edge.”
Hard Steel Die Drills from Hannibal Carbide Tool
Type 671 Fractional – 140º Point With Negative Edge
Modifications: (Prompt delivery)
EDP No. 67104 – 67111: Solid carbide
|Tool Diameter||Length||Type 671
|1/16||.0625||1 1/2||67104||$22. 95|
|11/64||.1719||2 3/8||67111||27. 35|
|3/16||.1875||1 1/2||3 1/2||67112||24.80|
|13/64||.2031||1 1/2||3 1/2||67113||24.80|
|7/32||.2188||1 3/4||3 3/4||67114||25.60|
|15/64||.2344||1 3/4||3 3/4||67115||26.45|
|9/32||.2813||2 1/4||4 1/4||67118||27.95|
|19/64||.2969||2 1/4||4 1/4||67119||29.25|
|5/16||.3125||2 1/2||4 1/2||67120||29.25|
|21/64||.3281||2 1/2||4 1/2||67121||31.15|
|11/32||.3438||2 3/4||4 3/4||67122||31.15|
|23/64||.3594||2 3/4||4 3/4||67123||33. 50|
|29/64||.4531||3||5 1/2||67129||47. 75|
|15/32||.4688||3 1/4||5 3/4||67130||50.00|
|31/64||.4844||3 1/4||5 3/4||67131||60.65|
|21/32||.6563||4 1/2||7 1/2||67142||81.20|
|11/16||.6875||4 1/2||7 1/2||67144||83.35|
|25/32||.7813||4 3/4||8||67150||173. 30|
Aluminum can be hard to drill, despite its easy rep
When drilling, perhaps no variable is as important as the workpiece material. It dictates drill geometry and substrate, tool coating, coolant application, and speeds and feeds.
While known for its relative softness and ductility, misconceptions abound among those who regularly drill aluminum.
“Aluminum is considered by many to be one of the easiest machining materials, but it does present its own unique challenges”—particularly when drilling, explained Elliott Frazier, a product manager at Tungaloy America Inc., Arlington Heights, Ill. “Aluminum is a generally soft, nonferrous, ductile material with low density and naturally high resistance to corrosion. Aluminum is difficult to drill because its ductility and softness causes the material to make constant prolonged contact with the rake face, or cutting edges, of a drill.”
While there are many different aluminum alloys with unique machinability characteristics, Frazier said the most widely drilled aluminum alloys are 6061 and 7075, adding that there are pockets of aerospace and medical work that use specialty alloys exclusively.
Edges, Flutes and Coatings
The two main issues when drilling aluminum, explained Chad Lynch, field sales engineer for Allied Machine & Engineering Corp. (AMEC), Dover, Ohio, are chip formation and chip evacuation. “If you approach it without the proper tool geometry, without the proper coating, without the proper coolant, it can very quickly turn into a situation where long, stringy chips are wrapping themselves around the tool.”
Frazier added built-up edge to the list of primary challenges when drilling aluminum alloys. The aluminum will build up and adhere to the cutting edge and interfere with the formation of new chips from the parent material, which can lead to chip packing, as flutes become clogged. This leads to deposits of aluminum adhering to the drill, promoting even further adhesion and chip packing.
The guide path pressure of a gundrill can impact surface finish, depending on coolant lubricity, due to the inherent plasticity of aluminum. Image courtesy Sandvik Coromant.
“Chips tend to ‘string out’ because of the softness of the material,” Lynch explained. “The primary way to get around that is through geometry. ” AMEC offers an aluminum-specific geometry for its TA product line, which has a high rake angle that effectively forms a chip in gummier, 6061-type materials, he said. A higher rake creates more shear in the cut and forces the material into the impact site on the tool.
The main difference between drilling aluminum and harder materials, noted Jason Hout, global DHM (deep hole machining) product and application specialist for Sandvik Coromant Co., Fair Lawn, N.J., is that the shear point of aluminum is low enough that it can be sliced by the tool’s cutting edge, as opposed to being pushed out
of the way when machining harder materials. This means an upright, high shear angle with a minimal edge hone is ideal for drilling aluminum.
“Generally, drills with a high helix angle, polished flutes and 130° to 140° point angle will provide the best chip evacuation and cutting performance,” Frazier said. “However, since aluminum is so soft, drilling operations using the aforementioned geometry tend to present difficulties in maintaining proper hole diameter and sidewall surface finish. If maintaining hole size, finish and hole roundness are the goals, using a straight-flute, through-coolant drill is advantageous.”
However, a sharp edge is a weak edge, and many aluminum grades contain high levels of silica—a hard, glass-like particulate in the matrix of the aluminum that can rapidly break down a tool’s edge. “Wear [from silica] can sometimes be combatted with coatings or by switching from carbide to a superabrasive tool material like PCD,” Hout said.
When applying a carbide tool, it’s important that it doesn’t have an aluminum-based coating, because the aluminum will tend to stick to the workpiece surface, he added. Common coatings such as Al2O3 or AlTiN, when brought into contact with aluminum under heat and pressure, will not only react with the part, but have abrasive properties that can contribute to BUE. Instead, Hout recommends either titanium diboride or an amorphous diamond film.
If those aren’t available, uncoated carbide with a polished surface provides more-than-adequate performance in most applications, Hout noted. “You want the flutes polished to help material slide out, and if there is a radius within the flute, you don’t want a square edge or a straight wall unless it’s unavoidable [such as when gundrilling].”
Frazier recommends a micrograin carbide with a hardness from 92 to 93 HRA for low-silicon alloys, but said some aluminum alloys used for forgings or castings contain more than 11 percent silicon and are best approached with drills tipped with PCD or diamond-like carbon.
“Usually, coatings are not applied to drills in aluminum applications, as a majority of coatings contain aluminum,” he said. Because the majority of coatings contain aluminum as one of their base constituent elements, Frazier said some manufacturers have begun utilizing a titanium-zirconium-nitride coating in aluminum applications. “But the conventional wisdom in this field is to utilize a sharp, high-polished, uncoated carbide drill.”
Using a straight-flute, through-coolant drill is advantageous if maintaining hole size, finish and hole roundness is the goal. Image courtesy Tungaloy.
One such manufacturer is R.I. Carbide, a tool grinder and machine shop in Smithfield, R.I., that offers its ZETA ZrN coating as an alternative to TiN when extra lubricity is needed.
“We had a customer who needed to drill 3,000 holes in a plate of aluminum, and if they broke a drill machining one hole, the whole part was scrap,” said John Lombardi, company president. “So they came to us with the problem, and we made a 0.156″-dia. drill with a ½” base about 3″ long for the job.” R.I. Carbide used the ZETA coating on the drill, and by running that highly lubricious drill with through-coolant capability at high speeds, the customer was able to successfully complete the part on the first pass.
Proper chip evacuation involves proper application of coolant, and drilling aluminum is no exception. Pecking is always an option, but many part manufacturers like to avoid withdrawing the drill when possible, which means polished flutes and through-coolant drills are the order of the day.
“Especially when you go to longer depths, the issue is always coolant flow for chip evacuation, and that’s not anything unique to aluminum,” noted AMEC’s Lynch. “We prefer not to peck, and I feel that if people have to do any pecking, it’s probably because they’re not forming a good chip. We’ve actually found that the type of cutting fluid is less important than the concentration—the higher the concentration, the better your results, generally speaking.”
Tungaloy’s Frazier always recommends through-coolant. “Higher metal-removal rates require [applying] a lot of coolant, very quickly, to move the chips from the cutting zone, and mrr is typically very high in aluminum.” Flood coolant would require peck cycles, and minimum-quantity lubrication simply doesn’t have the displacement value when holemaking, especially drilling deep holes, he said. “The higher the flow, and higher the pressure, the better.”
Sandvik Coromant’s Hout has observed at least one characteristic unique to aluminum when deep-hole drilling. “When using self-guided drills like gundrills, because of the plasticity of aluminum, the guide path pressure can impact the finish of the hole either positively or negatively, depending on the lubricity of the coolant,” he said. Neat cutting oil typically results in a smooth finish, while a synthetic, water-based fluid might allow some of the aluminum to stick to the guide path, creating a rough, “smeared” finish.
Running at high cutting speeds while resisting the temptation to overfeed and applying a coolant with high lubricity and moderate-to-low viscosity is the best way to ensure a fine surface finish, Hout said. “You want the oil to move fast.”
How high can those cutting speeds be? According to Hout, modern machinery has not yet advanced to the point where the surface speed ceiling for aluminum can be hit.
“The threshold for aluminum is something like 60,000 sfm, which is enormously fast,” he said. “I’ve seen aluminum run at 24,000 sfm with an uncoated carbide insert, and it didn’t harm the aluminum or the insert. I tell our customers that, within a safe working environment, don’t be afraid to crank it up because I’ve seen that higher speeds in aluminum gets you both better tool life and a better surface finish.”
Because aluminum is considered by many to be cheap and easy to work with, it’s easy to fall into the trap of thinking any machining setup will work. However, some of the “easiest” materials to machine end up yielding the lowest profit margins at the end of the job, according to Tungaloy’s Frazier.
“If more shops are able to do the work on ‘easy’ materials, there is more competition for those same jobs, inevitably driving down the price of cutting aluminum,” he said. “In this sense, it is important to maximize your speed and efficiency when working with these materials, using updated tooling and advanced concepts, in order to stay competitive.”
While North Americans know it as “aluminum,” most English-speaking countries use the suffix “-ium. ” The Canadian Oxford Dictionary lists the spelling as “aluminum,” while the Australian Macquarie Dictionary prefers “aluminium.” The reason?
“In 1926, the American Chemical Society officially decided to use aluminum in its publications; American dictionaries typically label the spelling aluminium as ‘chiefly British,’” explained Tungaloy America Inc.’s Elliott Frazier. “The earliest citation given in the Oxford English Dictionary for any word used as a name for this element is alumium, which British chemist and inventor Humphry Davy employed in 1808 for the metal he was trying to isolate electrolytically from the mineral alumina.
“Essentially, the British thought ‘aluminium’ sounded more classical and scientific, so they added the extra letter.”
—E. Jones Thorne
Flowdrill, Baby, Flowdrill
Drilling involves generating chips. It’s just a given—after all, the material that’s removed has to go somewhere, right? But while a process that doesn’t generate chips might not sound like drilling to some, St. Louis-based thermal-friction-drilling specialist Flowdrill Inc. offers an alternative to traditional drilling.
“Thermal-friction drilling is a process that involves generating heat through friction and pressure,” said Mitch Ray, president of Flowdrill. “We create what we refer to as a bushing in thin-walled material, which extends approximately three to four times the original wall thickness.”
This bushing adds more thread to the hole and gives the customer an alternative to current fastener methods like weld nuts or threaded inserts. Once the bushing is created, a form tap can create threads, or a self-threading screw can be inserted to complete the job. There are no chips created in either case.
Flowdrill’s Aludrill geometry is specially designed for use in aluminum. Image courtesy Flowdrill.
Every tool bit diameter has a certain set of parameters, Ray explained. For example, a ¼-20 thread size would require a tool to be run at 2,400 rpm in aluminum or mild steel, require 1. 5 hp and have a cycle time of about 3 seconds per hole. The bit contacts the material, and the friction of that contact heats the material while the pressure behind the bit pushes through the material and forms the bushing. There is no external heat source, and Flowdrill bits can be used on any standard CNC machine without any special adapters.
The company’s newest geometry is called the Aludrill, which is designed specifically for aluminum.
Thermal-friction drilling creates a hole and a bushing—but no chips—through the use of heat and pressure. Image courtesy Flowdrill.
“Unlike our other bits, it doesn’t require our special lubricant; it can operate with standard machine coolant,” Ray said. “It also countersinks a chamfer into the material, which makes it the only one of our bits that generates a chip.”
On a standard Flowdrill bit, a polygon is ground, consisting of four peaks and four valleys, each referred to as “lobes,” which are what generate the friction and cause the heat. The Aludrill eschews this geometry in favor of more contact with the metal, which creates enough friction in the softer aluminum to generate sufficient heat.
“We’ve got some large applications for the Aludrill,” Ray said. “Last year, it was used on the new Ford F150 pickup, making holes in the front aprons of those trucks. They use a self-tapping screw to attach the different wiring lines to the front of the trucks.”
—E. Jones Thorne
Allied Machine & Engineering Corp.
Sandvik Coromant Co.
Tungaloy America Inc.
A tale of two cutting tools: solid and indexable-insert drills
A solid drill is a rotating end- or side-cutting tool with one or more cutting edges and one or more straight or helical grooves for the passage of chips and the admission of coolant. An indexable-insert drill accepts inserts that clamp into a tool body designed to accept them. A cutting edge of an insert is used until it becomes dull, then it is indexed, or turned, to expose a fresh cutting edge. When all cutting edges of an insert are dull, it is usually discarded and replaced with a new one.
Solid and indexable-insert drills each have advantages and disadvantages, and the type selected for the job depends on the application. Hole diameter is one consideration. Toolmakers can produce indexable drills with much larger diameters than solid tools, while solid drills can be made with significantly smaller diameters.
The diameter of a solid-carbide drill will typically range from about 3mm (0.118″) to 20mm (0.787″). A solid-HSS drill can be larger than 20mm in diameter, but it will not be as accurate as a solid-carbide tool. When an application calls for hole diameters larger than 20mm, explore indexable options.
A factor to remember is that the horsepower required for drilling will increase as the drill diameter increases. If a parts manufacturer is purchasing a machine that it knows will be used to drill large diameters, the company must check that the machine has the required horsepower.
Horsepower concerns really come into play when switching to an indexable drill from a solid drill, whether HSS or carbide. With two inserts in use, users must reference the torque and horsepower charts that come with every machine. For example, the charts on machines at Dormer Pramet clearly state that a machine can run at 40 to 45 hp for 15 minutes. Going beyond that point can cause the machine to stop and trigger an alarm.
Tolerances are another differentiator between solid-carbide and indexable drills, with the former able to achieve tighter tolerances than the latter. Using the ISO 286 hole-tolerance scale, where the smaller the number, the more precise a hole’s diameter, a solid-carbide drill can deliver an H9 tolerance while an indexable drill can only reach h20 to h22. So, for example, an 18mm-dia. (0.709″) hole that’s H9 on the ISO scale will have a tolerance of 43µm (0.0017″), whereas an h21 hole’s tolerance for the same size hole would be 130µm (0.005″).
Investment and Maintenance
From a cost perspective, indexable inserts and their holder—the cutter body that accommodates the inserts—represent a significant investment. However, when a cutting edge is worn and needs replacement, the ease of replacing an insert is more efficient than exchanging a solid tool because only the insert needs to be indexed or changed. A solid drill, on the other hand, usually requires removal from the toolholder and resetting the depth of the drill after the tool is changed.
To help support the long-term investment of indexable inserts, they are interchangeable and versatile. Machinists can reuse the cutter from one job while easily switching out the inserts for another job that requires machining a different workpiece material.
Solid drills offer a long-term investment advantage of their own because they can be reground, sometimes seven to 10 times. On the other hand, indexable inserts are typically not reground.
The geometry, substrate and coating of a solid drill determine its performance. Drills that optimize each element for a specific application have the potential to be more accurate than general-purpose tools.
Looking at geometry, the 118° conical point is the most common drill point. When properly produced, it will effectively drill a variety of materials. The drill point may require some form of web thinning when used on a drill whose web thickness has increased because of repeated resharpenings or on a drill with a heavy web construction.
In addition, the split point was originally developed for use on drills designed for producing deep oil holes in automotive crankshafts. Today, the split point is used on many designs of drills for cutting various hard and soft materials. The split point can be applied to a variety of drill point angles, with the most common being 135°. The main benefits of the split point are that it enables self-centering of a drill and prevents the tool from “walking” before penetrating a part’s surface.
The split point greatly reduces thrust and adds a positive-rake cutting edge, which extends to the center of the drill. The split point also acts as a chipbreaker to produce small chips, which can be effectively evacuated through the flutes. This is beneficial in most applications, but especially when using a portable drill or a drill press where bushings cannot be used.
Conversely, indexable drills offer a versatility that is beyond the capability of solid tools. Inserts can provide stable results even in adverse conditions and are able to perform multiple operations beyond the scope of solid drills. These operations include plunging, helical interpolation, profiling and enlarging a hole.
For example, when a manufacturer needed to remove material as fast as possible, it plunged with an indexable drill. The company applied a 1″-dia. (25.4mm) drill that plunged straight up and down, then moved it more than ¾” (19.05mm) and plunged straight up and down again. For quickly removing material, it was a great solution—and one a solid drill couldn’t accomplish.
Both solid drills and indexable-insert ones have distinct advantages and disadvantages based on workpiece material, the application and operational requirements. They complete a toolmaker’s standard offering by providing users overlapping diameters so tooling engineers can assess applications and advise parts manufacturers where and when it is appropriate to apply each.
HSS is a very tough, but not very wear-resistant, material. HSS tools are applied in many common, demanding applications.
Carbide is the most widely used wear-resistant cutting tool material and is suitable for making solid tools and indexable-insert tools. Approximately 85 percent of all carbide indexable inserts are coated.
Indexable inserts are made of cermet, ceramics, polycrystalline cubic boron nitride (PCBN) or polycrystalline diamond (PCD).
Cermet provides effective flank- and crater-wear resistance and is not prone to built-up edge. Because of this, the cutting edge maintains its sharpness for a long time.
Ceramic has a wide application area in cutting materials hardened to 45 to 55 HRC and has a high resistance to abrasive and thermal conditions.
PCBN offers an extremely high thermal resistance, and PCBN tools are applied for cutting challenging materials such as hardened steels and cast iron.
There are two types of PCD: natural and industrial diamond. PCD tools are suitable for machining nonferrous materials, such as aluminum, because of PCD’s high resistance to wear. Because PCD is extremely hard and brittle, it is not a good choice for high-hardness or high-impact applications.
Development is ongoing for new geometries, new coatings, new substrates and advanced manufacturing processes, including edge preparations, surface finishing and other treatments.
—G. Kirchoff and J. Nava
Full-court, V-cut drill gets practices started
All coaches are aware of the importance of getting practice off to a good start. One of the best drills we’ve used to ensure a good start to practice is the full-court, V-cut drill.
This is a drill designed to incorporate multiple offensive fundamentals into a full-court drill in a short period of time. Once your players learn how to correctly do the drill, it usually takes only 10 minutes from start to finish.How it works
The drill begins with players evenly distributed in four lines — labeled A, B, C and D — with each player in line A holding a basketball.
DIAGRAM 1: Full-court, V-cut drill. The first player in line B executes a V-cut downcourt and comes back to receive a pass from player A. Stress to the players in line B that they must aggressively come back to meet the pass.
After receiving the pass, player B uses a front pivot and passes to the first player in line C without traveling. Player C also uses a V-cut, and breaks hard to meet B’s pass.
Focusing on skills such as proper V-cuts and pivoting prevents many turnovers when pressure defense is applied in a live-game situation.Communication and timing
To get your players in the habit of communicating, have your players constantly making verbal calls throughout the duration of the drill, with the passer calling out the receiver’s name and the receiver calling out the passer’s name.
One of the keys for good timing in this drill is to have the next player in line begin his or her V-cut while the ball is in the air and going toward the player who will become the passer.
All passes — except for backcut, backdoor or post-entry passes — should be crisp chest passes.
After passing, players run to the end of the next line. The first player in line D rebounds any misses and uses a 2-foot power layup to finish the play. After making the shot or follow-up shot, player D grabs the ball as it comes through the basket and speed dribbles the length of the floor outside of line C and shoots the appropriate shot at the other hoop. To keep things at a good pace or to mix things up and keep the players alert, have the coach call out or set up a sequence for the type of shot that your players in line D are to use (e.g. speed layup, reverse layup, pull-up, jump shot).» ALSO SEE: Time-tested rules for defending screens
If player D misses the shot, he or she rebounds and follows it up with a 2-foot power layup. The next player in line A takes the ball as it comes through the net and passes to the next player in line B, who is making the V-cut move toward line A.
As the drill progresses, the sequence of shots for the players in line D should be:
- Speed layup.
- Reverse layup.
- Catch-and-shoot jump shot.
- Pull-up jump shot, after a crossover dribble.
- Catch-and-shoot 3-point jump shot.
- Return pass to C for a 3-point jump shot from the top of the key.
- Return pass to C at the top of the key. D then posts up on the opposite low block, and C dribbles over to get a wing-to-low-post passing angle.
- Hard dribble by C directly at D, which is D’s signal to execute a backcut and look for a backdoor bounce pass from C.
The first player up in line A is called the “change-it” player, and when he or she gets back into the first-position spot in line A, it’s time to change to the next shot in the sequence. Shoot each shot twice.
Which Drill Point Angle Should I be Using?
The selection of an appropriate drill point angle for your bit should be informed by questions about your application. Yes—a hole is a hole is a hole—but what is the purpose of the hole, what type of metal are you cutting into, and what are the specifications for the finished hole?
In addition to the drill point angle, factors that can affect successful drilling include:
- Length of the Drill
- Coolant Flow
- Type of Drill Point
There are two main characteristics that define a drill point. First is the included angle of the point and the second is the configuration of the point. The point configuration is a key element in the choice of drill styles for a particular job.
Common Drill Angles
The most common included angles for drills are 118° and 135°. These angles are an artifact from the time when drilling was largely a manual process, and the drill bits were conventional conical shapes. Over time, tool makers learned that by grinding a conical point with a flat surface (a facet) to create a linear chisel, they could reduce the thrust required and also improve the process of cutting the metal or wood and removing the chips. If you’re drilling by hand, this is a clearly a major benefit.
Today, with advanced drilling machines, multi-faceted drill points are the norm. Not only do they require 50% less thrust, but they also generate 60% less heat than a conventional drill point. And there are a number of different configurations, each of which—when combined with a particular drill point angle—is suitable for specific jobs.
The general purpose drill points found on most jobber drills are 118° angled drills. They are typically used for cutting into soft metals such as aluminum, whereas the 135° variant is best suited for hardened materials, such as stainless steel. A 135° drill is flatter than 118°, which means that more of its cutting lips engage with the material surface sooner to begin the full metal cutting action. Check out our guide below for what angles are optimal based on the material that is being drilled:
(Click Image to expand)
There are a number of drill point configurations and these may be found in both 118° and 135° variants. The different configurations are selected based on the drilling application—for example:
- Are you cutting into hard metal or soft?
- Is self-centering possible or will a guide bushing be needed?
Specialized Drill Point Configurations
Conventional points with 118° point angles are used most commonly for drilling in a wide array of materials. Other drill point configurations include:
|Notched points: were developed for drilling hard alloys and have reduced drag on the chisel edge.|
|Helical points: have an S-contoured chisel that is self-centering and cuts close to actual drill diameter.|
|Racon® points: have a continuously varying point angle that generates less load and less heat while cutting into the metal and have a longer usage life. However, Racon points are not self-centering and must be used with a guide bushing.|
|Bickford™ points: combine the features of the Helical and Racon points—self-centering, long life, burr-free breakthrough and higher feed capacity.Nowadays, there are few excuses for not seeking and using the right point configuration for the job. Specialist companies make drill pointing equipment and have the skill to provide many other style points for tough applications.|
There’s an old proverb “A bad workman always blames his tools,” which means that success is not dependent on the tools we use, but how we use them. In the case of drill points, that may not be 100% true. While you can drill a hole with almost any drill point, the one you use may not be the best for the whole job, whether you are drilling one hole, a hundred holes, or thousands! By choosing the right drill point configuration and included angle, you can receive longer tool life, more precise hole geometry, cleaner breakthrough and improved job productivity.
If you have questions about the right drill point for your job, just ask us at Regal Cutting Tools.90,000 Which drill bits for metal are better?
Drills for metal are made of tool high-speed steel HSS (High Speed Steel ). These are alloy steels containing elements such as tungsten, molybdenum, as well as vanadium and cobalt. These additives have a positive effect on such characteristics of steel as hot hardness (heating temperature that steel can withstand), redness (time that steel can withstand high temperatures), fracture resistance.
During the operation of the cutting tool, there is an intense release of heat, which is used to warm up the tool. For tools made of ordinary carbon steel, it is unacceptable to operate when heated above 200 ° C, because the hardness of the steel begins to drop rapidly. Modern high speed steels retain their properties at 500-600 ° C, which can significantly increase the drilling speed.
A very important role is played by the manufacturing and heat treatment of drills. Large enterprises – industry leaders – have at their disposal expensive control and measuring equipment, which allows them to maintain a consistently high quality of their products.NoName drills are often made of poor steel, the geometry is not maintained, it is almost impossible to re-sharpen them – after working off the factory sharpening, the drill becomes unsuitable for further use.
Briefly list main types of drills for metal from high speed steel:
- Steel of drills HSS-E contains cobalt and surpasses other steels in cutting properties, therefore they are used for work on tough and complex materials. They are mainly used for drilling stainless steel as well as alloyed and unalloyed steel with tensile strength up to 1200 N / mm2.
Testing Diager HSS-E Co drills 5% Diager HSS-TiN drill in operation
- Three-layer coating of drills HSS-TiAlN (titanium-aluminum-nitrite) has a lower coefficient of friction, and also forms a thermal barrier (the drill does not lose its properties when the outer shell heats up to 700 ° C), increases the strength and increases the service life of the drill approximately 5 times.A TiAlN coated drill should not be re-sharpened; damage to the coating will negate the benefits of this drill. HSS-TiAlN drills are used for productive drilling of alloyed and unalloyed steel with a tensile strength of up to 1100 N / mm2, aluminum, cast iron.
- Drills HSS-TiN made of steel coated with titanium nitride also heat up significantly less during operation, which increases such characteristics of the drill as strength and service life by at least 3 times. TiN coated drills should not be re-sharpened. HSS-TiN drills are used for drilling alloyed and unalloyed steel with tensile strength up to 1100 N / mm2, cast iron.
- Drills HSS-G — Ground drills made of HSS have increased durability and low radial runout. HSS-G drills are the most common cutting tools for standard tasks. HSS-G drills are used for drilling in alloyed and unalloyed steel with tensile strength up to 900 N / mm2, cast iron.
- Drill bits HSS-R are rolled and heat treated. Drills have the lowest durability. They are mainly used for drilling in mild steels and cast iron.
Separately, it is worth highlighting carbide drills or drills with a soldered carbide tip, they have maximum strength, can withstand heavy loads. Used for drilling heat-resistant steels, stainless steel, titanium alloys.
To the question “Which drill bits for metal are better?” we will answer this way – drills that will allow you to perform a specific task as efficiently as possible.
Northern Arrows Service –
Drilling is the term used for operations that create through and blind holes, including subsequent operations such as countersink and tapping. The power tools used for this work are either hand-held (portable) or stationary drills with appropriate attachments and clamping devices. The drilling process is the result of feed pressure (feed movement) and rotary movement (cutting movement).They have the following effect: The cutting edge of the drill penetrates the material as a result of the applied pressure (feed movement). In addition, the rotary motion (cutting motion) rotates the drill and helps the outer edge of the cutting edge advance further into the material. The material is cut in the form of shavings, which are removed from the drilled hole with a rotating motion and thanks to the geometry of the drill spiral. A basic prerequisite for successful drilling is knowledge of the characteristic properties of the workpiece material. Holes are drilled most often in wood, composite materials, plastics, minerals, metal. And depending on the material, different cutting speeds are used. Natural materials such as wood tend to have an irregular texture, such as softer and harder spots within the same part, and a directional structure (fibers). You can choose from different types of wood with soft or hard textures. Natural stone usually has a uniform structure, while artificial stone, such as concrete, has an irregular structure and hardness.Its structure consists of soft aggregates and hard crushed stone. Both natural and artificial stones can be soft or extremely hard. Metal always has a homogeneous structure and therefore each type of metal has a characteristic tensile strength. There are various types of soft and hard or hard and brittle metals, as well as metals with hard surfaces such as roll sheets or mill scale.
The number and position of cutting edges, cutting grooves and corners used are called drill geometry. The following basic concepts describe drill geometry and its effect on the drilling process.
Point angle: In a twist drill, the point angle is required for the drill to center itself in the workpiece. The angle must be less than 180 °. The larger the nose angle in a drill with a specific diameter, the shorter the cutting edges. Reducing the length of the cutting edges improves the precision of the drill and reduces the required downforce. The smaller the nose angle on a drill with a certain diameter, the longer its cutting edges.Increasing the length of the cutting edge makes it harder to guide the drill and increase the required downforce. Standard apex angles are 118 ° (universal angle for softer materials) and 135 ° (preferred for harder materials). Other apex angles tend to be negative and are only used in special cases.
Clearance: Clearance allows the cutting edge to penetrate the workpiece. Without a clearance angle, the cutting edge would slide over the surface of the workpiece without penetrating into it. The clearance angle is created by grinding the flank of the cutting edges of the drill. If the clearance angle is too large, that is, if the flank surface of the cutting edges of the drill is too ground, then the cutting edge may wear prematurely under load or even break out. There is an additional risk that the cutting edge will get stuck in the material due to its low cutting resistance.
Rake angle or flute angle: The flute angle of the drill cutting edge is determined by the working angle in the rake plane of the cutting tool (side rake angle) of the drill spiral.It has a decisive influence on chip formation and removal. Therefore, the angle is selected in accordance with the properties of the material being processed. The three most important angle types are designated N, H and W. Type N has a side rake angle between 19 ° and 20 °, which is considered the standard angle for steel. Type W has a side rake angle between 27 ° and 45 °, which is recommended for soft, long chip metal types such as aluminum and copper. Type H has a side rake angle between 10 ° and 19 °, which is recommended for brittle types of metal (brass).The ATN type has a side rake angle between 35 ° and 40 ° and is equipped with additional chip flutes. Used for deep hole drilling. In the field of woodworking, special rules apply. Different cutting angles are used depending on the type of wood.
Main cutting edge: The main cutting edge is responsible for the actual drilling process. The twist drill always has two main cutting edges. They are connected by a transverse cutting edge.
Cutting edge: The transverse cutting edge is in the middle of the drill tip. It does not affect the cutting process. It exerts pressure on the workpiece, causes friction and, in principle, interferes with the drilling process. With appropriate grinding procedures (which are quite costly), the length of the transverse cutting edge can be reduced. The result is a so-called sharpened transverse cutting edge, which, together with a mesh-ground edge, results in a reduction in frictional forces and a reduction in the required feed pressure. At the same time, the centering of the drill tip in the workpiece is significantly improved.
Auxiliary cutting edge (chamfer, back edge): The flutes of the cutting tool are provided with two chamfers. They are very sharp and allow for additional cutting of the sidewalls of the drilled hole. The quality of the wall around the drilled hole is highly dependent on their design. Drills for wood sometimes come without any chamfers at all. This improves the guiding accuracy of the drill.In addition to drill geometry, the most important criteria are drill material, surface structure and processing techniques.
Effect of drill material:
Tool steel: These drills are also called chrome vanadium or CV drills and are recommended for drilling in wood. They are easy to sharpen. They should not be used for drilling metal.
High Speed Steel (HSS): Increasing the proportion of chromium and cobalt improves the hardness and high temperature stability of the drills. The addition of chromium and cobalt improves the hardness and heat resistance of the drills. Special cobalt alloyed drills are recommended for tough metals and hard alloys (corrosion-resistant steels). Cobalt-alloyed drills are particularly recommended for tough metals and hard alloys (corrosion-resistant steels).
Carbide: These are artificially created metals with a high tungsten and cobalt content. They are manufactured using a sintering process that makes them extremely hard and brittle.For this reason, they are only used for the cutting edges of the drill. Hand-held machines use drills equipped with carbide inserts to process non-metallic materials such as ceramics, glass and glass fiber reinforced plastics. Their special properties are optimized by using the correct geometry of the cutting edges of the drill in accordance with the material being processed.
Influence of the surface of the drill: Uncoated: the quality of the drill depends on the surface finish. The smoother the surface, the less friction.
Oxide: Friction is significantly reduced by using a hard oxide layer. A prerequisite is the highest quality drill surface finish.
Titanium nitrite coating: The effect is the same as with the oxide coating. Excellent friction reduction due to the properties of titanium nitrite. When drilling aluminum materials, it is not recommended to use without cooling.
Effect of production method on drill quality:
Roller cone drills : A drill with very high resilience, formable without using a cutting process. Cheap way of production. Service life, drilling quality and speed of work are in line with the price level.
Milled drills: Chip flutes are milled from the workpiece, the edges are polished. A production method that ensures the creation of medium quality drills.Chip removal in deep holes is not optimal due to the roughly milled chip groove surface.
Ground drills: drills are milled from a workpiece with excellent surface quality. As a result, the specified dimensions are perfectly maintained and a high rotation accuracy is ensured. Easy chip evacuation, long service life and fast turnaround times. The following drill types are distinguished:
Design: Twist drills have two cutting edges at the end of the drill and a double flute along the shank.
Operating principle: The feed pressure penetrates the cutting edges into the material. Chip flutes ensure correct removal of chips cut during drilling from the hole.
Applications: are well suited for machining metal structures, and twist drills from the smallest to the largest diameter are used for a wide range of tasks in the processing of almost all types of material.
Features: universal drill.The drill requires a high feed pressure from the user. Tends to get clogged with chips in deep holes. Not recommended for woodworking, the drill “takes you out of the center”. Cheap drill.
Applications: Drilling or reaming through holes in abrasive materials.
Special drill with short shank: Twist drill with short working length for working in sheet metal, pre-drilled for blast rivets.
Tungsten Carbide Multi-Purpose Drill Bit
Design: Twist drill shank with tungsten carbide insert. The cutting edges on the tungsten carbide insert are sharply sharpened.
How it works: The geometry of the cutting edge provides a more scraping than a cutting effect.
Features: Tungsten carbide multipurpose drills recommended for drilling in ceramics, earthenware, masonry, masonry and glass fiber reinforced plastics.Metal applications require high feed pressure and slow speed, and softer materials and woods produce very rough cuts. Tungsten carbide multipurpose drills are highly recommended for drilling in composite materials (3-layer chipboard). They combine several different materials such as wood, fiberglass and metal. Naturally, you will need to use a drill bit that can handle the toughest material in the composite.Not recommended for hammer drilling due to razor sharp tungsten carbide inserts.
Design: Milling bits have a twist drill head, but they do not have chip flutes. The cutter teeth are located on the shank behind the cutting head.
How it works: The sharpened tip of the drill drills the first through hole in the workpiece. After the cutter head has penetrated the workpiece, you can move the drill sideways and the cutter teeth will cut.
Applications: Drilling or reaming through holes in abrasive materials. Milling long or free-form holes and slots.
Features: Milling bits can only be used for processing thin parts (plates, sheet metal). When using hand tools, the accuracy and quality are not the best. Use aids such as drill stands or restraints to improve the quality of your work.Cannot be used for drilling holes in solid material.
Tapered drill for sheet metal
Design: Tapered cutting head has two chip flutes, the outer edges of which form the cutting tool. The drill point is usually sharpened for drilling. The shank has a reduced diameter.
How it works: The sharpened tip of the drill cuts the pilot hole first in the workpiece, and then the cutting edges widen the hole.The deeper the tapered cutter head penetrates the material, the larger the bore diameter becomes.
Applications: Drilling or reaming through holes in thin materials.
Features: The drill requires high user feed pressure and high torque at low power tool speeds. This drill is only suitable for drilling through holes in thin materials (eg sheet metal). Cannot be used for drilling holes in solid material. Prone to sticking when drilling aluminum.
Design: The stepped tapered cutting head has two flutes, the outer edges of which form the cutting edges. The transition from one step to another is beveled. The drill point is usually sharpened for drilling. The shank has a reduced diameter.
How it works: The sharpened tip of the drill cuts the pilot hole first in the workpiece, and then the cutting edges widen the hole.The deeper the stepped and tapered cutter head penetrates the material, the more the diameter of the drilled hole increases step by step.
Applications: Drilling or reaming through holes in precisely dimensioned thin workpieces.
Features: The drill requires high user feed pressure and high torque at low power tool speeds. This drill is only suitable for drilling through holes in thin materials (eg sheet metal). Cannot be used for drilling holes in solid material. By means of beveled transitions from one step to another, during drilling, the burrs are removed from one side of the drilled hole. Prone to sticking when drilling aluminum.
Design: Tapered countersinks have a tapered tip with three or more cutting edges. They have an apex angle of 60, 75, 90, or 120 degrees.Typically, the shank diameter is less than the head diameter.
Principle of Operation: Thanks to the large number of cutting edges, countersinks can center more easily and perform neat cuts. Chips generated during tapered countersinking remain under the cutter head; they are not removed from the hole.
Application: Deburring of drilled holes (60 ° point angle) Tapered screw countersink (90 ° point angle)
Features: Tapered countersinks with 3 cutting edges are used for deep countersinking as chips are easily removed by large chip flutes. Tapered countersinks with 5 or more cutting edges are used for shallow countersinks.
Tapered countersink with cross bore
Design: Tapered countersinks with cross bore have a tapered cutting head that has an angled bore. As a result, the cutting head has two cutting edges.
Principle of Operation: A sharp cutting angle produces a cutting motion, rather than a scraping motion as with tapered countersinks, which results in a very high surface finish.
Applications: deburring of drilled holes; tapered countersinking for screw heads in thin workpieces.
Features: Ideal countersink for thin metal sheets. Provides a smooth cut and works without vibration.
Design: Removable countersinks have a design similar to tapered countersinks, but instead of a shank, they have an additional hole for inserting a twist drill.
Principle of operation: Removable countersinks are screwed onto the twist drill at the required distance from the drill tip.
Applications: Deburring of drilled holes, countersinking for screw heads in wood.
Features: Removable countersinks allow you to combine drilling and tapered countersinks in one operation. This is only possible when drilling through holes. A special countersink is required for each drill diameter.Countersinks, which are fixed upside down on the drill, serve as depth stops for drilling blind holes.
Twist drill bit for wood with centering point
Design: Twist drills for wood are equipped with a centering point for centering, two cutting edges and an additional chip flute with double thread.
How it works: The centering point fixes the position of the drill in the workpiece before the cutting edges enter the workpiece. Chip flutes ensure correct removal of chips generated during drilling from the hole.
Applications: Drilling small to medium diameters in wood with low drill hole quality requirements. Drilling small to medium diameter holes in imitation wood and soft plastics with good hole quality.
Features: The drill requires high user feed pressure and has a tendency to clog up with chips in deep holes.Cheap drill.
Flat milling cutter
Flat milling cutters have a centering point and two cutting edges. The centering point and cutting edges combine to form a flat cutting head that ends in a shank with a small diameter. There is no chip groove for chip removal. A modified version is an adjustable flat milling cutter. It is equipped with a guiding device that allows adjustment and positioning of one of the cutting edges.
How it works: The centering point fixes the position of the drill in relation to the workpiece before the cutting edges cut into the workpiece. Drilling chips remain on the cutter head and are not removed from the hole.
Twist drill for wood
Design: twist drills for wood are equipped with a centering point with a single or double screw thread, one or two cutting edges, one or two scoring tools and a screw conveyor with a single thread (chip flute).
How it works: The centering point locates the position of the drill on the workpiece before the knives cut into the workpiece. The screw thread of the drill ensures self-feeding. The cutters define the circumference of the hole and give a clean edge without scoring when cutting. The large chip flute of the screw conveyor ensures the removal of chips from deep holes without blocking the drilled hole.
Applications: Small to medium diameter deep hole drilling.
Features: This drill requires very low feed pressure. Twist drills for wood for hardwoods have a special type of threaded drill grip.
Countersink for wood
Design: Wood countersink has a centering point, two cutting edges and two peripheral cutting edges as scoring tools. The wood countersink has a small diameter shank without spiral or chip flute.
How it works: The centering point locates the drill position on the workpiece before the cutting edges cut into the workpiece. The peripheral cutting edges define the diameter of the drilled hole and ensure a smooth cut. Drilling chips remain on top of the cutter head and are not removed from the hole.
Applications: For high quality drilling of shallow holes in solid wood with a small to medium diameter, eg for furniture fittings, or for knotting wood.
Features: The drill requires high user feed pressure and has a tendency to clog up with chips in deep holes. It is important to be able to adjust the rotation speed. It is possible to drill overlapping holes that extend beyond the edge of the part. To be used only in drill stands.
Design: Hinge groove drills resemble wood countersinks.They are equipped with a centering point and two cutting edges. They have a small diameter shank with no helix or flute.
How it works: The centering point locates the drill position on the workpiece before the cutting edges cut into the workpiece. Drilling chips remain on top of the cutting head and are not removed from the hole.
Applications: Drilling shallow holes with standard cup sizes.
Features: The drill requires high user feed pressure. Tungsten carbide cutting edges are required for drilling in plastic laminated materials. Not recommended for deep hole drilling. It is important to be able to adjust the rotation speed. The quality of the overlapping holes is unsatisfactory. Under certain conditions, it may not be possible to drill holes that extend beyond the edges of the workpiece. To be used only in drill stands to prevent the drill from jumping off the mark and thereby protect the workpiece from damage.
Design: Open end of cup bushing Keeps saw teeth. The closed end has a drive shaft that is either fixed or threaded and removable. Attached to the drive shaft is a center drill that goes through the hole saw and extends beyond its teeth.
How it works: The center drill determines the position of the hole saw in relation to the workpiece before the saw teeth cut into the material.Chips produced during drilling partially remain inside the hole saw.
Applications: Drilling holes from large to very large diameters in sheet metal, plastics and composites.
Features: For cutting holes in metal You will need an HSS (bimetallic hole saw) hole saw with so-called Vario teeth (that is, alternating between small and large teeth), which ensures a good working speed. Cooling must be used when cutting holes in metal.
Hole saws for wood
Design: The rear of the disc-shaped base is connected to the drive shaft and has several concentric slots on the front. Annular blades of various diameters are inserted into these slots. The center drill is attached to the base and the tip extends beyond the inserted hole saw.
How it works: The center drill determines the position of the ring blade in relation to the workpiece before the saw teeth cut into the material.Chips produced during drilling partially remain inside the hole saw.
Applications: Drilling large to very large holes in wood and composites.
Features: Hole saws for wood are usually supplied as a set with different blade diameters and bases. They are easy to use and inexpensive, and quality blades give good results in woodworking.
Design: Tungsten carbide arrowhead cutting tool is brazed to the shank.
How it works: The sharpened tip of the drill makes a path through the material thanks to its hardness.
Applications: Drilling through holes in thin workpieces made of glass, ceramic or stone.
Features: It is absolutely mandatory to use kerosene as a coolant when drilling glass, while ceramics are usually drilled without coolant. Use the tool with minimal pressure, the best speed should be determined by trial and error.This drill is only suitable for drilling through holes in thin materials. Cannot be used for drilling holes in solid material.
Drill Shank Types
– round shank
– round shank, stepped
– hex shank
– taper shank (Morse taper, taper)
Conventional shanks are round. They are used wherever there are high concentricity requirements.This is usually the case in the metalworking industry. Round shanks are common up to a diameter of 13 mm, sometimes up to 16 mm. A modified version of the round shank is a stepped shank (turned). This design feature allows drills with a diameter greater than the range of drill sizes to be clamped by the drill chuck into the chuck. Caution: The use of shorter shanks should only be considered a precautionary measure, as the torque required for large drills often cannot be transmitted by the frictional engagement of the three-jaw chuck.As soon as the drill is turned when the drill is turned on, damage to the shank clamping section occurs and accurate rotation can no longer be guaranteed. In addition, damaged drill shank sections have sharp edges that can injure the user. Hex shanks are better suited for high torque transmission. In this case, the jaws of the drill chuck grip the hex shank well and prevent the drill from slipping. Hex shanks are typical for large drilling diameters in wood, where slightly reduced rotational accuracy is not as important.If very high torque transmission is required with a simultaneous high rotational accuracy, the so-called taper shank (Morse taper) is the solution. Drills achieve great orientation accuracy by using a cone that transmits torque using its entire surface area. The drill diameter determines the rotational speed. The smaller the drill diameter, the higher the speed. The larger the drill diameter, the lower the speed. The speed also depends on the material being processed. The softer the material being processed, the higher the speed.The harder the material, the lower the speed. Since different materials have different degrees of hardness, you must always select the correct drilling speed and diameter for the specific material. Detailed reference tables with empirical values can be found in professional guides. The speed values shown in our table should be regarded as simplified standard values that will give good results when working with hand tools. When using special drills and drill bits, other speeds can be used.You must follow the recommendations given on the packaging or in the instruction manual. If the RPM of the drill cannot be accurately determined, use the closest suitable value.
Short drills are intended for drilling holes for countersunk rivets in thin metal sheets. They have standard diameters to match the countersunk head rivets (blast rivets) used, for example 3.4mm, 3.9mm, 4.4mm, 4.9mm.Due to the usual error caused by hand drilling, rivets with appropriate dimensions (3.5mm, 4mm, 4.5mm, 5mm) will match the drilled holes exactly.
To begin with, the so-called “titanium drills” are HSS drills with a thin titanium nitrite coating. The color of the coating gives the drill a characteristic golden color. The coating is extremely hard and thus reduces friction during drilling.Less friction means better energy use for the actual drilling process, which means faster work progress and less tool wear. Even if the titanium nitrite coated drills are reground and the coating under the cutting edges is lost, the remaining coating on the flutes and flank will provide better performance than “conventional” HSS drills. But titanium drills are not suitable for machining aluminum. From the point of view of chemistry, titanium has a special affinity with aluminum, and, as a result of the pressure and heat during the drilling process, some chemical and physical diffusion processes occur that lead to the fact that aluminum is fused, and it kind of foils the titanium surface.Because of this, friction increases significantly, and therefore both cutting performance and chip evacuation deteriorate to such an extent that further drilling becomes impossible. Therefore, titanium nitrite coated drills should not be used for drilling aluminum. They can only be used for drilling aluminum on stationary machine tools with forced water cooling. Cooling is a decisive factor for the service life of the drill. The cutting edge stays sharp longer and its cutting performance is improved.The coolant is selected according to the material to be processed. Typical coolants for hand-held machines: Ferrous metals: biological oil, mineral oil, grease or so-called cutting oils for drilling. Aluminum: kerosene, a mixture of alcohol and water. Brass: no coolant. Glass: kerosene. Acrylic glass: a mixture of alcohol and water. Wood, plastic: generally without coolant or lubricant. It is recommended to use a cooling lubricant for drilling with a hand drill.It is very easy and economical to use. It is suitable for most types of metal. It is worth learning to understand the crucial differences between “cheap” and “expensive” drills. Compared to “expensive” drills, “cheap” drills provide lower quality of work, have a lower speed of work and a shorter service life. Reasons for this: – A cheap drill is often made of material that is too soft or poorly hardened. – Inaccurate and often uneven cutting edge geometry. – Poor dimensional accuracy: drills with the same nominal diameter show significant deviations from one drill to another.- Poor concentricity due to too soft drill shanks or warped during hardening. “Expensive” drills, on the other hand, are more accurate and, thanks to their best qualities, are more durable and provide better use of the power of the tool. Ultimately, they are actually a better deal than the cheaper drill options!
Basic types: drills with one gear transmission and drills with two or more mechanical transmissions.The first is used wherever convenience in handling a power tool is required or where it is predominantly working in a certain area of drilling diameters. Typical drilling diameters are: up to 6.5 mm, 6.5-10 mm, 10-13 mm. The largest drilling diameter of these power tools is specified as 6mm, 10mm or 13mm. Two gear drills are used wherever power tool versatility is required and often work with different drilling diameters. These are typical drilling diameters: 6/10 mm, 8/13 mm and 10/16 mm.Power tool specifications typically include the largest possible hole diameter and the designation “two gears”.
The range of drilling diameters is usually indicated on the nameplate of the drill. Historically, drills became common in times and countries where the Anglo-Saxon imperial system of measures based on the inch was adopted. The currently used categories are derived from the following values: 1/4 “= 6.5 mm 3/8” = 10 mm 1/2 “= 13 mm 5/8” = 16 mm This means that, for example, for 10 mm Drill motor power, speed and required torque are designed for drilling holes in steel with a maximum diameter of 10 mm.It is possible to drill smaller or larger holes. But in this case, you should take into account the following: The smaller the diameter of the used drill, the slower its linear speed, and this implies that the speed of work will also be slower. It takes much longer to drill a 6 mm hole with a 10 mm drill than a 6 mm drill, although the motor power of a 10 mm power tool is usually greater than that of a 6 mm power tool. The larger the drilling diameter, the greater the stress on the power tool.If, for example, in a 10 mm power tool you use a drill bit larger than 10 mm, the increased load will reduce the speed of the power tool and the motor will no longer cool sufficiently. If this overload condition continues for too long, the power tool will eventually overheat and “burn out”.
For hammer drills, the maximum drilling diameter is indicated, designed for drilling holes in stone (with additional technical data for steel and wood), because hammer drills are usually selected for drilling stone.
There are various forms of drills: pistol grip, pistol grip with additional grip and end grip. The choice depends on the application of the drill. The pistol-shaped body makes power tools more compact and easier to use. For this reason, it is widely used in drilling diameters up to 13 mm. The lever arm of the pistol grip drill helps to compensate for the restoring moment in the event of a rig jam.The use of an additional handle is recommended. This is a must when drilling large holes. The end grip provides the ability to ergonomically apply higher feed pressure directly along the tool spindle axis. For this reason, it is widely used in drilling diameters above 13 mm. Since the lever arm at the end grip is virtually absent, it is impossible to compensate for the restoring torque when it occurs. Power tools with an end handle should always be used in conjunction with an auxiliary handle.It improves control and handling of the drill for better work results. Its most important function is to reduce the risk of accidents if the drill gets stuck in the hole. The sudden recovery moment can only be compensated for with the auxiliary handle. When working with drills with a face handle, the use of an additional handle is a must!
It may be very useful, under certain conditions, to have a depth gauge on the drill.Here’s a quick example to explain this: An industrial firm has to drill 1000 holes with a depth of 30 mm. Without stopper, the hole depth ranges between 30 and 36 mm, that is, on average, the hole is 3 mm deeper. With 100 drilled holes, this means that an additional distance of 3000 mm has been drilled. You can easily calculate wasted time and additional wear on drills and power tools.
It is worth choosing which tool will be more useful to you – a drill or an impact drill, depending on the purpose of application. The drills have a spindle that is rigidly fixed in bearings. This ensures high concentricity of rotation. The rotation speed is optimized for drilling metal. On impact drills, the spindle can move in bearings. As a result, the concentricity of rotation is naturally not as good as that of the drill. Impact drills tend to rotate faster because they are designed for drilling in stone, which requires impacting at a high speed. The concentricity of the drill spindle is better than that of the impact drill spindle.The drill spindle is firmly guided by a bearing located on the side of the drill chuck, which prevents linear or radial play. The drill spindle in a hammer drill must be able to move back and forth to enable hammer drilling. The shaft bearing on the side of the drill chuck must have a linear play (and for the same reason also a small radial play), which causes a decrease in concentricity of rotation. Impact drills are usually chosen by home craftsmen.They are widely used due to their versatility. Professional “highly specialized” drills are available from specialized distributors. They are better suited for frequent drilling. A distinction must be made between electronic control, electronic speed control or electronic control and torque or power limitation. The rotation speed usually varies smoothly; however, the speed drops under load, which cannot be fully compensated for by pressing the control button.The advantage for the user is that the controls help pre-drill accurately without the risk of the drill jumping off the mark. If you use electronic control to reduce speed, the drill has less power (torque). This is because the electronic control reduces the voltage supplied to the motor. This leads to a decrease in speed. At the same time, the electric current flowing through the motor is also reduced. Less current means less motor power.The advantages of electronic speed control come from the following reasons. The rotational speed usually varies smoothly, so that the selected speed is kept constant under load. The user benefit is the same as with electronic control. In addition, speeds can be adjusted according to the material being processed or the type of work being performed. The result is better performance. The speed does not drop under load, which means that the work will be completed earlier, which means that time is saved.
Electronically controlled drills should not be operated at low speed or high loads for long periods of time. Power tools that work under high loads always draw a lot of current. In addition, a high load causes a decrease in the rotational speed. However, electronically controlled power tools will maintain the selected speed despite the heavy load, which is usually not even noticed by the user of the tool. The engine temperature will rise due to the increase in power consumption.This rise in temperature cannot be compensated for by the built-in fan, which also runs slower due to the reduced rotational speed. There is a risk of overheating of the power tool.
To prevent overheating or overloading of power tools, in particular those with electronic control, During high load and low speed operating modes, from time to time, you must put the power tool into high speed mode and let it run without load for a short period.As soon as the air escaping from the ventilation openings reaches the permissible temperature, you can continue to work.
It is possible to additionally limit the torque and therefore the power consumed by the power tool. The advantage of torque control to the user is that it can be used as an individually adjustable overload clutch that prevents the drill from breaking, material from bursting or the gearbox from being damaged during hazardous operating conditions.To some extent, these power tools can also be used to screw fasteners like screwdrivers. In most cases, torque control is combined with electronic control.
Electronic stabilization of rotation speed for the drill used with a special stand, Allows you to maintain the selected speed under load. Therefore, you do not have to manually “speed up” the power tool; instead, you can keep your hands on the work piece and feed lever.
Drills and impact drills are available with multiple power transmissions. What are mechanical transmissions for, when you can set the number of revolutions from zero to the highest rotational speed using electronic control? This is best explained by the following example: We all know that you can use the accelerator pedal in a car to “increase speed” from idle to top speed. However, we need a transmission with multiple gears to set the required torque for various load conditions from starting up hills to driving at high speed.The drilling process also has different torque requirements, which largely depend on the diameter of the drill used. Since the electronic control can only change the speed and not the torque, different ranges of transmitted torque must be created through different gear ratios. As a result, manual transmissions with two or more gears are used.
If you are at a loss when choosing a drill – with an electronic speed control or a drill with mechanical transmissions, it is best to use a combination of both: each gear in the manual transmission determines the speed and the range of transmitted torques in which you can use the electronic control, to fine tune the speed.Single speed power tools only adjust speed, not torque. In a drill stand or lathe, you need to use a drill equipped with both electronic speed control and several mechanical transmissions, and torque control for preselecting and limiting the torque. For sheet metal, powerful, slow-running taper drills are used, since tapered drills for sheet metal require a lot of torque.Powerful, slow-running power tools are recommended for hole saws, preferably with a torque control system that will stop the power tool if the hole saw suddenly gets stuck in the material.
DIYers can use drills (best with electronic regulation and power regulation) to drive screws into wood from time to time. For professionals, the use of drills to screw fasteners is uneconomical.Special screwdrivers give better results and save time.
Never use a drill to screw in fasteners, so called “hard” screw connections (metal to metal, bolts, nuts). Rapid tightening torque can destroy the screw connection, damage the power tool and injure the user.
Also, do not use a drill for mixing. Mixing semi-liquid viscous materials (mortar, glue) can overload the engine and transmission.For mixing, only powerful drills with low speed gearboxes should be used. The best results are obtained with special agitators. The transmission and bearings are designed for heavy duty use; the powerful engine is supported by very low gears and can be subjected to extreme loads at low agitation speed. Agitators should not be used to stir flammable liquids and diluents such as solvents.The power tool can draw in vapors through openings in the cooling system, which can then be ignited by the switch. Some agitators mix from the bottom up. They are designed for viscous liquids as they draw solids from the bottom and prevent air bubbles from being entrained in the agitated substance. Some stirring devices perform top-down stirring. They are intended for highly mobile liquids as they prevent the stirring material from splashing out.Mixed air bubbles can easily float to the surface of the liquid after stirring.
When using a drill as a drive motor for attachments such as water pumps, consider the significant continuous load the drive motor, transmission and bearings will carry. Ideally, therefore, choose a drive motor that is “slightly more powerful” than originally planned. The use of electronically controlled drive motors is preferred.Choose a tool that can run continuously at high speed to ensure adequate cooling.
Angle drills are used to drill holes where other drills cannot reach. Typical applications: bodywork, furniture making, lighting fixtures and interior decoration, automotive electrical work (antenna installation) and flush-mounting. A small corner width is required for work in this area. Width by corner is a measurement that refers to the distance of the center of the drill from the top and side corners of the drill.The smaller the corner width, the tighter you can drill to the corners.
Drills are mounted in drills using a drill chuck or Morse taper. A drill chuck usually contains three chuck jaws or collets that, when the chuck yoke rotates, move along a tapered sliding surface until they are positioned on the drill shank. As the chuck sleeve is tightened further, the chuck jaws are clamped so tightly on the drill shank that they can reliably transmit any torque from the drill spindle to the drill.You can see that the same three clamping jaws are responsible for both centering and torque transmission. The clamping force of the drill chuck is created by the frictional engagement of the clamping jaws on the drill shank and depends on the force with which the drill chuck is tightened. The drill chuck will release the drill if the sleeve is rotated in the opposite direction.
Keyless and keyless drill chucks each have their own characteristics. The force required to close and open the drill chuck is applied using a toothed chuck socket wrench that is secured in a ring gear on the front of the chuck holder.Tightening and opening can only be done with one hand, but this always requires a socket wrench for the chuck. The force required to close and open the drill chuck is applied by turning the profiled, easy-to-tighten drill chuck by hand. The required clamping force is achieved by the sophisticated technical design of the drill chuck. A socket wrench is not required for the chuck.
There are double collar keyless drill chucks and single collar keyless drill chucks.In the former, the drill chuck holder consists of two sections. One section must be held tightly while opening or closing the chuck while rotating the other. This procedure requires the use of both hands. Due to the relatively small gripping areas, the clamping forces are slightly lower than with a keyed drill chuck, especially in the case of small drill chucks. Single-clip cartridges have a single-piece clip and are therefore shorter. Only one hand is required to use this drill chuck.However, the power tool must be equipped with a so-called spindle clamp to prevent the drill spindle from turning when opening or closing the drill chuck. Thanks to the good clamping force, higher clamping forces are achieved than with the double collar drill chuck.
The spindle clamp is a device that locks the drill spindle while the drill is not running. Combined with the single collar keyless drill chuck, this device allows you to use only one hand to open or close the drill chuck.Single collar drill chucks always require a spindle clamping. In some applications, the drill chuck is subject to increased vibration (hammer drilling). To prevent the clamping jaws from expanding by these vibrations, their position is fixed by an automatic self-locking locking device or by a screw on the drill chuck. Anti-clockwise anti-rotation device – is a left-hand screw additionally used to secure the drill chuck to the drill spindle to prevent the chuck from loosening during counterclockwise rotation (for example, when loosening screw connections).
Morse taper corresponds to drills that have an outer taper shank that fits into the inner taper on a power tool. When these two tapers are connected, they provide precise guidance and excellent drill concentricity. Torque is transmitted by a flat section at the end of the drill taper that matches the counterpart on the taper of the power tool. To remove the drill from the tool holder, a so-called drill wedge is used at this point.The torque is transmitted very evenly and reliably over the entire surface of the Morse taper. Morse tapers are especially suitable for transmitting high torque forces with optimal concentricity. Since it does not make sense to use the same Morse taper for small and large drilling diameters, tapers are available in different standard sizes. Power tools, however, always use the largest possible tapered fit. To use small tapers, so-called Morse adapter sleeves must be used.These reducing sleeves are also available in standard sizes.
Thread cutters are tools that can be used to cut screw threads in pre-drilled holes in a wide variety of materials using taps. The thread cutters are equipped with an automatic right / left rotation clutch, a floating drill chuck and the ability to install a roller clutch (torque limiting clutch).The automatic clutch allows you to work at high speed and, together with the drilling depth limiter, protects the tap from destruction when threading in blind holes.
Roller couplings are used for tapping threads. The roller clutch is a torque controlled clutch. It is configurable and limits the torque transmitted from the power tool to the tap. If correctly set, the clutch will interrupt the power transmission between the power tool and the tap before the tap breaks if the rig is blocked.
The so-called floating drill chucks are used in the thread cutters. When the power tool is tilted to one side, the floating drill chuck prevents bending forces from being transferred to the tap. The rigid drill chuck did not give way when the tool or tap was tilted. In this case, the hard and relatively brittle tap could break. A two-jaw chuck is most suitable for taps as it transmits torque by gripping the square shank of the tap (forced locking).Professional users usually do not use drills with adjustable torque setting and rotation to the right / left for threading. A hard drill chuck will break the tap if the tool is twisted. In addition, the frictional engagement of the three clamping jaws is not capable of transmitting the required high torque to the tap.
When tapping, observe:
– The thread hole (pre-drilled hole) must have the correct diameter.
– The tap must have the corresponding shape
Blind hole taps are helical in shape to remove chips from the drilled hole. Through hole taps have a special spiral shape to remove chips forward through the drilled hole. The use of specially shaped taps improves thread quality and ensures trouble-free tapping. A tapping hole is a hole that must be drilled before tapping.The thread hole diameter for machine tap drills and standard threads is equal to the thread diameter minus the pitch.
Warning: Familiar formula thread diameter x 0.8 = hole diameter applies only to 3-way hand taps! The most convenient method is to find the thread hole diameter for machine taps in the appropriate tables. If the hole is too narrow, the tap is likely to get stuck and break. If the hole is too wide, the threads will be cut too thin and the screws will not hold well.When tapping, the tap must be lubricated. Without lubrication, the surface of the threads will become rough and cracked. Its strength will be significantly reduced. The choice of lubricant depends on the material being processed. Oil should be used for steel, kerosene is recommended for aluminum, a mixture of alcohol and water for plastics. The so-called cooling lubricant is easy to use and universally applicable. Tin-plated taps should not be used when threading in soft materials such as aluminum or copper.The coating will react with the material and cause material build-up on the cutting edges, making the tap unusable soon. There are metric threads and so-called imperial or inch threads. The metric system has become accepted throughout the world, while the British system of measures is used only in Anglo-Saxon countries or in special cases. The difference between standard and fine threads is the relationship between thread pitch and thread diameter. Metric threads are calculated and measured in millimeters, imperial threads in inches or fractions of inches.
Abbreviations for international thread types:
Threads USA: NC National Coarse UNC Unifi ed National Coarse NF National Fine UNF Unifi ed National Fine
British threads: BSW British Standard Whitworth Coarse BSF British Standard Fine
The following rules should be observed: If possible, use a drill stand for stationary tapping.When manually tapping, use the auxiliary handle to control the high torque and avoid the tool from skewing (risk of injury). The taps are very fragile and break at the slightest mistake in the operation. For this reason, you should try to wear safety glasses. For threads M8 and smaller, a roller clutch must be used to limit the torque. Torque limitation with roller clutch reduces the risk of tap breakage. Lubricate the tap continuously.Tapping requires training. Make a few preliminary attempts on a test piece before starting the actual assignment.
How to sharpen a drill bit for metal?
A dull drill will generate smoke and grinding noise even when drilling in soft metal. When the drills become blunt, you will press harder while drilling, which inevitably leads to damage to the drill and may even lead to your injury. Before heading to the store to buy new drills, try a simple sharpening technique first and save time and money.It takes about 30 seconds to sharpen the drill and no more than a minute to repair a damaged, broken or chipped drill. Twist drills are fairly easy to sharpen. And if you screw it up, the worst thing that can happen is that you have to grind off a few millimeters of the drill until you can get it right.
Contents of the article:
Signs of a drill that needs sharpening
There are several signs on a drill by which you can determine that it needs sharpening.For speed, you can only pay attention to 3 main parts of it: the cutting edges, the flank surfaces (area behind the edges) and the bridge in the center of the drill tip. The two cutting edges on the drill must be sharp and symmetrical. The flanks are what follow the cutting edges and will support the cutting edge when the drill is drilling. These “pads” should be angled so that there is a gap between the part you are drilling.The bridge is located in the very center of the drill tip and affects its centering and entry into the material when starting drilling. It shouldn’t be too thick.
How to sharpen a drill for metal
- Sharpening a drill consists in restoring the sharpness of the cutting edges. You need to grind both the edges themselves and the back surfaces that follow the edge. The drill will cut into the material if only the tip of the drill and cutting edges are in contact with the surface, and the clearance surfaces behind these edges must be spaced from the surface.The back surfaces (areas behind the cutting edges) should be at an angle of 7-10 degrees relative to the perpendicular line of the drill axis. They have a curved shape, which gives support to the edges. If these pads do not bend at a certain angle, but are flush with the cutting edges, then drilling simply will not work.
- Grinding machines usually have two grinding wheels, one coarse and one for finer sharpening.If the drill is large, badly worn and damaged, start with a rough circle, then switch to the second circle. If the drill looks fine, start right away with a fine sharpening wheel. Please note that the edge of the grinding wheel should be smooth and even. If it is not, it needs to be processed for smoothing and flattening. The width of the grinding wheel should be more than the length of the cutting edge of the drill to be sharpened.
- It is not recommended to wear protective gloves before sharpening, as they can be pulled into the machine with your hand.In addition, gloves impair the ability to hold the drill securely. In this case, it is advisable to wear protective goggles.
- When sharpening, the drill should be positioned at an angle of approximately 59-60 degrees relative to the surface of the wheel. This is the angle for each of the two cutting edges, forming a total apex angle of 118 degrees (most metal drills, hard metal drills may have a different angle, see this article for “nose angle”).That is, you need to hold the drill so that the cutting edge is horizontal and parallel to the surface of the circle. This is not difficult to accomplish, but with little experience, to facilitate the process, you can use the following techniques.
- You can draw a line (or several, as in the photo) on the handcuff or stick masking tape at an angle of 60 degrees so that the side of the drill can be visually aligned with this line. This will act as a guide to sharpen the correct angle at the tip of the drill.Also, on the handcuff, you can position the corner at the desired angle to the circle and attach it with a clamp. You will need to press the drill to the corner, and bring it to the circle.
- Not critical if the nose angle is not exactly 118 degrees, but the angles and cutting edge lengths must be symmetrical on both sides. In this case, the holes made with a sharpened drill will be of the required diameter.
- Practice holding the drill.It will rest on the fingers of your right hand, which are supported by a handcuff. The drill is pressed on top with the thumb. The fingers of the other hand grip the drill shank and allow it to move. You can change the position of the hands as it is more convenient for you.
- Hold one of the cutting edges of the drill at 60 degrees to the surface of the grinding wheel. At the beginning of sharpening, the cutting edge line must be horizontal.
- Turn on the emery. Move the drill slowly until it touches the edge of the circle. Next, you need to easily press the edge to the surface of the circle and start moving the tip up (lowering the shank, the angle of the drill to the circle remains 60 degrees). That is, the cutting edge is sharpened, then the platform continues to be turned behind the edge (rear surface), and the cutting edge moves away from the circle, maintaining a horizontal position (but the drill continues to contact the grinding wheel with the platform behind the cutting edge).After turning the back surface, you need to move the drill away from the grinding wheel. Do this one or more times and move on to sharpening the second side of the drill.
- Next, turn the drill 180 degrees, keeping its position at an angle of 60 degrees relative to the circle (the cutting edge of the drill is horizontal), and start the process of sharpening the second side of the drill.
- If you have to grind a lot of metal, the metal will heat up.Keep a container of water nearby to dip the drill bit into it periodically to cool it down. Do not overheat the drill when sanding. Overheating will cause the drill edges to turn blue, indicating that the drill has lost its hardening. If this happens, then the blue area should be completely abraded.
- If both cutting edges are sharp, check if they are the same length. Comparison of the length of the edges can be determined both visually, by eye, and by measuring with a caliper.The longer edge can be re-sharpened.
- Inexperienced, it can take a lot of repetitions for the two cutting edges of the drill to become symmetrical. This is normal and requires a lot of patience. Continue sharpening until the result is achieved. Flip the drill more often to avoid sharpening one side more than the other.
- For minor adjustments of cutting edges, as well as for correcting its sharpness, it is possible to grind not the entire surface following it, but only the edge itself (a small strip along it).This can be done by lightly touching the cutting edge of the wheel when it is horizontal.
- To check the shape and position of the turned back surfaces, you can use either a special template or a homemade one that can be cut from sheet material. Another well-known way to determine the correct angle at the top is to put two hex nuts close to each other so that their two edges touch (as shown in the photo).Check the drill after several grinding passes. It should fit right into the corner of the two nuts. This checks the apex angle of 118 degrees.
Reducing the bridge of the drill tip
When sharpening a drill, most people make the mistake of not reducing the bridge at the tip. In the future, you have to use more pressure when drilling. Why is the jumper wide when sharpening the drill? The thickness of the central part of the drill (core) is uneven.It grows from the tip of the drill to the shank to strengthen it. The jumper is, in fact, the tip of the “core” of the drill. In larger drills, when the drill has been sharpened repeatedly, the web becomes thicker (as the “core” of the drill gets thicker, closer to the shank).
During drilling, the center of the drill slows down the process, creating 50–70% resistance. This can be corrected by reducing the lateral edge by stitching.Reducing the web is very effective in reducing the cutting resistance of the drill and also contributes to better chip evacuation.
It is ground on a less coarse grinding wheel with its edge. An equal amount of metal must be removed from each groove. When grinding it, be careful not to make the web too thin or damage the cutting edges. Be especially careful with small diameter drills so as not to grind off excess.
Testing a Sharpened Drill
For a quick check, place the tip of the drill on a block of wood and simply turn it slowly by hand (clockwise). A properly sharpened drill will easily cut into wood, even with very little pressure.
For this test, insert the drill bit into the drill. Try to drill a block of wood.The drill should go into the tree without effort. Both edges must cut the same layer of material. The chips must come out equally on both sides.
Anatomy of a drill
When sharpening a drill for metal, you must have an idea of its structure.
Twist drills are most commonly used for metal drilling. Basically, when choosing a drill for your job, consider its length, tip type, spiral flute type, metal it is made from.
The working part of the drill is divided into two parts – cutting and calibrating (guide). The cutting (or lead-in) part consists of 2 cutting edges, back surfaces (go on the same site just behind the edges) and a bridge. The guide part has 2 spiral ribbons, to which the chip grooves adjoin, and on the other side – with backs.
Let’s analyze the basic characteristics of a twist drill: corner at the tip, angle of clearance of the cutting edges, main cutting edges, the bridge between the edges and the angle of the helix.
It is located at the tip of the twist drill. This is the angle between two cutting edges. It is required to center the twist drill on the material being drilled. The point angle varies with different drills and must be adapted to the material (its hardness) that you will be drilling. The stiffer the metal, the larger the tip angle (and therefore the flatter the tip).
The most versatile metal twist drill has a 118 degree point angle, suitable for use on wood, soft metal, medium hard metal, plastics and most other non-hard materials. For hard materials such as stainless steel, the tip angle should be larger (135 degrees). With a large nose angle, most of the cutting edges take effect earlier. A smaller angle, such as 90 degrees, is suitable for very soft plastics and other soft materials (such as aluminum).It will dull when drilling hard materials.
Flanks and their angle
Both cutting edges must have a relief that allows them to enter the workpiece for cutting metal. The flanks (areas behind the cutting edges) of the drill are at a different level than the cutting edges. They flex smoothly to create a “gap” and allow cutting edges when drilling. General purpose drills have a “gap” of 8 ° to 12 ° (or even 15 degrees).Too large a gap will cause insufficient support for the cutting edges, and there will be insufficient edge thickness to dissipate the heat generated during drilling. The value of this angle affects the hardness of the material being drilled. A smaller angle is for a harder material, and a larger angle is for a softer material. A gap angle that is not large enough (less than 9 degrees) will require increased drilling pressure, which can damage the web at the drill tip.
The two cutting edges together with the back surfaces (areas following the edges) form a jumper at the junction. It is located in the middle of the tip of the drill and is also involved in cutting, but does not cut as efficiently as cutting edges. The central bridge is responsible for inserting the drill into the material, centering it.
Located on the outer screw surface of the drill guide.The bands reduce friction, improve heat dissipation and guide the drill into the hole.
Helical flutes for chips
Helical flutes serve as a channel for removing cut material (chips) from the hole, allowing special cutting and drilling fluids to reach the cutting edges.
The helix angle for metal drills may differ.Large helix angles ensure efficient removal of soft, long chips. Smaller helix angles are used for hard materials with short chips.
Drills with a very small helix angle (10 ° – 19 °) have a long helix. In turn, drills with a large helix angle (up to 45 °) have a short helix. Drills with a normal helix have a helix angle of 19 ° – 40 °.
This is the end of the drill without a helix and is held by the drill chuck.The shank diameter is important to consider when purchasing a drill.
Total Drill Length is the measurement from the base of the drill to its cutting tip. The length of the twist drill affects its rigidity. A shorter drill will be stronger and less likely to stray or break, but may not be of sufficient length for all jobs. While longer drills can drill deeper holes, they are more flexible, which means that the holes they drill may be inaccurate or off-axis.
What the drill bit is made of
- For the manufacture of drills for metal, high speed steel (HSS / high speed steel) is used. These drills are marked with “HSS” on the shank. This is the general name for foreign-made metal drills, additional designations provide extended information on the composition of the drill. It is an alloy steel used to make metal cutting tools that operate at high cutting speeds.The drills are made from carbon steel with added tungsten, chromium, molybdenum and other elements. This allows them to be used at fast rotational speeds. HSS drills are more resistant to loss of hardening, they are quite common in kits and are suitable for almost any automotive use. If you do not need to drill very often, then even the most inexpensive HSS drill will do.
- Cobalt Steel (Cobalt drills are marked with “Co” and the percentage of cobalt on the shank (HSS Co ‑ 5 and HSS Co ‑ 8 or HSS ‑ E)).These drills remain sharpened for a very long time, do not lose the sharpness of the cutting edges, even at higher temperatures. If you need to drill in stainless steel, cobalt is the best option. This drill also has disadvantages. It is more fragile than simple HSS drills and can be damaged more easily, especially by lateral stress or when the drill gets stuck in the hole. They are also much more expensive. Cobalt drills last a very long time if handled correctly.
- Tungsten Carbide / Solid Carbide. These drills are extremely tough, but fragile at the same time. This limits their widespread use in manual drilling. Most often found in industrial applications, in engineering shops. These drills are required when drilling high strength steel, cast iron or titanium alloys.
Protective coating of the drill
The coating applied to the drill affects the efficiency and its service life.
- Black Oxide is the most economical coating. Black oxide adds protection against corrosion, increases tempering and stress relief in the drill. This coating also reduces abrasion and helps to retain coolants and lubricants for drilling on the drill. Black oxide is suitable for drilling cast iron and steel, but not recommended for drilling aluminum, magnesium or similar metals.
- Bronze Oxide – Increases tempering and stress relief in the drill and is typically used alone to visually identify cobalt steel or with black oxide to identify the best high speed steels.
- Titanium Nitride (TiN). A more expensive coating that increases the hardness of the drill and provides a thermal barrier resulting in increased productivity and longer tool life in harder materials. Drills with titanium nitride coating are suitable for drilling in cast iron and steel, as well as aluminum, magnesium. In practice, however, the titanium coating will eventually wear out, and if sharpened, the coating is completely lost.Titanium drills look like HSS drills in brass or orange color.
- Titanium Carbonitride (TiCN – Titanium Carbonitride). Has a blue-gray tint. Titanium carbonitride coated drills are harder and more wear resistant than many other coatings.
- Zirconium Coating. Although not a basic material for drills, zirconium plated metals serve very well. A zirconium nitride coating can increase the strength of hard but brittle materials.The zirconium compound also reduces friction for improved drilling accuracy.
Designations on metal drills HSS
Foreign manufacturers add designations to HSS metal drills, which indicate the technologies used and other features of the drill.
- HSS ‑ R. This mark indicates that the drill has been heat treated and rolled.
- HSS ‑ G. The cutting parts of these tools are ground with borazon (CBN). HSS ‑ G drills are widely used due to their combination of high performance and affordability.
- HSS ‑ E VAP. This is how drills are marked, the main purpose of which is the processing of stainless steel workpieces. Chips practically do not stick to the surfaces of such tools. Because of this, they wear out more slowly and break less often.
- HSS-E (HSS-Co8, HSS-Co5, etc.). This mark indicates a high cobalt content in the alloy. These drills are suitable for cutting tough and difficult metals.
- HSS ‑ G TiN. These drills are coated with titanium nitride. It significantly increases the hardness of the tool and its heat resistance.
- HSS ‑ G TiAlN. These drills are coated with aluminum-alloyed titanium nitride. It further increases the hardness of the tool and its heat resistance.
How to drill metal correctly?
- Even the most expensive and sturdy drills will only last a few holes if misused.
- Better to apply less pressure to the drill and use a lower RPM. The speed must be adapted to the hardness of the material and the size of the hole. In general, the larger the diameter of the drill, the lower its rotation speed should be, and vice versa, the smaller the drill, the higher the speed can be.Drills from 1.5 to 4.5 mm can drill metal at a rotation speed of 3000 rpm. For larger diameter drills, rpm 350 to 1000 is recommended. During drilling, if you start to see smoke or the metal you are working with begins to discolor and darken, you are drilling too fast. The rotation speed affects the heating of the drill. A hot drill dulls faster. There is no single drilling speed for all types of metals.As a general rule of thumb when drilling metal, the larger the drill and the harder the metal, the slower the rotational speed. If the drill is sharp, it does not require tremendous pressure to drill the hole. Breakage often occurs when you try to push hard on a blunt drill bit to make it drill faster. It doesn’t work, it just overheats the metal.
- Since metals have smooth surfaces, it is useful to use a center punch to center the drill.When drilling large holes, you can pre-drill the metal with a smaller drill bit. This will guide your drill and prevent it from moving or slipping as you rotate. It is better not to drill through with a drill of a smaller diameter. It will also serve as a reservoir for special coolant and lubricant.
- Try to keep the drill stable. If not kept perpendicular while drilling, it can bend and break.
- When drilling sheet metal, be careful when the drill starts to drill through the metal to the other side. The drill can get stuck when exiting from the back and snag material from the bottom of the hole. Ideally, a block of wood should be placed under the metal so that it does not bend at the end of the drilling. With experience, you will feel changes in sound and resistance to reduce the pressure at the end of the drill.
- Depending on the material and hole size, drill cooling may be beneficial or even necessary.When drilling, the metal heats up significantly, which can lead to overheating of the drill. This reduces its hardness and pungency. Pause during operation to allow the drill to cool down. For hard metals, large diameters and deep holes, it is best to use a special cutting and drilling fluid as well. Immediately before starting drilling, some lubricant must be added to ensure that the heat build-up is reduced.
- When drilling a small workpiece, do not hold it in your hand. It needs to be securely fastened. Otherwise, the workpiece may be ripped out and the hand may be injured. This is not necessary when drilling heavy or stationary objects.
- The drilling process will inevitably create sharp edges. These are small jagged pieces of metal that may be around the edge of the hole you want to remove. You can simply smooth out uneven edges with a file.Another little trick is to use a drill bit larger than the burr hole. Place the tip of the larger drill bit into the hole and rotate it. The end result is a completely smooth and even hole.
Drilling in hard metals
Obviously, hard metals are more difficult to drill. For example, stainless steel is difficult to cut and drill. Consider what to consider when drilling hard metals.
The drilling speed in hard metals must be slow. Ideally, a harder drill should be used, such as cobalt, titanium nitride coated or tungsten carbide. The third point concerns cooling. When drilling hard metals, it is recommended to use a special cutting and drilling oil.
Ideally, drilling in hard metals should be done with a drill press, as this will give more control and create more force.
Drilling in sheet metal
When drilling with a conventional drill in sheet metal, the hole is uneven. This happens because the tip of the drill, coming out of the sheet from the back side, ceases to be centered, and the drill strips still do not center the drill, since they are not yet in contact with the metal surface.
At a certain moment, the drill jams and starts tearing metal or slipping in the drill chuck.A conventional twist drill is made to drill thick and hard materials. Special drills for sheet metal drill an even hole.
The special drill for sheet metal has a sharp edge in the center and cutting tips on the sides. This drill has the following advantages: good centering, minimal burr formation when drilling through, accurate drilling in thin sheets and pipes. Such a drill can be made from a conventional metal drill.It sharpens in the same way as a spot weld drill.
Drilling starts from the tip, then the cutting edges immediately drill a hole of a certain diameter.
When drilling a sheet of metal, it is also advisable to place a flat piece of wood underneath it.
Compare the two holes in the photo, drilled in 1.2mm aluminum. Both holes were drilled with a 1.25 cm drill at 150 rpm.in min. with a wooden backing underneath a metal sheet. The hole on the left was drilled with a standard twist drill and the hole on the right was drilled with a modified tip. No hole has been machined to remove burrs.
If you want to drill through thin sheet metal, never hold the sheet metal in your hands. When the drill cuts through a sheet of metal and exits from the back, there is a danger that it can unexpectedly get stuck in the sheet of metal and the sheet will injure your hand.Better to fix the sheet firmly between the two plywood. Then drilling is safe. It also reduces the amount of burr, making it easier to finish the workpiece. In this way, you can get an even hole with a conventional metal drill with an angle at the tip of 118 degrees.
Cooling and lubrication when drilling metal
- In addition to using the correct drill bit for metal, the correct rotation speed, when drilling metal, it is recommended to use a special oil for cutting or drilling metals.This agent prevents the drill from overheating and also reduces friction, making drilling easier. Not to mention, the special tool provides higher rotational speeds, which increases productivity. It also prevents chips from sticking to the cutting edge and flutes of the drill. Many modern coatings on drills do not involve the use of lubricants, therefore, first you need to clarify with which drill, at what speed and when drilling which metal you need to use drilling oil.
- A special oil is applied to the work area to dissipate some of the heat and lubricate the cutting tool, providing better cutting action with less friction and increasing tool life (in this case, drills).
- There are both special and universal coolants and lubricants for drilling (eg Specialist ® Multi-Purpose Cutting Oil from WD-40).
- It should be noted that there are craftsmen who never use any oil or liquid during drilling, including on the machine.They explain this by the fact that oil or other lubricants are contrary to the purpose of the drill. If you have a properly sharpened drill bit, it should cut through the metal, not slip. If the drill is sharp, has the correct sharpening for a specific metal, and the correct rotation speed is set, then nothing else is needed. Most of the heat during drilling goes into the chips.
- If you are only drilling thin sheet metal, cooling and lubrication may not be required.It will only be important to observe the frequency of drilling, the speed of rotation and the pressure on the drill.
How to make your own cutting and drilling fluid?
If it is necessary to use cooling when drilling, it is advisable to use a special fluid. It cannot be replaced with anything. Special fluid for cutting or drilling metals contains lubricants, corrosion inhibitors, mold and bacteria inhibitors, flame retardants, stabilizers.A liquid (or fusible solid) is required that does not become a gas at the temperatures generated by drilling. Plain water can cool, but it will evaporate without leaving a lubricating film behind, and can also corrode the cutting edges.
Care must be taken to use anything for cooling during drilling that is clearly not intended for this purpose. You will breathe in smoke that can be toxic.For example, the use of antifreeze with water, which can withstand high temperatures, has anti-corrosion and some lubricating properties, is logical, but when it evaporates, toxic fumes are formed.
There are many recipes for homemade cutting and drilling oils that have their own advantages and disadvantages. Here I cite only one recipe, which was used more than once by one familiar master who had to drill a lot.
Recipe for homemade liquid for cutting and drilling metal:
- 3 parts water,
- 1 part gear oil, possibly motor oil,
- a few drops of dishwashing liquid.
First add the detergent to the water and then stir it a little. If you just mix all the ingredients into one container at once, they don’t mix very well. Soap is a catalyst that allows oil and water to mix.Otherwise, due to the different densities, the oil will float on top of the water. When drilling, water will cool the drill and evaporate, and a thin film of oil will act as a lubricant and also prevent corrosion. If a sticky residue remains when the water evaporates, too much soap has been added.
The only metal that requires a special cutting or drilling fluid is aluminum. Many specialty metal cutting and drilling fluids indicate that they are suitable for all metals except aluminum.For this metal, ordinary wd-40 or kerosene can be used as a cooling and lubricant.
Read also on the topic:
How to sharpen a drill for drilling spot welding?
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VHM (solid carbide) drills for wood, plastic, fiberglass, aluminum, steel
This section contains carbide drills for wood, carbide drills for PVC plastic, carbide drills for aluminum, carbide drills for fiberglass .Data Solid Carbide Drill Bits are used in CNC machining centers.
|designation, dimensions A x B x D||country of origin||article||price, €|
|CNC Center Drill Right 2.0 x 12.0 x 38||Germany||484.000.002€ 90,023 € 90,024|
|CNC Center Drill Right 2.5 x 14.0 x 43||Germany||484.000.025€ 90,023 € 90,024|
|CNC Center Drill Right 3.0 x 16.0 x 46||Germany||484.000.003€ 90,023 € 90,024|
|CNC Center Drill Right 3.0 x 27.0 x 46||Germany||484.001.030€ 90,023 € 90,024|
|CNC Center Drill Right 3.5 x 20.0 x 52||Germany||484.000.035€ 90,023 € 90,024|
|CNC Center Drill Right 4.0 x 22.0 x 55||Germany||484.000.004€ 90,023 € 90,024|
|CNC Center Drill Right 4.5 x 24.0 x 58||Germany||484.000.045€ 90,023 € 90,024|
|CNC Center Drill Right 5.0 x 26.0 x 62||Germany||484.000.005€ 90,023 € 90,024|
|CNC Center Drill Right 6.0 x 28.0 x 66||Germany||484.000.006€ 90,023 € 90,024|
|CNC Center Drill Right 8.0 x 37.0 x 79||Germany||484.000.008€ 90,023 € 90,024|
|designation, dimensions A x B x D||country of origin||article||price, €|
|CNC Center Drill Left 2.0 x 12.0 x 38||Germany||485.000.002€ 90,023 € 90,024|
|CNC Center Drill Left 2.5 x 14.0 x 43||Germany||485.000.025€ 90,023 € 90,024|
|CNC Center Drill Left 3.0 x 16.0 x 46||Germany||485.000.003€ 90,023 € 90,024|
|CNC Center Drill Left 3.0 x 27.0 x 46||Germany||485.001.030€ 90,023 € 90,024|
|CNC Center Drill Left 3.5 x 20.0 x 52||Germany||485.000.305€ 90,023 € 90,024|
|CNC Center Drill Left 4.0 x 20.0 x 55||Germany||485.000.004€ 90,023 € 90,024|
|CNC Center Drill Left 4.5 x 24.0 x 58||Germany||485.000.045€ 90,023 € 90,024|
|CNC Center Drill Left 5.0 x 26.0 x 62||Germany||485.000.005€ 90,023 € 90,024|
How and with what to drill ceramic tiles and porcelain stoneware?
When planning a renovation in a bathroom, it seems that the most difficult thing is to lay tiles, but another difficulties await us when installing plumbing fixtures, shelves, cabinets, mirrors and other accessories on tiled walls.To do this, you will have to drill holes in the tiled flooring.
In this article, you will learn how to properly drill a tile wall, which drills to use for small and large holes. We will show you some simple ways to protect tiles from chips and cracks. You will learn how to use masking tape for more accurate drilling and what a tile ballerina is.
Ceramic tile is a hard and brittle material that is difficult to drill but easy to crack.One mistake or awkward movement can lead to its damage, and you will already have to read other instructions for replacing cracked tiles. Therefore, before you start drilling, make sure you know how to drill the tiles. Fortunately, we have a lot of tips for you to help you do everything accurately and accurately.
Step 1. Know your tile.
The first thing you should know is the tile type you are working with.
It is important to understand that not all ceramic tiles are created equal.It has a wide range of hardness. Porcelain stoneware is especially difficult to process due to its high density and hardness. It is more difficult to drill than conventional ceramics and tiles, so you need a special tool for porcelain stoneware.
Ceramic tiles are often glazed. The glaze on its surface is nothing more than a thin layer of liquid glass, which is very difficult to break through. The drill tip slides over it, making it difficult to start drilling and can lead to scratches.
When you know what you are facing, you can start choosing a tool.
Step 2. Choose the correct drill.
Regardless of the type of ceramic you are trying to drill, never use old and worn out drills. Not only are they ineffective, but they also increase the chances of surface damage. Conventional concrete drills will not drill the tiles, but simply crumble them into pieces. To work with it, you will need a tool, the cutting part of which is much harder than ceramics and tiles.
For making holes of small diameter (for a dowel) use:
- Tubular diamond-coated drills.
- Spear drills with carbide tip.
- Carbide Twist Drills.
Drill types for ceramics
Diamond tubular drills are very efficient, durable and easy to use, although they are much more expensive.Thanks to the diamond grit on the cutting edge, they are able to cut through the hardest materials such as stoneware and porcelain. However, it makes no sense to buy them because of the few holes, unless you have a desire to become a professional tiler in your plans.
Carbide tiled drills have an easily recognizable spear shape and a maximum drilling diameter of 12 mm. Hard tip due to the special sharpening of the cutting edges reduces the likelihood of cracking and splitting.Its hardness is so high that it can even be drilled into porcelain stoneware, but after five holes the sharpening decreases sharply.
Tip! With a small amount of work in porcelain stoneware, it is more profitable to purchase lance-shaped drills with a victorious tip, despite the fact that they quickly become blunt in hard material. Diamond tooling costs about 5 times more, so it is worth buying for large volumes of work.
Drills of the spiral type with victorious solder are often used by home craftsmen instead of a special drill for ceramics due to the high availability of this tool.They are designed for drilling concrete and stone, but they can easily cope with ceramic tiles. Before starting work, punch the surface with light hammer blows on the drill, and drill at minimum speed with utmost care.
How to drill large holes in tiles?
For drilling large sockets with a diameter of up to 150 mm, for example, for socket outlets, lamps, mixers, pipes, use:
- diamond core bits
- circular adjustable drill (ballerina)
Tool for making large holes in ceramics
Diamond core bits are sometimes referred to as diamond hole saws.There are no restrictions on the hardness of the tiles for them, they will drill whatever you put in front of them – tiles, ceramics, porcelain, tempered glass, reinforced concrete. Due to the exceptional wear resistance of industrial diamonds in their working segment, more than 100 cuts can be made with one bit. To extend the service life of such equipment, water is supplied to the working area; in extreme cases, the crown is periodically dipped into a container with water.
A circular drill with adjustment or in the common people “ballerina” is used in all existing types of non-solid ceramic and tile tiles.Its cost is low, and its service life is quite long. The advantage over crowns is that the “ballerina” allows you to set any non-standard diameter within the specified values, as a rule, it is from 30 to 90 mm. Its spear-shaped cutter with a victorious soldering lends itself to sharpening.
Tip! If you want to achieve a smooth cut without chipping the glaze, choose a diamond core bit. If the cleanliness of the cut is not required, for example, under the switch, then – “ballerina”.
Step 3.Prepare the surface for drilling.
To prevent the drill from slipping on the smooth surface of the ceramic at the start of drilling, you can use ordinary masking tape. On top of the markings, stick two strips of tape crosswise. Then redraw the mark onto the duct tape to make it clearer. The masking tape will improve traction and prevent the drill from slipping to the side.
Step 4. Start drilling at low speed.
Tiles are drilled in non-shock mode .Start at the slowest speed and slowly dig deeper into the material. Many people make the mistake of thinking that increasing tool speed and pressure will increase productivity. In fact, you will only overheat the cutting edges and increase vibration. After you have passed the hard glassy coating, start to build up the speed gradually and apply constant, but not strong pressure.
Step 5. Remember to cool down the instrument.
To extend the life of the drill, the cutting ability of the bit and reduce the risk of cracks, accompany the drilling process with water cooling.If you are unable to water the drilling site continuously while you are working, stop from time to time and spray some water on the drill. Make sure that no water gets on the motor part of the drill. Another method you can use to keep the drill from overheating is to keep a damp sponge underneath.
Step 6. Replace the drill when hitting the wall.
After the special drill for ceramics has completed its task, it should be replaced with another one suitable for the wall material – a drill for concrete, a drill for brick or wood.Its diameter should be slightly smaller so as not to damage the ceramics and not chip off the glaze. If necessary, you can turn on the shock mode, make sure that the nozzle does not deviate from the axis.
Step 7. Install the wall plug or anchor bolt.
It remains to install a dowel or anchor in the holes obtained. When hammering them in with a hammer, apply light blows with maximum accuracy. Make sure that the spacer part is located only in the wall material. If it gets on the tile or mortar layer, there is a high probability of cracking of the tile at the time of anchoring the fasteners.Mark the drill with a marker to obtain the desired hole depth.
You are familiar with the theory of how to drill a tile. Let’s highlight the 5 most important points that will help you do your job efficiently:
- Understand the characteristics of your tile (hard or soft).
- Choose the right rig, it will increase your chances of success.
- Apply masking tape to prevent slipping.
- Drill the tile slowly in a non-impact mode.
- Periodically cool the rig with water.
When drilling ceramic tiles, patience, perseverance, a steady hand and the right tools are essential. If you’ve never done this before, it’s best to experiment with the remaining clippings first. Skill comes with practice. With the acquisition of a certain experience, drilling a tile will no longer seem impossible to you.
Useful Tips Updated: 29.09.2020 13:25:19
E-mail: [email protected]
Phone: 8 (800) 333-21-68
Drill types and sizes – Plumbing
The industry manufactures drills of the following types and sizes:
– spiral small-sized with a cylindrical shank with a diameter of 0.1 to 1.0 mm;
– spiral with a cylindrical shank with a diameter of 0.25 to 18 mm;
– with a cylindrical shank, equipped with carbide, with a diameter of 5 to 12 mm;
– spiral with a tapered shank from 6 to
– with a tapered shank, equipped with carbide (with a spiral or straight flute), with a diameter of 6 to 30 mm;
– tapered drills for pin holes with a taper of 1: 50;
– conical drills for Morse tapers;
– spiral drills with a square tapered shank (for ratchets) for drilling holes with a diameter of 9.5 to 40 mm;
– centering drills with a diameter of 0.5 to 12 mm;
– Perforated drills (for deep hole processing) with a diameter of 35 to 130 mm;
– circular drills – for processing large holes (in the process of drilling, circular blanks are formed from the material of the product) with a diameter of 90 to 200 mm;
– drills with a diameter from 3.1 to 5.2, made entirely of special hard alloy VK5M, for manual drilling of hard steels;
– drills equipped with carbide plates are mainly used for drilling in cast iron, hard and hardened steel, plastics.
The cutting edges of the drill must be straight, of the same length and located at equal angles to the axis of the drill. If these conditions are not met, the drill is pulled to the side during operation, and the hole to be drilled is larger than the diameter of the drill. The correctness of sharpening of twist drills is checked with a template.
Drill shanks are in most cases cylindrical or with Morse taper. Morse tapers are numbered from 0 to 6. Each number corresponds to a specific diameter, length and taper (tapers are different for all numbers).
Karnasch Main Catalog 2021 – Page 515
CORNER DRILL • ANNULAR CUTTERS one 2200 11228844 BLUE-DRILL LINE 30 DURABLUE powder coated core drill, RAILPRO Weldon shank, effective length 30 mm APPLICATION ∙ APPLICATION 2 For all types of rails up to a strength of 1100 N (UIC 60).More than 100 holes possible in Weldon 30 mm | one” rails UIC 60. Tires Weldon Rails For all rail types up to 1100 N (UIC 60). 19 mm More than 100 holes in UIC 60 rails possible.3/4 ” 3 Art. mm inch € Art. mm inch € Art. mm inch € Art. mm inch € 20012844012 I 12 15/32 “48.75 20012844020 I 20 25/32” 55.75 20012844028 I 28 1.7 / 64 “83.05 20012844036 I 36 1.27/64 “111.45 20012844013 I 13 33/64 “48.75 20012844021 I 21 53/64” 56.10 20012844029 I 29 1.9 / 64 “84.40 20012844014 I 14 35/64 “48.75 20012844022 I 22 55/64” 58.90 20012844030 I 30 1.3 / 16 “86.45 20012844015 I 15 19/32 “52.95 20012844023 I 23 29/32” 61.95 20012844031 I 31 1.7/32 “88.75 20012844016 I 16 5/8 “52.95 20012844024 I 24 15/16” 66.10 20012844032 I 32 1.17 / 64 “92.50 20012844017 I 17 43/64 “52.95 20012844025 I 25 63/64” 66.10 20012844033 I 33 1.19 / 64 “97.90 4 20012844018 I 18 45/64 “52.95 20012844026 I 26 1.1 / 32” 75.25 20012844034 I 34 1.11/32 “97.90 20012844019 I 19 3/4 “52.95 20012844027 I 27 1.1 / 16” 75.30 20012844035 I 35 1.3 / 8 “101.65 Attention! Inch dimensions do not correspond exactly to diameters in mm. Attention: The inch sizes do not correspond exactly to the mm diameters. 2200 11228844 BLUE-DRILL LINE 30 ACCESSORIES ∙ ACCESSORIES RAIL PRO five EJECTOR PINS 20 112261 6.34 × 77 mm I € 6.65 6 Standard packing 2 pcs.∙ Packaging unit 2 pcs. FEATURES ∙ PROPERTIES ASP WEICH HARTSOFTHARD 7 NES Manufactured from powder – Only a few of the products – Seven different geometries Our high quality Solid material ASP for drills in bend-cut condition for each diameter crown drills are fully ground.complex materials, core drills, and the cutting depth of the crown – unique patented – This fine grinding such as rail-hardened drills are provided with a DURABLUE coating. increases productivity ny rails, high- stages.For us, this is the highest production steel, exotic standard. At the same time, the volume of cutting. surface is provided with a temporary reduction chemical alloys. We always strive to maximize friction life.For increase 8 is used where hard tooth tips (68 Seven different cutting require a high degree of HRC), but the movable geometry is optimally used even with sub-optimal service life. wear and service life. core drill. adapted to the different overhead work, dry Completely made “FULLY diameter and drill depths drilling, etc.e. GROUND ”. This refining OIL Made of ASP powder steel Only few manufacturers leads to high performance increases the cutting ability for drilling of difficult ma- are capable of producing cutting results. Our first-class annular cut- while reducing friction at terials like railway tracks, step-hardened annular ters are equipped with the same time.For an stainless steels, exotic cutters. For Karnasch this is unique and patented DURA extended lifetime. alloys. Applicable wherever “standard”. Only this makes BLUE-coating. Extreme 9 a high wear resistance and us produce extremely hard surface hardness and lifetime are required.tooth tips (68 HRC) and yet a sleekness yield extreme flexible annular cutter. lifetimes even under non- optimum circumstances like “overhead work”, dry drilling, etc.