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| AI image generated by Bing Image Creator |
When drilling any material, the correct bit is essential so that holes can be bored quickly and with ease. If you’re a newbie at DIY, this article explains how to go about choosing the right drill bit for the job when boring through various materials such as steel, aluminum and other metals, masonry, plastics, wood, glass, and tiles.
I outline some tips for drilling, the proper way to use a hand power drill, and how drill bits can be sharpened. At the end of the article, you’ll find an 11-minute video that shows you how to drill.
Word of Caution
Power and hand tools can be dangerous. Read and understand all manuals before use and take reasonable precautions, including wearing personal protection equipment (PPE) to prevent injury. A dust mask is strongly recommended when drilling masonry or glass to protect your lungs from the fine particulate matter.
What Is a Drill Bit?
A drill bit is a cutting tool that fits into a drill (an electric, pneumatic, or hand-powered tool used for boring holes). It is used to cut holes in various materials by rapidly rotating. Bits come in various shapes and sizes, depending on the material to be cut and desired hole characteristics, but all have similar parts.
Parts of a Drill Bit
- Point: the cone-shaped tip of the bit
- Spur: the tiny, sharp tip of the point that is used to centre the bit in the hole to be cut
- Cutting Lip: the sharp, spiral edge of the bit that cuts the material
- Flute: the spiral channel that runs along the lip to help remove the material during drilling
- Shank: the end of the bit that slides into the drill’s chuck (a clamping mechanism)
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You can use any of the following, depending on application.
- HSS
- Titanium coated or cobalt steel
- Metal hole saw
- Unibit (step bit)
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| A HSS drill bit for drilling steel © Eugene Brennan |
HSS Bits
HSS or high-speed steel bits are made from carbon steel with the addition of other elements such as chrome and vanadium. This allows them to be used at high drilling speeds.
HSS bits can be used to drill:
- Iron
- Steel
- Other metals, such as brass, copper and aluminium alloy
They can also be used to drill plastic, and you can drill wood with an HSS bit if nothing else is available. However, if the hole is deep or of large diameter, the bit will become excessively hot and drilling progress will be slower.
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| Titanium coated bit Binter, CC BY-SA 3.0, via Wikimedia Commons |
Titanium Coated Bits
Bits coated with a titanium compound are more durable and harder than uncoated HSS bits. Titanium bits look like HSS bits with a brass or orange colouring. They are suitable for drilling hard materials like:
- Stainless steel
- Tool steel
- Springs
In practice, though, the titanium coating eventually wears away, and if you sharpen them with a drill bit sharpener or by hand, the coating is lost.
Cobalt Steel Bits
Another option for drilling hard steel or stainless steel is a cobalt alloy bit. These are manufactured from solid alloy, not just coated like titanium bits, and sometimes marked “HSS Co.”
The addition of cobalt makes the drills more durable, and they can withstand higher temperatures during drilling without losing their edge. The disadvantage is that they are more expensive, more brittle and therefore more likely to chip at the cutting edge. Cobalt steel bits can, of course, be used for drilling “normal” mild steel or other metals.
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| Step bit also known as a unibit Junkyardsparkle, CC0, via Wikimedia Commons |
Step Bit (Unibit)
Step bits are conical-shaped with multiple cutting edges of varying diameters. They are suitable for drilling:
- Sheet metal
- Thin softwoods
- Laminates (e.g. plywood) and particle board (chipboard)
- Plastics
- Drywall (plasterboard)
Step bits are ideal for electrical work when varying-sized holes have to be cut in junction boxes, panels, etc. The advantage of this type of bit is obviously the convenience of drilling various hole sizes without changing bits.
Also, because the bit generally comes to a point, a pilot hole isn’t required, as is usually the case if a large hole needs to be drilled.
These bits are designed for specific uses, which I will detail below.
- Spade or flat wood bit
- Lip and spur (Brad Point) bit
- Forstner bit
- Hole saw
- Masonry bit
- Step bit
Remember, you can use an HSS bit if none of the above is available.
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| Spade/flat wood bit Luigi Zanasi, CC BY-SA 2.0 CA, via Wikimedia Commons |
Spade or Flat Wood Bit
These are suitable for rapid drilling through wood and are commonly available in sizes from 1/4 inch (6 mm) to about 1 1/2 inches (36 mm).
The disadvantage of spade bits is that they can produce a splintering effect as the bit emerges from the timber if you apply too much pressure.
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| Lip and spur bit Emrys2, CC BY-SA 3.0 Unported via Wikimedia Commons |
Lip and Spur (Brad Point) Bits
These are another option for drilling timber and are available in sizes from 1/8 inches (3 mm) to 5/8 inches (16 mm).
They can also be used for drilling soft plastic and are less likely to cause melting of hole edges due to friction, which can happen when drilling with an HSS bit.
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| Forstetner bit Public domain image by Clint Patterson on Unsplash.com |
Forstner Bit
These have a cutting edge like a chisel, but give a cleaner cut than a flat bit because of the cylindrical sides.
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| Hole saw The original uploader was Emrys2 at English Wikipedia., CC BY-SA 3.0, via Wikimedia Commons |
Hole Saws
Drilling very large holes greater than 1 1/2 inches with a standard bit is impractical as you would need a huge amount of power and torque to overcome friction to drill through timber.
Instead, drilling large holes can be accomplished with a hole saw. This has small teeth like a handsaw and the “blade” is wrapped around in a circle, creating a cylinder.
Some hole saws are only designed for drilling wood or plastic, while others are made from HSS steel and suitable for drilling iron, steel and other metals in addition to wood.
Which Drill Bit for Plastic?
You can use the same bits as for metal or wood. However, drill slowly. If you drill fast, friction can rapidly cause plastic to melt, clogging the tip and flutes of the drill with melted shavings, especially if the bit is blunt.
As shavings cool and get stuck in the flutes or coat the bit, the problem gets worse, and the bit can get stuck. It’s not such a big deal when drilling through thin plastic, but I’ve found that when drilling through thicker sheets and specifically acrylic (commonly known by the brand names “Plexiglass” or “Perspex”), this can be a problem. The same goes for cutting this plastic with a jigsaw; use a slow speed.
Which Drill Bit for Brick, Solid Concrete, and Block (Masonry)?
You can use either of these type of bits:
- Tungsten carbide bit
- Diamond hole saw
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| Masonry bit with SDS shank Emrys2 at the English-language Wikipedia, CC BY-SA 3.0, via Wikimedia Commons |
Tungsten Carbide Masonry Drill Bits
These types of bits are used for drilling holes in the following surfaces:
- Stone
- Solid concrete
- Concrete blocks
- Breeze blocks (aerated concrete blocks)
- Brick
They are available in sizes from just under 1/4 inches (5 mm) to 1 1/2 inches (approx. 40 mm).
Masonry bits are available with a round section shank for use in a conventional chuck. However, a better choice is an SDS-type bit. The shank on this type of bit doesn’t slip in a chuck and can be quickly inserted and extracted from the SDS chuck on the power drill.
Masonry bits are used in what is known as an impact, hammer or percussion drill. This percussive or hammering action pulverises the masonry in contact with the tip of the bit.
Masonry bits can be used for drilling rough holes in timber. However, the hole will be rougher and progress slower. This is because the drill just chips its way by brute force through the wood. (A proper wood drill bit shaves its way through timber like a chisel.) For construction work, though, finesse isn’t an issue.
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| Diamond core hole saw Image via Wikimedia Commons, CC SA 1.0 |
Diamond Core Bits
These are similar to hole saws but used for drilling large holes in concrete or aerated cement blocks.
Which Drill Bit for Glass and Tiles?
Depending on the job, you’ll want one of these specialised bits:
- Spear head bit
- Diamond bit
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| Spear point glass drill bit Image courtesy Dealextreme |
Spear Head Bits
These are made from tungsten carbide and suitable for drilling glass or tiles. When drilling glass, if possible lay it flat on a soft cloth or newspaper for support.
Drill at low to medium speed and either spray the area being drilled with water to cool and lubricate the bit, or make a “dam” of plasticine around the area and fill it with water.
Drilling Tip: A piece of PVC insulating tape stuck on glass or tiles stops the bit from wandering and slipping on the surface.
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| Diamond coated bits Junkyardsparkle, CC0, via Wikimedia Commons |
Diamond Tipped or Coated Bits
These are used for drilling tiles and glass. However, they only have a limited lifespan before the coating of grit wears away.
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| A countersink bit © Eugene Brennan |
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| Public domain image via Pixabay |
What Are Countersink Bits Used For?
A countersink bit is used for drilling a conical depression at the top of a drill hole, allowing the top of the tapered head of a countersunk screw to be flush with the surrounding material. This is for cosmetic reasons and also to prevent the head projecting and causing an obstruction (e.g. the screws in the hinges of a door).
Historically, when driving screws by hand with a screwdriver, it was necessary to pre-drill holes for screws to make it easier to drive them, especially in hardwood, and then countersink the top of the hole.
When driving countersunk screws into softwood construction timber with a cordless drill, generally it isn’t necessary to pre-drill holes, because screws usually have a deep thread (often serrated) and sometimes a drilling tip that cut into timber. Also the torque of a cordless drill can easily bury heads so that they’re flush, without the need to countersink.
Pre-drilling and countersinking is usually necessary in hardwood timber though, to avoid cracking the timber (especially narrow sections) and because heads can’t be buried so easily. However, countersinking drill holes is always necessary in metal and plastic because these materials don’t compress like timber as screws are driven home.
When do I need to countersink?
- When countersunk screws are being used in hardwood
- When drilling holes in steel or other metals and plastic
- If screw heads are very large and a cordless drill can’t easily bury them
Combination countersink bits that have a section for drilling holes and also countersinking are available that allow both operations to be done simultaneously.
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| Clockwise from top: Chuck key, keyed chuck, SDS chuck, keyless (hand tightened) chuck © Eugene Brennan |
Are There Different Types and Sizes of Chucks?
The
chuck on a cordless drill is usually either 10 mm (3/8 inch equivalent)
or 13 mm (1/2 inch). Lower voltage drills (e.g. 12 volts) tend to be
fitted with a 10 mm chuck.
Corded drills usually come with a 13 mm
chuck as standard, but 16mm (5/8 inch) chucks are also available. Drills
bits with a diameter larger than 13 mm normally have a reduced diameter
shank so that they can be inserted into a 13 or 16 mm chuck. SDS chucks
also come in various different sizes, but the 10 mm SDS-Plus type is
the most common version encountered on DIY/ low powered professional SDS
power drills.
For more information on chuck sizes and choosing corded and cordless drills, see my guide: A Complete Guide to Power Tools for Beginners.
Drill Bit Sizes
Drill bits are available in metric (mm) and Imperial (inch) sizes. HSS drill bits range from 1mm (3/64″) to over 25 mm (1″), although smaller diameter bits are available for specialist applications. Bits greater than 13 mm diameter generally have a reduced diameter shank so that they can fit in a 13 mm chuck.
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| Vernier calipers top and electronic calipers bottom Public domain image via Pixabay.com |
How to Measure the Diameter of a Drill Bit
Normally, the size is stamped or engraved on the shank of a bit. Unfortunately, manufacturers insist on placing the marking near the end of the shank, so it can get worn off over time if a round profile shank slips in a chuck. So you can end up with a lot of unknown-size bits in your collection.
You can roughly measure the diameter of a bit with a tape or ruler, but a vernier or electronic calipers is the proper tool for the job. You can also use it for measuring the thickness of materials, internal hole diameters and general purpose measuring.
Resolution is normally about 0.05 mm or two thousandths of an inch. You can buy a purely mechanical vernier calipers, which has a vernier scale.
Alternatively, an electronic calipers displays the result on an LCD scale which can be read directly. The advantage of an electronic calipers is that the display can be read directly, switched between imperial (inch) and metric and the jaws can be zeroed to cope with any drift or wear.
How to Hold a Power Drill
Hold the drill with the trigger handle horizontally in the “3 o’clock” position and the side handle in the “12 o’clock” vertical position. If the drill bit sticks, the power drill will turn violently counter-clockwise, the side handle will get pushed into the palm of your hand and you may just about be able to hold it before you release the trigger.
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| How to hold a power drill © Eugene Brennan |
If you hold both handles in the “6 o’clock” position, i.e. pointing vertically down, the side handle of the drill may pull out of your hand. This will almost certainly happen if it is a high-power drill without a safety slip chuck. In any case, hold a drill tightly and brace your arms, ready for the unexpected.
Tips for Drilling Holes
- Use as slow a speed as possible. In general, the larger the diameter of the drill bit, the lower the speed and vice versa
- Use a centre punch to make a dent in the material being drilled. This stops the bit slipping. It’s practically essential to do this on smooth surfaces such as steel.
- Clear the hole periodically of swarf. When drilling, back out of the hole every so often to remove material. This prevents the power drill from being overloaded and the bit overheating. This is essential with flat wood bits which don’t have flutes (the helical slots on the sides).
- Lubricate the bit and workpiece with light machine oil if drilling steel. If you’re using a pillar drill, you can use an oil can or some form of “squirty” bottle to spread oil into the hole. Alternatively If using a power drill, keep a bottle capful of light oil nearby, and dip the tip of the drill bit every so often into it to cool it. Kerosene or soapy water is suitable for lubricating softer metals such as aluminium or brass which have a more “sticky” swarf (the waste material which spirals out of the drill hole). Diamond drill bits can be lubricated with water. Wood or masonry bits don’t need to be lubricated.
- Don’t hold small workpieces while drilling. Make sure they are held in a vice or clamped securely with quick release or G clamps. Otherwise if the bit jams while drilling, the workpiece can spin around uncontrollably. When drilling heavy or fixed objects, this is unnecessary.
- Keep your bits sharp. When drilling plastic, especially acrylic (Perspex), a sharp bit is essential to reduce friction and heat which will tend to melt the plastic and coat/clog the bit, further increasing friction. Use as slow a speed as possible. A lip and spur (brad point) wood bit is best for drilling plastic.
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| Small diameter drill bit © Eugene Brennan |
How to Avoid Breaking Drill Bits
Narrow-diameter HSS, cobalt or titanium drill bits are easily broken, even by pros, so a little care needs to be taken when using them.
Some Tips
- Small bits often break when they snag or catch in the workpiece. So if you have a cordless drill, use this instead of a mains corded drill. If the bit snags, the chuck will slip, lessening the danger of snapping the bit. Set the torque setting low and increase the setting if the chuck tends to slip during drilling.
- Apply light pressure, just sufficient for the swarf to start spiralling away from the workpiece.
- Try to hold the drill steady. If you move it to one side rather than keeping it perpendicular when drilling, this can bend and over stress the bit, breaking it.
- Lastly when drilling metal, take it easy as you break through to the other side. The bit can snag as it breaks through and catches the material at the bottom of the hole. Ideally, place a block of wood under the workpiece to stop the metal from pushing outwards as it thins before breakthrough (this is easier to do if you are using a drill press). With experience you get to know the change in sound and feel the resistance and reaction of the bit as this is about to occur, so ease off on pressure. If bits are sharp, a huge amount of pressure isn’t needed to drill a hole. Breakage often occurs when you try to lean heavily on a blunt bit to make it drill quicker, which doesn’t work; it only overheats and burns it out!
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| A de-magnetizing tool removes magnetism from a drill bit © Eugene Brennan |
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| © Eugene Brennan |
How to Demagnetize Drill Bits
Over time, drill bits can become magnetised so they collect shavings while you’re drilling. This can interfere with the drilling process by increasing friction, clogging the flutes and getting in the way of the cutting edge so that it can’t shave through a hole properly.
A demagnetising tool is a useful gadget for removing magnetism from drill bits, screwdrivers and other tools. Often, these de-magnetising tools can also be used for magnetising. This is useful, for instance, for magnetising the tip of a screwdriver. The tip then holds the screw when you need to drive it in an inaccessible location where you can’t fit your fingers.
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| A typical drill sharpener (Lidl Parkside own brand) © Eugene Brennan |
How to Sharpen Drill Bits
With some skill, you can learn to sharpen a drill bit on the fine grit wheel of a bench grinder. However the bit needs to be held to the wheel at a relatively precise angle, which takes a bit of practice.
An alternative is to use a sharpening tool like this one by GOODSMANN, available on Amazon. These machines are basically composed of a motor driving a small grindstone. To sharpen a drill, you insert it in the appropriate sized hole in the top of the sharpening tool and twist it a few times. This product covers all sizes up to 12 mm or 1/2 inches.
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| Keyed chuck and adapter for use with an SDS drill © Eugene Brennan |
Can I Use “Normal” Drill Bits With an SDS Drill?
Not directly, but you can use a standard keyed or keyless chuck. These are supplied with an SDS adapter for fitting into the SDS chuck of the drill. This enables non-SDS conventional round shank drill bits to be used. (or hex shank, flat wood bits).
Note that you normally can’t use these chucks with hammer action for drilling masonry.
Using Drill Bits With a Cordless Drill
My guide detailing settings for cordless drills explains the function of the various settings on these types of power drills and how they should be used.
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| © Eugene Brennan |
A Summary of Materials and Drill Bit Types
| Material | Drill Bit Type | Notes |
|---|---|---|
| Metal | HSS, Titanium coated, Cobalt Alloy, Step bit, HSS hole saw | Preferably Cobalt for stainless steel or hard steel |
| Wood | Spade(flat bit), Lip and Spur, Auger bit, Hole saw, Step bit, HSS bit | HSS for small to medium sized holes if nothing else available, but use a slow drilling speed |
| Plastic | Lip and spur, hole saw, HSS, Step bit | HSS should be used at low speed to avoid melting edges of hole |
| Masonry | Masonry bit, Diamond core bit | Ideally use an SDS bit and power drill with an SDS chuck for drilling large holes |
| Glass and Tile | Spear head, diamond coated bit | Use water for cooling and lubrication |
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| A pillar drill LHOON, CC BY-SA 2.5, via Wikimedia Commons |
What Is a Pillar Drill Used For?
Pillar drills (also known as bench drills, pedestal drills or drill presses) are common machine tools tools in a workshop or industrial setting. They consist of a base that rests on a floor or bench, an attached column, adjustable table that can slide up and down the column (usually with a vice attached), a drill head that drives a spindle and a chuck.
A motor inside the drill head drives the spindle via a pulley or gear arrangement. A lever with three or four handles is used to move the spindle and chuck vertically. A pair of pulleys with stepped diameters inside the drill head are connected using a v-belt. By adjusting the position of the belt on the two pulleys, the rotational speed of the spindle can be varied. This control of gear ratio allows high speed, low torque to be selected for small diameter drill bits, and vice versa for larger diameter bits.
The bench drill version of the pillar drill is ideal for DIYers because it is more portable and can be located on a workbench.
Pillar drills have several advantages:
- Holes can be drilled perpendicular to a workpiece without the bit going off course at an angle.
- The spindle is moved downwards by a lever using a rack and pinion mechanism. The mechanical advantage makes it easier to press the bit into the workpiece than would be the case with a conventional corded or cordless power drill.
- The vice enables the workpiece to be held securely so it doesn’t spin if the bit sticks.
- Large diameter drill bits can be run at low speed, higher torque by varying belt position. (Lowering the speed on a conventional power drill, just reduces power but torque isn’t increased).
Troubleshooting Drilling Problems
- Bit doesn’t cut. Is the bit turning the right way? Apart from the drill bit not being sharp, a common mistake by newbies is to set their drill on reverse so that the bit turns the wrong way. A bit should turn clockwise when looking from the chuck towards the tip of the bit.
- Squealing bit. This is usually the result of a bit being blunt or not lubricated.
- Bit finds it difficult to turn in material. Speed too high and not enough torque or feed rate too high. When drilling timber or other soft materials, listen to the power drill. If it’s struggling and the bit is slowing down, reduce the pressure and ease the bit into the material.
How to Drill Steel, Wood and Masonry
FAQs
What is the best drill bit for wood?
The best drill bit for wood screws is a pilot or countersink bit. Pilot bits create a small hole for the screw to start in, while countersink bits ensure the screw head sits flush with the wood surface.
What is the difference between a wood drill bit and a regular drill bit?
Wood drill bits typically have pointed tips and flutes designed for efficient wood chip removal. Regular drill bits, on the other hand, are more versatile and can handle various materials. Wood bits may not work as well on metal or other hard surfaces.
Which drill bits make large holes in wood?
For large holes in wood, use spade bits or hole saws. Spade bits are suitable for holes up to 1.5 inches in diameter, while hole saws are designed for larger holes, typically ranging from 1.5 inches to several inches in diameter.
Can you use a metal drill bit for wood?
While it’s possible to use a metal drill bit on wood, it’s not ideal. Metal drill bits are designed for harder materials and may result in a rougher finish in wood. It’s recommended to use wood-specific bits for cleaner and more efficient drilling in wooden surfaces.
References
- Jackson, A., & Day, D. (1993). Collins Complete Diy Manual. HarperCollins.
- Drill Bits Buying Guide | Screwfix Direct
Disclaimer
This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.
Power and hand tools can be dangerous. Read and understand all manuals before use and take reasonable precautions including wearing personal protection equipment (PPE) to prevent against injury.
© 2012 Eugene Brennan
Questions from readers. You can comment at the end of the article
Akshay Chauhan on November 01, 2019:
which Drill i should prefer if i want to drill through holes of 22 mm Dia into a 2 ft. X 2 ft. X 150mm Solid MS Block
Eugene Brennan (author) from Ireland on November 01, 2019:
That’s quite a hole if you want to drill all the way through. It sounds like a job for a pillar drill so that the hole is drilled perpendicular and doesn’t go off at an angle. A HSS or cobalt bit would work, but a hand operated power drill would turn too fast for a bit of this diameter (a pillar drill allows you to change belts, reduce speed and increase torque). You could drill slowly if the hand drill has variable speed, but risk burning it out. A drill with a safety clutch is also essential when drilling large holes in case the bit gets stuck. Lubrication/cooling of the bit would also be necessary.
Kels on June 16, 2018:
Hello,
Thanks for the great article!
I was just wondering.. I am needing to get a drill bit for some hard wood like tree stumps etc. Would I need to get a hole saw drill bit or a spade drill bit ? The stumps are really big and I want to put decent holes in them to put tea lights in them.
What drills bits and drill would you recommend for this project?
Thanks for your help!
Eugene Brennan (author) from Ireland on March 27, 2019:
Hi Kels,
Hole saws are only useful if you can drill all the way through (e.g. when drilling through boards) so that the waste can drop out.
You can use spade bits or auger bits. Spade bits are available to 40 mm diameter and similarly for auger bits. Both can be used with extensions for deep holes.
If you only need to drill shallow holes, a Forstner bit is probably the best option. These are available in diameters up to 2 1/8″. The only issue is the fact that your drilling into the end grain when drilling a stump, so progress may be quite slow.
nathan on April 18, 2018:
what type of drill bit to make a big hole in spadikam stones.already have small hole.
Eugene Brennan (author) from Ireland on April 19, 2018:
The normal technique for drilling holes in stone and concrete is to use a core drill. Minimum size would be about 20 mm. However you can buy small diamond core bits, similar to the diamond coated bits used to drill glass. Google “small diamond core drills”.
Larry Canada on April 01, 2018:
Great article. Thanks for sharing. Was looking through all my bits and now i know what they are specifically made for
Vijay Ratnakar on March 31, 2017:
Thanks . I stand much benefited by going through this article and am now in a position to use a drill effectively. In fact this is the only guide from which I have learnt the art of drilling and that too in just one sitting all by myself.
alex on March 26, 2017:
Thanks for a great tutorial
Stephen C Brand on March 16, 2017:
Very helpful, thank you
Tammy on March 07, 2017:
Yeah this was useful…. Thanks for the brief tutorial
Gail on May 26, 2016:
Thanks for this useful info. have shared it on facebook. Can I use any brand of drill bits with my about to be purchased Black & Decker?
Eugene Brennan (author) from Ireland on May 26, 2016:
Hi Gail! Yes you can use any brand of drill bits (although Black & Decker would like you to use theirs!). Some are better quality than others, and cheap bargain basement bits can snap easily or wear out rapidly, especially those used for drilling masonry.
Binter, CC BY-SA 3.0, via Wikimedia Commons
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