How to sharpen a metal drill bit (2026)
Quick Answer
To sharpen a metal drill bit, restore the original point shape evenly on both cutting edges, keep the bit cool, and check that the tip remains centred and symmetrical. The most reliable home methods are a bench grinder used carefully or a purpose-made drill bit sharpener. If the bit is badly chipped, overheated, unusually large, or a specialist geometry bit, it is often better to have it sharpened professionally or replace it.
Overview
A dull metal drill bit does not just cut slowly; it creates excess heat, wanders off centre, leaves poor holes, and can strain the drill and the operator. Sharpening works by recreating the cutting lips and the clearance behind them so the bit can shear metal cleanly instead of rubbing. For common twist drills used on steel and other metals, the key is not removing lots of material but restoring an even, balanced point. Both lips need to be the same length and angle, with the chisel edge centred at the tip. If one side is longer than the other, the bit will cut oversize, vibrate, or pull off line. Routine care matters as much as sharpening: clean bits after use, avoid overheating them in service, and touch them up as soon as performance drops rather than waiting until they are badly worn. For occasional users, a drill bit sharpening attachment or dedicated sharpener is easier to repeat accurately than freehand grinding. For experienced users, a fine grinder setup can be faster. Carbide bits, coated bits where preserving the coating matters, and bits with split-point or specialist geometries need more care and may not be worth casual freehand sharpening.
Who this is for
DIY users, maintenance staff, and workshop users sharpening common high-speed steel twist drill bits for metal by hand or with a drill-bit sharpener.
What you’ll need
- Clean metal twist drill bit
- Eye protection
- Bench grinder with a suitable wheel, or a purpose-made drill bit sharpener
- Good lighting
- A container of clean water for cooling when grinding
- A drill bit gauge or the manufacturer’s setup guide if using a sharpening jig
- A brush or cloth for cleaning swarf and oil
Before you start
Confirm the bit is a standard metal twist drill and not badly bent, deeply chipped, cracked, or missing a large section of the tip. Read the grinder or sharpener manual first, especially for wheel condition, guards, rests, and correct setup. If the bit is carbide, masonry-tipped, step-drill, or a specialist production bit, do not assume the same method applies; check the manufacturer guidance or use a professional sharpening service.
Step-by-step
- 1
Inspect and clean the bit
Wipe off oil, dirt, and packed swarf, then inspect the point under good light. Look for rounded cutting lips, chips, blueing from heat, cracks, and whether the point is visibly off-centre.
Why: You need to know whether the bit is suitable for sharpening and how much material really needs removing. Dirt also makes it harder to see the existing geometry.
- 2
Choose the sharpening method
Use a purpose-made drill bit sharpener if you want the easiest repeatable result, especially on smaller bits. Use a bench grinder only if you can control the angle steadily and safely. Set up according to the machine manual and make sure the wheel is in good condition.
Why: Accurate geometry matters more than speed. A jig or dedicated sharpener helps keep both lips even and the point centred.
- 3
Match the original point geometry
Before grinding, study the existing point or compare it with the manufacturer’s guidance for that bit type. The aim is to preserve the correct point form for metal drilling and sharpen both cutting lips equally. If you are using a sharpener, set it for the bit type and size as instructed.
Why: Different bits use different point shapes. Grinding without reference can create a point that rubs, wanders, or breaks quickly.
- 4
Grind one lip lightly, then the other
Remove a small amount from the first cutting lip, then repeat on the second, alternating sides frequently. Keep the bit supported and controlled; do not force it into the wheel. If grinding freehand, maintain the lip angle and create relief behind the cutting edge so the edge leads and the heel falls away.
Why: Alternating sides helps keep the lips equal in length and angle. Relief behind the edge is what allows cutting instead of rubbing.
- 5
Keep the bit cool
Make very short grinding passes and cool the bit in water between passes if it becomes hot. Stop immediately if the tip starts discolouring or you cannot hold it comfortably.
Why: Excess heat can draw the temper from high-speed steel and damage the cutting edge, leaving a bit that dulls quickly.
- 6
Check symmetry and the centred point
After a few light passes, stop and compare both lips. The cutting edges should appear equal, and the centre of the point should not be pushed to one side. If one lip is longer, remove a little more from that side only until the point balances.
Why: A centred, symmetrical point is essential for straight drilling, proper hole size, and smooth cutting.
- 7
Test on scrap metal
Drill a test hole in suitable scrap using the correct speed, firm support, and cutting fluid if appropriate for the metal. Watch the chips and feel the cut. A sharpened bit should start more cleanly and cut without excessive pressure.
Why: A test cut confirms whether the bit is actually cutting properly or still rubbing, wandering, or producing uneven chips.
- 8
Store and maintain the bit
After sharpening, dry the bit, remove grit, and store it so the point is protected from knocking against other tools. Touch up the bit when cutting performance first drops rather than waiting for heavy damage.
Why: Proper storage prevents edge damage, and early touch-ups remove less material and help the bit last longer.
Why this works
A twist drill cuts mainly at the two lips near the point. Sharpening restores those lips and the clearance behind them so the edge can shear metal while the rest of the point clears away. When both lips match, the chisel edge stays centred and the drill cuts straight with less heat and pressure.
Common mistakes to avoid
- Grinding one lip more than the other so the point is off-centre
- Overheating the tip and ruining edge hardness
- Removing too much material instead of making light corrective passes
- Failing to create enough clearance behind the cutting edge
- Trying to sharpen cracked, badly chipped, or bent bits that should be replaced
- Using a damaged or unsuitable grinding wheel
Troubleshooting
The bit still squeals or rubs instead of cutting
Add proper relief behind the cutting lips and check that the cutting edges are actually sharp rather than rounded.
The bit drills an oversize or rough hole
Check whether one lip is longer than the other or the point is off-centre; regrind lightly to restore symmetry.
The bit wanders when starting the hole
Make sure the point is symmetrical and use a centre punch on the work if appropriate. If the tip geometry is uneven, resharpen.
The edge goes dull again very quickly
You may have overheated the bit during sharpening or are drilling at the wrong speed or pressure. Resharpen carefully and review drilling technique.
Chips come from only one side
One cutting lip is doing more work than the other. Correct the lip lengths and angles so both sides share the cut.
Compare your options
Bench grinder, freehand
Best for: Experienced users sharpening common workshop bits quickly
Pros: Fast, flexible, no special bit-specific accessories needed once set up
Cons: Easy to get the geometry wrong, higher risk of overheating, less consistent on small bits
Purpose-made drill bit sharpener
Best for: DIY users and anyone wanting repeatable results
Pros: Better control of angle and symmetry, easier for smaller bits, lower skill barrier
Cons: Less flexible for unusual bit types, depends on correct setup, may not handle every geometry
Professional sharpening service
Best for: Specialist bits, larger quantities, carbide, or high-value tools
Pros: Accurate geometry, suitable equipment, useful for damaged or specialist bits
Cons: Takes time and may not be worthwhile for cheap common bits
| Option | Best for | Pros | Cons |
|---|---|---|---|
| Bench grinder, freehand | Experienced users sharpening common workshop bits quickly | Fast, flexible, no special bit-specific accessories needed once set up | Easy to get the geometry wrong, higher risk of overheating, less consistent on small bits |
| Purpose-made drill bit sharpener | DIY users and anyone wanting repeatable results | Better control of angle and symmetry, easier for smaller bits, lower skill barrier | Less flexible for unusual bit types, depends on correct setup, may not handle every geometry |
| Professional sharpening service | Specialist bits, larger quantities, carbide, or high-value tools | Accurate geometry, suitable equipment, useful for damaged or specialist bits | Takes time and may not be worthwhile for cheap common bits |
Alternatives
- Replace the bit if it is inexpensive, heavily worn, cracked, or repeatedly overheated
- Use a manufacturer-approved sharpening attachment or jig for your grinder
- Send specialist or carbide bits to a professional sharpening service
Pro tips
- Touch up bits early; a lightly dulled bit is easier to restore accurately than a badly worn one.
- Label or separate bits by material and use so your metal bits are not damaged by unsuitable jobs.
- If you are learning freehand grinding, practise on larger worn bits first because the geometry is easier to see.
- Use scrap metal for testing rather than judging the edge by appearance alone.
- If the point repeatedly goes off-centre, switch to a sharpening jig or dedicated sharpener.
Safety notes
- Wear eye protection whenever grinding or test drilling.
- Keep grinder guards and tool rests correctly fitted and adjusted as specified by the machine manufacturer.
- Do not grind a bit that is too hot to control safely; cool it first.
- Keep loose clothing, gloves, and long hair away from rotating wheels and drills.
- Inspect grinding wheels for damage and use only wheels suitable for the machine and task.
What this guide does not cover: This guide covers common metal twist drill bits only and does not give exact angles, machine settings, or wheel specifications because those depend on the bit design, the sharpener or grinder used, and the manufacturer’s instructions.
Cost considerations
Sharpening usually extends bit life and reduces replacement costs, especially for quality drill bits. For low-cost small bits, replacement can be more practical than spending time trying to correct severe damage. Specialist sharpeners or professional services make more financial sense when you maintain bits regularly or use higher-value tooling.
Frequently asked questions
How often should I sharpen a metal drill bit?+
Sharpen it whenever cutting performance drops: slower drilling, more heat, squealing, wandering, or needing extra pressure. In routine care, inspect bits before use and clean them after use; heavy users may touch up frequently, while occasional users may only sharpen when symptoms appear.
Can I sharpen cobalt drill bits?+
Many cobalt alloy twist drill bits can be sharpened, but they are harder and less forgiving than ordinary high-speed steel. Use the correct equipment and a light touch, and check the manufacturer guidance if in doubt.
Should I cool the bit in water while sharpening?+
For ordinary grinder sharpening, keeping the bit from overheating is important, and brief cooling between light passes is common practice. Follow the sharpener or grinder manufacturer’s instructions and avoid heavy grinding that generates excessive heat in the first place.
Can I sharpen coated drill bits?+
You can often restore the cutting edge, but sharpening may remove coating at the point. That can reduce some of the original coating benefit, so it is worth checking the manufacturer’s advice for that bit type.
When should I stop and replace the bit instead?+
Replace it if it is cracked, bent, deeply chipped, repeatedly overheated, or so worn that restoring the point would remove too much material. Also replace cheap common bits if sharpening takes more effort than the bit is worth.
Sources & references
Guidance on this page is traced to documented sources. Last checked 25 September 2026.
- OSHA - Abrasive Wheel Machinery and Tool Rest/Guard Safety · government
Supports grinder safety points such as proper guards, work rests, and safe operation around abrasive wheels.
- DEWALT - Drill Bit and Accessory Guidance · manufacturer
Supports checking manufacturer guidance for bit type, point geometry, and maintenance recommendations rather than guessing settings or suitability.
- Dormer Pramet - Drilling Knowledge and Drill Geometry Guidance · manufacturer
Supports the importance of drill point geometry, balanced cutting lips, and selecting geometry appropriate to the material and application.
Basic drill sharpening principles and grinder safety practices change slowly, though machine-specific instructions vary by manufacturer.