How to Sharpen Drill Bits on a Bench Grinder

The bit stops cutting and starts smoking. It squeals against the metal and throws off a fine blue dust instead of curled chips. It polishes a shiny little circle into the workpiece without ever going deeper.

Every shop has felt that exact moment. The point is dull. The fix is learning how to sharpen drill bits on a bench grinder instead of reaching for a new one.

It takes a steady hand, a dressed wheel, and a clear idea of what a good point looks like. This guide covers point geometry, grinder setup, and the grinding motion itself. It also covers the tricky calls, like quenching and knowing when a bit is done.

Drill Point Anatomy in 90 Seconds

A twist drill has two cutting lips that meet at the very tip. Where they meet is the chisel edge, a short flat section that pushes and scrapes rather than cuts on its own.

Behind each lip sits a relief surface. It is ground back at an angle so the heel of the bit clears the hole instead of dragging against it.

Without that relief, a lip cannot cut no matter how sharp it looks. Down the center of the bit runs the web, the solid core between the two flutes. It thickens slightly as you grind further up the bit over its life.

118 vs 135 Degrees: Point Geometry Explained Plainly

Most twist bits leave the factory at 118 degrees or 135 degrees. The number describes the actual angle at the tip, not just a style choice.

A 118 degree point is the general purpose angle. It cuts well in wood, mild steel, and aluminum.

A 135 degree point is flatter and paired with a split point, two extra facets ground into the chisel edge itself. Drill Doctor, maker of bench top sharpening machines, describes that split point as turning the chisel edge into one continuous cutting surface. It replaces what would otherwise be a blunt scraping ridge.

The practical result is a bit that starts on contact without walking. It also needs noticeably less thrust to feed into hard steel.

Regrind a 135 degree bit freehand and reset only the two main lips, and you lose the split point. The bit then behaves closer to a plain 118 degree tip.

A close eye on the actual angle helps more than guessing. Our sharpening angle calculator gives a fixed reference to check against. It keeps a regrind honest to the bit’s original geometry.

Reading the Lips and Chisel Edge Before You Grind

Look at the tip under good light before you touch a wheel. A dull bit usually shows a small shiny, rounded facet at the point instead of a crisp edge.

That shine is the same telltale sign covered in our sharpening basics library for edges generally. Light reflects off a rounded surface, not off a defined line.

If one lip looks longer or shinier than the other, that asymmetry is often the real problem. Squealing, smoking, and fine blue chips instead of curled ones all mean the same thing: the bit needs attention now.

A bit that walks sideways before it starts cutting is telling you the same story from the workpiece side.

Safety First: Eye Protection and the Rest Gap

Wear real eye protection, not reading glasses, before the wheel ever spins up. Grinding wheels throw sparks and occasional grit. A stray piece heading for an eye does not care how careful you normally are.

Check the tool rest gap before you start. Most grinder manuals call for no more than about 1/8 inch between the wheel and the rest.

A wider gap lets a small bit or its shank get pulled down into that space. Keep the wheel dressed and free of a glazed, shiny surface too.

A glazed wheel grinds slower, runs hotter, and makes it easier to overheat a bit before you notice.

Bench Grinder Setup for Sharpening Drill Bits

Set the tool rest so it supports the shank at roughly 59 degrees off the wheel face. That lines up with a standard 118 degree included angle at the tip.

A strip of tape or a scribed line on the rest gives you a repeatable reference. Good light matters more than most people expect.

Position a lamp so it lights the tip directly. You are judging a small shiny facet against a dull one, and shadows hide that difference fast.

The same wheel that handles this job can also work on other edges around the shop. Our guide to sharpening a mower blade on that same bench grinder covers those setup differences.

Keep a cup of water within reach before you start. You will be dipping the bit often, and reaching across the bench mid grind is how fingers meet the wheel.

How to Sharpen Drill Bits: The Freehand Grinding Motion

Hold the bit by the shank with your index finger braced against the tool rest. Bring one lip to the wheel first, flat against the face, and touch it lightly rather than shoving it in.

This is the core motion behind how to sharpen drill bits freehand. Touch the lip to the wheel, then slowly drop the shank while rotating it slightly.

That drop and roll is what grinds the relief angle in behind the lip instead of leaving it flat. Lift off, dip the tip in water, and repeat the same motion on the second lip.

Match the number of light passes on each side. Do not just grind until one side looks done and stop there.

Some experienced machinists ease pressure and slow the rotation on the very last pass. That leaves the cutting edge just slightly proud of the heel.

That final light touch is what separates a bit that bites immediately from one that needs a few extra seconds to start.

Checking Symmetry: Why Equal Lips Matter

Hold the finished bit tip up, point away from you, and compare the two lips by eye. Both should be the same length and meet the center line at the same angle.

An oversized or oval hole is almost always the result of uneven lips, not a dull bit. One lip cuts more than the other, and the bit wobbles around a wider path than its actual diameter.

A drill point gauge or a printed template removes the guesswork if your eye is not trained yet. Checking symmetry takes a few extra seconds and saves a ruined hole in expensive stock.

The Quenching Debate: Cool It or Not

Dipping a hot bit in water between passes is close to universal shop practice. Most people do it without a second thought.

Some careful voices push back on that habit, and the disagreement is worth understanding. Tormek’s own sharpening guidance warns against cooling a bit abruptly from a high temperature. That shock can cause micro cracks that are invisible to the eye.

The concern is real for a bit that has already gone blue hot at the tip. At that point the temper is already compromised anyway.

The middle ground most experienced sharpeners land on is frequent, small dips from a low temperature. Never a rescue dunk of a glowing or blued tip.

Grind light passes, dip often, and if a tip ever turns blue, back off pressure rather than reach for the water.

Drill Doctor: The Easy Path

A guided machine like the Drill Doctor removes most of the freehand learning curve. You set the bit diameter and point angle. The machine holds that geometry steady while you rotate the bit through the guide.

These machines typically handle bits from about 3/32 inch up to 1/2 inch. Larger models stretch to 3/4 inch, and most can regrind a proper split point along with the two main lips.

Plenty of owners who use one for everyday bits still finish larger bits by hand. The biggest sizes fall outside what most guided machines cover well.

Sorting through grinders, guided machines, and jigs can feel like a lot at once. Our tool for matching a sharpener to your setup narrows the options based on what you actually sharpen.

HSS vs Cobalt vs Masonry: What Survives Resharpening

Not every bit responds to sharpening the same way. The material behind the point changes what tool and technique actually work.

Bit type	What it is	Wheel needed	Resharpens well?
High speed steel	Standard tool steel, heat resistant	Regular aluminum oxide wheel	Yes, repeatedly
Cobalt	Steel alloyed with about 5 percent cobalt	Regular aluminum oxide wheel	Yes, holds up under heat
Titanium coated	HSS with a thin surface coating	Regular aluminum oxide wheel	Coating grinds away, becomes plain HSS after
Masonry	Carbide tip brazed to a steel body	Diamond or green silicon carbide wheel	Only with the correct wheel

Irwin notes that cobalt is alloyed through the entire bit, not applied as a surface layer. That is exactly why the improved heat resistance survives every future sharpening.

A titanium nitride coating, by contrast, only ever covers the outer surface. The very first grind removes it for good, and the bit performs like plain HSS after that.

Masonry bits carry a brazed carbide tip ground at roughly 130 to 135 degrees. A standard aluminum oxide wheel will not touch carbide effectively. Grinding one needs a diamond wheel or a green silicon carbide wheel instead.

When a Drill Bit Is Toast

Some bits are worth one more grind, and some are not. A bit under about 1/8 inch is usually cheaper to replace than to sharpen, since there is barely enough steel left to hold an angle.

A bit ground down repeatedly develops a noticeably thicker web near the tip. That means more force to feed it, and the chips stop clearing as cleanly.

A cracked, chipped, or bent shank is a hard stop, no matter how good the point still looks. On a masonry bit, a chipped or missing carbide tip cannot be restored on a home grinder either.

When a bit needs constant regrinding just to hold an edge for a few holes, that is the steel telling you it is done.

Frequently Asked Questions

Can you sharpen a drill bit without a grinder?

Yes, with a small file or fine sharpening stone, though the results are harder to keep symmetrical. Many shops use a hand file only for a quick touch up between real sharpenings.

What angle should a drill bit be sharpened at?

118 degrees is the standard general purpose angle. 135 degrees with a split point suits harder metals and starts without a punch mark.

Why does my sharpened bit still not cut straight?

Uneven lips are the most common cause, even when the point looks sharp overall. One lip doing more work than the other pulls the bit off center and produces an oversized hole.

Can you sharpen a titanium coated bit?

You can grind it like any HSS bit, but the coating will not survive the first sharpening. After that it performs like a plain HSS bit.

Is it safe to dip a hot bit in water while grinding?

Frequent small dips from a low temperature are standard shop practice and considered safe. Avoid quenching a bit that has already turned blue, since the temper is already affected by then.

Now you know how to sharpen drill bits on a bench grinder, from reading a dull tip through checking the lips for symmetry. For more equipment maintenance like this, browse our workshop tools guides for jigs, grinders, and shop sharpening projects.

Bench grinder already spinning? Chisels come back to life the same session. Follow the chisel method here.