Ask a cabinet shop owner when they last sharpened their saw blades. They’ll probably give you a rough answer. Ask them when they last sharpened their router bits — and you’ll usually get a blank stare, or “when they stop cutting.”
Router bits are the most neglected tool in the shop. They’re small, relatively cheap individually, and the degradation is gradual enough that nobody notices until something goes wrong.
Here are five signals your bits are past due — and what each one is costing you.
1. Fuzzing on MDF Edges
MDF is the ideal material for showing router bit wear. A sharp upcut spiral produces a clean, almost burnished edge. A dull one produces fuzz — fine fibers that don’t fully separate and stand off the surface.
If you’re sanding MDF edges before paint, ask yourself when you stopped having to do that. Chances are, you’ve been doing it so long you’ve forgotten it’s optional with sharp tooling.
What it costs: 30–60 seconds of sanding per linear foot of routed edge. In a production environment, that’s hours per week.
2. Burning on Solid Wood
Burning on a router profile almost always means one of two things: the bit is dull, or the feed rate is too slow. The fix for dull is sharpening. The common (wrong) fix is slowing down even more — which makes the burning worse.
A sharp bit at the right feed rate should leave a surface ready for finish sanding, not a charred edge that requires aggressive removal.
What it costs: Rework time, plus occasional outright rejection of pieces that burned too deeply to recover.
3. Deflection on Long Profiles
As a bit dulls, cutting resistance increases. The bit — particularly a long one — deflects under that load. The profile starts to drift off the bearing or fence. You’ll see this as inconsistent depth across a long profile, or a profile that “wanders” on the climb cut.
This is also a quality problem that’s easy to misdiagnose as feed rate, setup, or wood movement.
What it costs: Profile inconsistency on large runs, occasional part rejection, troubleshooting time.
4. You Can Hear the Difference
This one’s subjective but real. A sharp bit at the correct feed rate makes a clean, consistent sound. A dull bit sounds labored — a slightly lower pitch, more resistance in the sound. Experienced operators know this sound and usually say it’s “time to change the bit” without being able to articulate exactly why.
Trust that instinct. It’s telling you something.
What it costs: Nothing immediate. But if you ignore it, you’re heading toward one of the other signs on this list.
5. Burning on the Bearing
Examine the bearings on your profile bits after a long run. A sharp bit with a good feed rate generates minimal friction at the bearing. A dull bit, especially one where the operator slowed the feed to compensate, can get the bearing hot enough to damage it.
A failed bearing mid-cut is a quality problem and a safety problem simultaneously. The bit deflects unpredictably, and the profile is ruined.
What it costs: A new bearing ($8–$25 each), lost production time, and the potential for a ruined workpiece.
What Sharpening a Router Bit Actually Involves
Unlike saw blades, which most shops understand can be sharpened, router bits are often thought of as disposable. That’s partly a price perception issue — a router bit is $40, not $400.
But a half-inch upcut spiral bit sharpened four times over its life saves you $120 in replacement costs and cuts better than a worn new bit throughout. For profile bits with complex geometry, the economics are even stronger.
Proper sharpening requires matching the original grind angles on each flute and maintaining the balance between flutes. Done wrong, it’s worse than not sharpening. Done right, the bit is functionally new.
Ciklek services router bits, profile bits, and spiral bits alongside saw blades — on the same pickup cycle. One service. All your tooling.