Most shops send drills out for resharpening without asking a more important question first: is resharpening actually the right operation? A standard regrind restores the cutting edges — it does not address everything that heavy use does to a drill bit's geometry. When a bit has accumulated enough hours in difficult material, reconditioning is the correct answer, and a simple regrind will put a fresh edge on a tool that still won't perform correctly.
Understanding the difference matters because it affects your cost-per-part calculation, your reject rate, and how long a given drill lasts in your program.
What a Standard Regrind Actually Does
A resharpening operation restores the cutting lip geometry — point angle, lip relief, and lip height symmetry. On a well-maintained bit that has been returned for service at regular intervals, this is entirely sufficient. The web thickness is acceptable, the flutes are clean, and the drill runs true after the regrind.
The limitation is that resharpening only addresses the tip. It does not fix problems that have developed further up the bit: flute wear from chip evacuation friction, margin damage from rubbing in tight holes, or web thickness that has grown significantly from repeated shortening over previous regrind cycles.
What Reconditioning Adds
Reconditioning is a more complete operation. It includes the standard regrind but also addresses:
- Web thinning: Every regrind shortens the bit slightly from the tip. As the bit gets shorter, it's cutting at a section where the web — the solid core running through the center of the drill — is thicker. A thick web increases thrust and makes the chisel edge cut like a punch rather than a blade. Web thinning relieves this by grinding a relief into the web at the tip, restoring the original chisel edge width.
- Margin reconditioning: The margins — the narrow cylindrical lands on the outside of the flutes — guide the drill in the hole and maintain diameter. In abrasive materials or hard workpieces, the margins wear and the drill starts cutting undersize or drifting. Reconditioning dresses the margins back to correct diameter and surface finish.
- Flute cleaning and polishing: Buildup in the flutes — particularly on bits that have been run without coolant or in sticky materials — increases chip-packing, raises cutting temperatures, and accelerates edge breakdown. Reconditioning removes this buildup.
- Split point restoration: On bits originally manufactured with a split point, repeated regrinds can destroy the secondary geometry that creates the self-centering effect. Reconditioning can restore the split, recovering the thrust advantage that was one reason you bought the bit in the first place.
Reading the Tip After Heavy Use
The tip geometry tells you which operation is appropriate. Look for these indicators that reconditioning is warranted rather than a simple regrind:
Web thickness creep: Hold the bit point-up under a light. On a correctly ground jobber drill in the 3/8" to 1/2" range, the chisel edge should be roughly 15–20% of the drill diameter. If it looks wider than that relative to the tip, the bit has been shortened enough that you're now working in a section where the web is thicker. A regrind will put a sharp edge on a geometry that still produces excessive thrust.
Diameter loss: Measure the bit across the margins with a micrometer. If it's come down more than .003"–.005" from nominal on a precision drill, margin wear is affecting hole quality. You'll cut undersize holes regardless of how sharp the tip is.
Flute roughness: Run a fingernail along the flute. It should be smooth enough that chips flow freely. Roughness from corrosion, material buildup, or galling means chip evacuation is compromised and heat buildup will accelerate edge wear from the first cut.
Visible margin chipping: Small nicks or flat spots on the margins produce chatter and hole diameter variation. No amount of tip regrinding fixes this.
The Economics of Getting It Right
Reconditioning costs more than resharpening. That's the straightforward part. The less straightforward part is that sending a bit that needs reconditioning out for a simple regrind is often false economy. You spend money on the regrind, put the bit back in service, and it underperforms — either because thrust is still high, holes are still going out of tolerance, or the bit burns up faster than it should on the next job.
The correct framework is: if the regrind cost plus the cost of the performance problem exceeds the reconditioning cost, recondition. For a high-volume production drill in a tight-tolerance program, reconditioning is almost always the right call once the bit has been through two or three regrind cycles. For a general-purpose bit doing low-volume work in easy material, a regrind is likely fine for several more cycles before reconditioning is warranted.
When to Replace Outright
Reconditioning also has limits. A bit that has been shortened to the point where it's structurally compromised, where the flute depth is insufficient for the required hole depth, or where the margin has worn below useful diameter is a candidate for replacement — not reconditioning. A good service shop will tell you this rather than taking your money on a bit they can't recover. Ask for this assessment when you send a batch in.
The point is not that reconditioning is always better — it's that the question is worth asking. Knowing what your bits look like after heavy use, and what each condition actually requires, puts you in a position to make the right call rather than defaulting to the cheapest option every time.