Measuring drill bits at the tip
The point of a drill bit chips and wears faster than the cutting edges. Always measure about 1/8 inch back from the tip, across the full diameter of the flutes. A tip measurement can make a good bit look worn out.
Is your tool still good?
Measure your drill bits, saw blades, chisels, and router bits against published wear limits. Get a clear keep, sharpen, or replace recommendation in seconds.
Wear Limit Checker
Common measurement mistakes
Ignoring uneven wear on saw blades
Some teeth wear faster than others, especially if the blade has been used on different materials. Check at least three teeth spaced around the blade. If one tooth is significantly shorter, the blade may need replacement even if the average looks fine.
Confusing chisel bevel length with wear
A chisel that has been sharpened many times will have a longer bevel. That is normal. The real wear indicator is the flat area on the back of the blade. If the back is no longer flat, the chisel needs flattening before it can hold a good edge.
Not zeroing your caliper
A caliper that reads 0.002\" or 0.05 mm off zero will throw every measurement. Close the jaws fully and press zero before each session. This is the single most common source of error in the shop.
Full shop audit walkthrough
Once or twice a year, go through every cutting tool in your shop and check it against its wear limit. Here is a step-by-step process that takes about 30 minutes for a typical home workshop.
- Gather your tools. Pull out all drill bits, saw blades, chisels, router bits, and planer knives. Lay them on a clean bench so you can see everything at once.
- Start with the most-used items. The bits and blades you reach for most often are the ones most likely to be past their limit. Check these first.
- Measure and record. Use WearGauge for each tool. Enter the measurement, read the recommendation, and save it to local history. Write the result on a piece of tape and stick it to the tool or its case.
- Sort into three piles. Keep, sharpen, or replace. The sharpen pile goes to your sharpening station. The replace pile goes to your next shopping list.
- Check storage conditions. While everything is out, look for rust, damaged cases, or bits stored loose where they knock against each other. A small amount of rust can be cleaned off, but pitted cutting edges are done.
- Schedule the next audit. Set a reminder for six months from now. If you work wood heavily, check every three months instead.
Wear limit reference table
These are the default limits used by WearGauge. They are based on common manufacturer specs and workshop references. Your specific brand may differ slightly.
| Tool type | What to measure | Keep | Sharpen | Replace |
|---|---|---|---|---|
| Drill bit (twist) | Diameter at cutting lips | Within 0.5% of original | 0.5% to 1.0% undersize | More than 1.0% undersize |
| Circular saw blade | Tooth height remaining | Over 80% of original | 60% to 80% remaining | Under 60% remaining |
| Wood chisel | Back flatness (gap under straightedge) | No visible gap | Gap under 0.003\" (0.08 mm) | Gap over 0.003\" (0.08 mm) |
| Router bit | Cutting diameter | Within 1% of original | 1% to 2% undersize | More than 2% undersize |
| Planer knife | Knife width remaining | Over 85% of original | 70% to 85% remaining | Under 70% remaining |
| Forstner bit | Outer rim diameter | Within 0.8% of original | 0.8% to 1.5% undersize | More than 1.5% undersize |
Why this exists
Most of us learn tool maintenance by watching someone else or by trial and error. That works, but it leaves gaps. You might throw away a drill bit that still had hundreds of holes left in it, or keep pushing a saw blade that was burning every board. WearGauge puts the numbers in front of you so the decision is clear.
This reference is built from published specs by tool makers like Bosch, DeWalt, Irwin, and Stanley, plus common workshop practice. It is not a substitute for the documentation that came with your specific tool, but it gives you a solid starting point when that paperwork is long gone.
WearGauge v1.1.0 · Last updated 2026 · Wear limits sourced from manufacturer published specs and workshop reference guides.