How it works
A V-bit cuts a triangular groove. Its two flanks meet at the included angle, so the groove widens by 2 × tan(half-angle) for every unit of depth. That means the width at the surface is a fixed multiple of the depth.
Solving for depth gives the depth a chosen line width needs; solving the other way shows what a set depth will cut. A bit with a flat tip starts with that width at zero depth, which is subtracted first.
Worked example
A 60° V-bit with a sharp tip cutting a 0.5 in wide line:
- Half-angle = 30°, tan = 0.5774
- Depth = (0.5 − 0) ÷ (2 × 0.5774) = 0.433 in
| Input | Value |
|---|---|
| Find | Depth for a line width |
| Included angle of the bit | 60 ° |
| Flat tip width | 0 in |
| Line width wanted (find depth) | 0.5 in |
| Cut depth (find width) | 0.25 in |
| Result | Value |
|---|---|
| Cut depth | 0.433 in |
| Line width at the surface | 0.5 in |
Assumptions and limits
- Uses the bit’s nominal included angle and tip width from the maker’s data. Worn or mis-ground bits differ.
- Ignores bit deflection and wood springback; measure a test cut.
- Depth is the cut depth of the tip below the surface. Flat-tip bits and stepovers in V-carve software may work differently.
Common questions
How deep should I cut with a 60 degree V-bit?
For a sharp tip, the depth is 0.866 times the line width. A 1/2 in line needs 0.433 in.
How deep for a 90 degree V-bit?
Depth is half the line width, so the groove is as deep as it is wide on each side.
What does the flat tip do?
It adds a fixed width at the bottom of the groove. The calculator accounts for it in both directions.
Does this work for a chamfer bit?
Yes for the same geometry: use the bit’s included angle, and depth from the width of the chamfer measured across the groove.
Sources
- Right-triangle geometry of a V-groove; the same relation V-carve software uses to set depth from width.
Updated 2026-09-30