Dovetail CNC workholding hardware

Dovetail key inserts and knobs for CNC workholding, using M5 hex head bolts.

Designed for grooves using a 1/2", 14° dovetail bit. I'm using 3/4" MDF but other material work better.

Knobs use captive 5m nuts by pausing during print.

Strength:

If you apply twisting torque directly to the inserts, the bolts can strip out the plastic inserts fairly easily, but in practice the clamping force you're applying stops this earlier.

These hold stops very well, when clamping down to the bed directly.

Use only clamping forces that "pinch" the work surface between the insert and the clamping object. Do not use toe clamps and similar, where the clamp is hovering above the board. It's very easy to shear a layer of MDF hand with reasonable leverage. May be better with other materials.

Print instructions

Print knobs and inserts upside down with no supports. I'm using 0.3mm height, 4 perimeters, 0.6mm perimeter width.

I recommend glueing/cementing/epoxying the bolts into the dovetail inserts. The inserts can jam into MDF a little bit, and if the bolts can move freely, it's difficult to un-jam them without removing the knob and workholding block.

I'm trying some different designs for them that may help prevent this.