Fret slotting station

The blind station

The station does not know what scale it is cutting. Everything about the instrument lives on the template — a laser-cut sheet whose notches carry the fret positions — so changing instrument means changing template, not adjusting the jig.

You cut one template per instrument and keep it. The station itself you build once.

Calibration

Once, after assembly:

1. Print the fit coupon, read the clearances off it, and print everything else with the profile it chose.
2. Measure the calibration strip on the cut sheet: the 0→200 and 0→400 distances. A linear error you can ignore — it behaves like a slightly different scale, and the bridge is set from the real twelfth fret anyway. A non-linear error over 0.1 mm is a cutting fault; take it back to the shop.
3. Yaw. On a test template, cut a slot into a scrap board. Turn the board 180° on the same template and cut the same notch again. The difference between the two slots across the width is twice the yaw error. Turn the eccentric bushing on the +X stop until the slots coincide, then lock it.

Per saw:

4. Print the depth-stop halves for your plate thickness — the slot is thickness plus 0.30 mm.
5. Preload the compliant rollers: tighten until you feel light resistance as you push the saw through by hand, then lock.

Per board:

6. Tape the fingerboard to the template, its centreline on the engraved axis.
7. Depth stops low. Put the saw teeth on the edge of the board at its widest point. Turn both M6 screws up until they touch the spine, then back each off by N turns — N millimetres of depth at the edge, so 2.5 turns is 2.5 mm. Lock them.

Which saws fit

Between 17.7 and 36.0 mm of plate under the spine. Below that the plate cannot reach from its deepest tooth position past the guide bearings to the spine; above it the depth-stop halves run out of travel before the spine meets them.

• Hosco TL-H-FSW / Thomann Maxparts JS-BS1257 — 0.57 mm plate. The saw this station was designed around.
• StewMac fret saw — 0.58 mm plate. Works the same; print the depth stop for 0.58.
• A dozuki reground for fretting — Anything with 17.7 to 36.0 mm of plate under the spine fits. A deep-blade dozuki does not.

In what order

1. Generate and print the fit coupon. It costs a few grams and decides the clearance profile for everything else.
2. Generate the station with that profile, print the parts, and send the base plate DXF to a laser shop with the template.
3. Generate the depth stop for your saw and print two.
4. Generate a template for the instrument you are building. One per instrument, and you keep them.