Sharpener for Watchmaker Screwdriver

This is a simple to print and assemble fixture for sharpening a watchmaker's (or any other very small) screwdriver with a body smaller than 5.5mm in diameter.

Required Hardware:

• M3x12 bolt qty 2

• M2x4 bolt

• 608 bearing qty 2

• 7mm x 10mm spring, 9 lbf/in or similar. Smaller diameter such as 6 mm is also ok.

Printing:

Use 0.2mm structural default in pretty much any "usual" filament like PLA or PETG. I haven't tried glass or carbon filled materials but that may affect tolerances.

Assembly:

1. Assemble bearings onto housings (see cross section image, below)

   1. M3 bolt -> bearing cap -> bearing -> bearing cap -> housing

   2. Do not overtighten. Use just enough force so that the bearing doesn't have any axial play. Be careful to not strip out the plastic in the housings.

2. Place spring in outer housing.

3. Insert inner housing into outer housing, making sure that the inner housing M2 hole lines up with the cutout in the outer housing.

4. While compressing the spring, insert the M2 bolt into the hole in the inner housing. Use very light torque and bottom out the bolt, but do not overtighten. It is very easy to strip the plastic out.

Use:

Compress the two housings together, insert screwdriver, sharpen on a stone by dragging the tip back and forth as appropriate.