Years ago, I bought a DMT diamond whetstone to replace a worn out ceramic whetstone. Since then I’ve been happily using it for freehand sharpening of tools and knives.

While my freehand sharpening is OK, it is hard to get consistent angles when freehand sharpening. So when I got a 3D printer, I thought it would be nice to print a sharpening guide.

To start the design I measured the relevant dimensions of the cross-section of whetstone and base with my Vernier caliper. These dimensions I then drew into an outline in a sketch in FreeCAD to base the design upon. As usual, I’ve named this sketch “skeleton”.

Based on that “skeleton”, I sketched and extruded the body leaving some room between the whetstone and the sharpening aid. The sharpening aid is designed to ride on the inclined surfaces of the black plastic base.

Subsequent operations add the 25° bevel and radii.

The part was then exported as a STEP file, which was sliced in PrusaSlicer.

It was then printed in blue PETG filament on a Prusa MK4S. When oriented as shown above, it printed without problems.

Given how simple it is, it works really well. It slides smoothly over the base without lubrication. The sliding surfaces are long enough that there is no tendency for the jig to tip. There is enough room press my kitchen knives securely to the inclined plane of the jig.

For those interested in printing this sharpening aid themselves, both the original FreeCAD file and a (compressed) STEP file are available for download. These files are made available under the Creative Commons Attribution ShareAlike license.

Most people will want to download the STEP file. It is compressed to reduce the size. You will have to uncompress it with e.g. 7-zip or gunzip before opening it in you slicer of choice. The FreeCAD file is mainly meant for those who want to change the design, e.g. the angle of the bevel.