Easy to print knife sharpening jig

Last crawled date: 4 years, 3 months ago

[update 30-nov-2019] Just noticed that the ears of the stick made the stick print mid air. It's fixed now.
Disable support for all the prints.
Prerequisites
You will only need the few items on the photo:
Two M5 screws with thread length of 13 to 14 mm (if longer, just grind or cut them) and head diameter of 10 mm or less. Exactly 10 mm is best.
Two standard M5 nuts
Either grinding stones or just some strips of sandpaper
Grinding stones
You can use those $1 grinding stones from eBay that are roughly 148 x 11 x 4 mm (excluding any plastic base) and shown on the photo. If so, print holder2.stl for it.
There are also bigger stones around 150 x 20 x 5 mm (excluding any plastic base). For these, print holder3.stl. Note that I have not tested these stones, I'm not certain if they will fit.
You can also just use sandpaper strips. If so, print holder1.stl.
Stick
You also need to print stick.stl. Perhaps use 2 or 3 mm shell to make it more rigid.
Jig
The clamp on the jig needs to be strong. If using Cura, you can add a "support blocker" and set it to "Modify settings for overlap" to give the clamp area a 100% infill. See Photo.
Assembly
Break off the anti-curl-ears of the stick and knock it carefully into the holder with a small mallet or the handle of a screw driver or other suitable tool.
Insert the two nuts. This might be a bit difficult, but you can use a longer screw to pull them into place.
Finally glue the grinding stones or sandpaper to the holder.
Grinding
It's best to clamp the knife at its middle length such that the tip is better supported. Also adjust it such that that the cutting edge (and not the spine) is parallel with the clamp around the clamping area.
Don't tighten the screws too much or it will break. Put tape on the knife and clamp on the tape to avoid slipping.