Fine Adjustment Coffee Grinder addon

This adds a fine adjustment knob to those cheap Korean 60mm flat burr coffee grinders. I designed this to fit the generic kind with the big chrome knobs. I don't know whether this would work on an Urbanic one though.

it's pretty straight forward to print + build. I printed everything out of ASA however most parts would probably do fine as PLA and/or PETG. the spur gear should be printed out of the toughest stuff you have though as it's pretty thin and is under the most stress

print the spur gear vertically with supports. make sure to slow down the printer + increase cooling fan speed on the shaft part

use strong glue or epoxy to attach the ring gear to the main knob.

heat press 2x m3 brass inserts into the carriage where the spur gear sits

you will have to open up the bearing holes in the carriage in the cover plate with a drill bit. I just held the drill bit in my hand and used hand torque to open up the holes. no drill needed

use 2x very short m3 screws to secure the cover plate. you can tighten or loosen the screws to apply pre-load to the spur gear

I used this gear library to generate the gear profiles:

https://www.thingiverse.com/thing:4194148

I have included the required STLs as well as the original solidworks parts and assembly files. if you want to modify this to fit another grinder or improve the design go right ahead