I wanted to be able to clean watch parts occasionally, but without paying $$$ for a professional machine. This little project consists of a motorised carousel which spins a number of wire mesh baskets submerged in cleaning fluid. The motor is controlled by a microcontroller in order to create a simple 'washing program' such as alternately changing speed and/or spin direction every few seconds.
Total component cost is around £25, plus a few 3D-printed parts and scraps I had lying around.
This bit is optional - you could simply connect the motor to a battery or USB power source and it would spin constantly in one direction. However I suspect better cleaning results are obtained when the parts are sloshed back-and-forth in the fluid, so this controller circuit could be used.
Connect up the Digispark board and motor controller as follows:
(Actually the last two can be either way round, it doesn't matter much)
The connect the motor to the controller's "Motor A" outputs, again which way round the connections go doesn't really matter. You should end up with something like this:
Following these instructions to set up the Digispark board, program it with the source code in the Files section. Each time the board is plugged into a USB socket, after a few seconds the motor should start turning, alternately one way and then the other.
The heart of this build is a carousel with holes in (for the baskets) attached via a spindle to the motor's output shaft. The motor is attached on top of the jar lid, whilst the spindle and carousel hang down into the jar containing cleaning/rinsing fluid.
The carousel can be 3D-printed (STL file in the files area) or cut from acrylic, brass, whatever.
The jar lid needs a hole drilled in the centre large enough for the motor's output shaft, in my case 4.0mm. Place the lid over a wooden block whilst drilling to ensure a nice clean, burr-free hole.
The motor can be glued in place, but in my design I 3D-printed a small enclosure to hold it more robustly, and glued that to the lid instead. STL file in the files area.
The final, and most difficult, part is the spindle. I chose to modify a stainless-steel M5 cap-head screw:
drill a concentric hole in the cap head, large enough to take the motor output shaft snugly, in my case 3.0mm
cross-drill the cap head and tap in order to take two M3 grub screws. You could, alternatively, glue the spindle to the motor shaft, but it might not last long...
cut to length, so that the carousel and baskets just clear the bottom of the jar when it's all assembled. In my case the total length of the spindle was 34mm. Larger/taller jars may be used simply by making the spindle longer.
file a flat on the last 8mm or so of threads to fit the D-shaped hole in the carousel. Alternatively skip this step and drill out the hole to make it round.
The carousel can then be attached to the spindle using an M5 nut (and perhaps some threadlock).