Rotary Tumbler Mk1

Well, if you drink coffee a lot and have too many empty coffee jars laying around, then this is some use for those empty jars.

Part list:

• Empty coffee jar - 400gr version
• Micro Gear Motor - 100 RPM or 300 RPM
• M3x40mm - 4pcs
• M3x12mm - 2pcs
• M3 brass insert - 2pcs
• LM2596 DC-DC module
• DC jack female (panel mount)

Some note: 

• The gear ring is splitted intentionally since the bottom and the top of the jar are larger than the middle section
• Buy the micro gear motor with the shaft as long as possible
• 2 M3 brass inserts are for retaining the motor to the main body
• Print all the parts first, assembly the gears and all on the main body
• Use that as reference for the distance of the gear rings (65mm or shorter)
• Glue the gear rings on the jar. You have 20mm of the thickness of the gear so nothing to worry about the exact distance
• I used B-7000 glue, you may use different one as long as it stick well
• You can have as many bumpers inside the jar as you like, I decided to go with 5
• Set the voltage around 5V output for LM2596. You can add a rocker switch at the front but I think unplug the DC barrel jack is just fine
• The jar won't rotate smoothly because the spur gear tooth profile in used wasn't designed for this, it was designed for stationary shafts. Hence, a little bumping up and down so be the noise from motor
• The hole for DC jack is 7mm, a bit small for the DC female jack, so heat up the hole to 150 degree C with hot air gun to make it soften enough then push the DC female jack through.
• You can reuse the original lid, but if you lost it or feel not secure enough, then use my design for the lid. My lid is not air-tight, so you can use a rubber O-ring ID84mm to make it air-tight, O-ring with ID80mm should be fine

I decided to go with this tiny motor to save the trouble of driving Nema 17. But this motor is too small to get good torque, so I'll make a mk2 in the future that uses Nema 17 instead.