Cheap jar rock tumbler, drum polisher

thingiverse

A super cheap, low material rock tumbler/polisher that's designed to use one of three low-cost 5V hobby motors! This is an advanced project that requires some knowledge of electronics and mechanics. There are other tumbler polishers on Thingiverse, but I found these either need a lot of filament, metal drums or specialist motors. As I just required something small and cheap to polish metal filament prints, I decided to design my own using cheap parts I had to hand. I also wanted to build four polishers so I could have parts in every stage of processing, which meant it needed to be as cheap as possible. Overall, I found the geared 130 DC motor design to work best, with high speed and good reliability. Construction notes: It's essential to make sure the horn parts that attach the jar lid to the motor are perfectly centered to the jar lid. If they're not, it will cause a lot of wear on the motor and gearbox, which may cause the gearbox to fail or stall. I used this printable centre finder to help: https://www.thingiverse.com/thing:3283699. When pushing the horn/lid assembly onto the gearbox axle, don't push it all the way home. This allows the horn to flex slightly and make up for any inaccuracy in the horn mounting. This part will suffer high wear, and will need replacing from time to time. Seal holes drilled in the jar lid. The process of tumble polishing produces fine dust that WILL get out of any gap. It's probably not a good idea to breathe any dust created by tumble polishing! For geared designs, I suggest you lubricate the gearbox with some light oil before use to increase the gearbox lifespan. This is a demanding use of such gearboxes. DO NOT USE WD40 - it's not a lubricant! Use the shims provided in the bottom of the bearing clamp parts to make sure the jar is central to the gearbox axle, and as level as possible to prevent stress and binding. The shims allow a variety of jar diameters to be used. You should be able to get away with 87-79mm diameter jars. As mentioned before, it's essential to make sure the jar is level and centered on the gearbox axle. To glue the agitators to the inside of the jar, two-part epoxy glue works well. Make sure the inside of the jar is clean and grease-free before gluing. Agitators are not required, but will speed up the polishing process. Agitators will wear out over time. Depending on the length of your jar, one or two bearing assemblies are required. I found one to be the easiest to set up and level. As jars can vary in size, you may need to adjust the number of shims used. In the box: * 5V power supply (connection details left up to you) * For 3D pen motor design: + Small motor horn + No other parts are required. Be warned - this is a delicate motor with a delicate gearbox, so it's recommended only a lightweight plastic jar is used for the polishing drum. * For 28BYJ-48 stepper design (quite slow, requires Arduino skills): + 28BYJ-48 stepper motor + ULN2003 driver board + Arduino or similar + stepper program (provided in files) + Two M6 nuts and bolts + Printed parts: one stepper adaptor and one stepper horn * For geared DC 130 motor design (recommended design): + Geared DC 130 motor + Two M3 5mm self-tapping screws + One 25w+ 10 to 15ohm shunt resistor in series to reduce speed + Printed parts: one gearbox horn and one gearbox mount