I've always fancied a tumbler but not been prepared to shell out a couple of hundred bucks for something I wouldn't use that often, so I set about making a cheapo version. Here are the results.
Used a 12 Volt car wiper motor. It has two speeds, fast is about 68 rpm and slow about 44rpm. It draws about 2.8 A on fast speed and about 1.5 A on slow speed, it's a direct drive connection to the tumbling body and I only use the slow speed. I didn't bother trying to calculate the torque as I figured a couple of wiper arms on a car was a "fair bit" and would most likely be sufficient. The body is a bit of old pvc plumbing pipe I grabbed from a building site. I was going to use plumbing fittings for the end caps, but at over $10 each they would have blown the budget, so used scrap wood instead. I used a few chair wheels to support the end on the pipe and the 12V power comes from an old atx pc power supply.
All up costs were $20 for the wiper motor, $3 for the wheels and the rest was scrounged.
I put the bits below through for the first run today and it worked pretty well. 3rd picture is bits before, 4th is after about 4 hours. I reckon it would work better if I'd done a bit more cleaning of bits with a wire brush before tumbling and maybe I overfilled it. But all up I'm pleased with the results.
It's a pain fishing the stuff out, but made a bit easier using an old magnet from a hard disk drive.
