Probably not a bad idea. I made my PTO (power take off) base that I set on top of my double barrel harbor freight tumbler, from oak and used 1/2" aluminum rod slipped into 1/2"ID hose from home depot. The most expensive parts were the ball bearings I had left over from my R/C tinkering days. I use a barrel made from 4" black PVC consisting of an end cap, 10" of pipe and a 4"-2"reducer with a "flexible" end cap that tightens with a band clamp. After gluing it together like normal with PVC I used silicone to fill in the spaces between the fittings on the inside to try to keep from contaminating the next stage of rock with rougher media, but I've found it next to impossible to get all of it out so I just use this barrel for the sub first stage only. I could see eliminating one bearing for feeding the shaft of a fan motor through the base and extending said shaft with the same idea tube and rod and perhaps some epoxy like JB weld, I'm not sure about the speed of it though. MB

some of you might think I'm crazy but dumpster diving is a good way to find things as well. just because someone tossed it in the dumpster, does not mean that motor is junk.

squirrel cages(furnace fan motors) are great for many things...and they often have pulleys on them.

the motors that are the best for rock tumbling are ones that are about 1/3 HP to 1/2 HP. check out dumpsters behind hardware stores, behind heating/air conditioning businesses, look for store type places that are being remodeled....these are all good places to start looking for free motors & other stuff. I know this from experience. :)

I'm excited, I know they tumble pretty slow if the fan doesn't work try an old rc car engine, you can get them at garage sales for cheep

Try my rock tumbler.
http://www.instructables.com/id/Hobby-or-Case-Tumbler/
I built this one for polishing brass bullet casings for reloading but it also makes a good rock tumbler with the right polishing media.
Joe

Hey I just posted the comment below and went on ebay looking for something else. Accidentaly came accross lisitngs for BBQ spit roast motors!! I wonder? They are really cheap, (under £10 in UK money) powerful and slow. from about 3 rpm up, some even have speed control. could be sped up with a couple of pullies 1 to 8 would give 24 rpm. Just a thought.

I have just started building a tumbler. So far I have the axels taken from a dead laser printer toner cartridge. Long rods one rubber coated, perfect? Lots of these about and they have a few good parts in them but take care about the toner. For the motor I have one from a Panasonic bread maker, the element died and the whole thing got replaced so :) It's very powerful and has pully and belt reduction drive. Also have an old sewing machine motor as an alternative if the panasonic part doesn't work out. Not sure about hacking the Pana-speed control, may not need it or may have to make one, thinking about a drill speed controller kit. To start off the barrels will be Illy coffee containers, I got 4 so we'll see If it works out I'll think about buying some real ones. Bearings I got with a cheap scooter wheel set in a pound shop ( UK ). I have a lathe so I can make bushes and sleeves to fit the axles to the bearings so will let you know how it goes.

Where are you on this?  Did it ever come to fruition?  I've been thinking about the 4 inch PVC solution myself.  Wanted to now if it worked.

. Don't forget to attach some lifter bars on the inside or you won't get much tumbling action.

I still don't know what RPM these things are meant to run at, but try an auto windscreen wiper motor as that will have the power and will work all day long. has anyone out there got access to one of these things and can count the revs.....counting for six seconds and multiplying the result by 10 gives an approx RPM

A microwave turn-table motor should do the job - slow, steady, can deal with a good bit of weight. If they won't run with a vertical axis, add crown gears or a crossed pulley to turn your tumbler on it's horizontal axis.

Me thinks 50-100RPM is a little on the fast side, but the PVC pipe sounds like a good idea. How about a very small pulley on the fan motor with an O-Ring that goes around the pulley and the larger pipe. You'll need some bearings for the smaller pipes. That arrangement sounds workable to me.