Instructables

Rock Tumbler Ideas

Hello, first off, thanks for taking the time to read my post.

Second, I'm brainstorming ideas to make a dirt cheap rock tumbler, for polishing collected stones and maybe even making jewelry out of them. There are a few sites out there with instructions on making rock tumblers and other equipment. Some being:

Here
And here

The design seems to basically be a rotating horizontal plastic or rubber cylinder, set on two evenly spinning axises. I was thinking of using 4" PVC pipe as the tumbling barrel, and maybe 1" PVC for the axises. One of my first questions is, will a large desktop fan be (roughly) powerful enough to turn the 4" barrel at 50-100 rpm? Keep in mind these are plans for a dirt cheap rock tumbler, so I really don't want to spend much on these parts. Any other suggestions for motors?
And, does anyone have any plans that they have made, or even constructed tumblers?
Any tips, additions, etc. to my plans?

Thanks for reading my post :)

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
SIRJAMES092 years ago
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
Doom_Goat (author)  TheCheese99216 years ago
Well I'm hoping the fan will work, as getting good loot at garage sales out here is a rare occurance (new area). I will have to look out at possibly thrift stores for old motors from toys/hobby sets. Thanks!
what you want is torque(power) not speed.  stop and think about it for a second; washer & dryer motors are good for rock tumbling because they are high torque motors...they have the power to turn heavy loads without going too fast.  A fan motor might work, but those motors are built for speed not torque(power).  The Problem I have at the moment, is I have 2 motors from a furnace that work perfectly, but the RPMs are way too high. I need to reduce the RPMs, but I don't know how to do that.  I wish you luck on this. I'll be waiting to read the out come!!    8=D
gear reduction!
Have you tried a reistat??? I didn't spell it right, but in electrical isle of home depot it is a button that replaces a light switch, it regulates the electricity so that it doesn't use the whole 110 ie: sometimes called a "dimmer" switch.
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
casetumbler(b).JPG
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.
Zenock4 years ago
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.
NachoMahma6 years ago
. Don't forget to attach some lifter bars on the inside or you won't get much tumbling action.
Doom_Goat (author)  NachoMahma6 years ago
"Lifter bars" you say, I'm assuming this would be some kind of rod of some sort on the inside of the barrel to interrupt the motion of the rocks, and tumble them more. Could you please provide more details as to this, I'm very interested in improving the design. Thanks!
Look in your dryer. That should help.
. You have the right idea. It's just an irregularity on the wall to lift the media/object so it falls a few inches instead of sliding back down the wall.
lifter bars are for ball mills; I'm not sure you want them on a rock tumbler... It occurs to me that a garage-sale food mixer probably has about the right RPM; I'm not sure if it can handle the weeks-at-a-time operation, though.
Doom_Goat (author)  westfw6 years ago
It seems like there a bunch of appliances that would serve as potentially good motors, I guess I will have to weigh my options. Thanks!
. Maybe not. Most tumblers I've seen have them, but the ones I've seen may not have been for rocks.
pigglepogle5 years ago
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
Kiteman6 years ago
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.
Doom_Goat (author)  Kiteman6 years ago
Well, I found this, and it's at a good price. However, would i just take an old appliance power cord, and solder the two wires on the two copper leads on the motor?
. I believe so.
. Along the same line, how about a counter-top rotisserie drive? Already set up for horizontal operation.
Doom_Goat (author)  NachoMahma6 years ago
Sounds like a good idea to me.
Doom_Goat (author)  Kiteman6 years ago
Hmm... a microwave motor also sounds like a good idea, I'm sure Goodwill will have them on the cheap. Thanks.
HamO6 years ago
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.
Doom_Goat (author)  HamO6 years ago
I just now read that they actually tumble slowly, I was thinking they tumbled very fast. You were suggesting a large O-Ring, I assume? I'm glad it sounds workable though. Thanks!
HamO Doom_Goat6 years ago
After additional thought, finding an O-Ring large enough cheaply might be a problem. You might try a large "rubber band" (auto inner tube) which might mean you could do away with the pulley and run it right on the motor shaft. You could adjust the speed by putting rubber tubing on the shaft to change its diameter. This is now getting interesting as a great homebrew project, a cheap rock/shell casing/ballmill tumbler.
Doom_Goat (author)  HamO6 years ago
I think I might use a shortened bike innertube for the belt. However, I just realized a new problem: finding bearings so the axels can spin with reduced friction.
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