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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 :)

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drkoraf1 month ago

For a simple, under $40 DIY rock/parts tumbler, see the one I made on YouTube at:

FWIW, I use a "Click Clack" brand 5.4qt. acrylic storage container containing 2.5lbs. of crushed walnut shells to debur 5lbs. of steel straps (ea. 4.5"L x 1/5" w), and I run the tumbler at 60-70 container RPMs for 2.5 hrs. for optimal results. Over 100 runs later, I've had no problems except having to replace the drive belt twice (at $5 ea.). Since my needs have increased, I'm going to replace this 0.75amp motor with a 70rpm gear motor, and replace the container with a 4.5lb. Whey Protein container so I can increase my tumble capacity to appx. 20-25lbs (or 5lbs. of medium and 15lbs. of steel load) and increase my production capacity. I've found that 60-70 container RPMs works very well for my application though I'd bet that's a function of medium and load used. BTW, the video doesn't show it, but I added a small computer fan to cool the motor and keep it from overheating. I don't expect I'll need it when using the gear motor though. Make sure the drive rod is higher than the other rod otherwise the container won't rotate effectively!

drkoraf1 month ago
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
SIRJAMES094 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)  TheCheese99219 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
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