Introduction: DIY Rock Tumbler

Picture of DIY Rock Tumbler

My wife recently started making beads and other things from polymer clay, and wasn't getting quite the finish she wanted using sandpaper.  It turns out that even children's toy rock tumblers are relatively expensive and the professional models are definitely out of our price range, so she asked me to see if I could assemble something from old bits and pieces we had laying around.

The kind of tumbler I've seen before seemed like a fairly simple arrangement - some kind of barrel turned by horizontal rollers, similar to a tumble dryer, so that's what I set out to build.

Step 1: Parts List

Picture of Parts List

Parts list - these parts all came from my junk pile. Nothing was purchased for this project, so technically it cost $0 to build. As suggested by several people (iceng and ottwafm), the tumbler would be more durable if some kind of wheel bearings were used for the rollers. Bearings for skate board wheels or ride-on mower decks should be easy to find locally.

1) electric motor from Grand Am electric window lifter.
2) old PC power supply. This one happens to be a 90W supply.
3) rollers - could be broom handle or any round pole. These are actually mini rolling pins from my wife's craft supplies.
4) various bits of wood to make a frame and base board.
5) 2 inches of garden hose.
6) power switch.
7) screws, coach bolts w/ nuts
8) anti-slip shelf liner

Tools required:

1) Saw
2) Screwdriver
3) Drill + appropriate sized bits
4) Wrench
5) Sharp knife
6) Soldering iron (or use crimp-on spade connectors)

Step 2: Initial Sizing

Picture of Initial Sizing

Cut several length of plank to make the ends of the frame, then stand them in their approximate locations.  The position of the driven roller depends on the size of the motor mount.  The position of the other roller is variable, depending on the size of the drum.  The rollers here are 5" apart on centers.  Later I decided to add a third roller at 3.5" to accomodate smaller drums.

Step 3: Motor Mount

Picture of Motor Mount

The holes for the rollers are somewhat oversized.  This should eliminate binding and the weight of the drum will hold the rollers down.  The large hole is for the garden hose that connects the drive shaft to the roller.

The motor is built into its own mount, which is offset from the side of the motor, so I cut a shim out of a piece of scrap plywood.

Step 4: Static End

Picture of Static End

The static end just has holes for the rollers.  The slot above the middle hole allows the roller to be removed when a larger drum is being used.  In fact, a single non-driven roller could be used, with multiple slotted holes to suit different drums.

Step 5: Check the Spacing

Picture of Check the Spacing

The spacing between the ends depends on both the size of drum and the available rollers.  These are ready-made rolling pins, but broom handle or other round stock could be cut to length.

Step 6: Frame Assembly

Picture of Frame Assembly

After measuring the separation for the ends, rails are cut and attached.  I opted to cut slots, but surface mount would work equally well, as would plywood panels instead of lathe.

Mount the motor along with the driven roller.  I used coach bolts, which present a rounded head in the roller section.

The roller ends have a small amount of furniture finishing wax applied, to reduce friction in the holes.

Step 7: Wiring

Picture of Wiring

Take a look at the PC power supply cabling.  There should be a single green wire going into the big connector block.  That's the "power on" wire - it enables the motherboard to switch off the power supply when the PC shuts down.  Clip that wire and one of the nearby black (ground) wires.  Connect those to the power switch (any switch will do).  I soldered mine rather than buying spade connector clips.

Next, take one of the flat, 4 pin connectors and clip off the yellow (12 volt) and black (ground) wires.  Solder those to the motor.  I cut away the connector shroud to be able to get the soldering iron into it.  Again, spade connectors would work, as would the proper connector if available.

Plug in the power supply, flip the switch and watch the roller turn!

Step 8: Tidying Things Up a Bit

Picture of Tidying Things Up a Bit

1) clip off remaining wires.  I wrapped each end in tape, then bundled them with more tape.
2) screw the frame to the baseboard.
3) secure the power supply.  I had a length of pipe hanging strap available, which also sufficed to hold the power switch.  I oriented the power supply with the fan blowing towards the motor to provide cooling.
4) I had some spare storage drawers that just happen to fit nicely on the other end of the base board.
5) tests showed that the barrel would sometimes slip, which is why the rollers are now covered in anti-slip shelf liner.

Step 9: Finished Product

Picture of Finished Product

All done!

Step 10: Test Run on Assembled Frame

Picture of Test Run on Assembled Frame
First trial run - the glass jar originally contained a candle.  It has a plastic ring that makes a good, tight seal.  The jar contains a few beads and a slurry of water and sand.  This would eventually achieve the desired result, but it demonstrated the need for some kind of internal vanes to "lift" the mix as the container rotates.


BlaineB2 (author)2015-07-19

Try running several beads of bathroom caulk or liquid nails, evenly spaced, the length of your can or jar to create the needed bead and sand roll over. The tumbling affect should decrease the tumbling time immensely. If allowed to cure thoroughly these adhesives should not affect your polymer clay beads.

I'd also suggest that if the slurry climbs very high up the side of the can or jar you spritz the slurry with a little water. If you can't see the slurry in your container listen for slight thumping sounds of material falling (instead of rolling).

woodworking gentleman bear made it! (author)BlaineB22016-02-28

I did that but before the caulk cured, I realized that I could put objects on top of the beads that would churn up the mixture even more. I used sheet metal snips to cut some thin metal tubing and a hack saw to cut some 3/4" wooden dowels. used 5 of each thing

Thanks for the tip!

john.stacey.3956 (author)2015-01-15

Really great instructions Well done I've got the parts to make one but I'm going to use steel bars on small bearing's but your idea is brill john

LiamOSM (author)2013-11-02

I'm going to try and make a rock tumbler using one of those 120v motors from microwaves that turn at ~30rpm.

tacamaral (author)LiamOSM2014-09-16

I tried that - the problem is that it's so slow that the jar will do two or three revolutions per minute, so it will take forever to polish anything.
What I then did was connecting the motor through a flexible steel shaft to the cover of the jar. It works, but it's not as simple and functional as this one.

ottawafm (author)2014-08-30

I agree with iceng. Try using skateboard wheel bearings. Or something similar.

dontremember (author)ottawafm2014-08-31

Yes, some kind of wheel bearings would definitely be a good idea. At the time of building, I had a minimal budget to work with, and was really happy to be able to complete the assembly for $zero outlay. As it happens, the tumbler was used for less than two weeks, and has been gathering dust since. I have updated the parts list to suggest wheel bearings for durability.

arduinoversusevil made it! (author)2014-08-29

My free-ninety-nine take on your awesome tumbler!

iceng (author)2014-06-05

Running 4 tumblers 24/7. I loose a tumbler with good bearings every few months for some mechanical reason or motor.

Your Ible is well presented and made however wood on wood even with lubrication will not long last.

See if you can modify it to use a bearing for conger life.

dontremember (author)iceng2014-06-14

Thank you for the suggestion. I would probably fit some kind of ball-bearing races if it ever needs upgrading. However, right now it is barely being used at all, and the original dry sockets are holding up OK.

m6255 (author)2014-02-04

Awsome. I have a different use. I have a whole lot of ammunition brass I want to sell but needs to be cleaned. I had a vibratory cleaner that burned out. Then I saw online people using Thumblers Tumbler with number 47 stainless steel pins. It's in water with a few tablespoons of dish soap. The results were better than anything I did with my dry media and vibrator. When I looked to purchase the tumbler they were anywhere from 100 to 250 and up. 5 pounds of pins around 30 bucks. This invention will work wonderfully except I'm worried how the coffee can will hold up with all that brass and pins rolling around in there. Anyone use one of these for this?

agrodolce (author)m62552014-05-24

I'm going to make one for jewelry and my husband may use it for his brass. I was looking around on YouTube and saw someone using a big thermos. That's what I'm gonna try. They're pretty thick so I think it'll be fine.

dontremember (author)m62552014-02-04

You could equally well use something like a paint can, those generally fit tight enough to need a mallet to close. Any tube with a screw top would work too - a strip of duct tape would help stop it unscrewing. Once you find an appropriate container, you can size the frame to fit. Also, you'll want to pick a motor that can drive the weight without running too hot, and make sure the rollers don't bind. You could even pick up some cheap ball bearing races for the rollers.

spark master (author)2012-05-07

excellent project. I only suggest (unless another beat me to it) you can coat the rollers with silicone rubber in a tube (if you have left over from something else), or even several coats of rubber cement or rubber inner tube sleeves..

but use wut ya got!

verra nice indeed

Thank you! As it happens, we had a couple of yards of rubber shelf liner available, so that's what was used.

what do you put in it to polish the beads?

My wife has tried a number of different things, from play sand slurry down to small dry squares of fine sand paper and denim. I'm not sure which produced the best results. I suppose it depends partly on how smooth the beads are to start with.

well done thanks

gloflyer (author)2012-05-06

Totally awesome job. I have a VERY expensive rock tumbler, but needed an extra barrel. I tried the folger's coffee can, but it did not turn reliable. Now I will try adding the shelf liner. It was a big DUH when i saw what you did.

A few tips: Normally you would use tumbling grit instead of sand. I am going to assume that the beads are already reasonably shaped, you just want to add a polish, so a finer grit or even a polish should work fine.

There is way too much sand. Depending on the size of container, back it off to a few tablespoons of grit, and then fill it up about 1/2 way with water.

You do not need any vanes. If you get the slurry to the right consistency, it will slide as needed on its own.

Good luck and let us know how it works.

P.S. A lot of folks use a thin coat of Future floor wax on the beads, and then bake them gently in a low oven.

dontremember (author)gloflyer2012-05-06

Thanks!! I give my wife credit for the shelf liner - I thought maybe just wrapping the rollers would work, but she went ahead and wrapped the barrel too, which works substantially better.

ichibon (author)2012-03-26

this is such an awesome project. i will inddeed give it a go. 5/5 from moi.

rimar2000 (author)2012-03-18

Very good work!

Yes, to add vanes is a need. But it is an easy task, now.

dontremember (author)rimar20002012-03-18

Thank you!

We probably won't use the glass jar much. The big red tub in some of the photos is a coffee can with a built-in grip that functions very nicely as a vane. Also, being plastic, I can easily screw through it to add vanes as necessary.

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