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Workbench Creations is the place for conversation and discussion about do-it-yourself (DIY) projects. This DIY blog will feature projects completed by its owner as well as projects completed by other do-it-yourselfers. Workbench Creations is the place where DIYers can discuss ideas, learn about what others have done, and share their expertise.

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24 comments

DIY Rock Tumbler

Posted June 05, 2007 2:51 PM by frankd20
Pathfinder Tags: DIY DIY blog Rock Tumbler

About five or six years ago, a friend of mine bought a house. In his basement was a very nice rock tumbler. I'm not talking about your run-of-the-mill, department-store discount, rock tumbler for kids. The one I'm talking about was meant to hold 10 pounds of rock within a sturdy, hexagonal rubber drum. I don't know if you've ever purchased a good rock tumbler, but they cost anywhere from $150 to $200. Unfortunately, the rock tumbler in my friend's basement wasn't working – so he gave it to me.

About two years ago - after moving my own residence twice - I went looking for my good rock tumbler, but couldn't find it anywhere. I bought a 3-pound rock tumbler, but it just wasn't big enough. Plus, it took too long. I wanted more, so I decided to build my own.

The design of a rock tumbler is rather simple. The device needs to rotate a drum about one turn per second and be able to run for days at a time. The design I chose is similar to your standard tumbler with two parallel rods that are turned by a motor. The drum sits on these rods and is turned by them.

If I was going to build a rock tumbler, I was going to make it big. Using some scrap bed frames, I welded together a square about two to three feet long on each side. I then bought some short lengths of plumbing pipe and some rubber tubing to slide over the pipe for traction. For the bearings, I stuck some rollers meant for a garage door into the end of these pipes. Using brackets meant for pipes, I secured the rollers at the ends of the pipes to my frame.

When I designed my rock tumbler, I decided that I wanted to drive both rods instead of just one. So, I used a chain and sprockets from some old bikes that I had lying around. I mounted the sprockets onto the rods and mounted a smaller sprocket onto a motor. The motor I used came from an old oil burner. I chose this motor because I knew it was meant to run for long periods of time.

Next, I welded some mounts for the motor, put on the chain, and turned on the rock tumbler Although it worked, the chain bounced around a little. So, I used the derailleur from one of the old bikes as a tensioner for the chain. When I turned the rock tumbler on again, it worked even better. For the drum, I chose a large, approximately 4-gallon plastic container that was originally used for food. When I put this drum on top, the rock tumbler turned a bit too quickly. Still, it was good enough to do the job.

Last weekend, I filled my rock tumbler and ran it for a couple of days. It worked just fine, but that's where the story gets strange.

A few hours after I ran my do-it-yourself (DIY) rock tumbler, I found myself on the phone with my old friend – the one who gave the rock tumbler from his basement. During our conversation, I told my friend that I lost the rock tumbler that he had given me, but that I had built my own. "You didn't lose it," he laughed. "You gave it back to me. Do you want it? I haven't used it once"

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#1

Re: DIY Rock Tumbler

06/06/2007 3:09 AM

Call me ignorant, but why would one use a rock tumbler? First time I ever heard fo such a contraption. If I knew why I would need one, then your design would be ideal.

I have only one question and comment, if your frame is not exactly level, you might find that the drum tend to run accross the rollers towards the sprockets or away from them, how do you prevent that? You could have two small wheels running on the edge of the drum and fixed to the frame on both sides, thus keeping the drum in position.

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#2
In reply to #1

Re: DIY Rock Tumbler

06/06/2007 4:09 AM

Hi ignorant one. Thousands of people use a rock tumbler to polish rocks (gem minerals) and I use one myself from time to time. You place the stones in a tumbler with grinding grits (silicon carbide), and the motion of the tumbler will grind away the corners and edges before polishing. To polish you have to first wash out the tumbler and the stones, then put them back in the tumbler with a polishing agent ( cerium oxide, tin oxide etc) in powder form. You also add water at every stage. Spencer.

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#3
In reply to #2

Re: DIY Rock Tumbler

06/06/2007 5:16 AM

I consider myself informed about rock tumblers. My experience (or total lack of it) regarding polishing rocks is limited to seeing small bowls of gems being vibrated to achieve the same goal. This is done on very small scale though, so will take years to accomplish the requirements set when you need a rock tumbler.

Thanks for the enlightenment.

TC

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#4
In reply to #2

Re: DIY Rock Tumbler

06/07/2007 6:04 AM

Do you have to add small sponges near the end stages to prevent chipping ? Also what is the weight ratio of raw material in to finished stuff out ?

Curious Kris

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#5
In reply to #4

Re: DIY Rock Tumbler

06/07/2007 9:56 AM

Unlike the other projects I have posted which I did a long time ago, this one was just completed a few weeks ago.

So far I haven't run this tumbler enough to answer your second question of weight ratio of raw to finished material. I can't say I have ever weighed what I put in to what came out when I was using the small tumbler either however. I have not used sponges or plastic pellets any other media to avoid chipping, although thats not to say it wouldn't be a bad idea.

A lot of the projects I do are hobbies I have interest in, however most of the time I enjoy designing and building the equipment more than actually using it.

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#6
In reply to #5

Re: DIY Rock Tumbler

06/07/2007 10:44 AM

I have seen tumblers that use old tires as tumbling container. You could put several on your rotating rails and have different batches at different stages. You can also use the tumbler to polish ammunition brass, if you like to load your own ammo.

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#7
In reply to #6

Re: DIY Rock Tumbler

06/07/2007 12:08 PM

I have also seen tumblers that use old tires, and I bet with an extra bracket or two to hold them up I could put a couple on. Since my drum is a little fast a tire would be about perfect. I used to be a damn good shot in scouts with a .22 rifle but I don't do it enough now to load my own. Rock tumblers can have lots of uses other than tumbling rocks. If you are into pottery you can also use them to crush up your materials into fine powders.

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#8
In reply to #5

Re: DIY Rock Tumbler

06/07/2007 1:30 PM

I asked because I had a really tiny tumbler years ago when I was a kid. I gave up before the stones had started to take on a shine , but I recall the small sponge pieces supplied. Like yourself I didn't bother with weighing ! Who cares , it's just fun - well it would have been if I'd persevered. There must be lots of commercial operators who have refined the process , it's hard to pass a gift-shop that doesn't stock tumbled stones (usually quartz type stuff). Sounds like a great project to me.

Have fun , I may do the same myself one day. I've often looked at stuff in streams - it looks really interesting when wet , tumbling would add a shine instead of the dulled look you get when it dries (plus it's pre-tumbled).

Kris

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#11
In reply to #1

Re: DIY Rock Tumbler

07/23/2007 8:11 PM

Hi, there are probably several other things you could do with a rock tumbler besides tumbling rocks. If the tumbler is a large one, it seems like maybe you could use one to wash clothes, also you might could use it to mix things with also. I wonder if anyone has ever used a record player turntable to convert into a rock tumbler, also I wonder if you could use an electric fan to convert into a rock tumbler. Most rock tumblers I've seen are belt driven, but it seems like a gear driven one would be better, because the gears would last longer and you would'nt have to worry about broken belts and having to replace them. The possibilities seem endless as it seems anything that turns could be turned into a rock tumbler.

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#9

Re: DIY Rock Tumbler

06/20/2007 12:00 PM

Around 1988, my wife (at the time) and a friend wanted to make their own "beach glass" jewelry, so I set out to build a tumbler to sand the glass fragments.

I didn't have a welding machine or any plans (online info was much more limited then) and was too lazy to search out any information, so I just designed and built a tumbler out of my head.

I went to an auto junk yard and bought a rear axle with attached wheel and tire from a front-wheel drive econo car. I cut a 4" x 6" access panel out of the wheel (I remember it being a torch cut but forget where or from whom I borrowed the torch) I attached it to a piece of plywood using screws, metal strapping, and various pieces flotsam and jetsam for bracing. I had a dull handsaw I used to cut pieces out of a short length of waste 2" x 12". Using similar mounting means, I attached a washing machine motor so that the motor's bare shaft was pressed into the outer edge of the tire with enough friction that the turning shaft would directly rotate the tire. The inside of the tire was to serve as the tumbling chamber. For a test run, intended only as a proof-of-concept, I processed one batch of stained glass fragments overnight and made several pounds of perfect beach glass.

That was the only batch I ever ran, beacuse my wife and her stoner friend decided making beach glass jewelry was not fun to do more than a couple of times. Still, I felt like the concept was amply demonstrated. Had I needed to develop it further, I would have made a welded metal frame, replaced the direct drive with pulleys and belts, and replaced the tire with an attachment to hold a drum. The rubber from the tire turned the grinding mix into a really messy black substance that leaked from the inadequate seal I had rigged for the hatch cut through the wheel. As it was, it was relatively noisy, messy, and inconvenient to access the tumbling chamber, but it worked--once.

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#10

Re: DIY Rock Tumbler

07/10/2007 5:24 PM

If only I had access to such a fabulous invention!

While I am not in the business of professional rock tumbling, I do use half a dozen cheap little Rolling Stones tumblers which are typically used for kids tumbling rocks until they are bored of waiting. Crafts, hobbies and other ideas command my use of the wonderful rock tumbler.

Glass, rocks, you name it, I put everything into the little tumblers with water and a few spoonfuls of sand, tumble for a few days and presto. Then I use adhesive to glue them to a strip of tile mesh. When I have enough strips, it is time to use them in mosaic projects. Have you priced these strips in the home improvement stores lately?

Great idea, thanks for sharing!

Karen Marie

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#12
In reply to #10

Re: DIY Rock Tumbler

10/23/2007 11:16 AM

rock and roll

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#13

Re: DIY Rock Tumbler

11/16/2007 11:04 PM

The RT looks good! You might think about putting a chain guard on it now. The rocks might not be the only thing tumbling.

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#14

Re: DIY Rock Tumbler

11/24/2008 1:33 AM

Yeah an Inventer....

I was raised as a Rock/Shell Hound. [Also found a lot of parking lot change - always looking down...] In the mid 60's the family took a 6 weeks trip 'west' in a 12 foot Winnebago, 2 cars, [2 adults, 4 high school junior and senior age and 3 kids 10 to 5.] Much like Lucy in the Long Long trailer we came back [to my fathers dismay] with many pounds of GEM's. These GEMs, a few weighing over 25lb, needed cutting. We did not have a lap saw so we broke them or split down to smaller pieces for tumbling,

My mother had purchased a, {rather unique as I am finding out} tumbler somewhere on this trip. [I was only 10 so do not know where it was purchased just out west.] The tumbler was a 6 sided metal barrel, rubber coated inside and out - looked like it was dipped. {assuming metal because I do not think 1960 plastics would not have taken the torque the drive generated} It may have held 5 - 6 lb of stone. 6 - 7" diameter and maybe 12" long, but the unique thing was that not only did it rotate but it oscillated from end to end. It was a direct drive unit with the motor having a drive shaft with a clutch pin through it. The mating receiver was offset on the lid of the drum [maybe .5" in from the lip]. It was a split circle, the shaft fit into the split receiver and the pin in the shaft fits in the slots. I do not know how the lid locked [it may have been a bayonet lock to keep the correct orientation - I do remember a gasket seal that had to be cleaned] the other end had an offset pin that rested in a 'U' shaped mount. This pin was offset 180deg to the drive end, same inset. You mated the drive pin then dropped the other end's pin in the 'U' shaped 'bearing' cup. [The pin may have had a bearing on it but again I am not sure] This cup was on the same plane as the drive shaft. [I do not think there was a support stand on the drive end - this may have been what lead to the failure of the motor after 2 years. Having to support the weight and turn the drum.]

This offset to the drum caused the rocks to tumble more vigorously and uniformly, around as well as end to end, then just 'rolling' around the drum.

I am trying to get back into tumbling again, I have not stopped collecting [ask my wife] and would like to put a permanent polish to some of the stones I have collected and move them inside. My wife got me one of the 'toy' tumblers. Yeech... They seem to make more cylindrical shapes. Our old tumbler kept more of a natural shape while smoothing and polished off the rough spots. (My Mother made some really impressive pendents that had the character of the original shape still preserved, only smoothed)

I am really trying to find one of these old ones - or if some one knows how/where to have one built, at not too outrageous a price, I would be grateful. I love BETA testing things. :-}

[Did I just give a pattentable idea away??] ];-)

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#15

Re: DIY Rock Tumbler

12/22/2008 2:18 AM

Frank,

The biggest reason why I had no idea what a rock tumbler is used, is because it seems not to be a popular thing here in South Africa. However, it has begun. In all the major shopping malls in johannesburg you can now find these rock peddlars. My son (2 years old) had hours of fun playing in a pen full of polished rocks and his dad had to run all over to pick up flying rocks, while the mother was looking for the perfect piece of Jade for a cousin.

So, thanks for that interesting blog again.

Regards,

T

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#16

Re: DIY Rock Tumbler

06/05/2009 11:52 AM

can i have that other tumbler? will pay postage, shipping and handling, and reasonable price.. thank you, great story!!

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#17
In reply to #16

Re: DIY Rock Tumbler

06/05/2009 10:34 PM

sorry i will have to muddle through using the "toy' until i can find a really good one. I have a nice pink granet 'egg' that i found i canada [another story] i would like to put a polish on. 9" long 6" diameter aroung 10 lb. the 'toy' can not take it. I am glad you liked my reminising. Bob

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#18

Re: DIY Rock Tumbler

06/23/2009 2:38 PM

Is there any chance you could send me some close up photos of your tumbler. It looks like a great one to build. I've been thinking of buying one but yours looks more like what I'd like to have. Thanks,

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#19
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Re: DIY Rock Tumbler

06/24/2009 1:37 PM

I think I have included all the important parts and pictures in the post, but if you want more details or photos on any one part let me know which part and I will do my best.

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#20

Re: DIY Rock Tumbler

10/18/2010 8:58 AM

I think your DIY rock tumbler looks great - what sort of results do you get from it? Unfortunately, I'm not so skilled that I could build one myself. I have a found a site that does sell decent rock tumblers though - http://buyrocktumblersonline.com - and you can get one from less than $100, so I'm going to stick to using one I bought, but good luck with yours!

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#21

Re: DIY Rock Tumbler

05/21/2011 12:14 AM

I tried tumbling cartridge brass, and only ruined it. Seems tumbling wears off the corners. I now have a vibrating tool which I swear by! I use it for all my little bitsy pieces, like muskets and gun parts.

Sorry, I used the tumbler hardware to make a power hammer.

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#22
In reply to #21

Re: DIY Rock Tumbler

05/21/2011 4:03 AM

I do believe for brass they use a cereal, wheat or similar or ground up walnut shells, as the normal stone polishing agents would be far too aggressive for a soft metal like brass....its also done "dry" I believe.

Surely there is someone here who loads his own ammo who can detail it better than I can?

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#23
In reply to #22

Re: DIY Rock Tumbler

05/21/2011 8:55 AM

I tried walnut shells on brass...very aggressive. Wore the case markings off. It would be good for really corroded brass...that is, stuff which is brown from exposure, but only for the first 12 hour "spin".

I now use dry barley with a splash of brasso. 24 hours in the vibrator (stop every 4 hours to empty the cases...they get packed up pretty solid!) and the brass comes out as nice as anything. I don't reload myself...but am happy to do it for people that do.

The only rim fire stuff I ever did was to recover a bunch of .22 brass to decorate a "gangsta" belt. Its cheap. You can't re-load rimfire cartridges. But they can be pretty decorative in a costume belt.

The walnut shells are superb for little steel parts though. They are marketed as a media for sand blasting, and are cheapest by the 10kg sack. The muskets I repair have a half dozen little parts which get all rusty from the H2SO4 which condenses out of the gunpowder smoke. It is a two stage process...stage one uses a plastic media...little pyramids about a centimeter high. They make their own grit as they need it from the rust. 24 hours in the wet with that. Then another 24 hours in the dry walnut shells along with the pins and screws. Brass parts only get the dry barley treatment.

This can take two days, as you see. But compare to the hours of searching for that sear or spring that caught the buffing wheel and went flying "somewhere" in the machine shop!

Now I wish I had kept that old tumbler! Clearly I was using grit that was FAR too aggressive! Now that I am older and more experienced, I find that less is better. (I used sand once. It turned rather quickly into dust!)

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#24

Re: DIY Rock Tumbler

10/25/2011 4:07 AM

I turned mine into a kief pollinator (hash sifter) with some 150 micron stainless steel screen. Works great. Maximum buzz. Peace out tumblers.

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