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PVC barrel for rotary tumbler

Hi all, I’ve lurked for free for a long time, finally signing up so I can share this.

I saw someone on youtube present a replacement barrel for their rotary tumbler made out of pvc pipe, but they didn’t get into specifics about what or how. I couldn’t find a direct answer, so I set out to sort it out myself. (Also the day job has suddenly decided they want my hobby jewelry skills for a project, so work paid for the experiments :smiley: )

But the point is, this is how I’ve answered the problem. There could be improvements! This is not time-tested BUT it did end up costing only about $10 per barrel.

I have a single barrel Chicago Electric rotary tumbler from Harbor Freight. The barrel space is enclosed on each side, so the length of the barrel is limited.

I had trouble finding 4" PVC pipe at my local Home Depot, but discovered I could order a 2 foot length of “Charlotte Pipe” via their website for $21.36. This is enough to get 4 barrels out of, even with some less-than-totally-precise cutting. You can cut this pipe with just about anything: meiter saw, hand saw, twine supposedly, probably a dull kitchen knife if you’re dedicated. It does make a massive pile of plastic snow though, so do it outside or in a space you can clean.
Total length of your barrel pieces will depend on the caps and the length your tumbler can handle. I cut my length to 4.5", and with the smallest caps they just barely fit the single-barrel tumbler.

The easiest and cheapest way to cap these barrels is with “knockout test caps” for 4" diameter pipes. They were $0.78 each when I was shopping. They fit inside the end of the pipe very snuggly. I had gutter caulking around from a previous project, and used that to permanently attach -and water proof- a knockout cap to the bottom of each barrel. I suspect regular old bathroom caulk would work, or any number of other water-resistant and hard-drying substances. The cap was very nearly water tight on its own, only had slow drip leaks without the sealer.

I also chose to use knockout caps for the tops of each barrel. This is not entirely ergonomic, as the caps are meant to be smacked out from the inside, so there isn’t a convenient handle or anything on the outside. But I was already using a metal washer to pry open the lid of the original rubber barrel, and that continues to work fine for these.
To improve waterproofing at the top, I found a “Sink Strainer Washer” which is a very large rubber gasket. I had to cut out the inside a bit to fit over the knockout cap, but for $2.40 each it seemed a reasonable trade off.

The last touch I added was some grip tape to the outside of the barrel, to help the tumbler grab it since the pipe was fairly smooth. Grip tape of the sort used to add traction to steps is fairly cheap on Amazon and in hardware stores ($7-10 for a roll?) though I imagine there are lots of other options to add a little grip to the outside.

I did experiment with a different cap, a “Mechanical Test Plug”. This is a big red cap with a wingnut on the top, and a gasket around the side. When you tighten the wingnut, the gasket expands, so it caps and waterproofs the barrel in one go and is more ergonomic than the knockout caps. Unfortunately its also much bigger: the wingnut sticks out about an inch beyond the barrel, and the plug takes up an inch of the interior. When the barrel size is limited such as for my tumbler, this results in a really small tumbling space.
Also its almost $10 on its own.

So, 4 new barrels for around $40 total, if you’re just using knockouts and washers. I don’t have to swap dry media around, and I don’t have to worry about black rubber breaking down on anything.

Again, I haven’t run these more than a a few days, this is not backed by “years of experience” or anything. But this is the answer I was searching for several weeks ago, and couldn’t find! So I thought I’d share.

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I like to make my own tools too when I can. It’s fun to do and can save money. In the case of a tumbling barrel, I would buy them and have bought several along with three vibratory tumblers. If you look at a tumbling barrel made for the purpose, many are round on the outside, but most have a series of flat surfaces around the inside circumference. These flat surfaces pick up the media and cause it to break over much the same way as a wave breaks. This causes the media to impinge with some force on the pieces being tumbled. If the inside of the barrel is smooth as yours is described, the media and pieces being tumbled will just slide around the inside of the barrel. It will take a lot longer to tumble the pieces if they tumble at all. Others may have a way to make a tumbling barrel and I look forward to hearing how they did it. Good luck…Rob

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good point! don’t see why 4 vertical slices of pvc or similar couldn’t be epoxied to the inside of KatG00490: pvc pipe to create the necessary disturbance.

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That is what is done with smaller, less expensive, barrels. Just be careful that what you use for baffles doesn’t scratch the jewelry being tumbled…Rob

Thank you for joining and sharing! I’m wondering if ridges of epoxy putty along the inside would have the same effect as the flat areas? I honestly never realized why the inside of tumbler barrels have all the flat surfaces.

I use the standard barrel with flat sides, but sometimes small items just flow around with the pins. I keep some larger scrap items handy for this problem. Just throw them in with the small pieces and the large items will drag somewhat and break up the flow, allow the smaller items to be impacted by the pins.

A have a Harbor Freight double tumbler, but didn’t like the black rubber barrels and the rubber residue they left. So, for around 15 years now I’ve been using a large plastic mayonnaise jar for my tumbling. No problems, and if it ever wears out I’ll just have to double down on mayonnaise eating until I have a “new” tumbler barrel.

@hammettt I read a suggestion somewhere to use a peanut butter container, and I’m game! But we literally just bought a new one and don’t go through it that fast XD
I’ll be keeping them in the future for sure.

If your container is clear, you can see how the load is tumbling or not. You can find recommended levels of media, jewelry and water to make the load tumble efficiently on line, the same for lapidary. I usually just do it by eye as I am happy with the results most of the time. I may go looking for a clear glass jar and give it a try…Rob

You need flats inside to make the stuff “tumble” not slide… grin. I have seen some European ones with small triangles inside to make the tumbling even more effective.
Judy H

This was some years ago, but I merely piped three longitudinal lengths of self-curing silicone rubber (i.e. caulking) along the lengths of my round tumbler barrels to ensure that the items inside tumbled rather than merely dragged. I had earlier found that gluing vanes in was a bad idea, since the triple ‘drop’ during each rotation would texture softer metal items (such as fine silver). I realise that a drop could be useful for some work-hardening situations if the texture were acceptable.

After about ten years of use by students, the piped rubber (initially light-coloured) had turned black, but was still serviceable. Also, I had used some kind of activation liquid on the barrels where the stripes of rubber were to go to ensure permanent adhesion. I don’t remember what the liquid was, only that it was very poisonous and expensive. It may even not have been necessary.

Oh, I like this idea! I can try it on one barrel with the same caulking I’m already using for the bottom seal, and see if it lasts.

Thank you for sharing :slightly_smiling_face: