Diy tumbler.

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Old 07-02-20, 01:09 PM
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Diy tumbler.

Ive had it in my head for a while to make my own tumbler for small amounts of brass and supressors. Ive gathered up almost all of the parts necessary, but ive run into a problem. I have a 8mm shaft that will help suport the drum, as well as provide the drive to spin said drum. I need something like casters that would raise the drum off the shaft by at least an inch, and more appropriately 2-3 inches.
I seem to not know how to put it into words for the internet to show me what im looking for. Ive tried drive caster but they seem to be not quite right, as well as expensive. Id like it to be set screw locked to the shaft, though im getting real close to changing the shaft to a threaded rod and just cinch a caster between two nuts and washers.

Anyone here have any ideas or prods that may turn me in the right direction? Thanks for the help!
 
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Old 07-02-20, 02:14 PM
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I assume the rollers will be locked to the shaft to provide propulsion for your drum or will they be free rolling?

If you are looking for free rolling try searching for "skate wheel roller". Hopefully you can find some with 8mm shafts otherwise you might have to change your shaft size. A shaft roller might be an option and would incorporate both the shaft and roller though the roller would be continuous for the full length.

If you need a locked roller I don't know of a specific, standard, off the shelf item for what you want but there are some options. Look at "shaft bumper". Some of them are locked to the shaft and might work. You can also look at hand truck wheels but they would be much larger in diameter. Also look at "shaft collar". They normally aren't used as wheels but they might be round enough to work and they are really inexpensive.
 
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Old 07-02-20, 04:49 PM
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Simplest setup I know of - (geology stone tumbler, not brass, but effectively identical)

1) One-liter soda bottle filled with material to be tumbled & the abrasive
2) Soda bottle screw cap with drive rod connected to an electric drill.
3) Bearing surface is a kitchen loaf-pan partially filled with water to float the soda-bottle-full-of-material-to-be-tumbled. Set the drill on a cheap book and adjust the height by which page you're on.

This is most basic zero-friction-buoyancy-bearing setup I know of.

Something roughly similar, but with skateboard wheels, at
https://youtu.be/bGrSRc0Lv9k
 
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Old 07-03-20, 02:20 PM
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Something roughly similar, but with skateboard wheels, at
https://youtu.be/bGrSRc0Lv9k
What I don't like about that design is that there isn't a lot of "clashing" going on. It's the "clashing" -- either with the tumbling media or other pieces of brass -- that does the cleaning. He's even using the most expensive of all tumbling media -- stainless steel -- but it's obviously being under-utilized in this case. Watch the steel pins in the middle of the bottle and you'll see they're in no big hurry to get anywhere. The only place where you see any energetic collisions going on is where the bottle has an irregular shape -- at its bottom. And that's still not very energetic because how far the brass can fall is limited by the size of the 2-liter bottle (which is about 4-1/4" in diameter).

You'd rather your brass was being thrown around like the clothes in a tumble dryer.

One of the reasons that the Thumler rock tumbler (full disclosure: I have one) has such a dedicated following among hand loaders is that it's drum is hexagon-shaped.



It's not possible for either the brass or the media to just sit at the bottom and watch the drum spin around it, which is mostly what's happening inside that soda bottle.

Plus the drum is larger than the 2-liter bottle. It's 7" between opposite corners and 6-1/2" between parallel faces, so the brass has further to fall (= a more energetic collisions).

Knowing what I know from years of using the Thumler, if I wanted to DIY one on the cheap for small batches, I'd use a peanut butter jar for the drum and spin it end-over-end.

I don't just tumble brass, I also tumble bullets to coat them with WS2 (tungsten disulfide) or hBN (hexagonal boron). They're both like Moly (molybdenum disulfide), only better. But one thing both have in common with Moly is that the powder makes an awful mess. It will stain everything it comes in contact with, which means you don't want it running loose inside a tumbler drum that you intend to clean brass in later.

The solution is peanut butter jars. The standard height for a 40-oz peanut butter jar is 6-1/2", which happens to be how far it is between the parallel faces of the Thumler's drum. Two PB jars fit perfectly inside the drum, so you can tumble two separate batches of bullets with lubricant powder at the same time without staining the interior of the drum.



Which is what gave me the idea to make a tumbler out of a PB jar. Because that has proved to me that the jar is durable enough for what I have in mind. At least durable enough to withstand the clashing of the brass and the media. I'm not so sure how it will react to the torque this would apply, but hey, nothing ventured, nothing gained, right?

Besides a PB jar you need a threaded rod about a foot long and small enough to fit in the chuck of your drill. You also need four nuts and four washers (the wide type, like used in bodywork) that will fit on the threaded rod. And JB Weld.

On one end of the rod, hammer the threads into flat faces so the chuck will have something to bite onto. Measure the PB jar from end-to-end to find the middle and drill two holes the same size as the threaded rod in the middle and on exact opposite sides of the jar from each other.

Hammer the washers on a curved surface so they're a fair match for the curvature of the PB jar. Smear JB Weld on the convex side of two of the washers and on the concave side of the other two.

Run the rod through one of the holes in the jar. Before running the rod out of the other hole, slide on the first washer, one with JB Weld on the convex side, JB Weld side goes on first, followed by the two nuts and a second washer with JB Weld on the convex side, concave side first (JB Weld out). Then run the rod through the other hole. Adjust the two nuts so they trap the curved washers against the inside of the jar but don't distort the jar's shape. The rod should also be left sticking out on either side whatever distance is appropriate to the rest of your set-up.

Take the two washers with JB Weld on the concave side and slide one on either end of the rod. Then put a nut on either end and tighten by however much you think is reasonable. Before tightening the nuts make sure there's plenty of JB Weld worked into the threads of the rod where it comes out of the washer. JB Weld is supposed to be waterproof so this should prevent a leak around the "axle" if you decide to tumble wet. Then slather JB Weld on each of the outside nuts and washers so they will be bonded together once it's cured.

All you'd need to support the end of the threaded rod opposite the drill is a nylon surface, U-shaped or V-shaped to keep it rod located. No bearings, no rollers. It'll look like a peanut butter jar rotisserie. And turning end-over end will produce some serious clashing, twice in every revolution.
 
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Old 07-03-20, 08:05 PM
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What I don't like about that design is that there isn't a lot of "clashing" going on. It's the "clashing" -- either with the tumbling media or other pieces of brass -- that does the cleaning
Good point- I guess I should mention my kludged-together toaster-oven-rotisserie peanut roaster as an option.

Several years ago, I replaced our 12" wide toaster oven with a wider-deeper ~16"toaster oven that has a rotisserie spit & two prongs. The rotisserie is just big enough that a large steel coffee can will fit on the spit.
You need 1 empty coffee steel coffee can for the body, and then use a can opener to cut the steel bottom off of another can to make a lid that fits and seals the to of the can. Punch holes in the center of the can and the lid, then slide the spit & prongs (cut slits for the prongs) together to keep the lid sealed tightly against the can. I added "vanes" to tumble things on the inside of the can by cutting up the other coffee can and jamming them into the rotating drum.

So, you MIGHT be able to tumble brass using a toaster over rotisserie, or a BBQ rotisserie and a coffee can.
 
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Old 07-03-20, 10:19 PM
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Yeah, see i already have the tumbler built, like i said, almost complete. Im using a sewing machine motor and timing belt and pully kit from 3d printers kits. Just need to stand off the 6in pvc pipe that has stips of pvc welded inside it as agitators. I could go all janky like most out there and just wrap rubber around the shaft, to friction drive the pipe. But i really want this thing to be able to tumble for 4 to 8 hours, and to keep doing so for many years.

The drill method is fatastic for once or twice with a handful of shells only partialy clean. Im going to have a ten ounce supressor monocore plopping around with steel pins in this thing. Id kill the drill relativly fast doing that.

Im going to try some caster wheels. I bought a pair from the hardware store and am going to have to drill the bore a little wider to get them on the shaft. I still dont know how im going to lock them to the shaft. That is my main problem. Im seriously considering changing the shaft to a 18 or so inch threaded rod, using nuts and washers on either side of the casters to lock them on the shaft. Once i settle on it being finished i may post up a build thread for it. Im also considering making a second drum for rock tumbling, since yhe way im building it, it should last a damn long time.
 
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Old 07-03-20, 10:26 PM
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also the rotissery motors i looked at but settle away from them as the turn rates on them were too slow for proper tumbling. 40-60rpm is the standard range for brass and rock tumblers i think.

I have a bunch of coffee cans, but they arnt deep enough as the supressor is 10in long. And impossible to seal well enough for wet tumbling. Id also be weary of how long that steel can would last if i decided to use spent sand blast material as the polishing agent.
 
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Old 07-04-20, 07:22 AM
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So, it's a 6" PVC tube, suspended below and driven by a rotating 8mm shaft?
I'd slap gears from a child's bike on both ends, then suspend and drive it with two old bicycle chains.

If you really want agitation, I'd consider a "long throw" version driven by an aquarium water pump, put a screen on one side to retain the work and abrasive, let it slosh away.


https://www.youtube.com/watch?v=NK6iBVMHCfU
 
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Old 07-07-20, 10:08 AM
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As a reference, my Thumler is the "heavy-duty" model with the 1/3-hp motor. The 'standard' Model B has a 1/4-hp motor and is advertised to turn 30 rpm. I'm using SS media and 2 hours of tumbling is usually plenty long enough, even for brass that sat uncleaned in the weather for years. Motor speed isn't adjustable for rpm but if you got industrious you could change the belt and pulleys to alter the drum's rotational speed.

If you've got the foot pedal/speed control to go along with that sewing machine motor, or intend selecting pulleys for a specific rotational speed, I'm thinking 60 rpm should be good. I checked here and found that 60 rpm with a 6" diameter drum would only produce about 0.3 G-forces. Too much G-force and the brass won't fall at all but will stay pinned to the wall of the drum, like a motorcyclist riding on the "wall of death."



My guess is that you wouldn't have to get all the way to 1.0 Gs before the clashing would diminish. For instance if you dialed the speed up to 0.99 Gs, the brass wouldn't be pinned to the wall, strictly speaking, but it wouldn't fall very far either. So I suspect something well less than 1 G would be optimal.

My Thumler at 40 rpm is only producing about 0.2 Gs. What's tricky about setting the rotational speed is that centripetal acceleration changes with the square of rotational speed ( force=(mv^2)/r ). So adding 50% to rotational velocity (90 rpm rather than 60) creates 125% more G-force.

Just a hunch but you might be able to determine the speed that produces the most clashing by listening. Seems logical that the most clashing would create the most noise. Presuming you can hear the noise inside a PVC drum over the noise of the motor and rollers.
 
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