I hope this will work. If not, I am determined to fiddle with it until it works.
I found an old asynchronous motor in our cellar. It is a small thing, mere 140 W, and it lacked wiring, any elements to fix it to something and cam wheel completely with wedge. But I have managed to convince my father to connect a cable and a switch to it, and it was working. So last few weeks, whenever I have got an hour or two, I was building a tumbler. I did not document the building process, because there is not much to it, really.
Just like with my belt grinder, I started with a particle board leftover from kitchen renovations, which was the base for my old drill press. It is a nice >2 cm thick board, covered with waterproof plastic on the upper side. Stable, strong, simply ideal as a base for a machine. Because the motor lacked any flanges or wings or whatevers to fix it and only had 4 M5 threaded holes, I took two pieces of steel that had 90° angle, straightened them to about 120°C angle and screwed them onto the motor. This provided me with two ears, that could be screwed on wooden blocks connected to the base plate. The switch was attached to the plate by its standard holes, plus two wooden pieces to better secure the cable.
As I mentioned, the motor lacked cam wheel. So I stood in front of a choice – to buy V-belt cam wheels and V-belts, or try something else. I tried something else, because I deemed it easier and cheaper. I bought two PP furniture wheels of different sizes. One got attached onto the motor in the standard way – with a steel wedge ground from a piece of spring steel and a lot of cursing. The diameter of the axis was slightly smaller than the inner diameter of the wheel, but I was able to fill the space with a piece of steel pipe. For the bigger wheel I had more luck – it had inner diameter 15 mm. So I could just buy a 15 mm steel pipe and further I could put to use two old ball bearings that also had 15 mm inner diameter. With a bit of banging and a lot more cursing I was able to fix the two ball bearings and the big PP wheel onto the pipe (the PP wheel is further fixed with a nail, so it dos not hold on only by friction). Next step was to fix the ball bearings on two wooden blocks onto a separate particle board plate.
At this stage I also took a strip of leftover flooring PVC and glued it onto the PP wheels for better traction. It is actually nearly impossible to glue anything on PP with reasonable strength, but there are adhesives on the market that manage this task strong enough for this kind of application (I think). If it goes pear-shaped, I can always screw it on later.
For the tumbling drum I took a 100 mm diameter PP pipe and again I glued on it a few layers of PVC for better traction. The PVC lays directly on the steel pipe in order to reduce the fast rotations of the motor as much as I can.
Two small furniture wheels aid in keeping the tumbling drum in place whilst allowing it to freely spin. The tumbler thus lies between the axis and the two wheels and holds in place purely by its own weight.
Last week I cut a piece of thick leather 1 m long, 3 cm wide, and I cut the ends at an angle so they overlap whilst the overall thickness remains the same, and I glued it together with epoxy. Hide glue would probably be better, but the weather was way too cold for messing about with hide glue. Today I took last few hours in adjusting the positions of the two wooden plates against each other to have adequate tension on the belt without it wandering in one direction or the other. As of now, it has been running for an hour without problems.
It has about 120 rotations per minute, which might be a bit too fast. I put in shredded walnut shells, a soft coarse polishing compound and a broken blade from my failed machete build.
We will see what comes of it.
Oooooooh. Nice job, I hope polishes well!
Marcus Ranum says
I’ve been building one, too (a veritable F-35 of a thing) to remove scale off billets, maybe. It turns out you can get shot peening glass beads on ebay cheap. I used a belt and timing gear pulleys from a 3D printer.
Unfortunately with these things you have to build iy to find out if it works or not. Here’s wishing you success!
Ice Swimmer says
I have to admire your ability to make things out of leftover and cheap materials.
The small furniture wheels carrying the drum are reminiscent of the steel or rubber tyres (filled with water or air) used for carrying wood debarking drums, the scale is just a few orders of magnitude different.
My experience with tumbling stuff comes mainly from tumbling agates and other stones. Not knowing for sure what your tumbling medium is I can see what might be a couple of problems. One is if you only have the one blade and your tumbling medium, the blade will likely just slide around the inside of the barrel and not tumble because the walls are smooth. The barrel I use for tumbling is made of rubber and has like ten sides inside the barrel to aid in the tumbling motion. If the blade doesnt have anything to tumble against it will just slide around. If youre using a solid grit you will likely just get smoothing of the edges into rounded edges. Not sure what youre trying to achieve. There is ceramic grinding/polishing medium that can do more to work on the surfaces of the blade. If youve already got that figured, my apologies for being redundant.
Sorry for the dual post but I wanted to say that overall the tumbler looks great.
@StonedRanger, I forgot to write it in the article -- the walls are not smooth, there are three wooden ribs inside to prevent the contents just sliding around without tumbling. It is a good point to make, no need to apologize.
Have you had a look at how the blade is doing yet? /impatient
Marcus Ranum says
I’m with Jazzlet: you’d better get that blade out of there before it’s worn to powder!
I took the blade out today morning, and it seemed to have worked as intended. However the blade was not properly cleaned from file scratches and scale prior to this, so today I polished it properly on the belt grinder up to 120 grit (zircon belt). After that, I made microphotographs of the surface on two spots and gave the blade back into the tumbler. Tomorow, after approx 24 hours, I will take it out and evaluate it.