Make LARGE ball mill (4 5gal buckets) with a treadmill & still be able to use treadmill as intended!

So I was trying to figure out how i was going to build a mill for a 5 gal bucket - or even up to 4 buckets at once. It would require a good bit of building until I realized that I already had something that was 90% finished, had more power than I could ever need, very accurate speed control, was professionally built (not a fire hazard) and didn't need to be taken apart. A treadmill!

So I thought of ideas on how this could work. I found some old wheels off a baby stroller at a thrift store, these are about 8" diameter x 1" wide, the "tire" part is super nice soft grippy rubber and the tire is "domed" and gives about 1/8"-1/4" contact when sitting on edge with no weight. I thought these would be great "drive wheels" for the mill. They would roll on the treadmill belt. They had a 3/8" hole in the center and they glided/spun very nicely with little friction (it is a hard plastic of some kind). There is a 1.25" extruding ring surrounding the center hole with the lip around the ring being about 5/8" high - so this would accept a 1.25" bearing perfectly inside of this and epoxy it in place. I'd do this for all 4 wheels and these will all be in contact with the belt and will be the drive wheels for the buckets.

2 2x4 of about 7ft long will be used to hold the 4 drive wheels. holes will be drilled about 1/2" from the top of the 2x4's width (so about 1" of the wheel is below the bottom of the board) on both boards, directly across from each other. I'll either use a metal rod (size of the ID of the bearing hole) to hold the wheels and put nuts on the outside of the 2x4 to keep the rod in place. The width will be wide enough so that the buckets rest on the 8" wheels - offset

I also have 8 roller blade wheels, 2 of which will be used for each bucket and they can be adjusted to accept smaller than standard 5 gallon buckets. These wheels roll freely and are used to support the bucket and keep it in place.

There would be a few braces keeping the 2x4"s at proper distance apart. I mentioned an axel on the 8" wheels but those aren't 100% necessary, I did a trial without them and it worked fine.

Now you will need to secure this setup so it doesn't slide off the treadmill belt when it is running, not hard to do, use a rope and clips to attach to the vertical "beams" that the control rests upon. If you are worried about is sliding from side to side, it's possible to place a bumper on the side of the treadmill (off the belt) where one would stand when waiting for the belt to slow/stop.

Here is a pic of the design. I've made a smaller model that can run 2 buckets and isn't near as sturdy as my final design.




[Edited on 7-25-2018 by RogueRose]

That looks like it can handle a LOT of media!
If you can get ahold of paint or pickle buckets, they're a lot thicker than the hardware store brands.

Quote: Originally posted by CouchHatter

That looks like it can handle a LOT of media! If you can get ahold of paint or pickle buckets, they're a lot thicker than the hardware store brands.

Quote: Originally posted by RogueRose

I just found this seller on ebay that has some REALLY good prices on steel balls from carbon steel, chrome, stainless, etc in any size you might realistically want in quantities from 10 to 10,000 https://www.ebay.com/str/BC-Precision/Slingshot-Ammo/_i.html?_storecat=745152719 I'm torn between getting steel balls or ordering aluminum oxide or Al2O3/ZrO balls or rods from china. The latter won't spark if I'm doing things that are volitile, but you never know what you gonna get ordering from alibaba.

Your arrows are going the wrong way.

Quote: Originally posted by Loptr

Your arrows are going the wrong way.

You won't believe how many times I switched the arrows thinking it was one way, then the other. But I am correct that each barrel will roll the opposite way (when they are on the same drive wheel), correct?

Well if lead is best, I have plenty of it but I just need to make some moulds. I do have a couple 1.5" thick Al blocks (3" x 10" x 1.5") but IDK the best way to drill a spherical hole. I think aga did something awhile back with a washer welded onto a bolt or something, but I fear I will have less success, though I do have a drill press now instead of a hand drill, so that should help.