Building a stone polisher

Here's a link to a site that sells ball mills for amateur black powder milling. The photos may give you some ideas:

Here is another from a web page describining a home-built rock polisher or ball mill:

Enjoy!

Harry C.

The Surplus Center is also a great place for "stuff".

Build a Sponenmill:

Any tips for using your basic tumbler to shine/clean/restore old nuts and bolts? I've heard from vintage car restorers that they were great for this... I'd guess to use a polish and not an abrasive though...

Where do you get those ceramic pieces they use in vibratory tumblers? That and some fluid - kerosene maybe? should do it.

- - Rex Burkheimer WM Automotive Fort Worth TX

TheMan wrote:

Here is a rather interesting rock polisher I ran across when I was looking for info on a tumbler for some steel parts I cut.

Make a thick rubber liner and you won't grind up your tub. Six sided is nice not a big bump. Martin

Check out how it is done. Might surprise you. And a source of supplies.

Here is one I found: [ I have no contact with these or this person.)

Martin

There is one on the Net which uses a car tyre. 2 plywood plates fill in the hole in the middle and it ran on a couple of bits of shafting. IIRC the tyres lasted for years, despite being worn from the inside out Geoff

Round & rubber is better than polygonal & steel. The setup at the local serious rock shop back home was rather handy, if a bit large for a kid's project - they had a set of tires on powered rollers - no fuss with sealing the drum, and you could pull out a few to look at the progress without it being the huge production it is with the small drums. Perhaps for a smaller one you could scrounge a few lawn tractor tires - they used car tires.

There is no need for anything in the hole with a car tire or tyre. Simply keep the load size such that the fluid does not spew out the hole.

I built one years ago but it worked OK.

First I built a rectangle from Bed Frame angle iron. I mounted two self aligning bearings at each of the short sides to hold 5/8 inch rod parallel to the long sides. I made a couple of pulleys from some two inch solid round bar and put one on each piece of 5/8 rod at one end. I ran a heavy duty O ring (From some form of Caterpillar Dozer) on those pulleys.

I mounted an old washing machine motor under the frame and welded legs to the frame so the motor was not on the gound. The motor had a 3 inch pulley and it drove an 8 inch? pulley attached to one of the 5/8 rods..

I used the commercial plastic barrels as they lasted forever and weren't too expensive. The rectangular frame was long enough to run three barrels at a time.

I only used self aligning bearings as a mate gave me them and the housings. The 5/8 rod driving the barrels gave a really large amount of downwards gearing.

Bob T (>One standard 5- or 10-gallon propane tank, empty, flushed etc

There is a major distinction here. The "plasticky" tumblers are available from toy stores as children's toys and most certainly are trash. However, most any reputable gem and mineral store will carry the professional grade tumblers. The most common brand is Loretone. They come in different sizes and the price increases with size. I would definitely buy the drum but making the motor housing would be a good project. Another money saving tip: the good brands are nearly indestructible, so a used one is a good buy. Also, the drums wear out more frequently than the motors, so if you wanted to have one sure of not leaking, I would try to find a used motor unit with a new drum. Another thought when it comes to size: the silicon carbide abrasive is expensive. My large tumbler, a 12 pounder, uses a pound of abrasive per step and costs almost $30 per load to fill with the proper material. Hope this info is useful.

Thanks for all the useful information from different perspectives. I'm starting to assemble some ideas about the kind of machine I might build and the parts I'll need.

I think I have a suitable motor which I picked up from a skip when a laboratory was being cleared last autumn. It's a shaded pole induction motor rated at 30 W and it's really nicely built (they don't make them like this anymore). It took me a while to work out the motor speed as I sold my tachometer when I needed some cash. So I put a sticky label on the shaft and held a pencil against it so it made a clicking noise. Then I recorded the sound on the computer and looked at the waveform, and it turns out the motor runs at 1425 rpm. I took a picture of the motor and put it online:

The most important question is how big a barrel I can turn with this motor? I found one page showing a Thumler tumbler which had a 22 watt motor, but it didn't list the barrel capacity. I was thinking of two 1.5 lb plastic barrels, which are 11.5 cm diameter, but they're actually pretty small. The rubber 2.25 kg barrels (17 cm diameter) look nice but they're expensive. I also have a 50 W at 950 rpm shaded pole induction motor. It suffered a bit when the shed roof leaked, but it could probably be restored. The 30 W motor has the advantage of being totally enclosed so that no gunge can get inside, whereas the 50 W motor is open. What do people think about power requirements?

I've found a 2.5 mm pitch toothed belt and aluminium pulleys for about £12, which will provide the right reduction, and I can buy 15 mm round stainless bar to make the rollers (about £4 for each roller). But the bearings seem to be a problem. I really wanted to use those nice self-aligning ball races in cast iron pillow blocks (probably with a 10 mm bore), but they cost a fortune - about £20 each! I could perhaps afford £20 for all four. Any ideas where I might find surplus bearings in the UK? I want the quality of my machine to be decent but I can't afford to spend £80 on bearings. What do people think?

Once again, thanks for all the ideas.

Best wishes,

Chris

Thanks. Would be fascinating to see. What kind of spheres does he make?

Chris

did you check ebay? i bought self aligning 1.5" pillow blocks for about $10 each.

I did but I only checked eBay UK. Might be worth the postage from the US if they're really cheap I guess. I'll take a look.

Thanks,

Chris

Because the threads are so small don't they use the magnetically stirred burnisher type machine in a liquid? Basically it's lots of little stainless wires (needles) in a liquid and the magnet impinges them on the parts to be deburred/cleaned (or vice versa depending on the magnetic nature of the parts and media). From what I saw, you could do it on a small scale with a standard lab magnetic stirer if the media could be found.

Koz

He takes a chunk of rock, sorta kinda knocks the corners off with a saw, and then turns them into highly polished spheres using a wierd looking but really neat grinding arraingment of motorized cups and grinding media.

Like these

Gunner

"Pax Americana is a philosophy. Hardly an empire. Making sure other people play nice and dont kill each other (and us) off in job lots is hardly empire building, particularly when you give them self determination under "play nice" rules.

Think of it as having your older brother knock the shit out of you for torturing the cat." Gunner