Building a polisher

On Sun, 7 Dec 2003 10:25:01 -0800, SteveB put forth the notion that...

You're making a tumbler. You might be able to get by using clean sand as a tumbling medium. I'd try that first, because it's a hell of a lot cheaper than anything else.

I vote for PVC. Sonotube is made of cardboard and intended to be peeled off after the concrete has set up inside it. Gary Brady Austin, TX

Is that the stuff that HD sells as "play sand" meant to be used for kiddie's sandboxes?

Steve

You can sure try play sand. I have no polishing experience to share, but I done a fair amount of sand blasting. I would contact a local sand blast company or supplier. Ask about Black Beauty and flint abrasive sand.

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Keep the whole world singing. . . . DanG

Somebody made a tumbler out of a car tire hanging on a shaft, plans and descriptions were on the web but I have lost my bookmarks. There were other iterations with the tire sitting on rollers too.

On Sun, 7 Dec 2003 11:28:00 -0800, SteveB put forth the notion that...

That's what I use with my sand blaster. It's almost white in color. That brings up an interesting question. I've tried using that so-called "play sand" to make concrete, and the stuff takes weeks to set up, and is never very strong... anybody know why?

I've bought the gray sand that HD sells, and had to spread it out and put a fan on it for a week to get it dried out, they leave the bags out in the weather here in Seattle, so you get about 50% sand, 50% water, thankfully you're only paying for the dry weight of sand???Right??? The white sand that they sell as "Play Sand" seems to have been graded, at least to the high side, so you don't get stuff that's much bigger than 150 grit or so. (Oh for the days when Boeing surplus would plop a pallet load of silica sand bags out for 50 cents a 100# bag. It was worth drying, cuz that's all that was wrong.) I have used gray sand to clean cartridge brass with results that were ok, but not really that good, I don't know if it was because of the brass:sand ratio or running it dry, but I remember that I had to run it for almost a week to get the job done. That, in my opinion, was too long to wait for a 3 lb coffee can of brass.

I would suggest that you look around for some vibratory deburring media, some of it is like pyramid shaped soapstone, but I'm not sure what it is really, and there are other shapes available. They seem to have the weight to hit harder and cause a more agressive cleaning/deburring action.

As for the tumbler drum, make it out of something cheap, rubber coated seems to last the best, but PVC pipe is available and cheap. Five gallon buckets are cheap too, but how would you secure the lids??? Remember it is running on rollers and has to be contained somehow from walking off the ends. ?????

Almost makes you wish that you could remodel a front loading washing machine so that it would work. They seem to rotate at the right speed to make the load drop and slosh, which is why they work so well, I guess.

The white sand sold by Home Depot as "Sand Castle sand" is supposedly marble dust. I had bought a bag of it once and sifted it through an old nylon stocking to be used for sand casting. I got about a %50 yield through the stocking.

I'm pretty sure marble is softer than silica sand and so you should expect it to wear out faster. I have no idea how well it'd work as a polishing medium.

As far as a large capacity tumbler is concerned, I've toyed with the idea of making an attachment for my lathe, consisting of some rollers (small diameter rubber wheels) in a welded frame, driven by the lathe spindle. In back gear I can get 55 spindle RPM's, and it'd be easy to reduce that by a factor of 2 or 3 with a belt and pulleys. Simply load a 5 gallon pale, snap on the lid tightly, and lay on top of the rollers. Depending on bed length (maybe not even that) the attachment could be extended to roll several 5 gallon pales at once, either increasing your capacity or giving you several stages of polishing at once.

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Here is one for rocks.

Regards,

Boris Mohar

Got Knock? - see: Viatrack Printed Circuit Designs

I use walnut hulls and a teaspoon of jeweler's rouge in a vibratory tumbler for cleaning cartridge brass. It does an *exceptional* job, with even cruddy old range pickups coming out with that factory shine.

In general, I think that vibratory tumblers are the way to go. The parts don't bang against each other the way they do in a drum tumbler, so you don't get as many dings and scratches. There is a good selection of media for different part materials too, everything from incredibly harsh to very mild. Vibratory machines are quick too, and fairly easy to build if you don't want to buy.

Gary

You guys need rollers..Rollers I have...urethane covered aluminum rollers about 4" in diameter with a 3/4" through hole IIRC

Got lots of them along with belts, pulleys, pillow blocks etc etc.

Gunner

No 220-pound thug can threaten the well-being or dignity of a 110-pound woman who has two pounds of iron to even things out. Is that evil? Is that wrong? People who object to weapons aren't abolishing violence, they're begging for the rule of brute force, when the biggest, strongest animals among men were always automatically "right". Guns end that, and social democracy is a hollow farce without an armed populace to make it work. - L. Neil Smith

On Sun, 07 Dec 2003 20:59:50 -0500, Artemia Salina put forth the notion that...

Marble would be much softer than silica sand, but I haven't seen any of that in the Home Depots around here... it might be a regional thing. The "kiddie play sand" sold in my neck of the woods is labeled as silica sand, and makes a pretty good abrasive. I'd still like to know why it inhibits concrete from hardening, if anybody has the answer to that.

If you have a small cement mixer, that would probably make a pretty good tumbler for deburring parts.

Salt? If sea-sand.

And if you use a sealed system, remember that a variety of gasses will build up as you tumble so the pressure inside will increase. Rock tumblers have a nasty habit of blowing off the lids unless they are vented.

One question never answered is what is considered "polished"? For some that means no scale and rust. For others that means near mirror.

I would personally spring for ceramic or plastic media for tumblers because, although it will cost you in the short run, you will have control and finish in the long run.

Another alternative might be the bucket idea you have and dry tumbling in plastic pellets and carbide grit. Small plastic pellets and graded grit are available at most rock shops. A 5 pound bucket of medium grit should last a long time if you throw only 1/4 cup in with a bucket load of pellets. If pellets are not available, coarse sawdust with the grit will sand them also.

One final note: You want a tumbling action, not sliding. This means that you will need to monkey with the speed after you get it loaded. If the parts are in the "slide" mode from running too slow, they will take on the shape of the outside of the bucket on one side only. If they run too fast so they "throw" instead of tumble, the parts will be banging against each other and probably be left with dents.

Koz (who does more rocks then metal parts in the tumblers)

nic wrote:

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