Rockwerks Lapidary Forum

I'm a frugal person, and while strolling around a hardware store I noticed they sold blasting abrasive, like sand blasting. They had a huge 20 lb box of ALUMINUM OXIDE 70 grit, for the low price of $20, making it only a dollar a pound. My question is, could this cheap aluminum oxide be used for the rough tumble grind instead of silicon carbide? Has anyone tried alternative abrasives?
I guess I could spend the 20 bucks to try it, but of course if it doesn't work, I don't see any possible use I could have for the stuff, and its 20 dollars less I could have spent on silicon carbide, and it doesn't some any smaller, only larger.

Brian

Aluminum Oxide is generally for abrading metal whereas Silicon Carbide is for rocks. If you notice the grinding wheels on a metal grinder are red signifying Aluminum Oxide. If you try to grind rocks on them they load up and, get hot and do a very poor job. However; I have never tried to tumble with Aluminum Oxide so I can't say for sure whether it would work or not.
If you buy in bulk (100 lbs) you can get Silicon Carbide tumbling abrasive for about $1.40 a pound.
Bob

I don't know about Aluminum Oxide for tumbling, I never tried it.
Here is a link for lesser amounts of SiC grit for 2 bucks a pound
http://www.alpha-supply.com/lapidary/in ... tNum=G0928

Aluminum oxide is a hardness of 9 while silicone oxide has a hardness of 9 to 10. Sounds like it might work for softer stones. I don't know how fragile it is though so while its hard it might break down too quickly.

Buy a twenty, use it for rough grinding, and then report your results. You might be on to something here, since tumbling functions differently from a wheel..

Aluminum Oxide is a great abrasive. It might not be quite as agressive it will cut stone just fine. Use it just like you would any abrasive. It will break down and act different as all abrasives will.
Try it on more than one material as you may find it the perfect abrasive for one material yet it trashes or wont touch others.
I use aluminum oxide for prepolish a lot. I like it. That sounds like it would be a good cheap roughing abrasive. Jim