grizman
freely admits to licking rocks
Member since July 2011
Posts: 878
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Post by grizman on Apr 16, 2013 16:08:22 GMT -5
What are your thoughts and or experience using 46-60 grit in the tumbler? I know you can't use it in the vibe, but my attempt is to break down the "really rough" down to somewhat rounded rocks in the first stage. I also have 60-90, but I am a little disappointed in how little they seem to be breaking down the rough. I am tumbling some hard quartz crystal and blue agate.
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Minnesota Daniel
freely admits to licking rocks
A COUPLE LAKERS
Member since August 2011
Posts: 891
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Post by Minnesota Daniel on Apr 16, 2013 18:11:52 GMT -5
Griz, I missed your post to me earlier about the Cerium Oxide story, sorry. I don't remember that thread back in 2011. I think it was telling that the folks at Lot-O could only say not to use cerium oxide because it was proven to not work. You really need a significant body of unbiased factual evidence, not just anecdotes, to be able to say that so emphatically. I think the question though is largely irrelevant today. There is enough evidence to conclude that for the purposes of tumbling most kinds of rocks, Al2O3 (AO) produces an acceptable shine at a significantly lower price than CeO2 or SnO2.
I have tried using 46/70 SiC in my tumblers and saw no improvement over the 60/90. I use a 3lb and a 6/12 lb tumbler. People tumbling with larger barrels however do report that 46/70 does cut faster than 60/90. That seems to make sense to me. If by some odd circumstance you can get 46/70, or 45, or something else coarser than 60/90, but cheaper than 60/90, then definitely get whatever is the cheapest. The coarser grit will break down and you'll be just fine.
I tumble a lot of very hard stone, including weird shaped things I find myself. They take forever in the 60/90. What I and a lot of others here do is use a tile saw to pre-shape the rough before it goes into the tumbler. A $70 model from a big box hardware store is perfectly adequate. I slice the pitted areas off, cut right through the cracks and crevasses, cut down the sharp edges, the sharp points. That will reduce the time needed in the coarse grind better than anything else you might try.
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