jamesp
Cave Dweller
Member since October 2012
Posts: 36,583
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Post by jamesp on May 5, 2015 19:20:12 GMT -5
Thanks for the tips stonemaster499. I know you have dealt with this one many times. Having better luck w/the labra and amazonite than most of the granite. I could see why you would use some of those strategies. But would never know what grits to use other than what you suggested. Strange that 1000 step is the worst about undercutting.
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Fossilman
Cave Dweller
Member since January 2009
Posts: 20,715
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Post by Fossilman on May 5, 2015 20:15:22 GMT -5
I am running some granite from Alaska -got it with my gold based gravel............Just finished the barrel on the 2nd grit stage-it was looking great... Hope it keeps it's shine! Running it with agate,jasper and petwood...........
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Post by glennz01 on May 6, 2015 2:13:48 GMT -5
looks like what I see almost every river walk
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,583
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Post by jamesp on May 6, 2015 4:56:45 GMT -5
I am running some granite from Alaska -got it with my gold based gravel............Just finished the barrel on the 2nd grit stage-it was looking great... Hope it keeps it's shine! Running it with agate,jasper and petwood........... Good luck with it Michael. Time will tell.
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Post by orrum on May 6, 2015 9:53:45 GMT -5
We need pic updates James!
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,583
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Post by jamesp on May 6, 2015 18:11:40 GMT -5
We need pic updates James! I sidelined them Bill. Gotta to get some advise from one of these guru tumblers. But do have another load of harder granite running that should work. Like a quartzite, you have probably seen quartzy veins in granite.
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Post by orrum on May 6, 2015 20:15:06 GMT -5
Ye I have seen a huge amount of quartzsite. Some crumbles away in a tumbler but some gets really nice James.
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,583
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Post by jamesp on May 7, 2015 6:25:49 GMT -5
Ye I have seen a huge amount of quartzsite. Some crumbles away in a tumbler but some gets really nice James. This stuff chips like agate, should not have a problem in the tumbler Bill. super dense
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stonemaster499
noticing nice landscape pebbles
Member since July 2014
Posts: 97
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Post by stonemaster499 on May 8, 2015 13:54:05 GMT -5
I knew I read something in the Ed E. Smith book on undercutting that might be useful: Organic pre-shaped media such as wood shapes (cubes, diamonds, pegs..etc) are "especially effective when used in loads containing soft, dual hardness, and tough materials, or materials that tend to undercut or "orange peel" when processing". Smith uses the following stones as examples: Amber, apache tears, azurite, corals, chrysocolla, jade, malachite, tourquoise, and rhodochrosite.
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,583
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Post by jamesp on May 16, 2015 5:34:45 GMT -5
I knew I read something in the Ed E. Smith book on undercutting that might be useful: Organic pre-shaped media such as wood shapes (cubes, diamonds, pegs..etc) are "especially effective when used in loads containing soft, dual hardness, and tough materials, or materials that tend to undercut or "orange peel" when processing". Smith uses the following stones as examples: Amber, apache tears, azurite, corals, chrysocolla, jade, malachite, tourquoise, and rhodochrosite. Seems that impact cracks the felspar where it meets the quartz. And mica pockets erode out. Using padding type filler makes good sense. Still seems like the mixed hardness will be a problem in a tumbler. The quartz wears slower than the felspar. Not sure how to solve that one. Mixed hardness in a tumbler a challenge. Using chunks of crushed SiC 60 grinding wheels 1/2 to 1 inch in size did not help; it really caused undercutting on the granite. Which makes sense. Though they will grind homogenous materials well. Tumbling some metamorphosed granite (gneiss) and it is doing fine. About like tumbling rose quartz or clear quartz. Looks just like granite, but more melted together.
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SirRoxalot
freely admits to licking rocks
Member since October 2003
Posts: 790
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Post by SirRoxalot on May 24, 2015 9:38:32 GMT -5
Some pitting isn't the end of the world, it will take a polish, just won't look as good as you'd like. Most folks won't notice.
Trick is choosing your granite. Avoid stuff with mica flakes. Lots of granite just won't tumble that great.
If you simply must tumble it, stabilize it first. Dissolve both tubes of 330 epoxy in a pint of acetone and apply vacuum until the bubbles are gone, let dry a couple weeks and have at it. Lots and lots of interesting things have to be stabilized.
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Fossilman
Cave Dweller
Member since January 2009
Posts: 20,715
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Post by Fossilman on May 24, 2015 15:35:37 GMT -5
I posted the rock I tumbled,it wasn't too bad at all..............
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