mjflinty
spending too much on rocks
Member since September 2011
Posts: 356
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Post by mjflinty on Feb 15, 2012 10:01:47 GMT -5
So, I've been tumbling for years and have never had a batch come out like this. All the areas that are concave are not polished (look scratched) while all the edges and convex areas have a perfect polish. I'm using a vibe and I only polish in my polish barrel. Any ideas what happened? Thanks, Michael
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Post by Drummond Island Rocks on Feb 15, 2012 10:22:20 GMT -5
That dont sound like a contamination problem with the good shine on the high areas. Was there a good variety of sizes of stones with smaller ones to carry polish to the concave areas of the larger ones ? Chuck
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herchenx
Cave Dweller
Member since January 2012
Posts: 3,360
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Post by herchenx on Feb 15, 2012 10:40:06 GMT -5
kind of cool looking. I just finished a batch which had some concaves and they polished. Most of the batch was medium and small ceramic media, which pushed grit and polish against every little nook and cranny. I suspect that Chuck is right, maybe not enough small stuff in the load to reach every surface.
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mjflinty
spending too much on rocks
Member since September 2011
Posts: 356
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Post by mjflinty on Feb 15, 2012 11:01:58 GMT -5
Thanks for the insight. This batch didn't have much in the way of small stones in it. How far back should I go with these? I'm thinking 120? Maybe finer?
Thanks, Michael
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herchenx
Cave Dweller
Member since January 2012
Posts: 3,360
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Post by herchenx on Feb 15, 2012 11:53:57 GMT -5
Again I am new, but I think you don't go any further back than 120 in a vibe because it is too aggressive.
If you wanted to reshape them you could do that on a wheel or in a rotary, and then you would be going back to the 60/90.
If it was me (bearing in mind I am new) I would go to 120/220, those scratches look pretty serious.
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Post by johnjsgems on Feb 15, 2012 12:30:39 GMT -5
You need maybe a minimum of 30% small ceramics up to to 70% for flat surfaces. Acting as a grit carrier it will speed up the process and cushion as well.
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Sabre52
Cave Dweller
Me and my gal, Rosie
Member since August 2005
Posts: 20,466
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Post by Sabre52 on Feb 15, 2012 21:18:27 GMT -5
Your stones still look pretty angular. If you want really smooth highly polished stones, you need to run the stones in coarse grind much longer to round them off better. If you do this plus add a good mix of smalls you should eliminate most the concave areas and get a better overall polish....Mel
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peachfront
fully equipped rock polisher
Stones have begun to speak, because an ear is there to hear them.
Member since August 2010
Posts: 1,745
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Post by peachfront on Feb 16, 2012 14:41:03 GMT -5
No idea why your procedure worked in the past but for starters, looking just at these stones, I would go back to the coarse grind (not in a vibe) and re-shape the stones. Either on a wheel or in a rotary. They are not well-shaped enough to worry about the bad polish job, in my humble opinion. But maybe that's why it takes me all year to get out one load...so you may take my suggestion for what it's worth!
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Jasper-hound
starting to spend too much on rocks
Member since June 2010
Posts: 208
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Post by Jasper-hound on Feb 16, 2012 22:19:40 GMT -5
Did you have too much slurry or fluid in this run? That would cause the rocks to slow down and not polish evenly. Vibes are tricky that way. A little medium and water go a long way. Just enough to put a film onto the stones is all you need.
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Post by helens on Feb 17, 2012 2:40:33 GMT -5
While you may need some smaller rocks, don't get too small! When the rocks get below 1/4", they HAVE to come out... at that point, they can actually drill into your other rocks and get stuck in them. Have had this happen to me twice now, once in a soft load (glass and opals), and again in a hard load (jasper and agates).
This happened to me even in the 120 grit stage, or maybe it was especially bad in the 120 grit stage because when 2 big stones grind together, they smash the teeny piece into a crevice where it actually works a small dent into a crack.
So small means 1/2" and up, not 1/4" or below:P.
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