jamesp
Cave Dweller
Member since October 2012
Posts: 36,562
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Post by jamesp on Jan 1, 2014 11:11:38 GMT -5
Thought i would tumble high proportion of small chips 3/4 inch average. Wow, is that going slow. I tumble a lot of hard agate and know my rate of grind well.
For 6 and 8 inch(rotary) barrels i get the fastest coarse grind with 1-3 inch sizes. The small chips are cool but they slow down the rough grinding operations a lot.
Not sure what to do other than not putting more than 15% smalls in the barrel. End of story unless some body knows a trick they will let me in on.
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tkvancil
fully equipped rock polisher
Member since September 2011
Posts: 1,547
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Post by tkvancil on Jan 1, 2014 13:34:23 GMT -5
Not sure I've got any tricks. I once put a bunch of small chips in a 3# barrel. Like 1/8" neighborhood and 30% of total volume. The idea was to get more "grit carriers" in the barrel. Total fail. Didn't use up the grit and didn't make a slurry to speak of. The chips and grit were all massed together, clumped up between the rocks and stuck to barrel sides. Maybe the chips are "sticking" together as they tumble. I know your working on a larger scale but I can visualize that happening. Maybe some borax would lube everything up. It always makes slurry oily when I use it.
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,562
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Post by jamesp on Jan 1, 2014 13:49:42 GMT -5
Your description of my problem is exact. I guess the bigger rocks help grind too. My experience is if the grit is not breaking down then you ain't cuttin rock.
The lube effect is a great idea.
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Sabre52
Cave Dweller
Me and my gal, Rosie
Member since August 2005
Posts: 20,487
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Post by Sabre52 on Jan 1, 2014 15:00:29 GMT -5
Interesting question. I don't worry much about percentage of sizes until I get to prepolish and polish stages where I like to have a lot of smalls. I also like a lot of smalls in coarse grind when I tumble chippy stuff like amethyst to prevent chipping by cushioning the load. Never personally noticed a lot of difference in grinding speed related to the amount of smalls at all. I've always figured it would speed the cycle by creating more surface to surface contact and that the smalls would be a good carrier for grit. Guess I'll have to pay more attention in the future....Mel
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,562
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Post by jamesp on Jan 1, 2014 15:09:39 GMT -5
I had the smalls at about 45-50 percent by weight Mel. Sounded like i was tumbling sand-ha. No grinding sounds. I just had so much in there.
Good point though, for chippy stuff. And finish. Yes, amethyst, rose quartz are sensitive. I usually tumble a couple of rose quartz pieces with agate just to see if it is frosting. If it is, then hard agates seem to be grinding at a good rate.
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Post by Starguy on Jan 22, 2014 21:37:48 GMT -5
Try a little more water. I favor around 40-50% small pieces. I feel you Get a better sliding action in the tumbler and a better grind.
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