Henry
spending too much on rocks
Member since January 2013
Posts: 452
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Post by Henry on Mar 1, 2014 12:49:08 GMT -5
Hello all. I have a quandary in regards to filling my QT-66 with larger stones. By larger, I mean 3 inches-ish. Do I fill it with equal sized stones with less quantity in the barrel? Or, do fill it with a couple of larger stones with medium and smaller stones? My concerns are: 1)Filling it primarily with (all) so-called larger stones won't get the necessary surface area grind that it needs. 2)Filling it in with mixed sized stones will cause the dominant large stone to pulverize the smaller stones...Which leads to another question 3) In any circumstances, how high should I fill the barrel (minimum) to insure the larger stone(s) get the necessary kinetic action within the barrel? Thanks, Henry
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Steve
has rocks in the head
Member since June 2005
Posts: 506
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Post by Steve on Mar 1, 2014 14:15:28 GMT -5
Only put in a couple (or just one) of the larger stones and fill the rest with small peas sized stones of the same hardness. Fill to 3/4 full. Run a bit longer than usual in each step. I keep sacrificial filler stones for this purpose. The smaller stones won't get pulverized.
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Post by deb193redux on Mar 1, 2014 14:19:35 GMT -5
pulverize is not too much issue if similar hardness. most of the action is sliding action if you have good fill and reasonable slurry and do not rotate too fast.
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tkvancil
fully equipped rock polisher
Member since September 2011
Posts: 1,547
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Post by tkvancil on Mar 1, 2014 14:36:52 GMT -5
I personally would have no qualms about putting in two or three larger rocks as you have described, as long as the rest of the material is similar hardness smaller pieces. I have a couple batches running in my 66 right now that are probably 40% "medium" rocks by volume. I'm talking say between 1 3/4 to 2 1/4 inches. The rest of the material is a mix of 1/4 to 3/4 inch pieces. Both batches are doing well.
Lortones instructions say that 1/2 volume is the minimum. From experience I can tell you don't run a 6# barrel at half full, you will get chips and cracks. Fill to 2/3 minimum and 3/4 maximum from my experience. Steve's right the smaller stones won't get pulverized, although smaller thin pieces may chip but that can happen under "normal" conditions.
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Henry
spending too much on rocks
Member since January 2013
Posts: 452
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Post by Henry on Mar 1, 2014 15:46:08 GMT -5
Thanks everyone. Added more similar hardness stones and it doesn't sound as "thumpy" (nice even rumble) in the 60/90. Henry
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Post by Starguy on Mar 9, 2014 16:56:16 GMT -5
Henry
You are right-on about listening to the tumble. You can tell a lot just by listening.
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