koba
off to a rocking start
Member since January 2012
Posts: 4
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Post by koba on Jan 23, 2012 14:20:54 GMT -5
Trying to tumble some Lake Superior agates that are rough. I'm using 60/90 grit. Would it help to use a coarser grit such as a straight 30 or 40 grit and where can I purchase this? Thanks for any help. koba
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quartz
Cave Dweller
breakin' rocks in the hot sun
Member since February 2010
Posts: 3,341
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Post by quartz on Jan 23, 2012 22:43:40 GMT -5
For really coarse rock, we rough them w/16 grit. Many people use 46/70 mixed grade. Check your industrial supply places, and abrasives suppliers. You didn't say how large your tumbler is [assuming a rotary], the really coarse grits work better in larger barrels, say 12# and up, based on our experience.
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Post by paulshiroma on Jan 23, 2012 23:05:34 GMT -5
I use the 46/70 grade grit as my first stage and purchase it through The Rock Shed. Seems to work fine.
Paul
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koba
off to a rocking start
Member since January 2012
Posts: 4
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Post by koba on Jan 25, 2012 13:53:46 GMT -5
Its a 12#. I've found some 30 grit at Jesco. I've tried all the local suppliers around Oregon and no luck so I think I'll place an order. Thanks KOBA
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quartz
Cave Dweller
breakin' rocks in the hot sun
Member since February 2010
Posts: 3,341
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Post by quartz on Jan 25, 2012 23:21:45 GMT -5
You don't list your location, but now say Oregon. Try Kleen-Blast in Portland:503-228-3965. They have the best prices around, and deal in small lots. LaGrand Industrial Supply in Portland is another good place to shop.
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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 Jan 26, 2012 1:40:25 GMT -5
Keep in mind they are Lakers, one of the hardest rocks you will ever want to tumble, and coarser grit won't change that. I start them with 46/70 from the Rock Shed myself.
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Post by rockrookie on Jan 26, 2012 8:12:26 GMT -5
in my experience ...............i have run batch 6 months or more TIME and several series of fresh grit is needed on rough lakers . i have found that 46-70 is not real effective on small lakers . for some reason . my best successes and quickest batches were the times when the lakers were big enough to slice on my saw 1st . the hardness of rock combined with odd shapes & pits take forever to wear down . every time that i have finished a 6 month long batch . i swear , i'll never do it again . but , i'm hooked on the finished batches . so , i do it again . -paul
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Post by connrock on Jan 26, 2012 8:45:51 GMT -5
I've used 30 grit in the past and found it takes much longer to completely break down and had to use much less water or after 1 week I ended up with only dirty water and no slurry. I also found that by doubling the RPM's of the tumbler helped to break down the grit and grind the rocks faster but after several tumbles I decided that 30 grit wasn't all that efficient and didn't really cut down my roughing time.
Interested in hearing your results using 30 grit.
connrock
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Sabre52
Cave Dweller
Me and my gal, Rosie
Member since August 2005
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Post by Sabre52 on Jan 26, 2012 9:50:26 GMT -5
I'm gonna kid of break from the herd here and say I really prefer the 60/90 over the larger grit sizes. I've experimented a bit with the larger grit sizes for coarse grind and found the larger sizes tend to not stick to the rock surfaces as well and rather sink more to the bottom and actually, in my experience with 12 pound barrels, did not cut as well. I think 6o/90 actually cuts better than the 46/70 at best, or at least, I didn't notice any advantage to using the 46/70. I do pretty much nothing but agate and jasper type stuff and I now use nothing but 60/90 in coarse grind....Mel
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koba
off to a rocking start
Member since January 2012
Posts: 4
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Post by koba on Jan 26, 2012 11:18:54 GMT -5
Think I will just use the 60/90 grit as i have 100# of it on hand. Sounds as if it's just going to take a long time no matter what grit I use. Guess I'll start shopping for another rotary as my lortone will be tied up for awhile. I use a lot-o for every thing but the coarse grind and I didn't know how long these lakers would take to smooth out. I still have a lot of lakers I haven't touched. Thanks for all your imput. By the way I live in Powers Oregon. KOBA
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Post by connrock on Jan 29, 2012 11:36:26 GMT -5
I have to agree with Mel,,,, It is what it is and tumbling just takes time,,,
connrock
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