plankspanker
starting to shine!
Member since October 2021
Posts: 31
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Post by plankspanker on Nov 9, 2021 16:47:32 GMT -5
Hi everyone, i'm seeing a lot of the 60-90 grit and 80 grit tumbling media listed as what's recommended for the first stage in tumbling. I've already purchased the 80 grit per a friends recommendation, but i'm wondering which is better, the straight 80 grit, or the 60-90?
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rrod
having dreams about rocks
Member since December 2020
Posts: 72
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Post by rrod on Nov 9, 2021 16:54:29 GMT -5
Basically no difference in performance. Some claim that using graded grit (like 80) avoids undercutting more than using ungraded 60-90. I haven't seen any real experimental evidence provided.
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Wooferhound
Cave Dweller
Lortone QT66 and 3A
Member since December 2016
Posts: 1,432
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Post by Wooferhound on Nov 9, 2021 17:22:53 GMT -5
I use 30 grit in my 6 pound barrels and 80 or 60/90 in the 3 pounders
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Post by Bob on Nov 9, 2021 21:15:03 GMT -5
I start with 50 or 60 in 6lb or larger barrels.
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Post by knave on Nov 9, 2021 21:17:59 GMT -5
After the first 30 min it’s all 60-90 and climbing!!
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plankspanker
starting to shine!
Member since October 2021
Posts: 31
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Post by plankspanker on Nov 10, 2021 7:27:00 GMT -5
Thanks everyone, and that's funny Knave, i hadn't thought of that fact!
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ericabelle
spending too much on rocks
Instagram acct: @erica_shoots_everything
Member since April 2021
Posts: 482
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Post by ericabelle on Nov 10, 2021 8:25:19 GMT -5
I'm so glad to see this thread because I have been experimenting with 60/90 vs 46/70 SiCarb grit. Now, I do have a 15lb tumbler; and a lot of people recommend the larger 46/70 grit for that. I have tried different combinations of each together and also tumbled some batches with just one type of grit. The first ratio I tried was half and half, and I noticed a huge difference right away, so much that I started picking up less perfect rocks because I knew my tumbler could now quickly wear down those sharp edges. The thing that has surprised me is that, even when solely using the 46/70 grit, the grit is still completely worn down at day 4 or 5 of tumbling! I figured a larger grit would be grittier longer. Something else I have found is that, it doesn't matter what size grit I use if I add too much water. If there is too much water in the barrel, there is not much shaping going on.
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ericabelle
spending too much on rocks
Instagram acct: @erica_shoots_everything
Member since April 2021
Posts: 482
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Post by ericabelle on Nov 10, 2021 8:28:31 GMT -5
Does anyone use combinations of two coarse grits? I don't necessarily mean reusing slurry, because that grit would be much smaller than new 60/90. I just wondered if there was an advantage to the smaller grit breaking down faster and producing some slurry, while the larger grit does the bulk of the work.
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Post by As I in does tries! on Nov 10, 2021 9:10:54 GMT -5
Buy what is the cheapest within your local area!
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ericabelle
spending too much on rocks
Instagram acct: @erica_shoots_everything
Member since April 2021
Posts: 482
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Post by ericabelle on Nov 10, 2021 9:25:13 GMT -5
Buy what is the cheapest within your local area! LOL Not an option for me, unfortunately - I would have to drive four hours to buy grit in person. And I'm actually not positive that St Louis has a store that sells grit, but I assume they do somewhere.
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Post by knave on Nov 10, 2021 9:31:29 GMT -5
Zoom out 😂 Maybe he means in your country. Johnson brothers or Kingsley have the least expensive bulk amounts of grit.
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ericabelle
spending too much on rocks
Instagram acct: @erica_shoots_everything
Member since April 2021
Posts: 482
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Post by ericabelle on Nov 10, 2021 9:36:20 GMT -5
Zoom out 😂 Maybe he means in your country. Johnson brothers or Kingsley have the least expensive bulk amounts of grit. Now, c'mon! I'd have to catch a plane to get there!
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Post by knave on Nov 10, 2021 9:38:27 GMT -5
Zoom out 😂 Maybe he means in your country. Johnson brothers or Kingsley have the least expensive bulk amounts of grit. Now, c'mon! I'd have to catch a plane to get there!  Your grit will catch a plane maybe. Haha
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Post by knave on Nov 10, 2021 9:47:14 GMT -5
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ericabelle
spending too much on rocks
Instagram acct: @erica_shoots_everything
Member since April 2021
Posts: 482
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Post by ericabelle on Nov 10, 2021 9:59:43 GMT -5
LOL that's a good one, knave !
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rrod
having dreams about rocks
Member since December 2020
Posts: 72
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Post by rrod on Nov 10, 2021 11:32:44 GMT -5
Does anyone use combinations of two coarse grits? I don't necessarily mean reusing slurry, because that grit would be much smaller than new 60/90. I just wondered if there was an advantage to the smaller grit breaking down faster and producing some slurry, while the larger grit does the bulk of the work. I'm about to test how many runs of 80 grit it takes to make an effective slurry for 30 grit, at least with harder stones. I don't think this is much of a concern for any grit 50 and above, as they are light enough for the water to serve as an effective starting "slurry".
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Post by Bob on Nov 10, 2021 12:12:10 GMT -5
Does anyone use combinations of two coarse grits? I don't necessarily mean reusing slurry, because that grit would be much smaller than new 60/90. I just wondered if there was an advantage to the smaller grit breaking down faster and producing some slurry, while the larger grit does the bulk of the work. I predict due to impact physics that the larger grit (60) would break down first, or at least faster than the 90. So more or less I bet it would all get to 90, then proceed from there getting smaller and smaller. Not that I think it matters. I have mixed in a little 80 to make a full grit load when I had run out of 50 or 60. And vice versa. After doing this a dozen or more times, I've never noticed any advantage to it. I go through maybe 50lbs/month of 50/60--however much a big 5-6 gal bucket can hold lasts about a month anyway. But I don't start delicate materials in larger grit than 80, including feldspars, crystal quartzes, lapis, aventurine, and some others that escape me at the moment. Grits larger than 50 were tested, and results were inferior. I went all the way to 20 in that test.
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ericabelle
spending too much on rocks
Instagram acct: @erica_shoots_everything
Member since April 2021
Posts: 482
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Post by ericabelle on Nov 10, 2021 12:58:17 GMT -5
Does anyone use combinations of two coarse grits? I don't necessarily mean reusing slurry, because that grit would be much smaller than new 60/90. I just wondered if there was an advantage to the smaller grit breaking down faster and producing some slurry, while the larger grit does the bulk of the work. I predict due to impact physics that the larger grit (60) would break down first, or at least faster than the 90. So more or less I bet it would all get to 90, then proceed from there getting smaller and smaller. Not that I think it matters. I have mixed in a little 80 to make a full grit load when I had run out of 50 or 60. And vice versa. After doing this a dozen or more times, I've never noticed any advantage to it. I go through maybe 50lbs/month of 50/60--however much a big 5-6 gal bucket can hold lasts about a month anyway. But I don't start delicate materials in larger grit than 80, including feldspars, crystal quartzes, lapis, aventurine, and some others that escape me at the moment. Grits larger than 50 were tested, and results were inferior. I went all the way to 20 in that test. Very interesting - so I bet any increase in shaping I have been noticing from the larger grit was probably done the first day of tumbling. A few days ago, I added in some really rough, small quartz pieces; so it will be interesting if I see a difference from that. I'm tumbling chert, jasper, quartzite right now. I guess the inferior results you saw from the large 50-20 grits were because of decreased grinding surface area?
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Post by knave on Nov 10, 2021 13:26:35 GMT -5
I’ve tumbled with some true ungraded sic like it had pea sized chunks in it. At a certain point the chunks will not break down, and they actually kind of get rounded and would take a polish. So yea I imagine with too big of grit, it’s reducing the grinding surface area.
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Post by Bob on Nov 11, 2021 10:19:38 GMT -5
Now that I think about it, inferior results is misleading. Rather the grit didn't get used. I'd open after a week and hardly any was gone and rocks not much different than rubbing against each other...no slurry. Someone in this group believes large grit gets pulled away by centrifugal force, but I have no clue.
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