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Post by fernwood on Sept 25, 2019 5:51:25 GMT -5
Here I go again. Have had one batch in rough, 3 lb. rotary barrel for 2 months. They look almost like they did when I started. Been recharging with 2 TBS new grit every 7-10 days. Slurry looks to be correct consistency. Barrels are rotating fine. Barrels are about 3/4 full of mixed sizes of rocks and some ceramic tumbling media. When I wash off some samples to check, the 80 SIC appears the same as when I put it in. At the start I added some used slurry and then about 2 TBS of new grit.
I checked another batch that has been rolling for a month. Same results. A little shaping, but not much. For this barrel, I did not add used slurry. Noticed that the slurry was pretty watery. It was gray in color, but too thin. I had started with water just below the bottom of rocks.
What could cause the 80 not to break down?
I added some used slurry and 2 TBS of grit to this batch.
Both batches are mostly harder stones. Agates, jaspers and fossils. There were some Petoskey stones in one batch. Even they are not shaped much. No way Petoskey should even be in a rotary rough stage for a month.
Any ideas? Thanks.
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Post by Drummond Island Rocks on Sept 25, 2019 6:21:36 GMT -5
My guess would be too many things hampering the process. Between the ceramics, added used slurry and the few petoskey stones the rocks are probably enjoying a very gentle ride not capable of breaking down silicon carbide.
Chuck
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Post by fernwood on Sept 25, 2019 6:35:11 GMT -5
Thanks for the advice.
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Post by HankRocks on Sept 25, 2019 7:45:19 GMT -5
Unless I am running a load of slabs and shaped preforms, or a load of softer rock, I do not use any ceramics(in my case pebbles). I will(might) add them in the pre-polish and polish stage where I want the extra surface contact. I do try and segregate the softer rocks, Quartz, Obsidian into their own batches. I would think you would want to keep the Petoskey in their own batch, if you have enough or mix them with other soft material and maybe start with a 200 or 220 SiC.
Just curious, what is the rotation speed on your tumbler? As noted in other posts a 3 pound tumbler does not have the grinding/shaping rate as the larger barrels.
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gatorflash1
spending too much on rocks
Active in Delaware Mineralogical Society, Cabchon Grinding and Polishing, 2 Thumlers B's and a UV-18
Member since October 2018
Posts: 375
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Post by gatorflash1 on Sept 25, 2019 13:00:14 GMT -5
If it were me I would experiment, using 2 lb. of rocks and 1 lb of mixed ceramic media, 6 tbl of #60-90 grit in a clean barrel, no old slurry, just adding the proper amount of water to the bottom of the top layer of rock, and running all this for 3 weeks without any recharge. I would not even take the lid off the barrel.
See what that does. If nothing else it should really break down the #60-90 (or #80 if that's all you have) grit and work over those rocks. For stage 1 I usually use #60 grit in my tumblers but am thinking of trying a very course #30 grit to see if this speeds up the 1st stage.
If this worked, I would try another run of rocks with less grit, maybe 4 TBL, less time, maybe two weeks. If that is working I would cut down to 3 TBL of grit and 2 weeks running. I can't imagine doing the work in less than two weeks. In my experience the secret to nicely tumbled rocks is to use only nicely tumbled rocks that come out of stage 1. If any flaws, back into stage #1 they go. Patience is a virtue as the old tumbler saying goes.
I'm curious to find out how you make out. Please let us know. Good luck.
I never move from the course grit stage until the rocks are well formed with no pits or cracks. Then I tumble wash over night before going on to the next stages.
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Post by fernwood on Sept 25, 2019 13:21:31 GMT -5
I threw about 15% of ceramic media in to help protect the crystal formations in the LSA's. All I have is the 80 grit.
WOW on 6 TBS of grit.
I want most of these to be nicely shaped with no vugs.
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El JeffA
spending too much on rocks
Member since February 2016
Posts: 353
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Post by El JeffA on Sept 25, 2019 21:51:43 GMT -5
80 grit breaks down in my 3 lb Lortone tumblers in about 4 days. I do not use ceramics in rough grind...period, I use an assortment of sizes ( but I like to throw in one larger rock to help the grinding action, up to 2” in size), 1 1/2 tablespoons of pure clay cat litter and 3 to 4 tablespoons of 80 grit. These tumblers are usually used for smaller rocks that have been shaped in larger 12 lb tumblers using only 46/70 grit. The length of avalanche in 12 lb vs 3 lb is huge. There is much more about this subject in jamesp ‘s threads. I am eternally grateful for the amount of work done by James and posted here on RTH. Best of luck to James P and thank you for all of the informative posts!
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gatorflash1
spending too much on rocks
Active in Delaware Mineralogical Society, Cabchon Grinding and Polishing, 2 Thumlers B's and a UV-18
Member since October 2018
Posts: 375
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Post by gatorflash1 on Sept 26, 2019 20:02:35 GMT -5
I threw about 15% of ceramic media in to help protect the crystal formations in the LSA's. All I have is the 80 grit. WOW on 6 TBS of grit. I want most of these to be nicely shaped with no vugs. If I remember correctly the rule of thumb was 1-2 TBS of grit per pound. I don't use cat litter or clay, just mixed ceramic media. It last a very long time. rocktumbler.com/tips/using-the-right-tumbling-media/rocktumbler.com/grit.shtml
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Post by fernwood on Sept 27, 2019 6:15:56 GMT -5
I threw about 15% of ceramic media in to help protect the crystal formations in the LSA's. All I have is the 80 grit. WOW on 6 TBS of grit. I want most of these to be nicely shaped with no vugs. If I remember correctly the rule of thumb was 1-2 TBS of grit per pound. I don't use cat litter or clay, just mixed ceramic media. It last a very long time. rocktumbler.com/tips/using-the-right-tumbling-media/rocktumbler.com/grit.shtmlThis is the first time I have ever experienced anything like this. I started tumbling rocks in the 1970's. Again in the mid 80's. Only started again a couple years ago. Used 3 rounded TBS of coarse for the 3 lb barrels. Did about 20 runs with no problems. Some with ceramic tumbling media, some with polished pea gravel, some with no added media, just a mix of small and larger rocks for coarse stage. I adjusted media based on the hardness of the rocks. Sometimes use stage specific plastic media for softer/more delicate rocks. That is why I am so confused on these runs. Slurry looks correct. Rocks are similar to what has successfully run for up to a month prior. No changes in how tumbler is working.
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Post by arghvark on Sept 29, 2019 9:12:50 GMT -5
Kind of shooting in the dark here - Fill level ok? You're experienced so I suspect it is. Too full, less grind. I run 6 tbsp of 80 in my 3 lb barrels. Have never been able to get grit exhaustion in a week. I let them run 2 weeks (as opposed to full grit -46/70- exhaustion in 4-5 days in 6lb barrels.) Thanks to jamesp 's posts, I use a small amount of potter's clay, about the size of a golf ball, helps a LOT. (I get it free, so it's super easy.) I do use less water than typical directions recommend. I never use ceramics in rotaries, but do throw in some agate smalls (1/4" to 3/8"), a handful or two, even with soft stones. I don't do checks or grit additions. Just run to exhaustion, then full clean out and sort.
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Fossilman
Cave Dweller
Member since January 2009
Posts: 20,685
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Post by Fossilman on Sept 29, 2019 9:16:23 GMT -5
Yes, leave the ceramic pellets out of the first stage.... You should see some results within a few days..
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,159
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Post by jamesp on Oct 20, 2019 4:24:35 GMT -5
Adding clay or old slurry can certainly help circulate the 80 fernwood. Small barrels can be trickier to break 30-40-60 even 80 Sic down because they are so gentle. Best to use 60 or your 80. Especially if they are a bit overfilled with rock or running to high a percentage of smalls like ceramics. To full or too many smalls or both in a small barrel with only 3 pounds of rock used to kick my butt with the problem you mention. Never had many issues with Lortone 12#, Sch 40 6", sch 40 8", HDPE 6" and HDPE 8" barrels. They have higher grit breaking forces. Folks that can tumble in those small barrels must have some kind of talent. Higher speeds can help too as Hank mentioned. This variable may require serious mods though. And certainly too thick of a slurry as Chuck mentions.
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Post by Starguy on Oct 21, 2019 11:28:40 GMT -5
fernwoodDo you have a good mix of sizes from small to medium to large stones? I’ve had similar problems when running batches with gaps in the gradation of the batch.
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