ChicagoDave
has rocks in the head
Member since June 2016
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Post by ChicagoDave on Nov 23, 2016 17:35:29 GMT -5
OK, so I've seen all the discussions about grit breaking down really fast in PVC barrels and the magic clay involved. I've always wondered if 7 day clean outs were just a few days of rocks tumbling around with no grinding action. I currently use 1/2 cup of 46/70SiC and 1/2 cup of clay based cat litter (always leads to a nice pancake batter consistency). I fill my 6# Lortone barrels (which are rubber) about 75-80% full. Water just below the top layer of rocks. I always noticed a few bits of grit leftover after 7 days. But I was chatting with Garage Rocker and something he said made me want to do a little testing. I figured I had 4 barrels that were started on Sunday. I could test one today and then each day after. Would there still be grit in my slurry? So I just opened the barrel that has been running for 3 days. Emptied the slurry into a bucket. I don't have any scientific equipment to test leftover grit so I dunked my hand in there and began feeling around. I was shocked to find not much grit was left. I would even say it feels about the same as a barrel running for 7 days (yes, I have a habit of dunking my hand in slurry each week). There was a little bit that settled to the bottom, but I'm guessing it would amount to a 1/4 teaspoon or less. So I'm guessing I'll switch to barrel clean outs every 3 or 4 days. If I can't feel any grit left in the slurry, the grinding action doesn't really exist anymore, right?
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jamesp
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Post by jamesp on Nov 23, 2016 18:39:32 GMT -5
Answer is yes Dave. No more grinding, just rolling the rocks. 45/70 should be easy to feel and see. Sprinkle some fresh 45/70 on a white napkin to get an idea of what size it is.
You can pour the whole batch slurry and rocks into a light colored tub. Wash the barrel out briefly into said tub. Pour fresh water in with rocks and slurry, and mix it around to thin your slurry. Come back 10 minutes later, remove the rocks, pour off most of the liquid, and inspect the bottom of the tray for grit. Grit is a good bit denser than quartz and agate and will head right for the bottom of the tray. You can sprinkle a dash of fresh 45/70 next to the used grit to compare used to fresh.
Sounds like you are having efficient grinding. Might think about checking after 2 days.
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ChicagoDave
has rocks in the head
Member since June 2016
Posts: 720
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Post by ChicagoDave on Nov 23, 2016 18:41:53 GMT -5
jamesp, thank you for these directions. I will try it later tonight and see what happens.
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Post by paulshiroma on Nov 23, 2016 18:58:43 GMT -5
Great information, Dave. I think I'll move to 3-4 day change outs. Keep us posted on what you find as well!
Thanks Paul
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Post by Garage Rocker on Nov 23, 2016 18:59:19 GMT -5
Without litter, 6-7 days in QT12 and 66. With litter, 3-4 days. You may see slightly improved grind at 70% full barrel vs. 80%
My unscientific observations. Anxious to see if you come up with the same.
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doublet83
starting to spend too much on rocks
Member since March 2016
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Post by doublet83 on Nov 23, 2016 19:07:53 GMT -5
I have recently been experimenting on this topic, thanks to a new scale I purchased that is accurate up to 0.01 of a gram.
After about 4 days in a Thumbler's 15 pound model B, I can no longer feel any grit. I believe it should be 150+ sized at this point. However, at this point I found the rate of material reduction is only about 40% slower for the next 4 days than the first 4 days (originally 80 grit). This has led me to believe that grit can be used longer in the stage 1 process than I originally expected.
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Post by paulshiroma on Nov 23, 2016 19:22:48 GMT -5
Well, I have lots of clay cat litter available as I use it to clean off slabs so I think I'll add some into my barrels at tonight's change out; you guys have me really curious about this now. I never bothered trying this option.
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jamesp
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Post by jamesp on Nov 24, 2016 7:11:10 GMT -5
Consider an increase, adding 1/3 a cup 45/70(6 pounds rock) every day for 3 days with no clean outs, then let run for 2-3 days to make sure grit is broken down, and then do a grit separation test.
Running with good colloidal clay I can go 6 days adding 1/3 to 1/2 cup grit with no clean outs. May let it run day 7 and day 8 with out adding grit to make sure all grit is done. Then clean out. Trick is to not put too much clay to start with so slurry does not get too thick after 6 days of adding grit. Start with just enough clay to get grit circulating and breaking down. You can always pour some of the slurry off and add water to thin slurry at daily grit additions-as needed.
I used calcium carbonate(limestone of some sort from the wild) instead of colloidal clay and it would take grit additions every day for up to 3 days. Before gelling. Then run 2-3 days to make sure breakdown occurs.
By doing multiple grit additions WITHOUT clean outs the grit sees a lot more time in the barrel on say 5 grit additions on an 8 day run with out clean outs, Day 2 grit sees 6 days Day 3 grit sees 5 days Day 4 grit sees 4 days Day 5 grit sees 3 days AGAIN, you can always pour some of the slurry off and add water to thin the slurry out if needed say day 3 and day 6 when adding grit. Or as needed. This method puts a lot of time on the grit, condenses coarse grind. Rocks see a lot of time with 45 and 70 grit work horse grit.
I have tried clays from all over. They are NOT created equal. Most clay is felspar based. If you live in the east around granite geology you probably have COLLOIDAL FELSPAR BASED CLAY. Look up kaolin, a felspar based clay, it is a very common clay around granite geology. Granite is quartz and felspar. High felspar content(kaolin) is best.
The most extreme case: 6 pound barrel 55 RPM A single one pound rock mixed with one inch normal tumbles. One cup clay Half cup coarse grit With this overly aggressive arrangement SiC 30 grit was gone in 6 hours. Well, who can add grit every 6 hours ? And why run it 24 hours if the grit is shot at 6 hours ? So I slowed the machine to 30 RPM for one day grit additions.
The biggest pain in the but is the coarse grind, so all the experiments. The vibe does the rest of the tumble to polish in 4-6 days. It is the coarse grind that is the problem. I was getting bored with coarse taking 12 and 14 weeks.
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ChicagoDave
has rocks in the head
Member since June 2016
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Post by ChicagoDave on Nov 24, 2016 9:25:23 GMT -5
I played around with adding additional grit and ran into 2 issues. First, it was a pain in butt to clean the rim of the barrel. But I was trying to do it while all the rocks and grit were still in there. Second, when adding grit on the second day, the grit that was already in the slurry sunk to the bottom and solidified quite quickly. But, I was using my original amount of grit back then, 12 tablespoons (3/4 cup), so that might have been too much for one day of tumbling. I might try dropping the cat litter just a bit and starting with 1/2 cup of 46/70. Might then add another 1/2 cup of 46/70 on the third day. Then let the whole thing go for 3 or 4 days to break everything down. This would work out to about one full clean out each week, but I would be doubling the grit the rocks see in that time. I could also dump the whole barrel into a bucket so cleaning the lip would be easier during the second grit addition. BTW, here is the cat litter I'm using. Not sure of it's makeup.
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jamesp
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Post by jamesp on Nov 28, 2016 6:07:51 GMT -5
Cutting back to 1/3-1/2 cup grit every day is working. Too much grit too fast has a way of messing with the slurry. Density of most rock shavings from quartz rocks is 2.5-2.8. SiC is 3.5 and bigger particles than rock shavings in early grind, so heavy and hard for slurry to lift. Maybe at higher speeds.
Main reason for adding a bit smaller doses of grit daily is to maintain bigger grit particles every day without too much grit accumulation. Sometime open your barrel after 6-12 hours and do a separation in a tub. When I dump the entire contents in a tub, I use a water hose with valve set on sharp spray, spray contents while rolling the rocks around with other hand to wash them down well. Till tub is 3/4 full of water. That way all the heavy grit falls to the bottom. Then let tub sit and let gravity pull all the particles settle to bottom-like over night. Then pick rocks out by hand swishing them a bit in the cleaner water at the top to make any grit wash to the bottom. Then pour most of the water off slowly. Then you will find out how much your 45/70 has broken down in just 6-12 hours. You may find that your slurry is working well. So well that your 45/70 is smaller than 220 in say 6 hours. If it is 220 in just 6 hours then you are not doing any grinding for the rest of that day(18 hours). No big deal, but it is nice to know. If you are bored and have the time you may get away with adding small doses every 8 hours.
At least you know that your grit is breaking down efficiently. Better to know. A one time test.
Cause I am amazed at how short lived any coarse SiC is with half good slurry. I have no easy solution, adding grit so often ain't fun. And it does not hurt anything to let it roll longer if you can't add grit.
You can recapture the grit in the bottom of the little tub and put it back in the barrel if it did not break down. Just add a little water and slush it around while pouring contents back in barrel.
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jamesp
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Post by jamesp on Nov 28, 2016 6:17:29 GMT -5
There is no fine line between 45/70 and 220. 220 will not grind one iota off your rocks. Your 45/70 is shot. And when dumping slurry I often see a lot of 200-300 particles in the slurry. And yes you are throwing away SiC. So what. SiC 200-300 is useless at that point. So why waste electricity rolling it.
You can savage it if you want. How much SiC 220 do you need ? Just enough to move on to 500 step. Might as well wait till your rocks are finished coarse shaping and then let the last 45/70 addition run for several days and it will break down to 1000 or smaller with good slurry. That's a fact. The tumbler will scavenge every single bit of that 45/70 and crush it to about nothing. IMO, better than a thorough clean out and doing a short 220 run.
You may want to wash your cap off to remove any trapped 45/70 particles on the final 45/70 run about mid way.
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jamesp
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Post by jamesp on Nov 28, 2016 6:40:48 GMT -5
Unless you are tumbling black rocks this looks like too much grit Dave.
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jamesp
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Post by jamesp on Nov 28, 2016 6:50:48 GMT -5
SiC 30 in clay slurry after one hour. Note particles are spread out evenly. That is target. Same slurry as above, scooped off TOP with hand. SiC particles well mixed and distributed about slurry. See finger tips where slurry is thinning out.
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ChicagoDave
has rocks in the head
Member since June 2016
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Post by ChicagoDave on Nov 28, 2016 8:23:24 GMT -5
jamesp, again, thank you for all this information. The amount of grit on that plate was only about 2 tablespoons. This weekend I opened one of my barrels that had been running for 24 hours with 1/2 cup of 46/70 and the same amount of cat litter. Just as you thought, most of the grit had already broken down. I'm not really sure I can add grit everyday. So I split my two QT66s into different experiments. I actually added 3/4 cup of 46/70 to each of the 6# barrels on one machine. I will let this run for the entire week. I thought this might mess up my slurry a bit so I cut back on the cat litter a little. I added 1/2 cup to the other 2 barrels and will clean these out and add another 1/2 cup in 3 days. My main concern is slurry disposal. I dump everything into a 5 gallon bucket. I then rinse everything out over another one. I let the buckets sit for a few days and then begin pulling the "clean" water off the top. Once I get down to the slurry, I place the buckets on top of a radiator in the basement to dry out. I already have 6 buckets in this rotation. Cleaning out twice a week adds a little wrinkle to this. My house sits on a standard city lot (30'x120') so I don't really have somewhere just to dump the slurry. I might need to order a small bag of 30 grit SiC just to play around. I know others haven't had much success getting it to break down in these rubber barrels.
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huskeric
spending too much on rocks
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Post by huskeric on Nov 28, 2016 8:44:29 GMT -5
Very interesting. I have been running 7 days in my QT12, and have wondered why I'm so disappointed every week. I do believe I'm going to give this a shot. I only have 35 and 60/90. Maybe I'll start with the 35 and add 1/2 cup for the first three days, and then jump to 60/90 for two additional days. I'm getting really nice slurry starting with 12 oz of grit and about a cup of cat litter, I may need to thin it down as well.
Silly question, would you say the same would hold true for 120/220? I run stage 2 in a 6# PVC barrel, and I'm usually pleased with the results, but wondering if I can shorten up the tumble time.
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jamesp
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Post by jamesp on Nov 28, 2016 8:47:53 GMT -5
"This weekend I opened one of my barrels that had been running for 24 hours with 1/2 cup of 46/70 and the same amount of cat litter. Just as you thought, most of the grit had already broken down."
This is ALL that you need to be aware of. It effects the whole coarse grind and your grit/running time schedule. In a nutshell.
As far as used slurry, I do similar. Let the slurry settle. Pour off the clean water after it settles. Or scoop it and reuse it. Amazing how clean the top layer gets. Rotate 5 gallon buckets till they dry or can be dumped. When dry it shrinks to small amount.
The 30 grit just increases the 'short' life of effective rock cutting.
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jamesp
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Post by jamesp on Nov 28, 2016 8:50:33 GMT -5
I quite doing 120/220 Rick. I just let the 30 run till it breaks down to 500-1000 on last coarse grit addition. Then AO 500 in vibe is next step.
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huskeric
spending too much on rocks
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Post by huskeric on Nov 28, 2016 9:12:00 GMT -5
I quite doing 120/220 Rick. I just let the 30 run till it breaks down to 500-1000 on last coarse grit addition. Then AO 500 in vibe is next step. Hmmm... Veeeerrrry intereshting. That's so crazy, it just might work. I smell an experiment forthcoming... I just bought 5lbs of 120/220, so I may be holding off on doing that wholesale for a while, but it's certainly worth trying with the barrel I have running now. I loaded it Saturday, so it should be ready for another splash o' grit.
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jamesp
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Post by jamesp on Nov 28, 2016 9:51:58 GMT -5
I quite doing 120/220 Rick. I just let the 30 run till it breaks down to 500-1000 on last coarse grit addition. Then AO 500 in vibe is next step. Hmmm... Veeeerrrry intereshting. That's so crazy, it just might work. I smell an experiment forthcoming... I just bought 5lbs of 120/220, so I may be holding off on doing that wholesale for a while, but it's certainly worth trying with the barrel I have running now. I loaded it Saturday, so it should be ready for another splash o' grit. Fooled around the other day and took rocks out of well broken down 30 grit(ran it several days after 30 had broken down to 200-300) and jumped way up to AO 1000 in the vibe. Guess what, got a dang good polish. Says one thing- the 30 broke way down otherwise I would have never ever copped a polish with AO 1000. Without an electron microscope that is about a good a test for broken down grit as it gets.
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