jamesp
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Member since October 2012
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Post by jamesp on Mar 5, 2020 21:40:26 GMT -5
I don't know why the pace was set to run SiC 220 between the coarse SiC run and the finer 500/600 SiC run HankRocks . I find that SiC 500 step removes a lot of material in the rotary. Even the damage done by SiC 10 after not letting it break down. I have another theory. By the time the rocks get to the 600 SiC run they should be smoother with ground down surfaces. The 600 grit should provide a 1000 times more particles to do the cutting than the coarse grit, they may be smaller, but there are a lot more of them all working with more and better rock contact surfaces. Therefore still a lot of material removed. For a load of rougher rocks the 600 is not going to work as well, the 30 SiC or the 46/70 will be more effective. Sounds accurate Henry. There has to be a maximum scratch(pit) depth for SiC particles in a rotary with 3 to 40 pounds of Mohs 7 rock in it. Just because BB sized SiC particles are being run in a batch of Mohs 7 rocks there is no way a BB sized particle can leave a scratch(pit) but a few thousandths deep under 3 or 40 pounds. Like you said, the more particles the more micro-scratches(pits) being laid down. If the scratch(pit) is shallower than a 500 particle then a 500 grit particle is fully capable of competing with a larger SiC particle in scratching/pitting depth. I have good results with the raw SiC mix. 10 grit to about 1000 SiC all mixed in one. Most of it by weight is 20 to 100. Lots of 100 grit particles for lots of immediate cutting, 20 to 30 grit for time release soon to break down to smaller particles.
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Post by Garage Rocker on Mar 5, 2020 22:25:43 GMT -5
I have another theory. By the time the rocks get to the 600 SiC run they should be smoother with ground down surfaces. The 600 grit should provide a 1000 times more particles to do the cutting than the coarse grit, they may be smaller, but there are a lot more of them all working with more and better rock contact surfaces. Therefore still a lot of material removed. For a load of rougher rocks the 600 is not going to work as well, the 30 SiC or the 46/70 will be more effective. Sounds accurate Henry. There has to be a maximum scratch(pit) depth for SiC particles in a rotary with 3 to 40 pounds of Mohs 7 rock in it. Just because BB sized SiC particles are being run in a batch of Mohs 7 rocks there is no way a BB sized particle can leave a scratch(pit) but a few thousandths deep under 3 or 40 pounds. Like you said, the more particles the more micro-scratches(pits) being laid down. If the scratch(pit) is shallower than a 500 particle then a 500 grit particle is fully capable of competing with a larger SiC particle in scratching/pitting depth. I have good results with the raw SiC mix. 10 grit to about 1000 SiC all mixed in one. Most of it by weight is 20 to 100. Lots of 100 grit particles for lots of immediate cutting, 20 to 30 grit for time release soon to break down to smaller particles. Around here, THIS is known as 'the sweet science'.
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jamesp
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Member since October 2012
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Post by jamesp on Mar 6, 2020 5:32:04 GMT -5
Garage Rocker HankRocksI have been rolling tile sawn 5/16" thick glass "dominoes" over and over for a long while now. Like this: Target was to get them down to 3/16" thickness and have a vibe ready finish and have fine radiuses on edges and corners. All at one point. The starting 5/16" thickness yielded smooth edges and corners almost as if shaped on a wheel. But 160 per load. Coarse SiC stays rolling for 6 to 10 days depending on amount of material removed, then SiC 500 for a mandatory 7 days to arrive at vibe surface prep. The SiC 500 removes material quickly in those first 2 days. But then slows way down to almost zero removal days 3 thru 7 as it breaks to smaller 800-1200-1500-etc. I had to be careful not to remove too much material in step 1 because the SiC 500 would remove so much in those 1st 2 days. Surprising amount. It appears adding a fat tablespoon of costly SiC 500 every day would be a really fast coarse grind method. You would have to manage slurry for sure though. There is another angle to look at. The size of the SiC. The less SiC particles captured between the rocks creates a higher point load/particle which in turn gouges more material/gouge. Photos at same magnification(note fingerprints): This is the deeper pit effect of fresh SiC 10 on obsidian(less pits but more deep) This is the shallower pit effect of fresh SiC 500(more pits but less deep) Both situations were run with sticky slurry also increasing grind pressure. So the really deep pits in the SiC 10 photo for super fast material removal requiring slurry removal every day. The pits are so deep in the SiC 10 photo that the mahogany stripes can barely be seen. No wash not a good idea here.
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jamesp
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Post by jamesp on Mar 6, 2020 6:29:04 GMT -5
Agates, woods, jaspers and other Mohs 7 rocks will never pit this deep in a rock tumbler. Only softer rocks like this obsidian. Pits in harder agates can be found of this depth and size but is usually caused by an act of nature like a high pressure land slide.
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Post by HankRocks on Mar 6, 2020 7:33:12 GMT -5
jamesp I need to go process this statement for a while, " The less SiC particles captured between the rocks creates a higher point load/particle which in turn gouges more material/gouge."Some mornings my brain cells aren't all marching in unison!
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Post by knave on Mar 6, 2020 7:47:10 GMT -5
Bed of nails theory, HankRocks... If 75% of the nails are removed, the subject would experience higher point loading, with possible pitting and/or inclusions.
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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
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Post by gatorflash1 on Mar 6, 2020 10:04:00 GMT -5
I have never been successful attempting short cuts when tumbling. Patience is really a virtue in this hobby.
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Wooferhound
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Lortone QT66 and 3A
Member since December 2016
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Post by Wooferhound on Mar 6, 2020 11:30:25 GMT -5
I have never been successful attempting short cuts when tumbling. Patience is really a virtue in this hobby. My whole life has been tumbling in slow motion.
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jamesp
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Member since October 2012
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Post by jamesp on Mar 7, 2020 7:34:58 GMT -5
jamesp I need to go process this statement for a while, " The less SiC particles captured between the rocks creates a higher point load/particle which in turn gouges more material/gouge."Some mornings my brain cells aren't all marching in unison! Bed of nails theory, HankRocks... If 75% of the nails are removed, the subject would experience higher point loading, with possible pitting and/or inclusions. It appears knave has won the "Most Painful Analogy" award. Imagine a bed of nails with only two giant nails in the center ! I found a 2 step coarse grind to save more tumbling time than any other trick on hard Mohs 7 rocks. SiC 10 for the first 4 to 12 recharges. And SiC 60 for the last recharge will smooth out the SiC 10 damage in a week. Bigger abrasives just makes sense when it comes to speeding shaping time. Bigger abrasives has been the trend in the past few years.
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Wooferhound
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Lortone QT66 and 3A
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Post by Wooferhound on Mar 7, 2020 8:10:45 GMT -5
Bigger abrasives just makes sense when it comes to speeding shaping time. Bigger abrasives has been the trend in the past few years. I use 30-grit in the 6 pound barrel and 60-grit in the 3 pound barrel with very little water for the Win.
- James -
I loved that Ungraded SiC grit that I got from you. Screened it through 1/4 inch mesh and used it that way. Some larger particles lasted for a month in the 6 pound barrel. Still using the big SiC pebbles (1/4 > 1/2 inch) as Smalls in my stage 1 batches. The big ones will last 6 months.
These have been tumbled a coupla weeks
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jamesp
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Member since October 2012
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Post by jamesp on Mar 7, 2020 8:50:29 GMT -5
Bigger abrasives just makes sense when it comes to speeding shaping time. Bigger abrasives has been the trend in the past few years. I use 30-grit in the 6 pound barrel and 60-grit in the 3 pound barrel with very little water for the Win. - James -
I loved that Ungraded SiC grit that I got from you. Screened it through 1/4 inch mesh and used it that way. Some larger particles lasted for a month in the 6 pound barrel. Still using the big SiC pebbles (1/4 > 1/2 inch) as Smalls in my stage 1 batches. The big ones will last 6 months. These have been tumbled a coupla weeks If used with less than 2 inch rocks or barrel fill over 75% it doesn't often get crushed when 1/4 to 1/2". The 1/8" (SiC 10) usually fractures to smaller pieces in most rotary situations but it takes a good while which creating a time release effect. I don't imagine they do much cutting when the bigger pieces are tumbled smooth since SiC does most of it's cutting when broken and sharp. You can put the big chunks on a hard surface and crack them with a hammer to help them finish breaking down. About 25% of the raw SiC is bigger than 1/4 to 3/8" in most cases. It does vary bag to bag. After screening I set the big stuff aside to be crushed at a later time. my neighbors pit bull perhaps ? I wish they made fused SiC pellets about 3/4" for time release. I had a bunch of SiC 60 grinding wheels I broke with a hammer into 1 inch chunks that continually shed SiC 60, nice. After about 4 weeks. Time release 60 grit.
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Post by HankRocks on Mar 7, 2020 9:44:21 GMT -5
I use 30-grit in the 6 pound barrel and 60-grit in the 3 pound barrel with very little water for the Win. - James -
I loved that Ungraded SiC grit that I got from you. Screened it through 1/4 inch mesh and used it that way. Some larger particles lasted for a month in the 6 pound barrel. Still using the big SiC pebbles (1/4 > 1/2 inch) as Smalls in my stage 1 batches. The big ones will last 6 months. These have been tumbled a coupla weeks If used with less than 2 inch rocks or barrel fill over 75% it doesn't often get crushed when 1/4 to 1/2". The 1/8" (SiC 10) usually fractures to smaller pieces in most rotary situations but it takes a good while which creating a time release effect. I don't imagine they do much cutting when the bigger pieces are tumbled smooth since SiC does most of it's cutting when broken and sharp. You can put the big chunks on a hard surface and crack them with a hammer to help them finish breaking down. About 25% of the raw SiC is bigger than 1/4 to 3/8" in most cases. It does vary bag to bag. After screening I set the big stuff aside to be crushed at a later time. my neighbors pit bull perhaps ? I wish they made fused SiC pellets about 3/4" for time release. I had a bunch of SiC 60 grinding wheels I broke with a hammer into 1 inch chunks that continually shed SiC 60, nice. After about 4 weeks. Time release 60 grit. I wish I had a time machine. My 2nd job was working at an Abrasives manufacturing company that was right behind my Parents house, while I went to University of Houston. They made all kind of grinding wheels, both SiC and AlO. I remember when ever there was a bad batch, they had to be broken up with a sledge so as to prevent someone from using them and getting hurt. I suppose you can guess who the was the sledge hammer guy!! On top of that, the plant used big 30 inch by 1 1/2inch SiC wheels to dress all of the new wheels before packing and shipping. When the large wheels worn down, they were taken off the big machines and broken up. I could have filled barrels with busted up SiC wheels. On top of that they used to buy Grit by the truck load that came in 400 pound barrels, both wooden and super heavy duty cardboard. There were usually 80 to 100 barrels to a load and you can guess who had to unload them one at a time by hand!. It wasn't too bad with a 2 wheel barrel jack. The fork lift wouldn't do as it would fit into the truck or into the storage room. I could have gotten grit for 20 cents a pound. Henry
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jamesp
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Member since October 2012
Posts: 36,561
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Post by jamesp on Mar 7, 2020 13:29:39 GMT -5
Dang HankRocks. All that fine tumbling abrasive. Lots of it. Grinding wheels are not allowed to be unstable in any form. Bet they did have plenty of scrap. The beauty of tumbling abrasives for step 1 is about any silicon carbide will work. The county next over was known for it's garnet mines. They crushed the big iron garnets to make sand paper. They called it garnet paper.
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