jamesp
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Post by jamesp on Jan 3, 2017 8:35:44 GMT -5
These are hammer broken silicon carbide grinding wheels(not aluminum oxide wheels). They break down slowly. So the dose is 4-5 times bigger than a powder dose of SiC 60. They make a quick slurry. Takes about 2-3 weeks to break them down in a rotary. So once set up the barrel is left alone for 2-3 weeks. Then a complete clean out. Will be running fast at 55 RPM. 2.5 cups/8 pounds rock Assortment of hammer broken thick slabs of Texas pet wood and palm
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Post by HankRocks on Jan 3, 2017 8:56:26 GMT -5
Knew I saved those old silicon wheels for something!
Now if I could just find a use for all the Tumbler clean out slurry, it accumulates fast.
H
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jamesp
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Post by jamesp on Jan 3, 2017 9:28:25 GMT -5
Knew I saved those old silicon wheels for something! Now if I could just find a use for all the Tumbler clean out slurry, it accumulates fast. H Smash them w/hammer and let them work on those rocks in the rotary. 1-1.5 inch pieces last about 10-14 days depending on conditions. Then a few days to make sure loose grit is broken down. warning: hard on tumble barrels Tumbler slurry, not to good for anything.
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Post by HankRocks on Jan 3, 2017 9:41:45 GMT -5
My barrels seem to be lasting a long time, knocking on the wooden table as I type, it's the lid liner on the Thumlers that seems to wear out easiest. I probably need to look at making my own out of some rubber sheet stock, should be a bit cheaper than buying them. Could also make them out a thicker rubber which would extend the life.
10 to 11 days in the 15lb rotary on 80 grit with re-charge every 2 days produces about 1/2" of dried slurry cake in the bottom of a 5 gal bucket. I do use some as a slurry starter in subsequent loads.
H
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jamesp
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Post by jamesp on Jan 3, 2017 10:01:47 GMT -5
My barrels seem to be lasting a long time, knocking on the wooden table as I type, it's the lid liner on the Thumlers that seems to wear out easiest. I probably need to look at making my own out of some rubber sheet stock, should be a bit cheaper than buying them. Could also make them out a thicker rubber which would extend the life. 10 to 11 days in the 15lb rotary on 80 grit with re-charge every 2 days produces about 1/2" of dried slurry cake in the bottom of a 5 gal bucket. I do use some as a slurry starter in subsequent loads. H Thicker sounds like the ticket. Probably wears in the center. PVC barrels with round ends will wear really fast. Like the round shape converges the rocks to the center. Adding the coarse grit more often does add to the waste in a hurry.
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Fossilman
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Post by Fossilman on Jan 3, 2017 11:12:35 GMT -5
Saves on buying grit,that stuff isn't cheap anymore! I bet it grinds those rocks down pretty good too,huh James... Great idea..
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panamark
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Post by panamark on Jan 3, 2017 13:26:14 GMT -5
My barrels seem to be lasting a long time, knocking on the wooden table as I type, it's the lid liner on the Thumlers that seems to wear out easiest. I probably need to look at making my own out of some rubber sheet stock, should be a bit cheaper than buying them. Could also make them out a thicker rubber which would extend the life. Hank, I had the same problem. When I complained to Thumler they were like "yes they wear out if you use hard rocks" doh I ended up cutting a piece of flat rubber from a large truck inner tube. I used some really good glue to affix it to a new lid bought from Thumlers. Rough up the lid's surface a bit before gluing. Then trim the edge of the rubber so it matched the OD of the lid. It is really amazing how just a thin bit of rubber makes it sooo much more durable. I am on about 2 years of heavy use. The rubber gives just a bit instead of being gouged by the rocks. I tried spray on rubber like a truck liner stuff and it didn't work. Not sure why. anyway, try sheet rubber and it should solve the problem. HTH - Mark
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jamesp
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Post by jamesp on Jan 3, 2017 13:38:34 GMT -5
Saves on buying grit,that stuff isn't cheap anymore! I bet it grinds those rocks down pretty good too,huh James... Great idea.. It is a constant fresh 60 grit supply. Yes, fast grinds. For example, probably better than putting 30 grit for 4 days and having 2 days grit sized from 30 to 60 grit and then the last two days at 60 to 300. Those chunks are constantly shedding. Problem is those wheels are probably electro-fused or some hairy process to get them to stick together so well. Grinding wheels are not allowed to come apart, talking deadly projectile. Nice if there was a way to make similar time release chunks just for tumbling. Whatever way they fused them is about perfect for tumbling.
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Post by HankRocks on Jan 3, 2017 15:10:19 GMT -5
Early in my life I worked at an Abrasives company. They made wheels up to 14 inch, plug wheels, cup wheels and sanding disks. They used resin-ated(if that's a word) Silicon carbide and Aluminum Oxide. The resin, dry and liquid, was mixed before hand, grit added and then put into a hopper. Hooper fed into steel molds and then pressed with a couple thousand pounds of pressure and then baked at about 350 degrees for 48 hours. The wheels had to be dressed before they could be shipped otherwise they would not grind.
Wish that place was still in business as they received in 400 pound barrels of Aluminum Oxide and Silicon Carbide which yours truly would unload one at a time using a hand lift. Fun work in the Houston Summers. They only used up to about 200 grit, sure could use some at the price they used to get it.
H
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jamesp
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Post by jamesp on Jan 4, 2017 2:16:02 GMT -5
Early in my life I worked at an Abrasives company. They made wheels up to 14 inch, plug wheels, cup wheels and sanding disks. They used resin-ated(if that's a word) Silicon carbide and Aluminum Oxide. The resin, dry and liquid, was mixed before hand, grit added and then put into a hopper. Hooper fed into steel molds and then pressed with a couple thousand pounds of pressure and then baked at about 350 degrees for 48 hours. The wheels had to be dressed before they could be shipped otherwise they would not grind. Wish that place was still in business as they received in 400 pound barrels of Aluminum Oxide and Silicon Carbide which yours truly would unload one at a time using a hand lift. Fun work in the Houston Summers. They only used up to about 200 grit, sure could use some at the price they used to get it. H @shotgunner was contriving a way of epoxy/resin bonding some SiC coarse grit for time release pellets. You could mix the resin and SiC on a sheet of paper poster board and break it into smaller pieces ? Got to be some way to bond it together. resin-ated sounds good. Never thought about a powdered resin that reacts to heat. That could be done in the kitchen oven. Maybe mixed with common polyethylene with 240F to 280F melting point ? Then pour it into peat seedling trays. Drip it onto a bed of SiC ?
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Post by HankRocks on Jan 4, 2017 8:09:54 GMT -5
Once you found the right Resin/Resin Blend you could also lay "Silicon Dough"on an old cookie baking pan on parchment paper. That way the Silicon cookie would not stick to the pan(I think). Probably best not to use the good Cookie pan...otherwise..."no cookies for you!!" I don't see anything that can go wrong here!!
I am not sure if the dry Resin and the wet Resin were each a bonding unit, or combined they formed the bonding Resin. Of course the dry Resin would not have adhered very well to the Grit so maybe the wet resin helped the dry adhere to the Grit. It was all mixed in a big cement mixer type apparatus.
There were a few time where they made new wheels with an experimental formula, different blend of resin and grit. For different grinding situations you needed "harder" or "softer" wheels depending on the metal to be ground. Some of the formulas would fail and the wheels would come out looking like badly formed pancakes.
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jamesp
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Post by jamesp on Jan 4, 2017 10:02:01 GMT -5
Once you found the right Resin/Resin Blend you could also lay "Silicon Dough"on an old cookie baking pan on parchment paper. That way the Silicon cookie would not stick to the pan(I think). Probably best not to use the good Cookie pan...otherwise..."no cookies for you!!" I don't see anything that can go wrong here!! I am not sure if the dry Resin and the wet Resin were each a bonding unit, or combined they formed the bonding Resin. Of course the dry Resin would not have adhered very well to the Grit so maybe the wet resin helped the dry adhere to the Grit. It was all mixed in a big cement mixer type apparatus. There were a few time where they made new wheels with an experimental formula, different blend of resin and grit. For different grinding situations you needed "harder" or "softer" wheels depending on the metal to be ground. Some of the formulas would fail and the wheels would come out looking like badly formed pancakes. One of the barrels has been running 10 days and still has about a cup left of grinding wheel chunks in it. Started with 3 cups. Had to thin slurry, lots of rock mud and lots of SiC mud. Resin cost concerns. Epoxy is costly. Probably best for the job though. Melting down some black nursery pots would be cheap. They are low density polyethylene. Cheap plastic. 260F melt point. May cook up a batch and make some cookies as you mentioned. Try like 30% plastic to 70% SiC 30. 20%/80%. Maybe 10% 90% if that would bond it all. Just need minimum as possible.
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Deleted
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Post by Deleted on Jan 4, 2017 10:25:03 GMT -5
Epoxy in a plastic cement mixing tub. No paper to stick too. Way cheaper and less tasty than a silicon cookie sheet.
Epoxy and HDPe aren't friends.
As far as cost. Very little is needed. Maybe 1-30 ratio. One counce mixes 30 ounces of grit dough.
Maybe less.
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jamesp
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Post by jamesp on Jan 4, 2017 10:30:12 GMT -5
Epoxy in a plastic cement mixing tub. No paper to stick too. Way cheaper and less tasty than a silicon cookie sheet. Epoxy and HDPe aren't friends. Keep in mind a bit of paper will not be a problem in a rotary. It will disappear quickly. People use newspaper for slurry thickener. Me has, worked fine. My concern is the cost of the resin. LDPE is basically a waste product. Opinion of how it would work ?
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Deleted
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Post by Deleted on Jan 4, 2017 10:32:18 GMT -5
Epoxy in a plastic cement mixing tub. No paper to stick too. Way cheaper and less tasty than a silicon cookie sheet. Epoxy and HDPe aren't friends. Keep in mind a bit of paper will not be a problem in a rotary. It will disappear quickly. People use newspaper for slurry thickener. Me has, worked fine. My concern is the cost of the resin. LDPE is basically a waste product. Opinion of how it would work ? No opinion. Can't visualise a high temp bonding and mixing system. Epoxy is how those wheel are made. Trust me. Very little is needed. Bonding agent needs to be very sparse so as to not interfere with tumbling cutting action.
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Post by HankRocks on Jan 4, 2017 10:35:58 GMT -5
Holding the Silicon together with a fairly strong bond is obviously your goal. Not sure how well the Polyethylene will hold up. Only one way to find out. You may need to pour the silicon dough into something to contain the flow if it's too loose. Curious to see how this works out for you.
(be careful with fumes from the Polyethylene, it is most likely hazardous to health)
On a different note....
I did notice I can measure the viscosity of the slurry just by looking at it on the lid gasket. Just re-charged 2 barrels and both rubber gaskets had a very nice slow flowing slurry. The slurry density must be working as the rock level in the barrels keeps dropping, having to pour off a bit of the thick liquid a each re-charge to get the level down just below the rocks. Today I just added a small handful of rock to each.
H
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jamesp
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Post by jamesp on Jan 4, 2017 12:04:14 GMT -5
Bonding agent needs to be very sparse so as to not interfere with tumbling cutting action.
Makes perfect sense @shotgunner. Love epoxy
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Deleted
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Post by Deleted on Jan 4, 2017 12:06:39 GMT -5
Bonding agent needs to be very sparse so as to not interfere with tumbling cutting action. Makes perfect sense @shotgunner. Love epoxy Polyurethane is less expensive than bartop epoxy. Polyester less so even more. But really stinky.
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jamesp
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Post by jamesp on Jan 4, 2017 12:15:57 GMT -5
Holding the Silicon together with a fairly strong bond is obviously your goal. Not sure how well the Polyethylene will hold up. Only one way to find out. You may need to pour the silicon dough into something to contain the flow if it's too loose. Curious to see how this works out for you. (be careful with fumes from the Polyethylene, it is most likely hazardous to health) On a different note.... I did notice I can measure the viscosity of the slurry just by looking at it on the lid gasket. Just re-charged 2 barrels and both rubber gaskets had a very nice slow flowing slurry. The slurry density must be working as the rock level in the barrels keeps dropping, having to pour off a bit of the thick liquid a each re-charge to get the level down just below the rocks. Today I just added a small handful of rock to each. H If slurry gets too thick(and it should) you can pour some off and add water to thin. On PVC barrels the rumbling sound goes way low. Hint that slurry needs to be thinned. Visual inspection best though. I will shake the barrel when vertical and cap off and watch to see if rocks still move freely. I run them with fairly thick slurry. Darn if does not break the grit down quick. So thick that my PVC barrels are as quiet as a rubber barrel. So thick that the hard barrels probably have little effect on the grit breaking down. Sticking to my theory that the suction of the sticky slurry is pulling the rocks together as they rotate increasing grinding force.
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jamesp
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Post by jamesp on Jan 4, 2017 12:19:16 GMT -5
Bonding agent needs to be very sparse so as to not interfere with tumbling cutting action. Makes perfect sense @shotgunner. Love epoxy Polyurethane is less expensive than bartop epoxy. Polyester less so even more. But really stinky. If you are working with room temp bonding agent then I don't worry so much about fumes being poisonous. Epoxy is benign. Never thought about polyurethane.
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