jamesp
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Post by jamesp on Feb 7, 2016 16:51:26 GMT -5
DANGER- Dry silica dust bad for lungs, use proper ventilation and respirator designed for such dust. Using a pivoting kitchen cutting board as finger protection greatly improved nicking fingers. Open position, use great caution Protective position, safer Side view, 7 inch diamond cup wheel with M14-7/8 arbor, 40 grit, 1/4 HP 1725 RPM motor. Cost about $120, used motor. Geared 1.4:1, so diamond wheel spinning about 2400 RPM 2-3 inch nuggets of crazy lace 2 inch nuggets of super clear quartz Couple of 3 pounds. 30 minutes worth Clear quartz before on right
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Fossilman
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Post by Fossilman on Feb 7, 2016 18:12:29 GMT -5
Now there ya' go...Lookin' good!
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Post by manofglass on Feb 7, 2016 18:15:05 GMT -5
Try not to lose any fingers on that thing james
Walt
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jamesp
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Post by jamesp on Feb 7, 2016 18:52:48 GMT -5
Try not to lose any fingers on that thing james Walt No rocks less than 1 and a quarter inch Walt. Have singed the skin a couple of times.
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jamesp
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Post by jamesp on Feb 7, 2016 18:55:31 GMT -5
Now there ya' go...Lookin' good! I feel safer with that device than a 7 or 9 inch hand grinder for welding Michael. Thy are slap dangerous if you don't pay close attention.
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bushmanbilly
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Post by bushmanbilly on Feb 7, 2016 19:09:26 GMT -5
Now there ya' go...Lookin' good! I feel safer with that device than a 7 or 9 inch hand grinder for welding Michael. Thy are slap dangerous if you don't pay close attention. yes they are. Skinned my knuckles more than once. It really hurts when they self-destruct. Question ... Where did you find that quartz? Local?
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Post by Pat on Feb 7, 2016 19:16:14 GMT -5
Hard to tell which I like better: your rocks or your invention
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jamesp
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Post by jamesp on Feb 7, 2016 19:19:23 GMT -5
Trying to purchase this technology. Full circle wide face sintered diamond cup.No segments. 7 inches across. Should handle 1000's of pounds of agates and tumbles. Spin it slower if you are concerned about the speed. ETA: The manufacturer is Gushi. Must be ordered out of China. Sounds like min order is 10 units darn it. They are made in fine medium and coarse, probably 40 grit, 150 grit and 250 grit. Made to run dry or wet, telling of how rugged they are. I am researching cab like wheels that they make. This company has some liberal diamond sintering. Do not be surprised if 6 and 8 inch bench grinder wheels are made out of a solid sintered chunk. Saw blades and cab wheels too.
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jamesp
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Post by jamesp on Feb 7, 2016 19:31:31 GMT -5
I feel safer with that device than a 7 or 9 inch hand grinder for welding Michael. Thy are slap dangerous if you don't pay close attention. yes they are. Skinned my knuckles more than once. It really hurts when they self-destruct. Question ... Where did you find that quartz? Local? I am in a dyer position regarding that quartz Dale. I keep up with my gifts but lost it on this one. Almost sure quartz sent it to me. I believe it came from an estate sale he managed recently. Darn things are 2-3 inches across and have exactly zero cracks. I thought it was clear glass till I notice a couple of them retained hex shape, obvious quartz crystals. Amazing how fast that diamond wheel cut that clear quartz like butter, probably 8 times faster than hard agates. Mohs 7 deceptive, toughness may be more important making knoop scale more accurate for hard rocks. The southern coral is the absolute slowest to grind or break. Very slow to grind. Tried to saw a pipe with the 9 inch grinder ONCE. It hung and never did that again.
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jamesp
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Post by jamesp on Feb 7, 2016 19:42:33 GMT -5
Hard to tell which I like better: your rocks or your invention That is the simplest grinder Pat. Easy to use. It even grinds metal like nothing. Can't do without. I think it will shape as many rocks as 200-300 tile blades.
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Post by Drummond Island Rocks on Feb 7, 2016 21:54:07 GMT -5
Lots of labor in pre grinding tumbles but it takes weeks off of stage one and also makes some impossible rocks possible again. I do all my pre grinds on the 6" galaxy wheels. A sintered 6" wheel is always on my wish list but mega bucks.
Chuck
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jamesp
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Post by jamesp on Feb 8, 2016 0:29:15 GMT -5
Lots of labor in pre grinding tumbles but it takes weeks off of stage one and also makes some impossible rocks possible again. I do all my pre grinds on the 6" galaxy wheels. A sintered 6" wheel is always on my wish list but mega bucks. Chuck Yes, those big sintered wheels certainly are costly. I would put grooves and valleys in them, maybe that ould render it useless for accurate cab work, not sure. Industry uses diamond cups on such a large scale they must have targeted that market for mass production on a cheap scale. The way I read the specs the sintering thickness ranged from 7mm to 10mm thick for sizes 4 to 7 inches for the full face sinter. That is a darn thick slab of sinter. I think they make a 9 inch one too with what looks like at least a 2 inch wide working surface. Making it doable for lapper work up to 220 -300 grit for the fine grit model. Guessing they will come out with a solid sintered disc with no hole in the center. Perfect for sphere shaping and medium tumbles. I just figured I would go cheap and utilize the hand grinder cups for cost reasons Chuck. Doubt it will wear out for years. And I bear down hard. I could make it with a water spray but would have to make a surround. At 2400 RPM it would require some focus but doable. Running dry now with lots of ventilation and real good mask with replaceable filters easily filtering the dust. And never in the house, out in a greenhouse with a giant exhaust fan. it is loud and a bit intimidating. Bracing your hand and being ready to release the rock allows a fair degree of safety. It is a lot safer than running a 7 or 9 inch hand grinder. Bench grinders are not exactly safe either since the wheels can fly apart. But it is fun to make some really nice tumbles and shapes.
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jamesp
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Post by jamesp on Feb 8, 2016 9:05:37 GMT -5
If you hold the rock against the edge of the wheel, palms firmly planted on the base board, the edge of the wheel turns into a chipper. The wheel has approximately 40 diamond segments, it is turning at 2400 RPM. That calculates to 40 X 2400 = 96,000 impulses per minute from the gaps between the segments. That is tiny hammer taps at a rate of 1600/second, way beyond ultrasonic levels. By holding the rock against the edge of the wheel right on a fracture the wheel behaves like a vibratory hammer. If a fracture is running across the stone say on 1/3 of the rock the vibration will cause the fracture to continue and pop that side of the rock off. If you gear the wheel to turn slower at say half as fast 1200 RPM or even motor speed of 1725 RPM, the vibratory hammer effect is reduced. It is basically a fairly gentle ultrasonic chipper. Even on a larger rock say 2-3 inches across large fractures will be forced to propagate and split the rock in half. Using the edge as a chipper never creates more fractures. Even on obsidian and glass. It will break thin chips though. Now the wheel can serve as a sharp edge removal device by chipping instead of grinding. Faster way for material removal. Facial fractures like a thin layer chip still attached to flat faces of the rock fall away by simply touching the fracture to the edge of the wheel. May sound complicated but it's not. it is just a quick way to dress many rocks for the tumbler. Estimated time to coarse tumble the pre-ground pebbles at upper left is 2 weeks, the unground chunks to upper right about 8 weeks. And there would still be fractures left since they were not targeted on the grinder.
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jamesp
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Post by jamesp on Feb 8, 2016 9:32:25 GMT -5
Typical fine chips from using edge of wheel as a vibratory hammer. As the non-diamond back plate is exposed from the sintering wearing away I dress the edge of the back plate with a plain metal angle grinder. To keep the diamonds exposed on the edge. Hand grinder spinning and held up against baking plate while diamond wheel is spinning. Just the tip 1/8 inch or less. For about absolute safety a box or rigid cover could be tightened down and only allowing a the very edge of the wheel exposed, say 2 inches would be adequate. Edge of wheel sticking out 1/4 of an inch from the slot. Maybe better turned 90 degrees so you have a horizontal table top with the edge of the wheel sticking up from the slot. As if lowering a tile saw blade down into the blade slot. I prefer the orientation in the photo for visual access from the top and chip flow to the side and away from eyes. Note the dip in the center of the segments from usage. That dip actually helps put an edge radius on tumbles. Water drip would greatly increase life. Wheel is $39.95 7 inch model from Harbor Freight. Shaft is a(good) 16 inch bolt with the head sawn off, standard 5/8-14 thread. Two Surplus Center 5/8 pillar bearings. Used 1/4 HP 1725. A 2 inch pulley and a 3 inch pulley, also Surplus Center. 3 inch on motor. 2 X 12 treated 8' stick of lumber. Polycarbonate cover(not shown). Butt pad. Wife's butcher block oh yea.
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Post by mohs on Feb 8, 2016 9:41:31 GMT -5
that's really fine arbor set up james! plus you can switch that out to how big of a flat lap ? easily 8" and easily slow down the rpm if you wish?
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jamesp
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Post by jamesp on Feb 8, 2016 10:11:46 GMT -5
that's really fine arbor set up james! plus you can switch that out to how big of a flat lap ? easily 8" and easily slow down the rpm if you wish? Slowing is fine, but it chips better at +2000 RPM for 7 inch wheel. It will take 4-5-7 inch wheels. I would have to modify the wood surround for 9 inch. I dodged the 9 inch because of the added rotating weight. In the case on imbalance. Actually the 4 inch wheel does fine for an edge grinder. And it just takes a minute to remove the 7 inch wheel and replace it with the 4 inch one. 4 inch wheels are darn cheap, like $12. And do just as well for edge grinding. I have a 4 inch wheel that must have ground 200 pounds of tumbles.
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jamesp
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Post by jamesp on Feb 8, 2016 10:17:41 GMT -5
This was the finger eater that I did most of my testing on. Way dangerous. This is the rock sitting on the wheel being ground Same rock, only 2 weeks in coarse grind
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Post by mohs on Feb 8, 2016 19:49:47 GMT -5
ah ha I remember that set up james that could be a knuckle burner ! excellent innovations
if I had the money I send you ticket to come visit Phoenix could use your advise a rock consultant ha ! you'd be the MAN!
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Post by mohs on Feb 8, 2016 19:53:42 GMT -5
James at high rpm does that rock grind pretty smooth on edge like that? the disc is somewhat segmented...right?
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Post by MrP on Feb 8, 2016 20:04:12 GMT -5
jamesp What are you doing to that poor Chipmunk?........................................MrP
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