jamesp
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Post by jamesp on Oct 2, 2016 20:55:11 GMT -5
It is very brittle richardh. Aluminum oxide and diamond are real tough. Diamond scary tough. Basement rare in Florida and coastal areas. Must be soil or water table.
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Deleted
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Post by Deleted on Oct 2, 2016 21:15:20 GMT -5
"must be some durable crystals"
Diamond is stable to 4500°F. It's why we can weld or braze them.
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jamesp
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Post by jamesp on Oct 2, 2016 22:26:14 GMT -5
"must be some durable crystals" Diamond is stable to 4500°F. It's why we can weld or braze them. That is bizarre for a crystalline substance.
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Deleted
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Post by Deleted on Oct 2, 2016 22:52:22 GMT -5
"must be some durable crystals" Diamond is stable to 4500°F. It's why we can weld or braze them. That is bizarre for a crystalline substance. I had to look that up when we played with those segments. Couldn't figure out how they made the segments! I wonder what a kg of those yellow ones in a 30grit would cost. To give it a try.
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jamesp
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Post by jamesp on Oct 2, 2016 23:03:27 GMT -5
That is bizarre for a crystalline substance. I had to look that up when we played with those segments. Couldn't figure out how they made the segments! I wonder what a kg of those yellow ones in a 30grit would cost. To give it a try. Concerned about them being to dull to cut. SiC is razor sharp. Gotta have sharp edges to cut at low pressure. Thoughts ? I still like the ides of cutting up 50 grit rubber pads into 1/4 inch pieces. They are very sharp crushed diamonds, not roundish crystals. Tumbling process may tear the rubber up, who knows. Or they may be to light weight.
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Deleted
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Post by Deleted on Oct 2, 2016 23:10:29 GMT -5
Rubber pads need pressure to expose the grit. Maybe they float in the slurry too.
As for diamonds not being sharp. They grade them for sharpness on that website. 260 vs 290... Still maybe not sharp enough, I understand.
I hate not testing either...... Exploration is fun. You proved that!
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Deleted
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Post by Deleted on Oct 2, 2016 23:17:37 GMT -5
Don't be surprised if mono-crystal diamonds get bigger and cheaper. Need sharp edges for tumbling. Looks like those could be used as cutting bits on a lathe or mill. If I remember right, the yellow is due to being grown from solution in molten nickel metal at ultra pressure. That is the oldest diamond growth method, I'm aware of. I did research it a bit. Fascinated by crystal growth. Huge business opportunity in it. Many rare and desired crystals not produced. Benitoite is extinct in the known universe. Alexandrite, true Tanzania, there must be others. Agate, jade, Bridewell, imori...... The key with diamond is Color. Both lack of and varieties. Plus size. Put the right combination of those together and the world is your oyster.
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jamesp
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Post by jamesp on Oct 2, 2016 23:28:09 GMT -5
@shotgunner
Would like to see those squares with cutting teeth cut in them to make cutting media like ceramic media impeded with SiC. May were barrels out super fast.
Running several single big rocks in several new small barrels. Kinda freaking at the speed of shaping and appetite for fresh grit. Taking a break. Running them on the 30 RPM shafts for 24 hour grit life. 55 Rpm = 12 hour grit life. 24 hour intervals easier.
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Post by toiv0 on Oct 3, 2016 3:45:11 GMT -5
What about glueing your diamond impregnated rubber pads to the inside of a barrel. Just add rocks, a barrel for each grit.
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jamesp
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Post by jamesp on Oct 3, 2016 5:30:52 GMT -5
What about glueing your diamond impregnated rubber pads to the inside of a barrel. Just add rocks, a barrel for each grit. If you could get the rocks to slip against the barrel and tumble. Most tumblers don't have much wall slippage. Sure there is a way to make that happen, and it would be a wicked way to round rocks off. Maybe a slanted bowl type arrangement that made the rocks climb an incline and roll back down. Or a large diameter tire tumbler that has a lot of slippage like this one did lol Or an inclined slanted bowl arrangement
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Post by toiv0 on Oct 3, 2016 10:33:48 GMT -5
Ok then, make a shirt PVC barrel line it with diamond pads, have it teeter totter in stead if roll. Maximum contact.
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Deleted
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Post by Deleted on Oct 3, 2016 13:06:56 GMT -5
Ok then, make a shirt PVC barrel line it with diamond pads, have it teeter totter in stead if roll. Maximum contact. You mean, like a vibe tumbler?
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jamesp
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Post by jamesp on Oct 4, 2016 21:23:35 GMT -5
Whatever arrangement makes the rocks scrub the container toiv0. There is ways. @shotgunner, a vibe scrubs rocks for instance.
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budified
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Post by budified on Nov 26, 2016 0:35:35 GMT -5
What a great topic, I too have thought about how long diamond grit would last.
I have also considered collecting segments from warped saw blades generally discarded at work to use as small filler media, would work wonders in my opinion, and possibly with enough of then remove the need for rough grade SiC.
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metalsmith
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Post by metalsmith on Nov 26, 2016 7:21:10 GMT -5
It would be an interesting experiment to see what happens. I wonder why SiC breaks down when it is the hardest material in the tumbler. All of my work is done in the back yard, I'm definitely not allowed to do anything in the house. A basement would be nice but very few houses have them in the Houston, TX area. One thing I love about this forum is the diversity of questions asked. I don't always know the answers, but it is often a pleasure to research and find out. So "why SiC breaks down when it is the hardest material in the tumbler". My theory is that SiC has a cleavage. A quick review of Wiki tells me that the crystals of SiC are cubic / hexagonal. Hexagonal is pretty strong but cubic would shear. Hex SiC would also shear given the right conditions... I suspect that the breakdown occurs due to SiC breaking SiC Leading in a way to I think diamond cuts diamond only when subjected to extreme pressure. This I do know ... diamond cuts diamond due to the random orientation of the cutting diamond. With so many minute diamonds, out of the randomness there are some diamonds that are orientated in a stronger alignment than the diamond being cut. I believe the same would occur with SiC - unless there's any reason why not?
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jamesp
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Post by jamesp on Nov 26, 2016 7:59:42 GMT -5
I would think 'hardness' and 'toughness' comes into play. Toughness would prevent shear and shattering for any reason. Silicon carbide totally brittle, opposite of tough. But that is it's mechanism of cutting, it never rounds, it only breaks into sharp cutting particles.
Diamonds(synthetic anyway) are surely tough. Watch a 10,000 RPM diamond cup grinder with a man bearing down hard on it while grinding about any hard material. Lots of shock loading. I think the binding matrix wears and releases the diamonds. Doubt the diamond ever wears or shatters. Not to mention they were cast in metal at high temperatures.
Maybe one day they will manufacture diamonds cheap enough for use in a tumbler.
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budified
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Post by budified on Nov 26, 2016 11:30:49 GMT -5
It too much pressure, working on harder materials, diamonds "glaze over". This greatly reduces a diamonds ability to cut, and requires "sharpening" the diamond. Diamond blade sharpening can be performed with a sharpening stone, or at much cheaper cost with a cinder block.
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Deleted
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Post by Deleted on Nov 26, 2016 11:42:52 GMT -5
It too much pressure, working on harder materials, diamonds "glaze over". This greatly reduces a diamonds ability to cut, and requires "sharpening" the diamond. Diamond blade sharpening can be performed with a sharpening stone, or at much cheaper cost with a cinder block. In this scenario we believe it's not the diamond glazing over, but the matrix. Diamond is broken or worn off leaving only a matrix surface. So we cut thru a grinding wheel and the SiC in the grinding wheel removes matrix exposing diamond.
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budified
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Post by budified on Nov 26, 2016 11:55:06 GMT -5
I run 16-20" diamond blades on a 15×20' bridge saw. These blades cut granite 6-8 hours per day and starting with 1" of tooth depth, can last 4-6 months before they are completely worn down.
You can tell that the diamonds are glazed over because you can see where they are but they lack the sparkle a diamond inherently guarantees. Once "sharpened" these diamonds shine again. If the diamonds simply broke free I don't assume I would be able to run a blade for 500-1000 hours. The matrix will wear away before the diamonds inevitably causing diamond loss, and could possibly be the cause of the glaze as the matrix simply melts and hardens over top of the diamonds.
Another thing I have found is that blades with the diamonds laid out in a pattern (I describe it as a triangular pattern) cut easier and last longer than blades with random diamond scatter.
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richardh
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Post by richardh on Nov 27, 2016 7:26:57 GMT -5
I would think 'hardness' and 'toughness' comes into play. Toughness would prevent shear and shattering for any reason. Silicon carbide totally brittle, opposite of tough. But that is it's mechanism of cutting, it never rounds, it only breaks into sharp cutting particles. Diamonds(synthetic anyway) are surely tough. Watch a 10,000 RPM diamond cup grinder with a man bearing down hard on it while grinding about any hard material. Lots of shock loading. I think the binding matrix wears and releases the diamonds. Doubt the diamond ever wears or shatters. Not to mention they were cast in metal at high temperatures. Maybe one day they will manufacture diamonds cheap enough for use in a tumbler. I haven't done an exhaustive search but the information I have found so far suggests that diamonds are indeed quite brittle (which is what I would expect given their hardness) and do have cleavage planes making them susceptible to shock. I believe that they would break down in a similar manner to SiC in a tumbler over time. It would be very interesting to actually do some experiments to see if that hypothesis is correct. Unfortunately for me I'm in a bit of a cash crunch and can't afford to buy diamonds to test it out.
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