Old Hickory
having dreams about rocks
Member since March 2006
Posts: 67
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Post by Old Hickory on Apr 17, 2013 12:51:16 GMT -5
This is a question for all the tumbling professionals on this site. This question comes from the fact that I am a frugal, tight, penny pinching, skinflint and that’s putting it mildly. I don’t mind spending money, I just hate to spend more than is necessary and I hate spending it on products because they are time tested conventional standards that someone, sometime in history said I should use. So this brings to mind the question about the use of Silicon Carbide grit for rough tumbling. We all know that if you are tumbling any larger quantities of material that the cost of rough tumbling grit say 30 grit thru 120 grit is getting pricy and if you don’t have a source close to you the shipping costs are out of sight if you buy 50# at a time. A lot of folks use Aluminum Oxide in the finer grits in the finishing process, why not use A/O in the rough cycle. I live in the Seattle Metro area and found the prices on Silicon Carbide from three different dealers as follows Dealer #1 60/90 grit $161.50 for 50 lbs, $3.23 per lb., Dealer #2 60/90 grit $123.00 for 50 lbs, $2.46 per lb., Dealer #3 80 grit $85.00 for 50 lbs., $1.70 per lb. During my questioning of dealer #3 he asked me why I didn’t use Aluminum Oxide Grit instead of Silicon Carbide Grit??? and my answer was I don’t know - that’s what is always used. At this point he told me that they sell Aluminum Oxide grit in various grades for blasting and he quoted me a price of $0.45 lb for 100 grit A/O. I done some checking on hardness and found that Silicon Carbide is 9.5 on MOHS scale and Aluminum Oxide is 9 on the MOHS scale. So the question becomes why are we using Silicon Carbide ??
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Post by Toad on Apr 17, 2013 13:14:22 GMT -5
This is a question for all the tumbling professionals on this site. This question comes from the fact that I am a frugal, tight, penny pinching, skinflint and that’s putting it mildly. I don’t mind spending money, I just hate to spend more than is necessary and I hate spending it on products because they are time tested conventional standards that someone, sometime in history said I should use. So this brings to mind the question about the use of Silicon Carbide grit for rough tumbling. We all know that if you are tumbling any larger quantities of material that the cost of rough tumbling grit say 30 grit thru 120 grit is getting pricy and if you don’t have a source close to you the shipping costs are out of sight if you buy 50# at a time. A lot of folks use Aluminum Oxide in the finer grits in the finishing process, why not use A/O in the rough cycle. I live in the Seattle Metro area and found the prices on Silicon Carbide from three different dealers as follows Dealer #1 60/90 grit $161.50 for 50 lbs, $3.23 per lb., Dealer #2 60/90 grit $123.00 for 50 lbs, $2.46 per lb., Dealer #3 80 grit $85.00 for 50 lbs., $1.70 per lb. During my questioning of dealer #3 he asked me why I didn’t use Aluminum Oxide Grit instead of Silicon Carbide Grit??? and my answer was I don’t know - that’s what is always used. At this point he told me that they sell Aluminum Oxide grit in various grades for blasting and he quoted me a price of $0.45 lb for 100 grit A/O. I done some checking on hardness and found that Silicon Carbide is 9.5 on MOHS scale and Aluminum Oxide is 9 on the MOHS scale. So the question becomes why are we using Silicon Carbide ?? I'm not sure if you want an answer or not since you don't want to go by time tested standards. But I'll answer anyway: - Moh's hardness makes a difference, every little bit helps. - AO tends to round off as it breaks down which prematurely ends the grinding effectiveness. SiC continues to break with sharp edges as it gets smaller - meaning that the grinding action continues no matter how small it gets. I've never done a side-by-side of the two, but I'll go with the more expensive and more effective option for now. Speed is more important to me than $$$ at this point.
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Old Hickory
having dreams about rocks
Member since March 2006
Posts: 67
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Post by Old Hickory on Apr 17, 2013 13:49:09 GMT -5
Quote - I'm not sure if you want an answer or not since you don't want to go by time tested standards. But I'll answer anyway:
Toad - I am not trying to swim up stream, just trying to understand why it is not done. If A/O breaks down than that is the answer I am looking for.
Thanks
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Geoff
spending too much on rocks
Please add 1074 to my post number.
Member since December 2012
Posts: 446
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Post by Geoff on Apr 17, 2013 14:57:19 GMT -5
I thought Jerry's in Kent had good prices on SiC. Then again, everyone has good prices compared to what I pay in AK. I've taken to making my own grit from junk SiC face seal we use at work. I can recover about 5 pounds every two week hitch.
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Post by Toad on Apr 17, 2013 15:07:47 GMT -5
Quote - I'm not sure if you want an answer or not since you don't want to go by time tested standards. But I'll answer anyway: Toad - I am not trying to swim up stream, just trying to understand why it is not done. If A/O breaks down than that is the answer I am looking for. Thanks They both break down, but SiC is more effective longer... Some folks have had success putting rough in with 60/90 and then just letting it roll for months as the SiC just kept getting smaller and smaller. I don't remember how great their results were.
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,564
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Post by jamesp on Apr 17, 2013 15:08:26 GMT -5
I have run tests on on AO and it does not hold a candle to SiC.And recently.46 grit AO is not cutting well at all.Neither is broken up 36 grit grinding wheels.AO wears into a smooth balls that do not cut.SiC fractures continually into very sharp fragments,cutting constantly and efficiently till it is completely broke down. i have a thread on this page about 'tumbling with diamond segments'.It is a future experiment that i have high hopes for.
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