jamesp
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Post by jamesp on Jan 18, 2014 11:18:48 GMT -5
I found about 200 of these at the junkyard. 5" x 1" wide for 3/4" shaft. Look to be 60 grit. They are rated at 3600 RPM. What speed to do agate ? Thanks for any advise.
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Post by connrock on Jan 18, 2014 12:07:35 GMT -5
Agate is very hard material and I would imagine it could be ground using that type of grinding wheel but,,,, I wouldn't have it any faster then about 1725 or slower,,,,if I were to try it! The heat that would be generated grind agate on that type of wheel would more then likely be way too how to hold by hand and would probably not only destroy the wheel fast but also crack the agate. I don't know what will happen to a grinding wheel like that if water was used to cool it and the agate as I don't think the wheels were designed to have water on them? There are silicone carbide wheels designed for lapidary use but (as you know) most people use diamond wheels.etc for lapidary. connrock
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Post by roy on Jan 18, 2014 12:12:26 GMT -5
my first machine i got had those wheels it works kinda a pain but works to rough them in
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jamesp
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Post by jamesp on Jan 18, 2014 13:01:46 GMT -5
Thank you conn rock and Roy. I do not see anyone jumping out and saying they are better than diamond....
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cdfcal
having dreams about rocks
Member since June 2011
Posts: 59
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Post by cdfcal on Jan 18, 2014 13:20:53 GMT -5
James, I use sic wheels all the time when I have to do heavy cutting. They probably are not as nice as cutting with good diamond wheels, but like you I got a bunch cheap and they sure take a lot of pressure off my good wheels. They cut plenty fast, I bet those coarse ones you got will eat all kinds of rock........My only concern with sic wheels is how they were cared for, did they get dropped or cracked? You hear crazy stories about wheels coming apart....
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gemfeller
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Post by gemfeller on Jan 18, 2014 14:52:03 GMT -5
James, safety first. My first lapidary set-up used SIC wheels and they can be useful but they're far slower-cutting than metal-bonded diamond wheels. They can be dangerous too. The ones used for lapidary have a special bonding agent designed for rocks and are very dense. It's hard to tell how yours are made. I agree they shouldn't be spun faster than 1725 and be very careful when starting them up. Stand away from the machine in case there are cracks or imbalance that causes them to disintegrate.
You'll need to run them with water to keep things cool. After you've finished cutting be SURE to let them run until they're totally dry to prevent water-logging and imbalance on start up. You'll also need some sort of dressing tool, usually incorporating diamond, to keep the face of the wheel flat. Cutting even agate will groove SIC wheels pretty fast. I'll never forget my first experience grinding a star sapphire cab on one...a great lesson in relative mineral hardness. The sapphire ate more of the wheel than vice-versa. I used up about half the wheel's useful life cutting one cab! On a diamond wheel sapphire cuts easily. In relative terms, diamond's Mohs 10 is roughly 50 times harder than sapphire's 9.
Rick
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jamesp
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Post by jamesp on Jan 18, 2014 15:14:00 GMT -5
James, safety first. My first lapidary set-up used SIC wheels and they can be useful but they're far slower-cutting than metal-bonded diamond wheels. They can be dangerous too. The ones used for lapidary have a special bonding agent designed for rocks and are very dense. It's hard to tell how yours are made. I agree they shouldn't be spun faster than 1725 and be very careful when starting them up. Stand away from the machine in case there are cracks or imbalance that causes them to disintegrate. You'll need to run them with water to keep things cool. After you've finished cutting be SURE to let them run until they're totally dry to prevent water-logging and imbalance on start up. You'll also need some sort of dressing tool, usually incorporating diamond, to keep the face of the wheel flat. Cutting even agate will groove SIC wheels pretty fast. I'll never forget my first experience grinding a star sapphire cab on one...a great lesson in relative mineral hardness. The sapphire ate more of the wheel than vice-versa. I used up about half the wheel's useful life cutting one cab! On a diamond wheel sapphire cuts easily. In relative terms, diamond's Mohs 10 is roughly 50 times harder than sapphire's 9. Rick I follow everything you said Rick. I dress grinding wheels regularly. The water logging was news to me. And i know how dangerous bonded wheels can be due to flying apart. They can go right thru you. The balance is important too. That is very helpful info. And I thank you.
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jamesp
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Member since October 2012
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Post by jamesp on Jan 18, 2014 15:18:13 GMT -5
James, I use sic wheels all the time when I have to do heavy cutting. They probably are not as nice as cutting with good diamond wheels, but like you I got a bunch cheap and they sure take a lot of pressure off my good wheels. They cut plenty fast, I bet those coarse ones you got will eat all kinds of rock........My only concern with sic wheels is how they were cared for, did they get dropped or cracked? You hear crazy stories about wheels coming apart.... Well i will have to give them a try cdfcal. I will spin them on the slow side. Great info and thanks. I took one and rubbed an agate tumble on it and it certainly cut the agate but the agate left it's mark. Looks like they would not last too long.
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Post by mohs on Jan 18, 2014 15:50:54 GMT -5
some one threw that in the junkyard!? what a dirty shame
as they say tho...one man junk is another's man's treasure
send it to me James and I'll let ya know if it grinds
Ed Mohs 3740 E. Polk St Phoenix, Az 85008
that right on the corner of Hard St. Where I hawk hearts...mostly
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Post by pauls on Jan 18, 2014 20:40:22 GMT -5
I picked a stack of 12 inch by 1 inch wheels from a junk sale, fettlers wheels from a foundry probably, they cut OK but are actually too hard for Agate as the Silicon carbide grains are too well bonded and dont get replaced by new grains, once they stop cutting the wheel needs dressing or the heat builds up and fractures the stone. Be aware that running a silicon carbide wheel slow will cause it to get bumpy really quickly. Give it a go, as already stated silicon carbide wheels are different beasts but they do the job and as long as you are aware of safety issues you should be right.
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Post by mohs on Jan 18, 2014 21:05:49 GMT -5
Be aware that running a silicon carbide wheel slow will cause it to get bumpy really quickly. That really interesting pauls ! I struggle with keeping my S/C wheel true I'll bump up the speed and see if it helps I do it right now but no light ! I'll have to wait till the morning grind time edmohs
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jamesp
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Post by jamesp on Jan 18, 2014 21:09:49 GMT -5
some one threw that in the junkyard!? what a dirty shame as they say tho...one man junk is another's man's treasure send it to me James and I'll let ya know if it grinds Ed Mohs 3740 E. Polk St Phoenix, Az 85008 that right on the corner of Hard St. Where I hawk hearts...mostly A bunch of them Ed. They are very old. The hole is lead melted in.
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jamesp
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Member since October 2012
Posts: 36,562
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Post by jamesp on Jan 18, 2014 21:14:34 GMT -5
I picked a stack of 12 inch by 1 inch wheels from a junk sale, fettlers wheels from a foundry probably, they cut OK but are actually too hard for Agate as the Silicon carbide grains are too well bonded and dont get replaced by new grains, once they stop cutting the wheel needs dressing or the heat builds up and fractures the stone. Be aware that running a silicon carbide wheel slow will cause it to get bumpy really quickly. Give it a go, as already stated silicon carbide wheels are different beasts but they do the job and as long as you are aware of safety issues you should be right. These seem loose pauls. I can tell the grit is going to shed off. Just from rubbing an agate on the side of it quickly wore a groove and shed a lot of grit. Thanks for the advise, especially about the speed issue. I like the small 5 inch size. Less centrifugal force. Big wheels can be slowed to get the same surface speed though.
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Post by mohs on Jan 18, 2014 21:15:36 GMT -5
Right on James! I've never used the black S/C before not worth sending, I suppose
Could crush and use them for tumbling grit
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Post by pauls on Jan 18, 2014 21:37:53 GMT -5
Heck Mr Mohs Not only is it night time its also yesterday where you are. And winter as well.
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jamesp
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Member since October 2012
Posts: 36,562
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Post by jamesp on Jan 18, 2014 22:20:44 GMT -5
Right on James! I've never used the black S/C before not worth sending, I suppose Could crush and use them for tumbling grit It would be cheap grit. They weigh 1.5 pounds each. Heard of the Night Rider, but not the Night Grinder. Watch your fingers...
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Post by mohs on Jan 19, 2014 0:06:38 GMT -5
Right on James ! I been known to grind in the dark I like the sparks Ha Ha But my wild grind days are slowing down jus a slow mohs anymose...mostly O yeah pauls grinding at the grit just 10 more hours to sunrise to speed up my S/C wheel that's true if you get my drift edmohs
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Post by mohs on Jan 19, 2014 14:55:26 GMT -5
Be aware that running a silicon carbide wheel slow will cause it to get bumpy really quickly. That really interesting pauls ! I struggle with keeping my S/C wheel true I'll bump up the speed and see if it helps I do it right now but no light ! I'll have to wait till the morning grind time edmohs I gotta tellya pauls speeding up my S/C wheel as made a humongous difference in truing it up! This as really bothered me for a long time I was always excellent at truing/dressing a wheel in the sharpening biz But I had all kinds of problems when I went to lapidary It never dawned on me that the speed as lots to do with it That seems to be true & self evident now Thanks ! Ed one of the best tips I ever got on RTH and I've gotten many
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Post by pauls on Jan 19, 2014 15:37:22 GMT -5
Glad to help Ed. Speeding it up wont stop it getting bumpy but it sure helps extend the time between dressing it. Which extends the life of the wheel too. At my club they even managed to get a diamond wheel bumpy, no chance of dressing that. Some people are very hard on equipment that they have no commitment to paying for or maintaining.
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Post by mohs on Jan 19, 2014 17:53:13 GMT -5
Well I bumped the machine up to about 2500 rpms That the most I can get out my adjustable pulley I was grinding on big piece of Montana and could tell right away that the wheel was staying truer The S/C wheel is made for 3250 I used them a lot when rough grinding carbide never experience such out of roundness problem
Then I moved over to lapidary and couldn't keep the wheel true this as happened in my relationships also but that's another story mostly
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