docharber
has rocks in the head
Member since October 2008
Posts: 693
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Post by docharber on Mar 9, 2009 20:04:12 GMT -5
I am considering buying a cabbing unit- specifically the COvington 8" unit with 4 expando drums. Is there any reason to prefer this sort of unit (or avoid it) compared to a diamond or SiC wheeled unit? it sure is cheaper off the block. Thanks!
Mark H.
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Post by bobby1 on Mar 9, 2009 22:14:32 GMT -5
It probably depends on which type you learned to cab on. I learned on the SiC machine (back before Expando wheels were thought of) and I am still using that type. I've used all diamond units as well as teaching students to use them but I still prefer the old fashioned (but not outdated nor surpassed by diamond) unit. Both types can do an excellent job. Replacement wheels and belts are somewhat more expensive with diamond. I would recommend that you join a club (if you haven't already) and try out the different types, brands and styles of machines before you plunk down some serious dollars. Bob
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Post by texaswoodie on Mar 10, 2009 7:40:36 GMT -5
Man, I love my expando! I use diamond wheels to 220, then diamond paste on an expando from there.
Curt
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mirkaba
spending too much on rocks
Member since August 2006
Posts: 321
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Post by mirkaba on Mar 10, 2009 11:54:31 GMT -5
Wow 4 expandos!!! I only use 2. Just in the process of going with a full set of diamond belts. ;D Sounds like it might be a good deal. Start out with Silicon Carbide belts and upgrade to diamond (belts or wheels) later if you are so inclined. Although I would definately change out an expando for either a 100 grit Silicon Carbide or a hard 80/100 diamond wheel right off the bat............Bob
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Post by Titania on Mar 10, 2009 12:07:42 GMT -5
I've used both wheels and expandos, and I far prefer wheels. I just found I didn't like having to change out belts as I was working. To me, it's disruptive...but that is probably just me.
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Post by Hard Rock Cafe on Mar 10, 2009 12:09:17 GMT -5
Bobby1: You turn out amazing stuff on the SiC wheels. Just proves the point that "It's a poor craftsman who blames his tools."
I had just assumed that I would need to replace the SiC wheels with diamond wheels on the used unit I recently bought. I guess not!
Sorry, Mark; I'm no help. But I am interested in what others have to say.
Chuck
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1rockhound
spending too much on rocks
Member since July 2008
Posts: 286
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Post by 1rockhound on Mar 10, 2009 14:22:06 GMT -5
I use a 100 grit silicon carbide wheel for my rough grind on my cabs then switch over to my expando drum.
Jason
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mossyrockhound
fully equipped rock polisher
Member since January 2011
Posts: 1,278
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Post by mossyrockhound on Mar 10, 2009 14:51:45 GMT -5
Mark, I used SiC for years and then switched to diamond. I won't go back to SiC because diamond is so much more convenient. The expando drums I have will take either SiC or diamond belts. I use diamond belts on them, although they are quite pricey. I'm not sure what you are using for grinding, but you need a hard wheel, either SicC or diamond. The only expando wheels I am aware of are for sanding only. The cheapest (and best in my opinion) way to go is to buy a used SiC cabbing unit with worn-out wheels and then replace them with diamond wheels. I did that on my main cabbing unit and I really like it. It's not as portable as a Genie or Titan, but I don't take it with me when I leave home anyway. Garry
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docharber
has rocks in the head
Member since October 2008
Posts: 693
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Post by docharber on Mar 10, 2009 21:16:44 GMT -5
Thanks for all the input, guys. It seems the consensus is to use a hard wheel for rough grinding and the expando drums for finer sanding. i don't know why this unit has 4 expandos and no hard wheel. I thinnk I agree with Garry- for me diamond seems the best alternative but with sufficient experience I'm sure the choice of SiC or diamond would be less important. I have lookeed for used cabbing units in the 6-8" size but they're hard to come by for a reasonable price. I depend on this board for advice because the nearest rockhounding club is an hour and a half away and I don't drive. There aren't any rock shops here either. So, I have to teach myself for the most part. I have great friends with loads of experience but they're hundreds of miles away and there's nothing like having an expert standing buy. You folks are the next best thing for me. For grinding, I have aGraves Mark IV faceter that makes a pretty decent flat lap, too. I don't know how to facet yet but I'm definitelyequipped. A friend in San Antonio who made his living in the wholesale trade and doing lapidary work gave me this unit when he retired. I have lots of wheels and don't have a clue how to use some of them. Right now I am only using the 100, 360 and tentatively 600 and 1200 wheels for freeform cabs- I just cut my first pitifull attempts and I'm putting them in the next load of tumbling at 600 grit and then polish. I have a ceramic wheel, a new copper lap, and a tin lap that looks like it has been hammered. It has a little charge left, and I have 50k mesh diamond for it when I need it. I just don't really know for sure how to apply it. I think my friend used olive oil and diamond as a slurry to dress the tin lap. I also have plastic film coated with cerium oxisde and alumina polish but haven't gotten good results with these so far. I have a phenolic lap and a new master lap, too. I have a motorized preformer for the Mark IV abd a multitude of cams and dops for it. i have yet to dop my first stone; so far I've just hand held the slabbettes after trimming as needed. I'm on hiatus for a few days until the skin grafts take on my fingertips. If anyone knows a of a machine coming up for dale, or for that matter, a 10" or larger slad saw, let me know. These units often look so grungy I have a hard time guessing as to their condition and I hate to buy off eBay for that reason. It's like buying a used car- you can assume a lot about the quality of the machine by the quality of the owner. So, word of mouth from someone who would know is reassuring to me.
Thanks again,
Mark H.
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