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Post by Hard Rock Cafe on Sept 21, 2009 21:08:14 GMT -5
Sorry for the cross-post, but I wasn't getting any replies in the Creating Cabochons category. ( forum.rocktumblinghobby.com/index.cgi?board=ccabs&action=display&thread=33305) I'm just getting started cabbing and my Scott-Murray 8"x3" expanding drums are on their last legs, so I know I'll need to replace them before long. I might as well start my Christmas list now... Instead of replacing them with the same type of drum ($76), I was thinking of going to diamond for a little more money ($88-$130). I know I would be giving up an inch in width, since it appears 8" diamond sanding wheels only come 2" wide. Is that extra inch all that important? Is there any other reason why I should go with expanding drums again? Or should I get expanding drums again but buy diamond belts? This doesn't make much sense to me because the belts cost almost as much as the diamond drums ($68). FYI: I have an old Highland Park machine with 2 expanding drums, 2 SiC wheels (that will eventually get replaced with diamond), and a polish disc. Thanks for your help! Chuck
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buck570
starting to shine!
Member since February 2009
Posts: 46
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Post by buck570 on Sept 22, 2009 21:24:46 GMT -5
How about splitting the difference,one wheel and a drum. Give you the longevity in the course grits and adaptability in the finer.
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Post by Hard Rock Cafe on Sept 22, 2009 22:22:34 GMT -5
That's an idea, buck. I could swap out belts on the drum to give me two fine sanding grades instead of one...I hadn't thought of that. I had thought of adding another sanding wheel: I've got the space, but I'd have to rig up another water supply.
Chuck
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Post by johnjsgems on Sept 23, 2009 9:37:17 GMT -5
I'd go (money allowing) with an 80 and 220 diamond wheel where S/C wheels are and one or two expandos. You say two belts but with diamond you can have many belts (all the way to 50,000). The advantage to 3" is the ability to do larger pieces, flats, small geodes, etc. I would have a 400, 600, 1200 and 3000 belt at least. Whether you want the convenience of two belts mounted at a time is up to you. Changing the inside belt is harder than a single drum. Another option would be to install a third wheel where inside drum mounts in a 280, 325, or 400 and have just the outside belt for 600 and finer.
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Post by Hard Rock Cafe on Sept 23, 2009 12:25:27 GMT -5
Thanks John! I have noticed that changing the inside belt is kind of a pain compared to the outside one.
So, I'm thinking 80 and 220 hard wheels, 280 soft wheel, and an expanding drum with belts.
This may be a stupid question, but wouldn't I be limited on the size of pieces due to the 1.5" width of the hard wheels?
Dang, I'm going to be spending more on wheels, drums, and belts than I paid for the machine!
Chuck
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Post by johnjsgems on Sept 23, 2009 13:01:35 GMT -5
1.5" limits you to cabs and smaller sizes. If you wanted to do bigger sizes there are coarse belts available. I have had two customers buy pairs of wheels and mount them together to have 3" wide surfaces. Both used sintered wheels which are considerably more expensive than the wheels you mentioned. As far as spending more than you did for the machine, join the crowd. Many are doing just that. With a very few exceptions the old Highland Park quality is not available on anything currently made. The exceptions in my opinion are "old fashioned" units like the Barranca GP-8 and Covington 8" units. Both are unchanged except for diamond technology and prices from the 70's vintage units.
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Post by stoner on Sept 26, 2009 17:43:22 GMT -5
Thanks for bringing this subject up. I've been using an old Barranca GP8 that I got for a song, converted over to all diamond wheels and belts and one Nova wheel. My hard wheels are a 60g sintered, 220 wheel from Jadecarver, then I use a 280 Nova, then 600, 1200, 8k Raytec True circle belts. I cut a lot of cabs and usually will cut a dozen or so at a time, so swapping belts wasn't a problem. I'm at the point now where I will be switching over to using all Nova type wheels for my sanding because there just isn't any diamond sanding belt available that's worth a Damn. Eastwind belts don't last, Crystalite belts are way too aggressive, and the quality of the Raytec True Circle belts has gone down the tubes. So, the problem with Nova wheels is the inital cost, I use 8" wheels and they are $160 apiece, so I'm looking at $600+. However, Covington is now selling Nova type wheels for $88 for the 8" wheels and something like $60 for 6" wheels. I'm trying out the 280 wheel now, and if it looks like it's going to be as good or close to a Nova wheel, I'll order the rest of what I need.
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Post by Hard Rock Cafe on Sept 27, 2009 19:35:32 GMT -5
Thanks for commenting Stoner! It's nice to have some comments from somebody who has gone through the conversion.
How about the 3M or Kingsley North belts?
Chuck
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Post by johnjsgems on Sept 27, 2009 22:41:40 GMT -5
Stoner, the Covington Nova like wheels are the Reentel "Soft Wheels" made by the guy that makes the Cab Kings. Kingsley has them also and you would save CA sales tax. Not sure if shipping would equal that out. According to the manufacturer, the "Soft Wheels" last about 1/2 as long as the Nova and retail about 1/2 price. Covington just added them to their catalog this year but they are not Covington products.
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Post by Woodyrock on Sept 28, 2009 1:40:54 GMT -5
Now, just to throw a curve ball into this thread, if you all remember the method Dan (Highplainsdrifter) told us about to rediamond the Nova wheels how about runing the diamond belts on the expando drums until depleted, then rediamonding them using Dans method? That would be a dollars worth of epoxy, tens bucks for the diamond. Three inch sanders are better than 1 1/2 sanders.
I run an old Stardiamond GP-8 I converted to diamond with an 80 wheel a 220 wheel from Jade carver, a 260 Nova, and one expando drum with 600 diamond. I also have an arbor with expando drums with 1200, and 3000 diamond belts. When the 600 belt is depleted, I plan on rediamonding using Dans method, but using an LPU adheasive that is more flexible than the epoxy. Woody
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drjo
fully equipped rock polisher
Honduran Opal & DIY Nut
Member since May 2008
Posts: 1,581
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Post by drjo on Sept 28, 2009 10:45:50 GMT -5
Do we have a volunteer?
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highplainsdrifter
fully equipped rock polisher
Member since December 2008
Posts: 1,266
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Post by highplainsdrifter on Oct 1, 2009 15:51:43 GMT -5
I refined the wheel refinishing technique. Now, I mix the epoxy, dilute with acetone, and add 3 or 4 carats of diamond powder. I apply a pretty thin coat of the mixture and let cure for 24-48 hours. There was a guy seling diamond powder on eBay for $20/25 carats including shipping. I use refurbished sanding and prepolish wheels exclusively at this point.
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