Deleted
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Member since January 1970
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Post by Deleted on Nov 30, 2019 13:20:28 GMT -5
I’m refurbishing an old Star Diamond GP6 cabbing machine from the late 60s, and it’s my first experience with a cabbing machine. It can take three wheels plus a polishing head on the end. I have the original catalog, and it describes various wheel configurations, including “the ultimate in a 6-inch sanding and polishing unit,” which is three expandable rubber drums.
What are the pros/cons of going entirely with rubber drums? I know the initial investment is higher, but I assume long term is less than with regular wheels since I’d only be replacing the belts.
FWIW, I also have a 8” flat lap. I’m considering using that for all rough shaping, then the GP6 for smoothing and polishing. I work with a lot of agate/chalcedony, jasper, and petrified wood.
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Post by stardiamond on Nov 30, 2019 14:33:59 GMT -5
I have no experience with expandable drums. There are a lot of less expensive than Diamond Pacific wheels available now particularly from Baltic Abrasives. If I had one of those used machines, I would see if I could remove the dividers and the front lip, then replace what was there with possibly 5 6 inch wheels, add a moveable tray and cool with an aquarium pump and sprayers. Making it effectively a 5 wheel Genie. That is what I did with my star diamond machine that had two wheels and an expandable drum. The machine is a beast with 8 inch wheels and is attached to a large cabinet. The GP6 would be a table top version.
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Post by pauls on Nov 30, 2019 16:20:32 GMT -5
I don't know about any pros or cons for either expanding drums or soft wheels, I have a full set of both. Long story, I was building a new sanding setup and couldn't decide either way so bought half of each, had a ball building the setup so decided to build another, just because I could. So I bought the wheels I needed to complete the set of both. I would say that I seem to prefer the expanding drums, I don't know why but they are always the ones I gravitate to. Hans lapidary supplies in China has good expanding drums. www.lapidarytool.com/mall/index.php Be careful of putting too many drums on a long shaft, they are fairly heavy and may need a careful bit of fiddling to get them balanced. |
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Post by Starguy on Dec 2, 2019 12:03:00 GMT -5
@khlr Expando-drums work reasonably well. The belts don’t seem to migrate back and forth as much as some aluminum and foam soft drums I have used. They are strictly for polishing and will not work well for stock removal / shaping. If you use SiC belts you will go through them pretty fast. I use diamond soft wheels on a cabking 8v-1. I think diamond drums will be the most economical in the long run due to their durability and superior sanding speed.
Hope this helps. Good luck!
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Deleted
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Post by Deleted on Dec 2, 2019 14:42:41 GMT -5
Thanks all. Investigating the options has whet my appetite to maybe just skip refurbishing the 6" and instead buy/build an 8". I have a feeling I'm going to want an 8" cabber at some point, so it might be better to skip buying drums or wheels for the 6. It does seem like going with drums would work out well if the machine is dedicated to smoothing and polishing. (though diamond belts are a lot more expensive than I realized they'd be)
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Tommy
Administrator 
Member since January 2013
Posts: 12,993
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Post by Tommy on Dec 2, 2019 17:37:48 GMT -5
I have evolved over the years and now use a combination of both. After coming off the metal wheels I have found that a combination of 220/400/600 SiC expando belts works great. SiC belts are more aggressive and when needs-be I can position the water feed so that the wheel is dryer on the left side and wetter on the right side to quickly and efficiently knock out flat spots and tough scratches. All finishing is achieved on Nova diamond wheels from 1200 up to 50k.
To achieve this I have two machines - metal wheels and a single expando on one, and all Nova wheels on the other.
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Post by hummingbirdstones2 on Dec 2, 2019 19:19:57 GMT -5
As others have said, both are useful. It's great to be able to use a 3" expando to do your prepolish steps on. Makes doing larger cabs really easy.
We have one 8" arbor with 60 and 80 grit diamond wheels, and another with 8" 220 and 8" expando. Can do almost anything with just those two machines. Got the diamond wheels used at a club auction.
If you can find a production cutter who likes to keep newer wheels all the time, you might get some good ones with a lot of life left in them.
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rads
spending too much on rocks
Making clay each day!
Member since April 2018
Posts: 319
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Post by rads on Dec 3, 2019 9:01:59 GMT -5
I also still use both types. Going over to the rubber on the last stages of cabbing allows me to get everything nicely smooth and even before polishing. Belts are cheap and I only ever order 400/600/800 belts anyway. MTC.
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Fossilman
Cave Dweller 
Member since January 2009
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Post by Fossilman on Dec 3, 2019 10:25:41 GMT -5
I use expando belts/drums with my fossils( Love my "Poly's..)..... Diamond wheels with my rocks/material(Cabbing machine).... The best of both worlds..
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ADHD
off to a rocking start
Member since December 2017
Posts: 12
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Post by ADHD on Dec 21, 2019 17:03:35 GMT -5
When I first started out I only had a used Rock Rascal trim/single wheel machine. I would rough out 10 stones on the hard diamond wheel, put on the expanding wheel and run through a full set of diamond belts. It was a pain to change the belts, I was constantly having to drop back down to a lower grit because I missed a scratch and the belts wanted to walk off the wheel. so for necessity this worked but was not very productive or pleasant. The belts were less expensive than hard or Nova wheels but don't last as long either.
After I managed to score a 6 wheel arbor I only use the expanding wheel for the high grits above 3,000 and it is mounted on an old 2 wheel Lortone arbor.
Net net, work with what you have until you can get something better
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Deleted
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Post by Deleted on Dec 22, 2019 19:25:32 GMT -5
Yeah, after researching things more, drums no longer sound that appealing to me. I decided to go for an 8” cabbing machine and do the grinding and shaping there with regular cabbing wheels, then do the later stages on my flat lap (the opposite strategy from what I was planning when I started this thread). The 8” machine is still in progress, so I’m currently still working entirely on my lap.
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