chilerock
off to a rocking start
Member since June 2018
Posts: 19
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Post by chilerock on Oct 23, 2022 12:35:10 GMT -5
Greetings to everyone: We have a 6 wheeled genie, a 10" and a 6" saw and a regular 8" flat lap (not vibe). We need to import most equipment and supplies as we are in Santiago Chile so decisions are important as importing is quite expensive and also returns and guarantees from this far away are not doable. Anyway, looking to buy an 8" expandible drum and set it up sort of DIY with an extra 1 hp motor at 1700 rpm and we`re looking for advise about following: 1.) Obviously we`ll set up the drum on a metal shaft and lock in place with a flange type setup. But aside from this, is a full metal rim needed for the 8" expandible drum or not? We are looking at the Covington drum: covington-engineering.com/supplies/expandable-drums/ As a reference, here is a similar drum with a full metal rim: www.ebay.com/itm/2240492603322.) Our second question is about IF it is worhwhile to buy diamond belts for these 8 inch drums, as opposed to the normal silicon carbide belts (about $65.000 for a diamond belt versus $1.75 for silicon carbide). We are looking to use the 8" drum most with 400 to 600 grit belts for a medium step for quartz crystals, and well as some free form type figures in different jaspers. Thanks in advance.
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QuailRiver
fully equipped rock polisher
Member since May 2008
Posts: 1,621
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Post by QuailRiver on Oct 23, 2022 22:48:15 GMT -5
Every brand of expandable drums I have ever seen have an inner metal hub. You can get a much better price at Kingsley North, Minnesota Lapidary Supply, Arrowhead Lapidary Supply, or Covington Engineering than the price on the one shown on the eBay link you posted.
I used the 3M brand diamond belts for a few years for 600 and 1200 sanding. When I first started using them they were great. But then 3M outsourced production overseas and the quality got so bad that I was lucky to get more than two or three large agate cabs sanded on one belt before it wore out. So for sanding I switched to Diamond Pacific's NOVA wheels about 10 or 12 years ago.
I had a couple of Eastwind Diamond belts many years ago and they were good belts. But that was a long time ago and I do not know if their quality is still good or not. Maybe someone else here has bought Eastwind Belts more recently and can comment on current quality. I have heard good things about Crystalite's Plated Diamond Belts, but they are even more expensive than standard diamond belts.
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Post by Peruano on Oct 24, 2022 9:19:52 GMT -5
Are you asking if you need to place a shield over/around the expando wheel. If so yes, to contain water spray, etc. just as on a typical grinding/sanding wheel. Perhaps I did not understand you question. As to belts, I have had great success with 3M diamond belts but I only use the 3000, and up to 50,000 grits. For all lesser grits on the 8" expando wheel, I use silicon carbide or aluminum oxide belts. Perhaps that is why my 3m diamond belts last longer . . . I am only using them for finer polishing steps. The Microfinishing belts from Kingsley North are great and come up to 1200. Using an expando wheel give you so much flexibility especially if shop space is limited. Changing the belts is the key to success. The selection from Kingley North is good but you can find the same materials elsewhere. Good luck with your new setups.
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nik
spending too much on rocks
Member since May 2019
Posts: 315
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Post by nik on Oct 25, 2022 0:23:03 GMT -5
I have a couple of the Eastwind diamond belts, 220 and 600 if memory serves. The 220 has held up really well through some big projects and shown no signs of seam failure. The 600 is fairly new, so not much data to report.
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Post by rmf on Oct 25, 2022 12:34:02 GMT -5
When purchasing an 8"x3 expandable drum verify the circumference. Lortone use to sell one that was 25-1/8" in circumference and Raytech sold one that was 25-7/32 in diameter. You had to keep track of the belts you ordered. the problem was that the longer belts would not tighten completely on the 25-1/8 drum and if you used any pressure the belt started going off the side. on the drum that was 25-7/32 you could use the tighter belts though they were harder to get on. But they worked well. So it was best to have the 25-7/32 and either belt worked fine.
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