sak
noticing nice landscape pebbles
Member since December 2013
Posts: 88
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Post by sak on Jun 16, 2014 0:39:20 GMT -5
Hi all, You guys also give me great advice, so I need your help once again. I need to buy some grit and I was planning on getting it from a local industrial abrasives supply house. The best price I found is $5/lb if I buy 50lbs (that's for 500 grit SC w/median 11.3-13.3 micron). Meanwhile, I just ran across this on ebay: www.ebay.com/itm/500-ungraded-grit-for-tumbling-rock-25-pounds-500-silicon-carbide-/160902881980?pt=LH_DefaultDomain_0&hash=item25768f22bcThis guy is selling 25lbs of ungraded 500 grit SC for $40 with free shipping. That's $1.60/lb shipped!! Given the cheap price, I'm a bit apprehensive on what the quality will be. What do you guys think, is this something worth gambling on? Thanks again for all your feedback. Sak...
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tkvancil
fully equipped rock polisher
Member since September 2011
Posts: 1,546
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Post by tkvancil on Jun 16, 2014 10:24:55 GMT -5
Not knowing your equipment capacity or how much rock your processing I'll say this ... 50# of 500 is a lot. Finer grits don't get used as much as the coarse for stage 1. Last year I polished about 20 three pound batches and used less than 5# of 600 grit.
As to the ebay listing. Ungraded usually means a variation in size of grit particle. For instance 120/220 ungraded has those sizes, and in between, and 220 graded has only 220. Check with seller to be sure it fits your needs maybe?
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Post by Jugglerguy on Jun 16, 2014 11:25:40 GMT -5
If you have a vibratory tumbler, 5 lbs of 500 would last more than a lifetime. I use 1/2 tsp for each batch in my Lot-O tumbler. You'll use more if you're using a rotary tumbler. The only grit I buy in that quantity is 60/90 or 80 because rocks go through the rough grinding stage many times before moving on.
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Post by johnjsgems on Jun 18, 2014 14:05:19 GMT -5
500 ungraded (also called 5F) is an average of 500. In the old days it was called 600 ungraded too and was substituted for 600 graded to save money. Exact grit sizes won't affect tumbling very much. I buy from an industrial abrasives supplier that only carries graded grit. I've had more than one flat lapper tell me graded makes a difference for lapping but I'm a skeptic. You might check with the supplier to see if he knows anything about it. Generally the finer the grit the more expensive it is.
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Post by johnjsgems on Jun 18, 2014 14:07:29 GMT -5
Actually, now that I think about it, it isn't "average of 500" but rather 500 and finer. Next ungraded is 800 and finer I think.
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