Algrium
off to a rocking start
Member since November 2013
Posts: 4
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Post by Algrium on Nov 27, 2013 0:53:22 GMT -5
Just wondering what is preferred as a grit for tumbling, Aluminum Oxide or Silicon Carbide?
I understand Silicon Carbide is a little more expensive than AO, and SC has a MOHS hardness of 9.1 compared to 9.0 for AO.
Is it just preference to use one over the other or does one work better than the other?
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,563
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Post by jamesp on Nov 27, 2013 0:55:16 GMT -5
For hard rocks use silicon carbide. It cuts much better due to its sharp edges.
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jollyrockhound
spending too much on rocks
Member since March 2013
Posts: 409
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Post by jollyrockhound on Nov 27, 2013 11:49:53 GMT -5
For hard rocks use silicon carbide. It cuts much better due to its sharp edges. I agree, it works really good for them.
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fiona19021972
off to a rocking start
Member since October 2013
Posts: 11
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Post by fiona19021972 on Nov 27, 2013 13:03:10 GMT -5
I've got 2 batches Im tumbling now with AO for the first time one drum is on second stage and other drum is on third stage so can't really say yet but will let you know in another week or two
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,563
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Post by jamesp on Nov 27, 2013 16:22:22 GMT -5
I can speak for moh 7 agate. The AO is kinda useless in coarse grind. Silicon C is way best for coarse on hard silicates.
BUT, i use AO for all stages of surface finishing. I have found a 5 gallon bucket of AO 220 and AO 400 and have great end finish.
I know the AO is close to SiC in hardness hut they are 2 different animals. Each AO particle pretty much stays as one and slowly loses it's sharp cutting edges.
SiC is completely different in that each particle breaks to smaller and smaller particles but they always maintain sharp edges. Much more aggressive cutting.
But softer stones may do great w/AO. Ao does great w/metals...
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Post by pghram on Nov 28, 2013 12:01:03 GMT -5
I ordered some AO 500 by mistake once & I couldn't tell the difference, but I would not try it for course grind.
Rich
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,563
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Post by jamesp on Nov 28, 2013 18:39:18 GMT -5
It does fine for surface prep. May do better since it leaves a smooth finish.
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Deleted
Deleted Member
Member since January 1970
Posts: 0
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Post by Deleted on Nov 30, 2013 3:03:48 GMT -5
Greetings [algriumengraving], firstly may i welcome you to RTH Forums from the other side of the pond! It is best to use Silicon Carbide grit through out the entire grinding process as it keeps on breaking-down into finer particles than using Aluminum Oxide grit, which only breaks-down 50% then the grinding action stops completely. Please check out my Sticky's below. -- Please click images to open larger images in a new Tab, same with everything that is Underlined! I hail from (The Barony of Seabegs) Bonnybridge, Stirlingshire, U.K, where aliens (15mb) sometimes come for a visit & about 4 miles west from this monstrosity! Sticky's: their contents are resource information 1#: Vendors worldwide (2mb), 2#: How to use the forum, 3#: How to identify rocks & minerals, 4#: Save money on expensive grits & polishes, 5#: Aussie Lapidary Forum: Rock Tumbling Guide!
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charles kuchar
spending too much on rocks
getting ready for the second coming
Member since November 2010
Posts: 300
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Post by charles kuchar on Dec 5, 2013 7:43:01 GMT -5
thanks for the information on ao and sic grits. when I do the 500 grit in the vibrator, I use 1/2t ao and 1/2t sic. that seems to do the job but did not realize what the difference was. charlie
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