stoneme
off to a rocking start
Member since May 2008
Posts: 17
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Post by stoneme on Aug 1, 2008 7:56:10 GMT -5
hey guys, I am looking for some tips on how to deal with undercutting, ( ie :how do you you prevent it; what can be done to stop it/ correct it?)Any help would be appreciated, Mike P.S. here are some pics of what I am up against   Thanks again |
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Post by krazydiamond on Aug 1, 2008 7:58:35 GMT -5
i've been fairly sucessful with filling pits/cracks, etc. with superglue, let dry and reshape and polish. doesn't ALWAYS work, but if the defect is fairly small you can usually get away with it.
KD
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Post by Jack, lapidaryrough on Aug 1, 2008 8:06:31 GMT -5
soft material, pre-shape on 220 grinding wheel, if your tumbling start with 220 grit for your course run. then 3-F ( 400 ) so on.
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Sabre52
Cave Dweller 
Me and my gal, Rosie
Member since August 2005
Posts: 20,504
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Post by Sabre52 on Aug 1, 2008 10:29:50 GMT -5
That sort of undercutting ( onionskinning or peeling) is common in lots of jade, serpentine, rhodonite etc. I find it more common when cutting mixed hardness materials on diamond wheels as the diamond really grabs out the softer areas in the stone. You can sometimes correct this problem by sanding on very worn silicon carbide wheels or belts which don't seem to undercut quite as much and rotating the work piece so you don't cut excessively with the grain in the stone.....Mel
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