Lapidaryforum.net
Rock Art => Cabochons, Intarsias, Cameos => Topic started by: James D. Farrow on May 10, 2016, 06:09:17 AM
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When I got my Ameritool it came with a set of resin soft diamond discs. From 325 to 1200 grit.
The lower grit discs (80 and 180) were steel.
I did get, later on (from a different place), the 3000, 8000, 14000, and 50000 grit resin discs.
I just noticed that they also have the 60, 140, and 280 grit resin discs as well.
Has anyone used lower grit diamond discs?
Since I was thinking about getting some softer stones (Calcite for example at MOHS 3) I was wondering
if the gentler resin discs would be better than the steel ones, which can be quite harsh (especially on
rocks like Sodalite (5.5 to 6 MOHS)).
The higher grit resin discs work fine, just not sure if resin discs at the lower grits would be good for grinding.
Thanks,
James
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The velcro resin discs are the only thing I use on everything except malachite. Any of the real hard stones are started at 50 grit then up with 100, 200, 400, 800, 1500 and 3000. Softer stones get started at 100 or 200 then worked up to 3000, I seldom go over 3000 even though I have discs to 14000 because the difference in the shine is insignificant.
I have a 6 inch wheel machine with soft wheels but the only thing I use it for is malachite. The grooves in the velcro pads can cause the malachite to separate at weak lines probably because of vibration.
I have ground a piece of calcite with no problems but have never taken it to polish. It was quite some time ago so I am not sure but I probably ground it with the 100. It gets taken out every once in a while to see if it is ready to be carved but I can not get my mind wrapped around it so it gets stuck back in the corner for a while. It is nice and smooth so I probably took it to 400.
Even the 50 grit takes a long time if the hard stone like agate is really rough and a lot of material has to be removed but I have not used a hard diamond wheel so I do not have a comparison as far as speed goes. My solution has been to avoid stones like that or try to clean them up on the trim saw.
Hope this helps.
Jim
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I only use the finer flat pad grits but I do have a 60 grit resign soft wheel and it cuts like about a 220 hard diamond wheel.It is aggressive enough to pound a bit and it leaves very deep scratches.
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I used a flat lap for a long long time before I switched to arbors. I used the 80, 180, 325, 600, 1200, 3000 and then polish disks for 14k, 50k and 100k on my Ameritool. I still use my lap for 100k and doing flats. As far as low grit resins, I'm not sure? I have switched to arbors and use sintered wheels now for 60 and 180, then I switch to a Nova 140 soft and go from there through 9 wheels. The sintered wheels cut harder than the soft resin and I am sure it is the same for metal laps. The Galaxy wheels get worn and cut slower so depending on age determines the grit it cuts at. My 60 sintered I don't use that often because it still blows through 1mm in a few seconds on agate. It can still only be used for the hardest of the hardest materials.
As far as Calcite, I would start that on 325 on your Ameritool unless your disks are very worn, then you can start lower.
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Thanks for all the replies. As for the calcite, I think I will give it a pass.
Not because it's softer but because it's translucent (right word?) and
will probably show fractures. Buying on-line is risky. Can't see what
you are getting. Got some rose quartz and that really shows fractures.
Think I have learned my lesson and will wait till I can see calcite,
or fluorite, etc... in person before I buy any. Will stick to Jasper,
Aventurine, etc... for now.
James