Sapphire cabbing diamond wheels

[geowork]

After sorting out the sapphire faceting bit (I think I have, but maybe probably never), I now need to expand to cabbing sapphires (stars and otherwise). I have the equipment (refurbished 8" multi-wheel cabbing machines) and they are just for personal use.  I do not want to cab on my faceting machines. I am getting confused with the plethora of diamond wheels, nova wheels, expanding drum, etc. What are the type and diamond sequence that I need, and concentrate just on sapphire. I can see what combinations are loaded onto new cabbing machines, but not sure if they are the best for sapphire, or just more general purpose.

Thanks and much appreciated,
Bill

[xcvator]

bump

[MakkyBrown]

Not sure what is best for sapphire(I've only cabbed a small number). On my machine the soft wheels I have are 60,140,280,600,1200,3000,14000. I have other grits I've removed. I think that combo will polish pretty much anything.

MB

[mehoose]

Bill, I wouldn't go less than 280 hard(assuming here that the rough isn't massive and you've used a trim saw to get rid of 'larger' sections).
Hard
280/600 (I think you can also get a wheel in the 300's and 400's. If you didn't get the 280, I'd get the lowest in the 300 range instead. Any lower than the 280, you get back into the major subsurface damage scenario like with faceting which is also why I suggest removing/trimming what you can prior to starting.)

Nova soft
600/1200/3000 then either 8000 or 14000(or both of these last two and possibly dropping the 3k for a 6 wheel set up)

At the old club I LOVED the extremely worn 14000, glass polish finish on everything but note I said well worn.

You'll find the advice from dealers who use Nova's themselves will tell you to stay away from anything above the 14k.. all the higher ones do is add a gazillion scratches and these guys cut oodles of gems.

The soft wheels need breaking in. Cut and polish an agate to start with. I used to use a synth corundum boule but with the prices of those now, it won't be happening again.

Some folk will go to diamond grit/paste and use it on either a carved wooden wheel or a ceramic style one, not sure how effective a felt wheel would be? I'd love to hear from folk who do use these methods.

[MakkyBrown]

I love my coarse soft wheels. I really only use hard wheels al for grinding straight lines. I cab with my sawblade wheel, then onto the 60 soft. It is not real soft but has some give and still curves the stone a bit.
MB