I use my faceting machine for small cabs like opals, star stones and
small problematic stones that and like it better in many cases than
the standard cabbing wheels.
If you are planning to cut larger cabs in agates/jaspers I don't
recommend a faceting machine. It wears the laps out fast and is
much slower going. If you plan on making intarsias thats another
story, a faceting machine is just what you NEED to do these. Also
faceted top cabochons or even faceted beads the faceting machine is
a must to produce quality, precision stones. My preference is
Lapis cabs cut with faceted tops.
I don't use and haven't used the Sapphire brand machine so can't
offer much on that as far as dependablity/repeatability and parts or
anything like that. But it sounds like it might be a great deal at
that price! Other than a motor or platen bearing there is little
to go wrong with them. The biggest problem is keeping them perfectly
adjusted, most important for faceting not so much with cabbing. The
biggest problem I've seen is where people try to adjust the quill
and/or mast and get the adjustments so far out it gets real hard
even for a seasoned person to get it corrected. This would be my
biggest concern on buying a used machine.
I use Ultra Tec and have had very little trouble with it and have
never had to have it sent in for any repairs or buy any repair parts
and have had it longer than I care to remember.
Hope that helps some.