I thought I would wait this out and see what others have to say
I am a practicing dentist and in the mouth I use both the diamond
and carbide burs, but keep in mind that I am sometimes running at
400,000 RPM and always using water as a coolant. I do not apply much
pressure: a very light touch is all that is needed. I am cutting
porcelain, gold, mercury-silver amalgam, and sometimes something that
feels like stainless steel, as well as tooth structure. Keep in mind
that I have spent a lot of practice time learning to control this
Cutting metal with a carbide bur sometimes leads to the bur jumping
off of the metal and kicking back. When I cut off an old crown I
usually use a diamond for less vibration and better control. A
milling machine would be very rigid and probably never use a diamond
bur except for ceramic materials and perhaps some super hard metals.
The carbide would cut much faster. When I am the jeweler or metal
fabricator I like the carbides and I am prepared for the kickbacks.
Cleaning and carving soft gemstones such as opal can easily be done
with a slow handpiece: either a flexshaft machine or and electric
handpiece. Diamond burs give a good feel for removing sand and doing
the rough and fine shaping.
Removing stuck or broken taps or screws can be done with a high
speed handpiece and carbide burs and lots of patience, and lots of
burs. Sometimes a very small (less than.5mm diameter) bur is the only
one to get into a very tight spot so as not to damage the piece you
are trying to save.
Running the diamonds and carbides with coolant really shortens the
lifespan of the bur, sometime to only a few seconds!
Charles Friedman DDS
Ventura by the Sea