A previous thread brings up something that I would love to see
addressed by turners with A/C refrigerant type vacuum pumps anyone that
has experience with them. Our club is in a very spirited debate about
this subject and with a lot of us looking to build vacuum systems, we
are split on this pump type question.

I am in construction, and see the Robinaire, Gast, Yellow Jackets and
on and on used daily by the A/C guys to evacuate the lines before
charging with freon.
By nature, these pumps use replaceable oil that also traps and filters
out the particilates that are in the gases sealed in thesystem. These
pumps are used to evacuate a closed system, and they rarely "mist" oil.

However, I have been warned by my amigos that use these pumps that when
the system leaks (think 5 CFM pump trying to pull 27+ lbs.) it has the
tendency to mist oil. A very leaky system will cause not only for the
pump to be unable to attain proper vacuum and evacuation, but will also
make the pump "mist" or leak more.
Sometimes a "fair amount". This "fair amount" is a whole different
subject.

To further muddy the waters, I was in contact with a professional
vacuum pump rebuilding company in CA and they also told me that these
pumps would be unsuitable because of the misting problem. In fact,
they went so far as to advise me against buying their product! They
thought I should buy a true lab type vacuum with no oil bath (except
for the piston)and are watching to find one for me.

But it seems some are having great success with these AC vacuums. I
have only heard of the misting problem here and there, and I am
wondering if it is because the AC pumps are only actually used here and
there and most know better than to use them. For those using these AC
vacuums, how much mist is there?
I am a full time carpentry contractor, and I am here to tell you only
my planer makes more damn mess than the lathe, so I am wondering if it
is a matter of perspective.

Any thoughts? I can get a good 5 CFM pump with a 2 horse AC 115 volt
motor of many different manufacturers delivered any where from $100 to
a 6 CFM Robinair monster brand new with warranty for $250 or so (that
would also do some veneering!). But they are all oil bath pump for
AC. That also means that the oil needs to be changed every once in a
while.

The good capacity, multi CFM lab type oiless vacuum I need to turn
wormy mesquite is proving quite difficult to find. One of our club
members has made one and his GAST is a 3/4 hp pump pulls just a little
over 6 CFM. Cost? He bought the pump for $200, put a $125 dollar
rebuild kit on it HIMSELF over a period of two days. Cracks, spalts,
worms are no match for this pump on his OneWay. This pump new is $800,
and professionally rebuilt (IF available!) is around $500. Ouch!

But I am looking for something easier than finding a suitable pump,
then rebuilding it properly. I don't know how to rebuild a vacuum and
would rather be turning than learning something I have no interest in.
This pump will be used on my Jet mini, and my Nova 3000, so I don't see
the point in buying a tiny vacuum.

All thoughts and opinions are completely welcome.

Robert