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Vaccuum casting


#1

Hi all, I have a question for the group. I have Vacu-cast
investment/casting machine that I bought new about six years ago,
in that time I have used it only about a dozen times (I quit making
jewelry and went full time into stone cutting) I pulled it out,
dusted it off, checked the oil and turned it on. It pulled 27.5
pounds the guage goes up to 30 pounds and I cant remember if that
is enough pressure to cast with or if my machine needs some repair.
I am only trying to find this out because I am thinking of selling
this machine, I am quickly running out of room in my shop. Also
what would be the going rate for this type of used equipment. Thanks
to all in advance, Jason Penn


#2

The vac-u-cast with 27 inches of vacuum is OK. I have built
vac-cast units with auto ac vac-pumps with top end vacuum of 25
inches. Your gage may be out cal. or the pump was not lubricated
completly and that may also may be part of the problem. The other
area to check is the connections to and from the pump and chamber.
The gasket on the deck needs to be coated with a silicone lubricant
[spray] if the unit has not been used for 3 to 4 months. Jim Fagan
omf50@aol.com


#3
      It pulled 27.5 pounds the guage goes up to 30 pounds and I
cant remember if that is enough pressure to cast with or if my
machine needs some repair.

The gauge reads Vacuum. 27.5 inches of water Vacuum is not as good
as it should be. Probably if you were to get the rubber mat and
bell jar mating surfaces wet, you would pull 30 inches. I would
drain and replace the vac. oil. Replace the filter under the
casting platform. How much do you want for it?

Michael Mathews Victoria,Texas USA


#4

The gauge reads Vacuum. 27.5 inches of water

Actually, that is inches of mercury. A little closer the
equivalent of thiry feet of water.

Bruce D. Holmgrain
@Bruce_Holmgrain
http://205.177.16.22
703-593-4652


#5

Jim:

I will chime in here. I got an old Percast vac unit last year
and couldn’t get the pump on it to pull, so I rigged an old auto
a/c compressor off an old Big Three car (not sure if it’s Ford or
Chevy or what) with a motor and the gage on the unit says I’m
pulling about 27.8. I couldn’t “boil” water at 68 degrees but I
could at about 72, and friends who cast told me not to worry,
just use the slightly warmer water. i haven’t had a chance to
use the unit yet — hopefully next month when I’m in my new
house and have built the new workshop. Given what you say, I’m
not sure if my gage is out or what. Also, how does one change the
old in one of the old car pumps? There is a nut on the side I’ve
been unscrewing to add oil, but I think I might just turn the
unit on its side and drain out the oil, then fill with an equal
amount. But I guess I won’t get all of it out. Can you use
flushing oil in an auto compressor? Or would it be better to
drain and fill twice?

Anyone out there know? Thanks.

Roy (Jess)


#6

The gauge reads Vacuum. 27.5 inches of water

Actually, that is inches of mercury. A little closer the
equivalent of thiry feet of water.

Hello Bruce: Thanks, I don’t know why I always thought it was in
inches of water.

Michael Mathews Victoria,Texas USA


#7

Jess

The oil to use is standerd compressor oil. this is a thin oil you
will find at most Auto supply store. You ask for vacuum pump oil.
You will loose oil through the normal use of the auto compressor
pump so just keep adding as the level goes down. Check about ever
two hours of pumping…

jim
omf50@aol.com