Here we go again…
I can’t believe the lack on sometimes. Now keep in mind
I’ve been using this equipment for almost 40 years. Perhaps after all
this time I’m just misinformed. Please consider the following…
The only vacuum pump available is from the heating & air
conditioning folks who use vacuum pumps exactly like the ones sold
in all our vacuum casting/investing units. Most vacuum pumps sold are
used in this industry. They change the oil every time because they
have to clear out the refrigerant in any cooling unit (refrigerator
or freezer). This oil is now contaminated. Sometimes the vacuum pump
is left on for a full day to make sure there in no Freon (or the new
stuff) or moisture left in the system. The program next to me at the
Southeast Technical College is the HVAC (Heating Ventilation Air
Conditioning) Program so I know this first hand! I see the use
everyday in their shop as well as the jewelry facility. I’ve also
compared noted with both instructors about vacuum pump use.
The pumps are quite hearty. I have three that I use every week. I
change the oil once or twice a year. I have a good filter on my
casting unit to prevent plaster dust from entering the unit. I have
had several casting flasks blow out over the years that would put
quite a lot of investment into the unit, so a filter is absolutely
The pump I invest with and vacuum silicone molds does not have a
filter. This pump new in 1985 cost me $350.00. It still works like a
champ after all this time with the oil change schedule I use. And yes
sometimes I empty it with a bit of water that drains into the water
jug I use to collect it. Keep the oil level at the recommended level.
Sometime there is a small window to see the oil. Others may have a
dip stick just like a car.
You don’t need the jewelry supply vacuum pump oil either. If you
live near any farm store, vacuum pump oil for milking machines works
fine. It’s either that or an HVAC supplier. We continue to get
screwed by jewelry suppliers telling us that theirs is the only
product to use, when much of it is just renamed. Jewelry source
vacuum pump oil is very expensive and has to be shipped UPS because
of its hazardous definition.
To dispose of the oil, bring it to an automotive service station.
They recycle it just like motor oil. In the old days they would heat
their garages with it in some type of oil burning system.
The one change I would make in any of the vacuum systems in our
jewelry world is to increase the hose size in any of the units. I
have changed out all the vacuum hose to large diameter sizes and
improved every vacuum process from casting to investing and mold
making with this change. The problem I see is that these units are
designed by people who have never lit a torch or made any jewelry.
Southeast Technical College