I hope the casters out there can help me. I’m a year into working
with metals and I can’t get enough of learning about the different
techniques. Not to long ago I got a great deal on a centrifugal
caster and a burnout oven. My readings led me to believe that to get
a good casting one needed a vibrating table or better yet a vacuum to
get the air out of the investment. Somehow I came up with a vacuum
from a lab that I hoped would fit the bill. I made a bell jar and a
plate which would hold a good vacuum and I was off. The problem is
two fold. First I am at 6500 feet so I have been told that I should
expect less of a vacuum than I would if I were at sea level. I can
get about 22 ?? on the gauge of the vacuum. This will not boil water
as many of the books suggest as a test for the efficiency of the
vacuum. When I de-air the investment I get some bubbles but not the
1/4 inch rise in the investment level that again the books suggest.
Can anyone tell me if the vacuum I’m getting is still helping or if I
need to find another source for a vacuum.
This leads me to a second question. A friend and teacher uses system
that attaches to the sink and creates a very good vacuum. Harbor
Freight has a vacuum that uses air (which I have a source of) instead
of water to evacuate freon from air-conditioning, does anyone have
experience using this product and can it work as well as water. I
don’t have a lot of water pressure near my shop.
The books some very old suggest “green soap and alcohol” as a
debubbler. I have had no luck finding a source for green soap. A
pharmacy said they could order it but in a quantity larger than I
need. Any suggestions.
I hope the same people who have given me the good advice in the past
can come through again.
Darling by Design