Here is a little more info for those who are at higher
elevations .This may explain why some people have problems
casting with Vacuum.
At higher elevations, small vac pumps will not perform
satisfactorily… especially in a small vac casting table top
machine… ( for inexpensive small volume at higher elevations it
may be less expensive to use a broken arm centrifuge with proper
safety and protection.
To do vacuum casting at higher elevations it will require the
use of vacumm booster products such as the tyvac perforated
vacuum enhancer and also a reasonably powerful vac pump ( this
is at least a $2000. pump) A pump that pulls 29.9"mercury
witharound 20cfm will do the job nicely.
Those of you in the mountains have probably found that by
increasing your investing water temperature… you may get rid of
some of the bubbles you get on your castings.
hope this helps some of you