I purchased a used 3-phase 220v QVAC PC1824, which was designed as a skinner, but has the vacuum forming option installed. I first converted the 3-phase to single phase and run it off a 50 amp dedicated 220v circuit. I was told this machine would pull up to .125 inch material with the vacuum former option, but found out it needed more vacuum capacity. I changed out the 1/2 inch valve and lines to 3/4 inch and added a 60 gallon vacuum tank. The vacuum and capacity are now sufficient, but I have another issue: When I set the heater, which is on top of the plastic, to 475 F degrees or so, it will smoke the ABS just before the bottom the material gets to forming temperature of around 300 F degrees. When I set the heater down I can prevent this, but it takes longer time to get the material to 300 F degrees on the bottom before forming.

I was told that most good VF machines have heater element above and below the plastic. Should I use additional infrared heaters underneath the material to make up the temperature, or should I try to redesign another heater like the one above that also slides in and out below the the frame? Of course, I can also try to get by with .093 ABS material instead of the .125 ABS material, since presumably it would not insulate the heat and heat up to 300 F quickly and more evenly.

Your thoughts?

Thanks in advance.

Ray
Monterey, CA