I have a 24" x 24" vac former that I built using Doug Walsh's plans (top oven). The equipment works very well for 1/8" and thinner materials (mostly ABS and styrene) but I am having issues with thicker materials. I have been told to heat the material in cycles, (apply heat, pause, apply heat) in order to heat the material throughout without blistering the top. I have not been able to pull parts successfully in thicker materials and hope that you experts can lend some advice.
I have a two stage setup (5 gallon tank and rotary vane 10cfm pump) to pull the full vacuum after opening and then closing the main valve.
It could be that I'm just not being patient enough with the heat cycling...any ideas?