This is the redesign of the vacuum forming machine I built this past summer. Here my first design Vacuum Former
and if you look at the last step you can see why I redesigned it. If you don't know what a vacuum former is check out the links on the first step of my other instructable. I'm not going to go over everything again but you can use my other instructions to build the oven, platen, and frame. Only minor changes where made to these parts and a different base was made.
First I think I should go over why my old machine didn't work and why the new machine works a whole lot better. With my other design the plastic was heated while sitting above the oven, I did this because heat raises and I thought this would heat the plastic more effectively. As you see I underestimated how effectively this method actually heats the plastic. The plastic got to hot, sagged to much, touched the coils and caught on fire. The new design holds the plastic below the oven so that when it sags it falls away from the coils. It might not heat the plastic as fast but the heating process is much more controllable.