Vacuumforming heatbox/frame designs

Cpl Shepard

For those of you working with thermoform plastic, how did you design your heat box, what radial heater did you use, and what did you choose to do for a frame?

Recently I had to revise my vacuum table with a newly drilled board for adequate suction, but the MDF boards I used as a cheap heat box with stapled reflective lining fell apart. Another issue is I'm trying to a good square-ish radial heater to set on its back to serve as the heating element for the plastic, but most aren't intended to be laid that way and won't offer a good even heat to the plastic sheets. I'm going to build a new frame for the sheets by cutting the centers out of some thin boards and using wingnuts and bolts flush with the bottom for the vacuum suction. If you think there's a better option feel free to correct me.

If you have any dimensions or referrals from your own experience I'd appreciate it. I'm working with 24"x24" plastic sheets so I'm loosely planning for 26"x26" for the heatbox/frame.