[kiltic]

Hi everybody, I am looking to build a vacuum table. I will need to thermoform a 18" x 12" x .010" sheet of PC or PP. My problem is, I am not sure how much bigger the heater should be than the plastic. Like, if I just built a heater to match the size of the plastic, say 18"L x 12"W, I presume it would really only soften the middle 12"L x 8"W or something. Is there a formula for heater size? If you need to thermoform X than build the heaters to Y, something like that?

Also, what type of heater do you guys recommend I use? UV? Oven heating elements?


Thank you so much for your time. It really is a big help. I know enough to get me into trouble and not much more lol.

-Connor

[kiltic]

Sorry, I meant to say IR not UV... I don't know how that happened.

[kayaker43]

Infra red is the best way if tuned so the wavelength matches the IR absorption curve of the plastic. In other words its not so simple. Infra-red wavelength is not a simple calculation like wattage or resistance or temperature. Unless you have a spectrometer kicking around all you can do is guess. Having said this, the difference between getting it wrong and getting it right is significant but it still works to some degree even when wrong. The IR won't soak in as easily or as fast if you miss the target window but it will still get hot.

Learning and inventing is fun but if you just want to get some parts done you can always hit the "EASY" button and buy a set of plans for a 12x18 machine with tuned infra red oven. Build-Stuff.com