Vacuum Forming Heater Auto Shutoff

[RoboMike]

Hey All, I've been following the forming threads here and was wondering if you could help me as well. Anyone figure out how to disable the automatic shut off from the space heaters? I need more time with 2 , 1500W heaters and .177 thick abs black plastic for a robot chassis. The bottom surface of the plastic sheet only gets to 280F before the shutoff.

 

[Psicorp7]

Not knowing how your rig is setup, there are a number of ways to maximize your heating situation without creating a dangerous fire hazard. Removing the safety shutoff could cause them to overheat, short out, or flat out melt and start a fire. Fire bad, fire very, very bad!

Here are some options:

- Place the heaters in an enclosed, foil lined, box with the frame and plastic making up the top of the box. This directs all the heat to the sheet.

- Use a heat gun to augment the heaters and bring the temperature up.

- Switch to HIPs plastic. It has a much lower deformation temp threshold and will form quite easily.

- Turn one heater on for a minute, then turn the other one on. They will be staggered one minute apart, giving you more time.

- Switch to a custom heating element setup with your own thermostat and temp limits based on the components you select.

Good Luck!

 

[RoboMike]

Hi Psi Corp,

I have a heater box lined with aluminum flashing, I lowered the heaters and raised the box that helps so far with the auto shut off. Temp seems to have settled at a steady 215F top surface and 235F bottom surface.... waiting more and now it's heating. Up pretty evenly but still not reaching the temp to form

 

[stormtrooperguy]

That's pretty thick ABS, and ABS is hard to work with to begin with. If you can't get it working switching to HIPS as suggested might help, and going thinner too if you can.

 

[RoboMike]

Hi All,

Made some more progress today. I got the temperature up to 247F top surface, 257F bottom surface; aiming for about 285 - 300 F. Had a nice sag on the sheet and got the temperature up by adding aluminum flashing to the top surface of the ABS sheet. Wondering, if maybe some plastic would have been better instead of AL. The configuration on the bottom is still 2 quartz heaters on the bottom,. i did try a heat gun, but the sheet cools down too fast for that to work on a large piece of plastic. Insulating the top really helped, maybe foam panel would be better? Thoughts?

 

[cavx]

You almost want a thermal sheeting like that compressed fibre glass board. So long as it does not burn.