Vacuum Forming

[SSGLordBert]

So I’m having a lot of trouble trying to vacuum form a visor. I’ve built a 9x12 vacuum box and a frame for the 11x14 PET plastic. And I’ve got a buck for my specific helmet. But I’m having trouble getting it to work. I preheat the oven to 290°, wait for it the bubble down, flip the shop vac on, push down as hard as I can, but it only goes like half way and stops. Either all that or the plastic dogs white.

Am I missing something? And I not getting the plastic to the buck quick enough?

I’m lost.

 

[TurboCharizard]

If your plastic is turning white that sounds like one of two things, either you don't have PETG or there's another additive making it funky. There's also the slight possibility that it's an older sheet of plastic that's been exposed to excessive moisture and has absorbed some but that usually results in stars/pockmarks or limited discolouration and not the whole sheet turning white. Do you have an image of how bad it is?

 

[SSGLordBert]

If your plastic is turning white that sounds like one of two things, either you don't have PETG or there's another additive making it funky. There's also the slight possibility that it's an older sheet of plastic that's been exposed to excessive moisture and has absorbed some but that usually results in stars/pockmarks or limited discolouration and not the whole sheet turning white. Do you have an image of how bad it is?

This is the plastic. The label said PET plastic. But I’m just scratching my head at this. I tried like 5 times.

Then this is my DIY vacuum form. Work area is 9x12

 

[Cadet]

This is the plastic. The label said PET plastic.

That could be your issue. PET is different than PETG. PET plastic is much more brittle than PETG which could be why it is both not forming or stretching as well and turning opaque.

 

[SSGLordBert]

That could be your issue. PET is different than PETG. PET plastic is much more brittle than PETG which could be why vitamins is both not forming or stretching as well and turning opaque.

ok. that makes sense, ill order some actual PETG and try again. Hoping to get it done before c2e2

 

[TurboCharizard]

That could be your issue. PET is different than PETG. PET plastic is much more brittle than PETG which could be why vitamins is both not forming or stretching as well and turning opaque.

Oh, there it is. I misread PET as PETG because of vacuum forming.

 

[SSGLordBert]

Well after several hours and mishaps and failures… I got a (yes only one) good visor from vacuum forming. I also tried my hand at tinting it. Trial and error there too. But here’s the end result.

Though I’m still having trouble with actual vacuum forming. It’s still not stretching completely over the buck for the vacuum to actually suction the plastic. I might remake my vac box and frame. But it just seems as though the petg doesn’t want to cooperate…

What’s a good temp to use on my oven for the softening the petg? And how long do I let it sit in the oven?