Anyone have a vacuform table? i need visors done...

[tubachris85x]

I will just say that PETG can be difficult to form the first time, UNLESS you have a proffesional style machine or a really good idea of how much sag there should be while heating it. I formed I think .060 thick PETG, I formed these egg shaped domes for a queen amidala dress. I will say that this plastic is very, very sturdy. I stood on one and it popped in, but then popped back to the way it was right after I got off of it, I weigh around 300lbs. I also think that this plastic would be ideal for visors, its very clear, even after you form it. Its actually falls under the "acrylic family"

But for the thickness, depening on how thick you want it, 0.60 is pretty thin after being formed. You may want to beef it up a bit more, but remember the thicker it is, the harder it is to form.

 

[NZTK]

Its actually falls under the "acrylic family"

No it dosnt. its Polyethylene terephthalate modified with glycol. It falls under the polyester family I believe

 

[tubachris85x]

No it dosnt. its Polyethylene terephthalate modified with glycol. It falls under the polyester family I believe

I stand corrected. I missread my source then

 

[Culvan]

Thanks for the information. PETG is the same stuff they use to make most water bottles. Water bottles seemed pretty thin to me so I figured I could probably use thin stuff.

1-2 mm is about .040 to .080 inches. Sounds like I'll have to be very gentle with the stuff I have. I purchased it just to experiment. I'll learn.

One of the things I had read about it was that it helps to heat the bucks (molds for vacuumforming). I guess pressing hot PETG onto a cold object could cause it to cloud up. Is that something you've had to deal with? I think someone else suggested covering the bucks with felt for that. Although I suspect you would transfer felt texture onto your plastic.

Andy

 

[NZTK]

PETG is the same stuff they use to make most water bottles.

Usually for plastic bottles they use straight PET or PETE but they are all similar. PETG is commonly called ViVak. The clouding you're talking about is sometimes called "mould touch opaqueness" and is caused by having a cold master, or sometimes its caused by over heating your plastic. Its not something Ive ever had a problem with when using PETG. It happens more with acrylic and polycarbonate. Acrylic, while great for draping, is no good for home vac forming IMO, unless you can pre-stretch it, or you have a snap back box. You want a pretty grunty machine for that though, as it will always radius out when its cooling. Acrylic has a strong "memory" for its original shape. Polycarbonate (lexan) has problems with moisture. It needs to be baked on a low heat (80c) for a good few hours to cook it out, before you heat it up to forming temperature(140c-160c), or it can fill up with fine bubbles (generally called "orange peeling" other plastics can do this too, ABS if you heat it too fast and HIPS if it gets old). Felting or flocking your masters isnt really a good idea when dealing with thin sheets as you're right, they will pick up the texture, you can get some cool effects like that though. If you put a human hair on your master and vac over it, it will show through on the plastic, a good trick is to paint your masters with engine paint and polish them, that way you can get a very fine surface that can withstand the brief heat from the plastic without bubbling up.
I hope some of that rant is useful have fun and wear gloves, the plastic is hot and can be sharp. great for taking skin off knuckles.

 

[Vrogy]

This is good stuff. Maybe eventually we can start some vacuum-forming information resources.
There's something to be said for rapid duplication of parts..

 

[NZTK]

There are already piles of great resources on the net about it, and public library's are usually pretty good. The best way to learn this stuff is to have a go. Like anything, reading will only take you so far.

 

[tubachris85x]

Yea, if you go to tk560's forum, search for posts by "DrCrash," he makes very long, detailed and informative posts regarding vacu-forming as well as everything else from construction to plastics.

About that clouding thing, I only noticed that happend to areas that were touching the platen. I did set the molds either in the sun or on top of the oven prior to forming, and as NZ-TK said, it will pick up every surface detail. I had sanded the wood molds a few times, and put 4 layers of sanding sealer on them, and it still picked up the wood grain texture (you can see it, but it was barely raised on the cast)