vacuum form

[Masterdean]

Hey guys, I'm hoping this is the right place if not please let me know. I have recently discovered vacuum forming. I was wondering if anyone has experience with it if so how reliable is it? Can stuff be detailed or will it be hard to detail? What is the best plastic for the job and where can I find it? And what should my base modle be made of? Thanks a ton!:lol

 

[Wesman]

Well, I love vacuum forming. Once you get your heat and timing right, it can be very reliable. If you are looking for maximum detail in the pull, you may want to consider a female mold (with lots of tiny holes drilled through to allow vacuum to pull the plastic in) because the outside face of the plastic contacts the mold instead of the traditional male mold where it's like your are putting a thin coat of marshmallow on top of the mold, therefore losing detail. Molds can be made of several standard materials. Things that can take heat repeatedly--wood, hydrocal, fiberglass, metal all work well if the engineering is good. The type of plastic is usually dependent on its function. Opaque or clear? Styrene and PETG are good respectively, and you will have to look on line to find a supplier if you're not in a big city.

 

[Luke0312]

I made my own small vacuum form table out of scrap I had lying around the house. It's small, sized it for use with the signs that you find at home centers (15"x19"), doesn't seal perfectly (due to it being all wood and the frame has slightly warped), I hook it up to a shop vac, and heat the plastic in an oven. Obviously not good enough for any commercial work, but it works well enough for what I need.

What I've found in my experience is the amount you're heating the plastic is more important than the vacuum you're pulling. I've seen mostly 200-250F recommended, but I can't get much sag in my plastic at that temp, even after quite an extended time. When I crank it to 300, in just a couple minutes I've got a sag about 6" deep.

As for what I've used as a buck, pretty much anything that can withstand a little heat and a bit of pressure. Used plaster, metal, thick plastic, etc.

I haven't every used mine for visors or a completely finished piece. I have used it for a quick and cheap mold. It wasn't the mold for the final piece, just something to pour plaster into, so that I could have something easily sanded and could pull a finished mold later. I've also used it for the styrene on my training remote builds, was able to shape the styrene correctly so it fit flush on the sphere.

I'd recommend building something basic to start off with, then invest in something better once you have more experience and find more uses. As I said, I just used scrap, I spent less than $2 out of pocket (a couple of PVC fittings to hook up the shop vac.)

 

[Masterdean]

I love all the feedback I'm getting. I hope I'm not bothering you guys, anyhow I have a few more questions. So your saying the base mold that the plastic will be formed to can be anything? The materials that will be forming are they sturdy afterwards or are the flimsy like costumes? Is it possible to make 3d models? I'm trying to make my husband a storm trooper helmet. And last but not least are all the materials able to be painted after the process?

 

[TazMan2000]

The base mold has to be something that can withstand the suction, or else it will crush as soon as the air is evacuated from the chamber. Also as another member mentioned, it has to be something that can withstand a little heat. The plastic that you are using to form will be very hot. If you are using a form which is plastic, there is a good chance that you will wreck the form or at least put another layer on it. For your sturdiness, it depends on the materials that you use. Styrene for a stormtrooper helmet and armor will be ok for display, but might not survive several wearings. Depending on the form you have, it may not create an even thickness after you're done. You may have to go with a thicker material or another material other than styrene. PVC may also be used. I commend you for wanting to make a stormtrooper helmet for your husband, however, there are vacuform kits already out there that you can purchase of the stormtrooper. Also there are guys on ebay selling styrene armor. Why reinvent the wheel? I wanted a helmet badly as well, but finally realized that it was easier and probably cheaper to buy one already made.
Yes, the material is paintable, however, PVC sometimes has difficulty with some paint as they tend to flake off if the surface isn't prepared (sanded) properly. This may actually work out to your benefit, as it gives it that used look Star Wars is so famous for.

TazMan2000

 

[metal wood]

was about to start typing, then realized tazman just said everything i was going too say. when i was learning this stuff i just played around with molds and materials until i found what i was looking for for what ever project i had going at the time

 

[Paul Alfred]

I'm researching vacuum forming right now for some ideas I have, and this thread has provided some good initial information. Thanks!

 

[clonesix]

Vacu-forming is done with three things:
1) a Frame to hold the plastic.
2) A heat source to soften the plastic
3) An vacuum source to form the plastic

How complex and expensive it gets, goes up with size. I simple (one-off) method is a small frame that fits in your home oven to heat the plastic and formed by a vacuum cleaner, or shop vac. Naturally, this will make your house smell like burnt plastic for the day. You can form small things like model airplane canopies, or even helmet parts. The most forgiving material for this is High Impact Styrene (HIPS) as has a good temperature range, and gives a fair amount of detail. It must be painted, as it will yellow over time.

When you want to go larger/faster, you are moving up it price and complexity. A Shop-Vac will make good pieces, but a vacuum pump, and reservoir make better ones. Going larger also requires a better heat source. The important thing is consistent, even heat. You will end up building some type of oven to heat from the top, or from the bottom, depending on design. Since this involves wiring and use of electrial outlets, be sure to know what you are doing. You don't want to start a fire and burn your house down.

Then there are the forms, onto which you will form the plastic. These can be made from any heat resitant material. Wood, MDF, Stone or fiberglass will work. They don't last forever though, and will need to be replaced every so often. The best way to replace molds are to save a good pull, and use it as a mold to pour stone (Hydrocal) into, for more molds (forms)

Youtube shows many inspirations for tables and machines.

 

[TazMan2000]

In addition to tons of youtube videos. I found the best info from this guy. He's a pro but explains it in a beginner's terms. The guy's name is Lasse Henning and he is incredible.
Vacuum-Forming | The Model Shop with Lasse Henning

TazMan2000

 

[Fizbin]

The TK560 forum is also a great place for information. :thumbsup

 

[Paul Alfred]

Thank you all for the additional advice and links...I'm still doing lots of research. The nice thing is that my flatmate has some experience with vacuum molding for costuming, so he's going to help me out with my project (and likely re-make an old costume of his in the process). Still, even with his help, I'm not starting anything until I've got a much better understanding of the process, cost, etc.