Can anyone help me with vacuum-forming?

Hi,

I was wondering if anyone could give me some advice about vacuum-forming?

I want to start small, with as little expense as possible, as it all looks very complicated (have just read all the instructions at DH2!)

What I really need to know, is will it work with a vac which is only 2HP? I've got a leaf blower/sucker, which is 1600watts, am I being very silly to consider this as my vacuum?

And, where can I find the right kind of plastic to use? I live in the UK, and I have looked on the internet, but there are just too many kinds of plastic, and most only supply businesses.

I'd really apreciate any help at all on this - I actually want to make a medieval chestplate and helmet first (I make play props for a local drama group), and if that is successful, I'd love to have a go at a stormtrooper.

Thanks guys!

 

Don't know the answers to most of your questions, but the type of plastic you probablly want is Styrene. Does UK have a store called TAP Plastics? 1/8 to 3/16 of an inch thick (you'll have to do your own metric conversion).

You might also want to look into RTV
http://www.miniaturemolds.com/rtv.htm
Some of the materials are great, some were more trouble than profit.

Check with Society for Creative Anachronism (SCA)--they may be able to help.

Good luck.

 

go to usplastic.com and buy urself some sheet styrene. any thickness from .040" to .12" inches or so is fine. just depends on how thick u want it. and buy a bunch. its cheaper in the long run and trust me, u'll mess up a bunch. so get to disappointed when u do. styrene's cheap as hell when u buy 'em by the sheet, so dont worry about it. i made a prop gas mask for a photo shoot for my brother's cd cover by vacuumforming, and it turned out great. u can see it here: fun stuff art page
its the last 3 pictures at the bottom. the mask itself is vacuum formed plastic, with a bunch of crap glued to it to detail it and stuff. cool, no?

 

Well people seem to have you covered as far as the plastic goes.

What I really need to know, is will it work with a vac which is only 2HP? I've got a leaf blower/sucker, which is 1600watts, am I being very silly to consider this as my vacuum?


I have a 3HP and it just barely works. I would not go any lower than this, especially if you want to use .08 or .096 (thickness of plastic). I've only used .06 and the 3HP seems to work okay. I would go for a nice 5HP if you want to do thicker plastics or something other than Styrene. If you want that nice Trooper look, use ABS as it's sturdier and glossier. I would use it anyway just because it's tougher than Styrene.

 

Thanks guys!

I think I have found a source of styrene sheets in the UK, and the prices seem very reasonable.

I'm still stuck on the vac though, as I really can't afford to buy one for this project. I'll keep a look-out for something second-hand, but if anyone has a better idea, please let me know.

Thanks again, you've all been a great help!

 

Pawn shops, carboot sales? might be able to find a stronger vacuum there.

 

Don't get too worried about the horse power of the vacuum. An ordinary household cleaner works fine with styrene. If you get the sheets that are about 2 mm thick, you'll be surprised how much they will stretch when you get them really floppy in the oven. The Studio Creations site is the best out there as regards the vac table.
I have found that the easiest way to make a frame is to get a sheet of MDF or plywood, cut a piece that is the biggest that will fit in your oven, cut the centre out and use that as a template to make a duplicate that you can screw together, sandwiching the styrene between them. Saves the trouble of trying to join pieces of wood together. The styrene is only in the oven for a couple of minutes - not enough time to damage the MDF. It helps to use wooden drawer knobs as handles - good insulators in case you forget to put your gloves on in the heat of the moment. (Yes, it does happen...)
Anyway, use the grill setting with just the top elements on, at about 220 to 250 Celcius. I find that the styrene will initially buckle and distort, then flatten back as it starts to become pliable, then it will start to become more flexible. If you tap the oven door at this stage, the styrene will ripple like a sheet of water. Then it will start to sag slowly. This is your signal to turn the vacuum on, open the oven door and get ready to pull the frame out. I haven't let it sag past about 3" before putting it onto the mould, 'cause I'm scared of it tearing and dropping onto the bottom of the oven - another reason for only using the top element.
Anyway, my vacuum cleaner is an old Tellus (available in the UK?), about 1500 watts, over 20 years old, and it works like a charm. One other thing I have found is to use the biggest piece of styrene you can fit into your oven, even if the mould is reasonably small, because the styrene does not have to stretch as much to suck in against the base of the mould. This stops it ending up too thin at the edges.
I have tried ABS, but it needs far more suck than my old vac can give, and the styrene seems to have a far more forgiving nature. Anyway, end of saga - give it a go with your ordinary vacuum cleaner first. Have fun and good luck. Phil

 

Wow, thank you so much! I can definitely give it a go now, with very little expense.

If anyone wants to give me any more tips, on what type of clay to use, what type of plaster to cast, etc, it would all be so useful!

Thanks again!!!! (can you tell I am happy?) ;-)

 

We have used both hydrocal and ultracal plasters. Hydrocal seems to have a smoother finish, but ultracal is much more dense and solid.

 

It's probablly a no-brainer, but don't use clay that melts when you heat it...
Like I once did.

 

OK, I know it's probably a stupid question, but it has been bugging me-

If I get clay and make shapes for the pieces of armour, then have to create a negative mould from plaster, and then from that make another positive... Why can't I just vacuum-form over the clay original?

There's got to be an obvious answer that I have missed

 

'Cause it will deform. Even the plaster will not last forever. Eventually you will need to make another if you make very many pulls. People usually save a master to make more plaster casts from. That way, when the plaster your vacuforming over dies, you can replace it.

 

yup stubzilla hit it right on the head.

ultracal and hydrocal are VERY tough but over time they will deteriorate. you want to replace them when they do.

 

Hey, if you get a firm enough clay, I hear you can vacuum form once over it and it won't deform, but will fuse to the clay. Then you can just vacuum form over that first forming. Does anyone else know what I'm talking about?

 

I have heard that rumor, but I wouldn't risk my sculpt with it.

 

I have vacuum formed over several original sculpts, especially where the negative would end up being massive.

I use a water based sculpters clay. I let it firm for about a day after finishing my sculpt. Don't let it dry too long or it will contract and shatter over your inner forms. Once it is firm enough, put in on the table. I then talc the clay scuplt and vac right over it.

Now this only works if you are pretty sure of your molds and that they have no undercuts. I have gotten serveral pulls off the clay. I then choose the best one, pour stone in it, clean the stone casting up (cause the clay sculpt always have mirror waves/imperfections in them) and the re-vacuum form over the new, cleaned up stone postive. Vac two to three parts and pic the best copy. This becomes your "master" mold for production.

Pour stone in it, clean up that casting one last time and its off to the races. Azeem has parts from our Clone Trooper project made using this process. I am finishing off the torso this summer and all the body parts will be vac'd the first time over the clay sculpts.

Theatrix

 

Thanks everyone, loads of help there!

As I have never done this before, and I don't want to make a lot of repeat parts, and I also want to keep the cost low, I shall probably try straight onto the clay first.

OK, one more question and then I'll leave you all alone (hopefully)-

As you're doing the actual forming, if the plastic does not bend enough into small corners/parts, can I use a hairdryer to heat it a little in specific places? Or would I need something more powerful? Does this then make it uneven because some of the plastic has been heated more?

Mucho thanks!

 

Hairdryers don't get hot enough for that. But if you're wearing gloves and you're quick, you can usually just poke the plastic down before it cools all the way. But once I did it with an oven mitt on and the texture of the mitt got imprinted into the plastic. It's not that big a deal though. Just a little sanding and you'd never know I messed up. lol

 

Ok i have a vac form question. I searched and couldnt find anything so i decided to continue this topic instead of creating a new one.

I was told that Styrene gives off some dangerous gasses. I really want to vac form some stuff but my mom wont let me if there are noxious fumes involved. Is there any plastic that doesnt give off dangerous gasses that can be vac formed? I have heard of people using sintra for vac forming. I even saw a tusken raider mask shell that was vac formed from sintra. Can i use sintra to vac form, or is there another less dangerous plastic i can use?

Thanks.

 

sounds like you have things a little reversed so i will clarify.

all plastic, when burned gives off toxic fumes. there is no way around that.

with that said, vac forming is generally done with ABS or styrene. thats what i use. though in theory you could use anything.

sintra on the other hand is not a good choice for vac forming because when it burns the fumes are more toxic than styrene and ABS.

as long as you dont burn the abs and styrene and vac in a well ventilated area you should be fine.

 

So you are saying if i were to heat it up in the oven in the kitchen and form it there as well that i would be fine if i open up all nearby windows?

 

When I vacuform I don't open any windows and I've never noticed any fumes or odors of any kind (using styrene). It's probably a good idea to open the windows, though, for safety's sake. It's not like these horrid smoking plumes of killer gas coming pouring out of the oven! Of course, I've never let my plastic go too far and melt onto the burners. I imagine that would let loose a terrible stink, plus make a nice fire.

Scott

Disclaimer - if you kill yourself while vacuforming, I can not be held responible.

 

i vac'ed nearly 12 pcs the other day and i never smelled anything.if im gonna do a bunch of pulls i usually crank up the fan to keep the heat undercontrol in the kitchen.that would help with any fume issues.also opening the windows would be a good idea.
and i like styrene also,it works great for vac'ing.
as for pulling plastic over clay.you may not get a good result.if the item has dried out and hardened you might get 1 pull but that may be it.ill bet if you vac over moist clay it will just squish the clay under the plastic and youll have to start over.

 

Re: Plastic and fumes. I use styrene for a lot of my vacuum forming. Just heating the plastic (i.e. to prep it for forming) normally isn't a problem re: fumes. However if you accidentally ignite (i.e. burn) the plastic, then fumes you will indeed get.

In either case, I would recommend good ventilation. While off-gassing is minimal when doing normal vacuum forming, it is generally a good idea to have good air flow when working with plastics, resins, etc.

Anyway, just my two bits.

Theatrix

 

Just two quick questions:

I'm making myself some Jedi armor, and was wondering what would be better to use, sintra or styrene? Also, is .080 thickness good enough for thickness, or too much? Thanks!

-K