N00b Vacuum forming questions

[Meathead316]

Hi

I wanna try my luck at vacuum forming, now i see that a vacuum forming table is expensive so last night me and a buddy build one from some scrap bits of wood to attch to my vacuum cleaner hose. We used a heat gun to heat the plastic and it worked ok ish... it didnt take the shape as well as id hoped and i recon is down to 2 reasons:

1. vacuum cleaner isnt strong enough, so how much suction do i need?
2. Wrong plastic.

I tried using rigid corrigated PVC (but i had flattened it by heating it and then squashing it down first) this plastic doesnt seem to be very stretchy and am looking into an alternative and have found:

1220x915x1.0mm BLACK M/P HIPS - £4.56
http://www.plasticstockist.com/inde...=&SubGroup=NzA0Mg==&Code=MS4wSElQU0JMRzEyMjA=

1372x660x0.5mm BLACK M/M HIPS - £1.80
http://www.plasticstockist.com/inde...=&SubGroup=NzA0Mg==&Code=MC41SElQU0JMRzEzNzI=

1372x660x0.25mm WHITE M/M HIPS - £1.12
http://www.plasticstockist.com/inde...=&SubGroup=NzA0MQ==&Code=MC4ySElQU1dITTEzNzI=

As you can see they are all the same type of plastic, all about the same size just varying thickness.

What is best for vacuum forming and taking in as much detail as possible? Im hoping for the .25mm as cost is an issue and i would prefer it if it was a cheap as possible.

The aim is to make various things out of it, including replica armour (ironman/robocop etc) strength is that much of an issue as it would be reinforced from the inside just as long as its strong enough to hold its shape.

one last question, which type of glue will stick HIPs best? with pvc i have found that NOTHING will stick it strong enough and am hoping that this isnt the case with HIPs

Thanks

 

[Birdie]

Superglue will stick HIPS just fine, acrylic glue (you can get it on Ebay) will pretty much weld it

To get the best result you're gonna need to be able to heat the plastic equally over the whole surface area.

What are you using as a vacuum bed? That needs to be as airtight as you can possibly get it, or you're going to lose, ahem, suck.

 

[Meathead316]

Hi

I made the bed from wood, sealed up all edges with foil tape, its super airtight.

How long does acrylic glue take to set?

Problem with heating it equally is i need to do big sheets, bigger than my over so it hs to be a heat gun... i could always get a second heat gun but i have no other means of heating it... any ideas?

 

[Finhead]

Hi

I made the bed from wood, sealed up all edges with foil tape, its super airtight.

How long does acrylic glue take to set?

Problem with heating it equally is i need to do big sheets, bigger than my over so it hs to be a heat gun... i could always get a second heat gun but i have no other means of heating it... any ideas?

If your talking about Weldon 16 it takes about 20 secs.

http://www.tapplastics.com/shop/product.php?pid=132

 

[RAD]

Do a prof. table like they said for the most screen accurate pulls

 

[CustomPropSculptorGuy]

Go and buy an old fridge, and hollow it out, and then go get a couple of old stoves and take the coils out and run them in the fridge - build a plane to put the plastic on and you've got a poorman-engineered oven LoL

Honestly, A heat gun wont do it. The plastic will cool too fast for you to get an even dispersement of heat on to the sheet so you have a uniform vac-pull.

I used to make marque and other molded signs for banks, grocery stores, ect and we had HUGE ovens made just for vac-pulling, and heaven forbid if one of the burners went out.. it sucked...

But I would suggest kit-bashing some old appliances and see where that gets ya.

Hi

I made the bed from wood, sealed up all edges with foil tape, its super airtight.

How long does acrylic glue take to set?

Problem with heating it equally is i need to do big sheets, bigger than my over so it hs to be a heat gun... i could always get a second heat gun but i have no other means of heating it... any ideas?

 

[RAD]

check out studio creations website for another detailed build.

 

[n0x23]

This Forum has alot of great ideas and tutorials on vacuum forming builds, from the basic to the complex.

http://www.tk560.com/phpBB2/viewforum.php?f=1

 

[Dark asylum]

Ok as much as building a vacuum former out of old house hold appliances and tables sounds ok, it's not if you want high details and smooth pulls you'll need to head to the library and get a few old books and do real research the home made vacuum formers don't work near as good as a industrial design, as for the idea using a oven to pre heat a plastic sheet before clapping it on a table with holes drilled in it for pull, the biggest problem is those few seconds of cooling time are going to cost you details and the chance of edges flaring so I'm suggesting you take the time to build a machine that will give you the best pulls possible.

You really need to build a nice mesh covered rack not a table all steel no wood, design the vacuum former and heater box in 1 unit not seperate and use tungsten steel heater coiling that you can place any were nothing static. Remember sheet plastics come in 8x4 foot sheets so best you make a table that can take nice even cut sizes rather then haven't wasted material from odd sheet cutting.

Hope this helps and good luck.

 

[Meathead316]

Thanks for all the help. the vacuum form table i made from scrap was just a test really. will make a proper full size one next.

could i not bodge something like this together?

http://www.rcgroups.com/forums/showthread.php?t=621858

a portable stove and a metal housing to make a make shift buttom heated oven on the cheap as like i said before im on a limited budget.

 

[themanwoaname]

i have a really stupid question.
say you have the plastic heated from the oven and you put it on your master while the vacuum is on, while the vacuum is doing its job, say you take a heat gun to the plastic while the vacuum is on

would that make a difference by adding more minute details?

and another thing i dont entirely understand, is how often is a vacuform used as a mold to make pieces, vs the actual end product?

 

[tictoc]

Yes, you are right. I think the idea with the heat gun is to keep the plastic soft to assist in forming details. The plastic cools very rapidly when moving from your home ove to your machine. That doesn't happen with prof. type machines. Search some of GINO's or Stormtrooperguy posts and you will see a more prof. type home machine. There are others too...not saying they is the only one, but that's who I thought off the top of my head.

As for the the other question, I think the answer is that styrene doesn't stick to styrene. So if you made a one time mold out of wood, clay and odds and ends, then vacuum formed over it, you could simply use it again to make more pieces. You would lose more detail but thats how it is described in Thurston James' book on props.

If you wanted to simply use a styrene form and vacuum over it, you would need to support it somehow to keep it from collapsing.

But I am no expert. I search these threads too. Lots of experience RPF's will chime in on this I'm sure... That is just my understanding so far....

 

[Meathead316]

i read that styrofoam is good for making molds out of. but its not very smooth. so i was thinking, couldnt i take a square tub, fill it with expanding foam, then carve something out of that? what sort of finish would i get? could always smooth it out with putty or something after wards.

your thoughts?

quick edit, this is the stuff im talking about:

http://cgi.ebay.co.uk/LD40-Rigid-Po...tEquipment_Accessories_SM&hash=item4a9ba8c354

any idea how big a cube i will get out of that much?

 

[RAD]

styrofoam on vac table? Used foam for finished props and costumes but never as a mold for a vac table w/ heat....

 

[Bizarro Lois]

What should the original be made from? If you sculpt a mask in modeling clay, what would the best material be for the copy that actually gets vac-formed? Resin? Plaster? I guess it would have to be something rigid, that won't melt. Suggestions?

 

[Dark asylum]

i have a really stupid question.
say you have the plastic heated from the oven and you put it on your master while the vacuum is on, while the vacuum is doing its job, say you take a heat gun to the plastic while the vacuum is on

would that make a difference by adding more minute details?

and another thing i dont entirely understand, is how often is a vacuform used as a mold to make pieces, vs the actual end product?

Well that doesn't work as well as you think the vacuum oul cause colling so it a more neutral thought better to wait till the forms done leave the molds in the plastic the heat spots you wish the make deeper use a nice pair of leather glues for that so you dont toast your fingers pushing on the plastic.

And the idea using styro foam molds is a terrible idea unless you have a thick durible skin sculpted over them the pures and heat will compress the foam over time and plastic will stick to it so demolding will be a pain but your best molds are hollow so the vacuum pulls in the mold itself rather then the table being the only pull source just vent your molds vacuum forming is one of the best sure ways to get nice light weight durible kit parts made the problem is it's generally shund at cause of the home made pulls are far to simple and the molds are never done so they can get extreme details it takes alot of research and a great machine build if you what a nice production and you can build a budget machine as long as you buy the parts seperate rather buying junk to gut parts out of that will cost you more in the long run.

 

[Riceball]

What should the original be made from? If you sculpt a mask in modeling clay, what would the best material be for the copy that actually gets vac-formed? Resin? Plaster? I guess it would have to be something rigid, that won't melt. Suggestions?

I'd suggest something along the lines of plaster but harder. You'll want your bucks to not only withstand heat but a certain amount of pressure too, you'll want to be sure that parts of your buck won't chip, break off, or wear down from the pulling. I don't know exactly what kind of material most people use but if it helps any I have heard of it referred to as stone before. I'm sure that someone here who actually vacforms will chime in with suggestions.

 

[Dark asylum]

I'd suggest something along the lines of plaster but harder. You'll want your bucks to not only withstand heat but a certain amount of pressure too, you'll want to be sure that parts of your buck won't chip, break off, or wear down from the pulling. I don't know exactly what kind of material most people use but if it helps any I have heard of it referred to as stone before. I'm sure that someone here who actually vacforms will chime in with suggestions.

True best molds are hard woods, tiger bondo works pretty good, AVES epoxy sculpt by far the best with sculpting, and hydrocal and ultrical are the best plaster style materials, also note that you don't want to use resin nothing cheap or polyestor especially, the heating and cooling will crack it apart and distort within a few pulls of the pressure and heat now urethane casting plastics will work better but needs to super heavy cause the heat can still effect it and will cost more money so if you can go with a wood base form and use AVES Epoxy sculpt for all the surface work and shaping for the best quality molds that will be much lighter then stone like molds, good luck.

 

[tictoc]

What should the original be made from? If you sculpt a mask in modeling clay, what would the best material be for the copy that actually gets vac-formed? Resin? Plaster? I guess it would have to be something rigid, that won't melt. Suggestions?

I would experiment with plaster first. It's non-toxic, familiar ( we all made the plaster handprint dish for mom...) easy to work with and pretty cheap. It will hold through a couple of pulls while you get the hang of things. You could also try a slightly (slightly...) stronger morter type plaster called FixItAll. Plasters hold good detail but will eventually chip etc. It comes in big bags at Home Depot.

Once you experiment, then you could move on to stronger plaster materials like hydro-cal, depending on how big your buck is and how many pulls you make and what kind of detail, etc.

Look at what Stormtrooper guy does to sculpt a buck. He uses a kind of masonite (a kind of particle board, couldn't think of the word...) board. He piles several layers of board in the general shape of what he wants the buck to be, like a shin guard. Then he sands or grinds it down until it looks the way he wants. He can add layers or glue on more wood details etc. But he ends up with a pretty inexpensive, tough buck to mold over. Pretty neat. Hope that helps.

 

[Bizarro Lois]

Yeah it does. Solves a lot of problems for projects I'd like to do. I'll probably end up using wood as the base for my Iron Man helmet, since it's a simple shape.