Vacuform / buck construction question

[pandatrooper]

I have a question for the vacuform experts. I have made a ghetto vacu form table before (heating sheets clamped in a frame in an oven, and using a shop vac) with success. I am planning on building a more robust forming table for my next project.

I wanted to see if this process would work.

I plan on sculpting in pink foam, or even constructing an object with foamcore. I know you can't vacu form directly on top of these materials since they would collapse.

The reason I wanted to use foamcore or pink foam (besides the fact that I have some already) is that the shape I'd be making is more geometric / flat surfaces, and I can model something much more quickly in foam or foamcore than in clay. I know I could make something in MDF but I don't have a woodshop to handle modeling everything in wood for a buck.

I was then thinking I could seal the foam or foamcore model, then do a quick "waste" mold (negative), then out of that pour plaster in to generate a plaster buck for vacu forming.

Would this work?

If so, what would be the best way to make the waste mold? Plaster, let it cure, then seal it, apply mold release, pour in new plaster to create a positive that could be used for a buck? Or is there another material that would be better / cheaper / faster to create a waste mold?

I've even considered methods such as using casting casting silicone (I have a bunch on hand) to make an impression coat, then using expansion foam as a mother mold.

Secondly, is plaster the best material to use to make vacu form bucks? Previously, I used plaster and it worked fine, but I was worried about crumbling / wear and tear etc.. Is there another casting material that would be more appropriate for vacu forming?

Thanks!

 

[vaderman1701]

Not sure you can use plaster to make a negative mold, mold release it, then pour plaster in it. I don't think it will release. You can try doing a brush on silicone create some keys and then pour plaster over it. You can then pour plaster in the silicone jacket to make a solid master.

Look at Smooth-on's website. Plaster does tend to crumble after some use. Smooth-on has some materials that are better to use for make vacuforming molds.

http://www.smooth-on.com/Urethane-Plastic-a/c5_1120_1158/index.html

Scott

 

[propologist]

There are hundred ..i mean hundreds of links for your issues.

Whoever this site is has some made skills in that area in my mind:

http://www.studiocreations.com/howto/vacuumforming/index.html

here's a good one on plaster molds I have check out often

http://images.google.com/imgres?imgurl=http://trooperarmor.com/images/Tutorial/PlasterCasts/CreateCast_PositiveMold.JPG&imgrefurl=http://trooperarmor.com/Tutorial/BuildPlasterMolds.html&usg=__IWf5C6Cq_Boc06bVad9QcWDTqj8=&h=240&w=320&sz=22&hl=en&start=30&um=1&tbnid=4QXlCX7ffNwHDM:&tbnh=89&tbnw=118&prev=/images%3Fq%3Dplaster%2Bmolds%2Bfor%2Bvacuum%2Bforming%26ndsp%3D20%26hl%3Den%26sa%3DN%26start%3D20%26um%3D1

 

[Jumpin Jax]

I have a question for the vacuform experts. I have made a ghetto vacu form table before (heating sheets clamped in a frame in an oven, and using a shop vac) with success. I am planning on building a more robust forming table for my next project.

I wanted to see if this process would work.

I plan on sculpting in pink foam, or even constructing an object with foamcore. I know you can't vacu form directly on top of these materials since they would collapse.


Thanks!

Pink foam is pretty stout. If you don't use ridiculous amounts of vacuum pull I don't see why it would collapse. Ghetto or not, if you're just looking for a pull to work from, try it by hitting the vaccum, and if it does start to compress, turn it off. Works all the time.

 

[clonesix]

Yes, you can do it that way. You will need to seal and vaseline your waste mold well, and it will have to be broken away. Generally, it's not the best idea to pull a hard part from a hard tool, but it can be done.

Here is a better way: Skip the pink foam and get some 4 lb density polyurethane foam ( http://www.vandykestaxidermy.com/se...rr_variation_options][color][]=&Start+Search= )

Why? Because after you carve it, you can vacuform right over it. You can't do that with (polystyrene) pink foam. The plastic will adhere to it.

Once you have your first pull from the foam carving, pour stone into it and you've got mold. Simple?

BTW, when I read "plaster," I think plaster of paris, and that isn't strong enough. Hydrostone, or Ultracal are your friends.


Prop on my friends, and happy new year

 

[pandatrooper]

This is great, thanks for the helpful links everyone! Exactly what I was looking for.

 

[Jumpin Jax]

Why? Because after you carve it, you can vacuform right over it. You can't do that with (polystyrene) pink foam. The plastic will adhere to it.

That I did not know. I'm learning this year already :thumbsup

 

[propologist]

Yes, you can do it that way. You will need to seal and vaseline your waste mold well, and it will have to be broken away. Generally, it's not the best idea to pull a hard part from a hard tool, but it can be done.

Here is a better way: Skip the pink foam and get some 4 lb density polyurethane foam ( http://www.vandykestaxidermy.com/se...rr_variation_options][color][]=&Start+Search= )

Why? Because after you carve it, you can vacuform right over it. You can't do that with (polystyrene) pink foam. The plastic will adhere to it.

Once you have your first pull from the foam carving, pour stone into it and you've got mold. Simple?

BTW, when I read "plaster," I think plaster of paris, and that isn't strong enough. Hydrostone, or Ultracal are your friends.


Prop on my friends, and happy new year

Only problem with Poly foam is expense. If you doing anything of size it will put you in the poor house.

 

[StudioCreations]

Another reason not to vacuumform right over the pink insulation foam is that the foam will melt under the intense heat of the plastic. Just melt right before your eyes.

I use pink insulation foam for a Waste Plug Mold, but I coat it with 4-5 layers of spackling compound before I vacform. Takes forever to dry in my humid area, but it's very cheap and does what I need it to do to get the 1 or 2 plastic shells needed to pour Ultracal.

The spackling compound I use is the powder kind that you get at any hardware store. Just mix it with water, then trowel or spatula it onto your carved pink foam. Sand inbetween coats for best results (i.e lessen the change of air pockets).

The thicker the Plaster shell, the better the mold will hold up to the intense heat. and I do not use this technique for vacuumforming 1/8th (.125) inch thick plastic, just .080 and .060 guage plastic. I think the heat from .125
would sink right through the shell, melt the foam and the shell would collapse/crush a bit before the vacuumforming process was completed. I've had thin spots do this in .080 guage plastic, and have not dared to risk it with .125.

The guys at Hangar18 (Prey, Final Fantasy Deep Eyes, Stargate Horus heads) gave me the idea to use spackling compound for the final surface. It's not my idea, so I want to give credit where credit is due.

CloneSix, great link to some affordable polyurethane carving blocks. Probably the cheapest I have seen in smaller block size in quite a while. (I have no idea why I didn't think checking prices at Vandykes for this block stuff, as I already knew they beat anyones prices on foam animal blanks.)

 

[Hangar18Studios]

Coating the foam with spackle works best with a resilient type of foam. The pink insulation foam is not the greatest, and it's usually good for only a few repeated pulls. I like the carvable urethane foams, some of them you don't even need to coat with spackle.
Scott
P.S.: For the record, we didn't create the Stargate Horus heads. I wish we did!

 

[Yodajammies]

I've been working on a mass effect costume with a similar technique and I've found this product to be absolutely perfect - http://www.demandproducts.com/ureshell.php


It's a 2 part shell-coating that is safe for polystyrene. It's not quite as hard as a fiberglass shell, but it'll make your pink foam PLENTY rigid enough to stand up to repeat vac-form pulls. I highly recommend it.

 

[propologist]

I've been working on a mass effect costume with a similar technique and I've found this product to be absolutely perfect - http://www.demandproducts.com/ureshell.php


It's a 2 part shell-coating that is safe for polystyrene. It's not quite as hard as a fiberglass shell, but it'll make your pink foam PLENTY rigid enough to stand up to repeat vac-form pulls. I highly recommend it.

Good idea , i need something like that is i am ever going to make both my LEGO full sized battle droids and reg./ one