vacuum forming

hello folks.
as you may have seen, i have been making a blue foam canopy for the sea hawk.
some one asked why i was not moulding a clear version, so here we go.

blue foam will not lend itself to having hot plastic draped over it, so i will have to make a heat resistant plug instead.
to save carving another one from balsa i am going to try making a mould and then casting a plaster version complete with glazing frames.

My daughter had some latex liquid left from making models, so i thought i would have a bash at making a latex mould.


first job is to clean up the plug surface and place it on a solid surface.
then you just paint the liquid latex over thee plug and onto the flat surface, this is to create a flange for mounting the mould later on.

i will need to build up about 10 layers of latex to make a strong enough mould to take the plaster.
lets hope it works ok.

then i will have to build a vacuum former for the next stage.

This is interesting Tony, hope it works out

so do i Tony, but it has to be worth a bash.
blue foam is so much easier to work for making plugs than wood or filler.
i hope to be able to do this with all my models from now on, even things like nose cones and engine cowls.

for the vacuum former i am thinking of having two boxes side by side, one to hold the heater and the other to use the vacuum.
then have a flip over frame to hold the plastic.
heat it over one box and then flip it over to be moulded.

might work? more likely no knowing my luck

Tony B wrote:
for the vacuum former i am thinking of having two boxes side by side, one to hold the heater and the other to use the vacuum.
then have a flip over frame to hold the plastic.
heat it over one box and then flip it over to be moulded.

Check out youtube mate. Lots of ideas on there. Your idea is featured on quite a few of them ( as is the 'oven plunge' method that I'm currently using.) Was thinking the same way as you but not got a suitable heating element yet.

i have an electric panini heater that i use for normal moulding, will fit that in the second box....... i hope

Watching this with interest Tony. I want to build a vacuum former sometime this year so thanks for leading the way.

I've been using my home made vacu-forming box for many years. It's takes some practice to know when the plastic is soft enough. I started out using the sheet frame in the oven which works quite well. I also found I could heat the plastic just fine over an electric stove. I made my vacuum box from some pine and used perforated sheet metal for the platform. The sheet metal is more expensive than peg board but produces much better results. More holes reduces the webbing.

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I would suggest not planning to flip the frame over. If the plastic (petg) is soft enough, it will sag and try to fold as it goes vertical. It is very important to drop the frame slowly and without twisting.

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I've used many of the methods for vacu-forming

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Anytime I get a canopy or a wheel well from a kit, I make a mold from it by pouring plaster of Paris into it before I cut it out. The plaster makes excellent forms to reproduce canopies, etc. It is best to elevate any mold by gluing a 4-6mm sheet of wood cut to the approximate shape of the mold. This gives you room to cut the part out with scissors or dremel.

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Thanks for the info.
i will look out for some perforated metal sheet.

I'm still experimenting myself, just drilled holes in a bit of ply for this first one for the simple fact that it's what I had kicking around at the time. I think it was 3mm holes at about 1" spacings. sealed between the frame and bed with self adhesive draught excluder in a bid to make it airtight(ish).
All the joints of the box are sealed with silicone bathroom sealant.

Hmmm, think the picture filesize might have been too big. wouldn't insert or even add to the post as an attachment.

Just thinking back I worked for awhile for firm that produced vacuum formed signs They laid in the bottom of the formbox different patterns depending on what background was wanted. Expanded ali and wire gauze were most common. after plain sheet with a double row of holes round the edges.If any of this is any help experiment and see .John

Dunno where the pictures went.


liquid latex and plugs.

start painting the latex on.



15 coats later.



now i leave to fully set over night and tomorrow i will pull the plugs out................ i hope

well i took a deep breath and eased the first mould off of the plug.


not too shabby, all the frames have worked ok.

nose cone



main canopy.


Now i can play with making plaster males for vacuum forming from.