Vacuum forming on the cheap

[dtomko]

I've had to do a lot of vacuum forming on the Energia/Buran I'm working on. I got this idea from an article in FineScale Modeler about a year or so ago. It's very simple and very cheap. I got a Rubbermaid container and drilled a bunch of holes in the lid. Then, I cut out a hole in the side for our vacuum hose. I made a lip on the lid from squished masking tape. The frame is from scrap wood and the clips are heavy duty paper clips. Here are the parts.
Drew Tomko

 

[dtomko]

Here's a shot of the vacuum hose hole. Electrical tape makes the seal,
DT

 

[dtomko]

Here's a piece of styrene sheet attached with the clips. I hold the frame with a pair of insulated pliers over a stove burner until it sags. Then I flip it onto the Rubbermaid former and hit the vacuum. It works great; the styrene really pulls down tightly and I'm using an ordinary Panasonic canister vacuum.
DT

 

[n3tjm]

What do you use as a heat source to melt the plastic?

 

[dtomko]

Here's an example of one of the Energia strap on front parachute packs right off the former. I'm not sure you can see it in the photo, but it pulled so tightly that it made the tube spiral line in the .020" styrene! I was using a piece of BT-50 as the outer shell of the master. One issue is the odor; the fumes from heated styrene are intense. I only did this when the family was out and I could open up the house. Also, the master needs to be solid and strong. Mine, made out of balsa, body putty and body tube, didn't last very long before they started curling and breaking. For the Buran I may try a harder wood and carve a master, or else cast a resin master first. At any rate, the whole thing cost me little more than a couple of dollars. 4 sheets of Evergreen styrene at my local hobby shop are about $2.25. The parts are very lightweight and strong.
DT

 

[dtomko]

The heat source is my kitchen stove. I hold the sheet in the frame over an electric burner for about a minute until the plastic sags. Actually, it sags quickly, then contracts. When it sags the second time it's ready.
DT

 

[Silverleaf]

Drew,

Woah - thats cool.

So, the soft plastic is pulled down through the holes by the vacuum - how do you know when enough time has elapsed to turn off the suction ?

How do you attach the master mold in the container ?

I'm not familar with vacu-forming, so heres a stupid question:

Would a set of identical sized holes be better on the lid - for a better flow I mean ?, and what size did you make yours ?

I'd guess too big wouldn't allow the vacuum to work properly, too small not enough.

Thanks Drew, your pics explain it perfectly. 8)

I'm going to start saving and see what I can do about getting an alumilite kit for the Shuttle project...who knows, if the finished model using the Squish method is light enough, I might be able to avoid vacuum forming. My luck says it won't though. lol

Cheers,

 

[dtomko]

R.S.,
The vacuum "pull" is a very quick event. I makes a plop noise and it's done. I mean it's almost instantaneous when the soft plastic gets close enough to the former. I leave the vacuum on for maybe 10 - 15 seconds; the plastic cools quickly. I just hold the frame with a pair of pliers and place it on top of the master; the vacuum does the rest.
From what I've read and done, the spacing of the holes doesn't need to be precise. I think I used a 1/16" drill bit. You just want a lot of holes so you get suction all around your master. Mine are done at random, as evenly spaced as I could eyeball. The master I held on with masking tape doubled over. Just make sure it doesn't wobble.
This was my first attempt at vacuum forming and I was really surprised at how easily it went.
DT

 

[Silverleaf]

Drew,

Ahh, that explains it !

Ok, I've saved this thread just in case my Alumilite plans fall through. I'm trying to be as frugal as possible as it stands, but it looks like between your setup and Alumilite's - the possibilities of a couple cloned shuttles might happen - we shall see.

Ah well, I got plenty of time to do this project..I better get back to the Shuttle model - she's calling to me - crying she's naked and needed some weathering. lol

Thanks for the very informative post, 8)

Cheers,

 

[sandman]

That looks neat.

I think I might have had better luck by using a homemade unit.

The unit I tried to use was a little "extreme". I'll try to take pictures of it to show you.

sandmsn

 

[dtomko]

Among the advantages of a homemade unit is that you can make the vacuum forming base almost any size you want. I suspect a really big base would require a heavy duty vacuum, but if you have a shop vac you're probably fine. Mine is about 4" x 5" so I can cut each Evergreen sheet in half. The suction on mine is really strong, so I'm sure I could use a larger base. And Rubbermaid containers or the knock-offs come in a bunch of different sizes. When I do another one I'll use thick styrene strips to make a lip instead of just masking tape.
DT