Introduction

I have always been fond of 3d printing not merely as a way to produce an end result but to create models that would act as an in-between step in order to create something else. Therefore I wanted to explore the technique of vacuum forming. We don’t have a vacuum former in the lab at de Waag but, according to many people on youtube, it shouldn’t be too hard to make your own. I was particularly inspired by the instructions from the Punished Props channel.

If it all works I want to use this method to perhaps make molds from 3d printed objects for casting.

Make

The DIY vacuum former is basically a wooden box with lots of holes on top and a large hole on the side for a vacuum cleaner. A plastic sheet is heated up in an oven to get it to deform and when it deforms it is quickly placed on an object that is placed on the top of the box.

Bill of materials

For the box and frame:

For the vacuum forming I used:

• NiceDay overhead transparencies of unknown material. (Spoiler: it didn’t work)
• paper binder clips

Tools

To make the box and the frame I used:

• Jigsaw
• Disc sander
• 3mm drill with countersink attachment
• 2mm drill
• hacksaw

For the vacuum forming process itself I used a snack-toaster I had lying around to eventually use as a reflow soldering oven and a cheap shop-vacuum cleaner.

Design

Even though the design is very simple, I still took the time to draw the box and the frame in Fusion360, because I don’t trust myself when it comes to accurate dimensions. The size of the box was based on the size of the frame, which was based on the size of the snack-toaster oven. The height of the box was based on the type of spruce wooden plank I procured.

The size of the grill that came with the toaster oven was helpful for determining the dimensions of the box.

First a hand drawn sketch.	Also in fusion, to be sure to get the dimensions right,

The dimensions of the box and frame

For the holes on the of of the box I needed a template.

I used Rhino to make and print the template for the holes

The density of holes is high because I figured that many holes would distribute the vacuum more evenly, preventing molten plastic from being sucked in the holes.

Production

Making the box was basically an entire Sunday of measuring, marking, sawing, drilling, screwing, kitting and testing.

The entire box was made of spruce wood planks, cut to size

All the box parts were screwed together. The seams were coated with a thick layer of silicone kit to prevent air from leaking through any gaps and diminishing the vacuum.

A hole was made on the side to snugly fit the end of the vacuum cleaner

To better fit the vacuum hose I wrapped it in duct-tape	Quickly testing the vacuum. A piece of paper was sucked to the surface so effectively I could pull on it horizontally and drag the box along

A double frame was made to hold a sheet of plastic in the oven.

Aluminum angle profiles were marked and cut to size	Metal angle pieces were used to create a frame

Results

After finishing the frame and the box it wad ready for testing.

Using overhead transparencies

Putting the plastic in the oven. I moved the whole setup outside as to not inhale any toxic vapours coming from the plastic

The instructions told me to wait until the plastic started to sag in the oven. I gambled on using overhead transparencies because these are so widely available. It turned out these were of the wrong kind of plastic that is not thermo-deformable at all.

The plastic I used shrunk, got holes and deformed irregularly. Eventually it git brittle and started to crack. Overhead transperencies are definitely not the correct material to use for vacuum forming.

I am going to acquire plastic materials that will deform properly when heated. Probably polypropylene.

Using Aluminum foil

Still, I have great confidence in this setup. I tested it with some aluminum foil and, although it didn’t give as good a result as with proper plastic, I could clearly see great detail in the result. Even some of the layer lines of the 3d print were indented in the foil.

Using Polypropylene

Eventually I bought a large sheet of polypropylene.

I cut a piece to size and clipped in in the frame	It fit neatly in the oven

It turns out the material melts way faster than I expected.

I was faster at the second try.

Files

• Template for holes in Rhino
• Fusion360 design
• Magic fish