Walkthrough – Build Your Own Vacuum Former
Article by Dr Bish (theKillingDoll) posted Tuesday 14th August 2012
This is a brief outline of how to construct a cheap vacuum-forming machine and use it to vacform plastazote, the results of which can be seen in parts of my Priss Asagiri hardsuit.
In recent years plastazote has become an increasing popular material to use in costumes, particularly as a base for armour. Plastazote is relatively cheap, lightweight, flexible and robust as well as being easy to cut and glue (using a contact adhesive). Although most commonly available in 6mm sheets in black or white, it is possible to purchase it in a variety of colours and thicknesses.
One of the most interesting properties of plastazote is the ability to heat mould it. Using a heat gun, it is possible to heat it up and bend or mould it around objects and once cooled it will retain this shape. While basic moulding satisfied me to start with, I gradually wanted more complex shapes which are incredibly difficult to achieve. One good example is a shoulder pauldron. Attempts to mould plastazote into an even domed shape usually results in an uneven, wavy edge dome peppered with overlapping folds.
This tutorial will explain how to create a very cheap piece of equipment to enable you to vacuum form plastazote allowing you to create intricate 3-dimentional pieces.
To be able to build the vacformer and use it you will need the following:
- One air tight clip-lock food container (the bigger the better)
- A drill
- A vacuum cleaner with hose attachment
- An oven
- A support – I used a strong cardboard tube like the ones at the core of cling film
- Plastacine or clay for your mould
To keep it simple and cheap I used the largest clip-lock, air tight container I could find that had a very flat top for the base of the vacformer (Fig 1). This one is a 6.2L container I purchased for around £6. It is essential that it is air tight and has a very flat top. Firstly, the plastazote needs to form a seal in order to create the vacuum to enable it to mould around the object. An uneven top will prevent this. Secondly, the plastazote will mould to the lid, so the flatter it is the better otherwise you will have the shape of the lid moulded in to your plastazote too.
Figure 1. Large clip lock food container.
A series of holes need to be drilled in to the lid. This sucks the air through the lid drawing the plastazote down around the object creating the shape. I drilled a small hole in the lid every 1 cm or so apart across the whole of the lid (fig 2). This will take a bit of time but more holes allows for a better seal and definition around the object. In this version I used two diameters of hole to experiment and found the smaller holes were better.
Figure 2. Holes drilled in to lid.
A larger hole also needs to be cut in to the side of the box (fig 3). This is where the vacuum cleaner nozzle attaches to the box to enable the air to be sucked out. This needs to be tight so don’t cut the hole too big. I drew a circle the size of the tip of the nozzle, drilled lots of little holes to cut it out and then sanded it to get the shape. The nozzles are usually tapered so it should wedge in there and create a seal. I also added a strong cardboard tube to support the centre of the lid inside the container (fig 3). During vacforming this will stop the lid from collapsing in under the force of the vacuum, keeping it flat and helping maintain the seal. This was cut to the depth of the container so when the lid it clipped on it is in contact. A thin wood block could also be used.
Figure 3. Vacuum nozzle hole and centre support.
Once these are done, clip the lid on and you are ready to vacform plastazote. The basic set up should look like this (fig 4).
Figure 4. Equipment set up.
The other piece of equipment required is an oven. This needs to be preheated to around gas mark 2-3 (around 120-150°C). Cut your piece of plastazote a little bigger than the area of the lid on the vacformer, so it can create a seal and stretch over your object you are moulding. On mine this is just smaller than the size of the oven which is handy. The plastazote will sit happily on the top shelf of the oven and take around 30-60 seconds to soften enough to vacform. You can usually see it become slightly shiny as it becomes ready to remove. Sometimes it may require a little longer depending on the thickness of the plastazote.
Once ready, use heat proof gloves to remove the plastazote, place it on the object which should be positioned in the centre of the vacformer and switch on your vacuum cleaner. Sometimes it will require a little help to form correctly around the object but it needs to be done quickly while the plastazote is still warm. I usually lightly trace around the object with my fingers to ensure the seal is formed. I also find it is useful if you have a second person (if available) to switch on the vacuum so you can concentrate on the plastazote moulding. So those pauldrons I talked about at the start came be seen in figure 5, and look much smoother and consistent.
Figure 5. Vacformed pauldrons.
There are some limits to what you can vacform, stuff too large or too deep will be problematic. However, I have used this to create some difficult or unusual shaped pieces in plastazote, such as the pauldrons (above), the air jets and the concave hip sections on Priss, which would have been really difficult to create any other way. To give you an idea of how complicated the shape can be and still moulded, figure 6 is a mould of a can of oil. The plastazote has formed well around the curved edges and the nozzle.
Figure 6. Can of oil and the corresponding mould in plastazote.
If it doesn’t form correctly first time then it is possible to put the plastazote back in the oven, heat it up and try again. However, each time you do this the plastazote becomes gradually thinner, so be aware of this. If you are only vacuum forming small objects then I found that it is possible to decrease the surface area of the vacformer using duct tape. This allows a smaller piece of plastazote to be used, so you are reducing waste, while still maintaining the seal (fig 7).
Figure 7. Decreasing the surface of the vacformer for smaller items.
To build this vacuum former cost around £6, but it performs really well using plastazote for objects up 18 x 14 cm, provided they are not too high. Unfortunately this setup does not really allow you to vacuum form styrene as this cannot simply be placed on the shelf in the oven like plastazote. However, I have successfully used it with a secondary rig which the styrene sits on while in the oven and is then flipped over to enable it to be vacformed on this system, but I am still perfecting this rig as it presented some problems on my first attempt so I may add this at a later stage once I have it right.
I hope you find this tutorial useful. Once you have built it then the best way to understand the finer points and to create some interesting shapes quickly, is to experiment. Have fun!