Vacuum forming a helmet

Research into the type of helmet that you wish to produce. We are wanting to reproduce a fiberglass Brodie helmet and so the first stage is to make a vacuum form mould to fiberglass into. A Brody helmet is a steel combat helmet that was designed and patented by Briton John Leopld Brodie; giving it its name. A typical Brodie helmet looks like this.

The first stage in creating this is to get the correct dimensions of the hat. Then create a template out of foam-core (making sure that it only is of the circumference and half of the helmet). This needs to be attached to a piece of dowel that will stand in the middle of the helmet. This is also attached to a base piece of MDF. The piece of dowel needs to be able to move fairly freely and so do not glue it down to the base piece but slot it into another piece of wood with a hole in it, and then glue this down to the piece of MDF. When everything is attached together it is then time to start filling in the space with plaster. Mix the powder with water and make sure that you work fast as it sets fairly quickly. When adding more plaster into the helmet space make sure that you spin the template round so that it forms the right shape. Once you have enough plaster to fill the helmet shape you can then remove the piece of dowel and the template. It is important to do this before it sets. You then leave it to dry.

There will be a hole running through the middle of the plaster from where the dowel is. This will need to be patched up with a bit of poly-filler when the plaster has set. It is then ready to be vacuum formed.

To vacuum form you have to place the plaster onto the vacuum former and lower the level. Then place the sheet of plastic on top and pull the heater over it. Wait a few moments until the piece of plastic has melted and come away from the sides of the machine. Push the heater away from the plastic and then raise the level so that it is pushing through the plastic. Turn the vacuum on so that the plastic I pulled tight against the mold. Release it and then wait until the plastic has turned solid again. You can then release the plastic from the mould.

You then need to cut the plastic to shape using a hack saw and then sand it so it is nice and smooth.