While building the drum robot MR-808 I came across some nice prototyping techniques. Ever wondered what you can do with an unused pizza oven, a vacuum cleaner and some plastic sheets? It’s not rocket science – prepare for vacuum molding! (could also be used to build a rocket)
The aim is to shape boxes, bended surfaces and other things like masks or in our case huge TR-808 style buttons from a form, the so called “original mold”.
What do we need?
- Unused pizza oven
- Polysterol: a plastic sheet material 0,5-2mm that gets soft when warmed and grows stiff when cooling. Link to the seller Modulor; More about polysterol (german)
- Some wodden frame and a tacker
- Vacuum cleaner
- A Box and some (wodden) sheet to drill holes inside.
- Original form / mold: the form you want to replicate, e.g. a mask
And this is how it works:
The plastic sheet, fixed on the frame, is heated in the oven at 200-250°C until it gets so warm that it hangs loose in the frame.
The original Mold is placed in the vacuum box. Get the polysterol frame out of the oven and put it over the original form. It is sucked by the vacuum and is immediately cool. Remove and repeat.
The original form:
The frame in the oven:
The original form can be made of wood, of even softer material like modeling foam. When you have sharp edges inside, it is a good idea to drill holes through the form in the direction if the vacuum table to let the vacuum reach also distant areas of the original form.
Fix the sheet on the frame with more tacker needles than you think you need. When the polysterol starts to warm up it will need a lot of hold from the framesides.
The warming in the oven may take up to 15 minutes per sheet. Make sure that the polysterol is really soft enough before you get it out.
Polysterol can easily be painted, sanded, heated again with a heatgun or glued together. For stiffer cases you can also stick some molded polysterol pieces inside each other to increase the wall thickness.
Take polysterol cheet with a thickness of 0,5 to 2mm. The thickness will even decrease when the modling process starts, so everything below 0,5mm may start to break apart. When you have a wall thickness that is too high it takes to long to warm the whole thing.
Another nice tutorial from makeprojects