[rhino]

hi guys,

just wondering if its poossible to blow/vacuum mould rubber? i am trying to make some remote controlled (RC) 4x4 car tyres that are 10" O.D. x 5" I.D. x 3.5" wide, the tyre has to be atleast 5 mm thick(excluding the tread depth) when the moulding is complete.

tread depth is approx. 10mm (3/8") deep.

i have made a prototype out of steel and made a "plaster of paris" pattern from the casting, is this ok to use as a mould or do i have to make one out of steel? (probably would be more durable).

anyone who has done anything like this or just moulding rubber in general, give me some pointers?

RHINO.

[zigmart]

Go to smooth-on.com. You can make a mold out of rubber than cast rubber into it. Wont last too long, just depends on how many of the item you need. Perfect for prototyping before spending money on the steel mold. I have a friend that uses injection molding for silicon rubber.

[drcrash]

I'd think you could make a mold out of epoxy or some other resin, and cast rubber into it. That should be durable enough for a fair number of parts before making a new mold from the master---how many do you intend to make?

(Generally you want to cast hard things in flexible molds, but you can cast flexible things in hard molds, if the part is flexible enough to get it out.)

I wouldn't think that a functional tire would be a good candidate for vacuum forming, because it needs to have substantial thickness around 360 degrees, has little or no draft, and I'd assume it's double sided. You could probably manage it with a fair number of tricks (make two parts in negative molds, bond them, etc.) but it seems simpler and better to just cast rubber.