[jerryrig]

has any one tried to use pewter in a bi axial rotational moulding machine?

[under-dog]

It is standardly done on a single axis rotational centrifical..... "spin cast"

[jerryrig]

spin casting can't make sphere's,
have a bi axial roto machine but it's not working very well

[under-dog]

I have never had any issue making spheres or any other shape for that matter with traditional methods.

Every costume jewelry mfg. and pewter figurine mfg. uses spin casting and the shapes are nearly limitless that can be acieved. Pretty much, the only limitations, like most molding and casting, are minimal thicknesses and undercuts.

Even so the rubber molds used in spin casting are very forgiving to undercuts.


What sort of issues are you getting. Cavity pack out?.....

Shrinkage is always an issue too so a perfect sphere will usually not be mathematically perfect but to the eye it should be fine. This is usually acceptable for pewter based products anyways.



From what I know multi axis rotational molding is for hollow cored items with full under cut. Rubber doll heads and things of that nature.

[jerryrig]

yeah sorry should have said, trying to make a 300mm hollow sphere with a thin wall

[under-dog]

I have never seen it done. I have been working in pewter for over 16 years.

The metal cools fast and solidifies. Much quicker than a plastic I think.

Let me know how it goes though. You never know maybe noone has ever tried it. Typipically for a hollow sphere it is done in 2 halves and assembled

[High Seas]

That the project is pewter - its probably ornamental or at least not structural? Could a plastic/resin casting be a possible solution?

Adding the metal powders make it a "cold cast" and give quite a bit of weight to the project. I've used the bronze fillers. Haven't checked if Pewter is available.

As I recall there is an art supply shop in Auckland (the big smoke) that carried some of these products:
http://www.smooth-on.com/casting.htm

maybe didn't answer the question - but a different/alternate approach if the planned approach is too hard to do.

BTW -- I've hand "spun" cast these resins to a 1.5mm shell.
:cheers: Jim