rotisserie mud method?

[jimmyfu]

ok, so, i got this crazy idea while i was sitting in class earlier. and it's probably pretty dumb, and not even worth the effort. hell, it might not even work, since i haven't worked with bondo or mud yet. but it's worth a try?

so, with hollow round pep pieces, such as the shins and forearms, it's tough to get them to be totally round-smooth and even. most of the time, i see people's pep armor, you can still see distinct lines, even though they shouldn't be there. so, here's my idea:

how about making a rotisserie type machine, and "skewer" the piece through it? then, while it's revolving slowly, just slowly dump mud onto it? it'd kind of be like centrifugal, except it'd be drying on the outside. and perhaps dripping could be avoided if it's at a slow enough pace, but at a pace fast enough for it to just spread all around evenly.

just a thought

 

[Sean Bradley]

Good idea, so good that it's been in use for a long time. Known as 'rotational casting", or 'rotocasting' for short, many, many indistries use this, and it is widely used in armor making. Nightmare Armor uses this, as well as several others. Theres even a special type of resin for this method, make to cure evenly.

The difference of course is that you're talkign about coating the outside of something rather than the inside of a mold, but in practice it's about the same thing.

The problem with doing this with your Bondo/Resin mud is that polyester resin cures by a slow thermal reaction, meaning that as it cures it gives off heat that slowly helps the rest of the material cure. Rotating Mud would cure unevenly, and would potentially lump up in masses of warm curing material as it hardens. Roto casting resins cure faster, so that the material flash-cures while it's still clinging to the walls of the mold.

But for rotocasting it's better to use one of the urethane resins that is specially formulated to cure evenly as it rotates. See 'Smooth Cast Roto' here: http://tb.smodev.com/tb/uploads/Smooth-Cast_Roto.pdf

and here:

http://www.smooth-on.com/liqplas.htm

and here for some notes on process:

http://www.smooth-on.com/howto7.htm