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foam casting
timf - 8/12/03 at 03:38 PM

not sure where to post this

any one had any experience with the 2pk foam ? the chevy v8 lump is a bit heavy to keep pulling in and out so i may try making a foam pattern of it. any ideas how to produce a mould from the engine to do this.

Tim


chrisg - 8/12/03 at 06:57 PM

You wouldn't need to make a copy of the engine just the important points, the engine mounts and the gearbox flange, maybe the highest & widest point.

I've seen it done before with thin ply plates fixed to the engine mounts and flanges. these are held in place with a 1"x1" timber "skeleton" then a rough out line of the engine is made using cardboard and parcel tape.

The foam expands by about 10 times when mixed, don't try to do it in one, it bonds to it's self 100% so do it in small amounts.

When it's set you can carve it to exact shape if you need to, the cardboard usually bulges where it's not supported by the skeleton. Any missing bits can be added using a local mould.

Good Luck!!!

Cheers

Chris

[Edited on 8/12/03 by chrisg]


MustangSix - 9/12/03 at 02:48 AM

I got some parts sent to me packed in foam. They had wrapped the part in plastic wrap, put the part in a cardboard box, then filled the box with foam.

When I opened it up and extracted the part, it was a perfect mold of the part that could probably be used to produce a replica foam piece if I wanted to.

Maybe youcould do something similar. Wrpa the block in plastic, build a box around it, fill with foam, then use that for a mold.

[Edited on 9/12/03 by MustangSix]


Rorty - 9/12/03 at 04:53 AM

I've used slabs of polystyrene foam to cut sliced engine profiles from. The best bet is to use a hot wire. If you can't find one, make one from a length of tube (bent into a C), some fuse wire, and a transformer. The hot wire cuts through the foam like.....er.... a hot wire through foam.
I then glued the profiles together with PVA to produce a light weight "engine". It will last longer if you paint it with some sort of water based goo, like latex, or even acrylic paint.
Your local builders' yard should have broken slabs of foam which they're glad to get rid of. If they don't, then just break some yourself!