I was watching a tv commercial on expanding spray foam house insulation today and it got me to thinking whether that might be a good way to make a mold to use in a duplicating machine to make a semi inletted stock.

One could put the action in a square wood form and then spray in the foam, which would surround the action perfectly, thereby producing a mold from which to inlet a stock with a duplicator.

Anybody try it, or any other type of mold making product for this purpose?

The spray can foam has poor strength and does not cure in thick cross sections.
The two part is better and can be had in a range of density, higher the density the stronger it is and gives a smoother finish.

I don't know if it's available to individuals but when setting up NC milling machines it's common to mill a practice part out a dense foam. It can even me measured using a CMM.

But as I said I have no idea how to go about getting some but it would surly be dense enough to use on a stock duplicator.

To make a splash of the action and/or barrel for inletting patterns and similar tasks in another industry I have used bedding compound, cabosil filled epoxy, plaster of Paris, and this facsimile material. http://www.flexbar.com/shop/pc/Facsimile-d12.htm


Each has its own advantages/disadvantages and all require a thorough job of applying tape, putty and release agent to prevent locking the action into the splash or damaging the splash during removal.

Plaster is the cheapest but is the least durable. It has moisture issues to deal with and not perfectly dimensionally stable but good enough for a one time inletting pattern

Bedding compound and filled epoxy are durable and stable but take most of a day to cure.

The facsimile material cures in less than 10 minutes and is durable enough to use for a repetive pattern if supported by the wood box or form as mentioned by the OP. But it is expensive.

quote:

Originally posted by Cougarz:
I don't know if it's available to individuals but when setting up NC milling machines it's common to mill a practice part out a dense foam. It can even me measured using a CMM.

But as I said I have no idea how to go about getting some but it would surly be dense enough to use on a stock duplicator.

Do you mean dense foam as in RenShape type material? If so, I have seen it for sale on ebay. I have used cutoff pieces for model projects. It is great for machining and working by hand.

That may be it?

You can order 4lb density foam in two quart and two gallon kits, from most taxidermy supply companies. Like McKenzie.
It must be poured into a mould that is rigid and keeps pressure on it while it hardens. Otherwise it won't be as dense or cure properly.
I use it very often in my taxidermy shop to alter and make manikins.

For a complete stock shape could you use Formular (XPS) board. Hog it out and then just use glass bedding.

quote:

Originally posted by lindy2:
I was watching a tv commercial on expanding spray foam house insulation today and it got me to thinking whether that might be a good way to make a mold to use in a duplicating machine to make a semi inletted stock.

One could put the action in a square wood form and then spray in the foam, which would surround the action perfectly, thereby producing a mold from which to inlet a stock with a duplicator.

Anybody try it, or any other type of mold making product for this purpose?

Yes do not use that spray foam for residential use. It is unpredictable densness and degrades fairly easy.