Rigid foam?

[takevin]

Im doing a rifle project, and am building the buck for it to be vacuum formed. Depending on the thickness of plastic i use, i figure using rigid foam would be the way to go to fill it for support correct? Im assuming a non expanding version would be the best? What type would be good for this and where to get? thanks :thumbsup

 

[jonny5]

Have you considered that expanding spray foam insulation ?

 

[TK1536]

Well, you'll need something very dense, like 12lb. polyurethane foam. It can hold up to the pressure and temperature of vac-forming, but it's not ideal for continual use. I'd only recommend doing it once or twice to get a good negative mold that you can fill with hydro-stone, which would be your buck.

I also recommend covering your foam sculpt with multiple layers of polyester resin to make a solid and smooth surface, not to mention stop all the sandy grit from getting on everything.

 

[Mike Rush]

I think Takevin was talking about filling his rifle once it's vacuformed.

It's true, if you used expanding foam you would run the risk of the foam expanding and distorting the plastic (unless you also make a negative mould in order to hold its shape). I've used 2-part expanding polyurethane quite succesfully, but always with a negative outside the plastic. Sorry if that doesn't help much.

 

[takevin]

I think Takevin was talking about filling his rifle once it's vacuformed.

It's true, if you used expanding foam you would run the risk of the foam expanding and distorting the plastic (unless you also make a negative mould in order to hold its shape). I've used 2-part expanding polyurethane quite succesfully, but always with a negative outside the plastic. Sorry if that doesn't help much.

sorry yes, i meant about filling the rifle once its vacuum formed.