I am currently working on a pep sniper rifle and i was thinking of filling it with expandable foam you can buy from Lowes. I am not going to be using resin for support instead im thinking of using a wooden skeleton and filling the cracks with the foam. But the question i have is will expandable foam work and if anyone has used it before how strong is it? If you know a better way to do it your advice would be greatly appreciated.
Expandable Foam
- Thread starter Donphan99
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People ask this a lot. Read this post... http://405th.com/forums/index.php?showtopic=23995
I generally don't advise it. Trying to use a cheaper alternative to the already cheap alternative is just setting yourself up for failure. Maybe use Aqua Resin if you have some issue with the toxicity/fumes of regular resin.
I generally don't advise it. Trying to use a cheaper alternative to the already cheap alternative is just setting yourself up for failure. Maybe use Aqua Resin if you have some issue with the toxicity/fumes of regular resin.
Propbuilder
New Member
I would also not use it as it could expand the parts and distort the final product maybe a ridged plastic with airacell (micro balloons)to reduce the weight if you really think you need to fill the space.
Like my other borhters here have said..this isn't the way to go. The epanding foam will exapand in ALL directions until it hits an obstacle. If you are injecting it into a Pepped piece that has not been reinforced, once the back pressure hits the injection opening the expanding foam will create pressure in all directions as it tries to meet its maximum expansion and seep out the injection opening. The resulting pressure will distort and pop your pepped seams. Also some expanding foams do not like curing large masses in an enclosed space and the interior goo may not set up as many need air exposure to cure.
Now if you split your model in half and use a small amount of expanding foam to fill the two sides, you might be able to create a two part model. You would then join the split halves back together to make one solid piece. If you try this method I would recommend applying the foam in small batches and building it up into the split halves.
Now if you split your model in half and use a small amount of expanding foam to fill the two sides, you might be able to create a two part model. You would then join the split halves back together to make one solid piece. If you try this method I would recommend applying the foam in small batches and building it up into the split halves.
XxCALIBERxX
Member
I was using expanding foam not to long ago, and in my opinion i reckon it could work, if you reinforce the pep peice with resin (prob 3 layers, dnt cheap out on it or your model will explode, 4 maybe would be better), and then drill maybe two or three holes in the model to allow an exit for the foam, then when its hard, cut the expanding foam that leaked out flush with the model and bondo or resin over the top of it...
I reckon a wooden model would probably work better however.... Just my opinion.
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Cheers, Dave.
I reckon a wooden model would probably work better however.... Just my opinion.
.Cheers, Dave.
You can follow my results here: http://405th.com/forums/index.php?showtopic=22686&st=20
I used the spray foam from the can. It has a reaction coming out of the can that kind of locks it into the "Wormish" shape. There is a two part chemical that you could buy that is in pure liquid form. It will prevent the worming effect however it takes a very long time to cure and sometimes, depending on the size of the piece it may never dry. There is also pressure placed on the sides of the mold so there is some deforming. YOu can prevent this by using plaster molds but by the time you go through all this trouble to do it right, and wait for it to dry, you could have resined a piece, glassed it twice, and started on the bondo phase, if not already completed the bondo!
Take it from me I have tried it just to test the point and I failed miserably...!
I used the spray foam from the can. It has a reaction coming out of the can that kind of locks it into the "Wormish" shape. There is a two part chemical that you could buy that is in pure liquid form. It will prevent the worming effect however it takes a very long time to cure and sometimes, depending on the size of the piece it may never dry. There is also pressure placed on the sides of the mold so there is some deforming. YOu can prevent this by using plaster molds but by the time you go through all this trouble to do it right, and wait for it to dry, you could have resined a piece, glassed it twice, and started on the bondo phase, if not already completed the bondo!
Take it from me I have tried it just to test the point and I failed miserably...!
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