BigFish1973 Posted March 29, 2018 Report Share Posted March 29, 2018 My molds are turning out parts that are different sizes. It doesn't make any sense to me why my part pattern size is 0.62 thickness but I demold some that's thinner than that? Also I get some thats wider also. Am I missing something here? I use alumifoam to pour my molds. TIA Quote Link to comment Share on other sites More sharing options...
woodieb8 Posted March 29, 2018 Report Share Posted March 29, 2018 hi welcome. do you use a rtv mold? sounds like a mold box not secure. foams create expansion. if its not held back it will warp castings. .make sure your vent holes are sufficient also. 1 Quote Link to comment Share on other sites More sharing options...
BigFish1973 Posted March 29, 2018 Author Report Share Posted March 29, 2018 2 hours ago, woodieb8 said: hi welcome. do you use a rtv mold? sounds like a mold box not secure. foams create expansion. if its not held back it will warp castings. .make sure your vent holes are sufficient also. Thanks, I use the high strength 1 rubber from alumilite. I clamp them together with grip tight clamps. Quote Link to comment Share on other sites More sharing options...
Anglinarcher Posted March 29, 2018 Report Share Posted March 29, 2018 14 hours ago, BigFish1973 said: I demold some that's thinner than that? The Alumifoam is an aggressive expander. But, you have done well in choosing HS1 and by clamping the mold. My thoughts are that if the part is "thinner" thaa it is your clamping method. I make my mold walls pretty thick when I am doing a mold where I will be using Alumifoam. The proper way to clamp it is to put a piece of wood (plywood or similar) on each side. Clamp the mold between the plywood. I can use Alumifoam and get extremely consistent results using HS2 if I clamp it using the wood on the sides, then clamping it just enough to keep the mold closed and tight, but not enough to crush the mold. By going to HS1 or Quickset, I get more ability to clamp down without crushing the mold (thinner pieces) or getting Alumifoam deformation. My go to is PLAT 55 for a really good Alumifoam mold. I hope I explained this well enough. If the piece was thicker, than the vent holes would be suspect or we would need more aggressive clamping. But, the key word I read was thinner pieces were coming out. Let me know if that is not clear enough or we need to try something else. Quote Link to comment Share on other sites More sharing options...
BigFish1973 Posted March 30, 2018 Author Report Share Posted March 30, 2018 Thank you! Yes the answer was clamp pressure. When I claim real tight I turn out slightly thinner bodies (Which I like). So I will just continue to clamp tight. 1 Quote Link to comment Share on other sites More sharing options...
Anglinarcher Posted March 30, 2018 Report Share Posted March 30, 2018 Sounds good. Glad it worked out for you. Quote Link to comment Share on other sites More sharing options...
