elkamino Posted June 5, 2008 Report Share Posted June 5, 2008 For anyone into vacuum forming I need your help. I have a pretty awesome set up for vacuum forming however, I still have trouble pulling the eye sockets on a helmet. I've drilled relief holes but the center points above the nose keep coming out weak. I have since gone to using a positive mold to push the eyes in but requires a two person operation. BTW..when I go back and heat it with a heat gun during suction, the pull actually gets worse. Any engineers have input? Quote Link to comment Share on other sites More sharing options...
Chefhawk[501st] Posted June 5, 2008 Report Share Posted June 5, 2008 Any chance of some pictures of what you are talking about to make things clearer??? cheers Quote Link to comment Share on other sites More sharing options...
elkamino Posted June 5, 2008 Author Report Share Posted June 5, 2008 In the center where the eyes come together, they never fully define leaving only a shallow recess where they come to a point. Sorry for the poor picture. Quote Link to comment Share on other sites More sharing options...
journeymanprotector Posted June 5, 2008 Report Share Posted June 5, 2008 I don't have experience vac-forming myself, but here's an idea if no one has a better one: Maybe put a relief hole in the center of that center area? It'll create a dimple, but you can fill the pulled piece with a tiny amount of bondo or something. If you plan to repaint the helmet, no one will notice. If you're not repainting it would be trickier, unless you could match a gloss white paint to it. Probably not incredibly helpful, but thought I'd throw it out there. Phil Quote Link to comment Share on other sites More sharing options...
elkamino Posted June 6, 2008 Author Report Share Posted June 6, 2008 I don't have experience vac-forming myself, but here's an idea if no one has a better one: Maybe put a relief hole in the center of that center area? It'll create a dimple, but you can fill the pulled piece with a tiny amount of bondo or something. If you plan to repaint the helmet, no one will notice. If you're not repainting it would be trickier, unless you could match a gloss white paint to it. Probably not incredibly helpful, but thought I'd throw it out there. Phil I am planning on using ABS so a filler would not work, however, the ABS does not show a dimple if I use up to a 3/32 drill bit. Not a bad suggestion Phil, thank you. Quote Link to comment Share on other sites More sharing options...
Chefhawk[501st] Posted June 6, 2008 Report Share Posted June 6, 2008 Sounds like your over heating the plastic and its stretching over that point. How do you judge temperature, is by time or by droop/sag? Also plastics like paint vary slightly , even from the same manufacturer. Try different times and compare the results. Also make the holes a touch bigger (eye sockets)toward the centre ridge. keep us posted. hope this helps cheers Quote Link to comment Share on other sites More sharing options...
elkamino Posted June 6, 2008 Author Report Share Posted June 6, 2008 I made some progress last night. I was actually under heating the plastic. As for judgment, I just eye up the sag for heating time. Right now I am testing using styrene which shouldn't pose as much of a problem as it is turning out to be. ABS and styrene are basically doing the same thing. I really think this is a engineering issue related to where and how large the relief vents are. It seems the smaller the relief vent the better the suction...I guess this relates to the equation PV=nRT.....man I should've paid more attention in class. Quote Link to comment Share on other sites More sharing options...
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