Foam?

Got a question about techniques, materials or other aspects of physically building a model? This is the place to ask.

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karim
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Post by karim »

kerick wrote:Has anyone ever tried turning a foam shape on a lathe? I want to make a round fuselage shape like the space ark or Mercury 9.
I have done this with great success. The trick with turning the blue or pink foan on a lathe is to run a bolt or screw through the piece of foam, and chuck that up. The even more important trick is do Not use a cutter or tool on the foam while turning it. Use sandpaper. Anything else will tear out chunks of the foam and make you cry.

This is a very useful trick for making hollow shapes, as after you've shaped the foam, cover it with thin epoxy putty, then dissolve the foam out with MEK or other solvent.
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AbsoluteSciFi
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Post by AbsoluteSciFi »

karim wrote:
kerick wrote:Has anyone ever tried turning a foam shape on a lathe? I want to make a round fuselage shape like the space ark or Mercury 9.
I have done this with great success. The trick with turning the blue or pink foam on a lathe is to run a bolt or screw through the piece of foam, and chuck that up. The even more important trick is do Not use a cutter or tool on the foam while turning it. Use sandpaper. Anything else will tear out chunks of the foam and make you cry.

This is a very useful trick for making hollow shapes, as after you've shaped the foam, cover it with thin epoxy putty, then dissolve the foam out with MEK or other solvent.
This is very good advice! BUT: BE WARNED: MEK is a very nasty chemical, and dissolving foam should be done outside, with a fan to boot. Epoxie putty is good, so is a layer of thick resin, but be sure to seal the foam first. Do any sanding or cutting BEFORE dissolving the foam inside. You do not want the grinding and force of your blades to crack the shell. After the foam is gone, rinse the shell out with hot soapy water, to remove anything left behind.
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karim
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Post by karim »

AbsoluteSciFi wrote:
karim wrote:
kerick wrote:Has anyone ever tried turning a foam shape on a lathe? I want to make a round fuselage shape like the space ark or Mercury 9.
I have done this with great success. The trick with turning the blue or pink foam on a lathe is to run a bolt or screw through the piece of foam, and chuck that up. The even more important trick is do Not use a cutter or tool on the foam while turning it. Use sandpaper. Anything else will tear out chunks of the foam and make you cry.

This is a very useful trick for making hollow shapes, as after you've shaped the foam, cover it with thin epoxy putty, then dissolve the foam out with MEK or other solvent.
This is very good advice! BUT: BE WARNED: MEK is a very nasty chemical, and dissolving foam should be done outside, with a fan to boot. Epoxie putty is good, so is a layer of thick resin, but be sure to seal the foam first. Do any sanding or cutting BEFORE dissolving the foam inside. You do not want the grinding and force of your blades to crack the shell. After the foam is gone, rinse the shell out with hot soapy water, to remove anything left behind.
Quite Right!! I should have said so. Thanks for the catch.
kerick
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Post by kerick »

I may try the foam with a rod through the middle and chuck it in a variable speed drill. I'll place it in a jig to hold the drill and the free end. The project wouldn't be all that big, 12" x 3" or so. Lots of great help here, thanks a lot!!
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Jon Kunatz
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Post by Jon Kunatz »

Has anyone ever tried sealing the foam with Durhams water putty?...or will that not work?
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Post by DaveVan »

Balsa foam is what I use. Bought it last from Dick Blick art supply. Good stuff.
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Post by dizzyfugu »

Floral foam is a PITA. It tends to be VERY brittle (getting worse if the stuff ages or is exposed to sunlight for some time), very touchy, and it is designed to soak up ANYTHING, thoroughly, so that surface work is rather cruel.

Construction foam (the expanding stuff) is "better" as it - once it hardens - is easy to cut, it has a stable surface, is light and pretty stable. The DOWNSIDE is how to apply it, though... If you want to create a certain shape, forget it, as is expands enormously. It's also sticky - anything it gets into contact with adheres, and you have a hard time cleaning that surface. There are some special cleaners/solvents, but it is MESSY! Some people try to tame/direct the stuff with plastic bags, but I do not subscribe to that. It's an option for quick and vast diorama landscapes, or if you want to change your living room into an Alien lair...
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