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Vacuum Mold Help

Old 10-23-2011, 04:51 PM
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Mustang Mike
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Default Vacuum Mold Help

Hi all,
I am toying with the idea of getting into vacuum molding and I am trying to figure out what the best foam is to use to make plugs and where it can be purchased. All suggestions are greatly appreciated!
Old 10-24-2011, 01:05 PM
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Campy
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Default RE: Vacuum Mold Help


ORIGINAL: Mustang Mike

Hi all,
I am toying with the idea of getting into vacuum molding and I am trying to figure out what the best foam is to use to make plugs and where it can be purchased. All suggestions are greatly appreciated!
DO NOT use foam for your plugs - use wood. "Ideally" it should be yellow pine, however, I have used regular pine, oak and even balsa (for smaller parts).
Old 10-24-2011, 02:20 PM
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Chad Veich
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Default RE: Vacuum Mold Help

The best "foam" would be something like Renshape which is a very dense foam type material for prototyping. Very expensive but is fantastic stuff to sand and carve and can be finished to a near perfect surface. It's kind of like working with a slab of Bondo really. However, due to the exhorbitant cost of Renshape I generally end up using Medium Density Fiberboard (MDF) which carves and sands nicely and does not have any grain to fill. In most cases the MDF will work raw, ie, does not need to have any finish put on it. It's a really cheap alternative that works great for 90% of the pugs I make.
Old 10-25-2011, 12:57 PM
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Mustang Mike
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Default RE: Vacuum Mold Help

Thank y'all for the suggestions.  The wood is a nice suggestion but I am really wanting to use foam and coat it with FG/epoxy and then fill the gaps with something in the bondo category.  Also, the plugs don't need to be very durable because I will more than likely use the mold until I get one good final product and then let it gather dust.
Old 10-25-2011, 07:41 PM
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Chad Veich
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Default RE: Vacuum Mold Help

If you just want a quick and dirty "one shot" kind of plug then you may look into the foam used by florists. It's the stuff they stick artificial flowers into for making arrangements. Most craft stores carry it. I think it is a urethane type foam which is relatively dense and sands and carves very nicely. It can also be glued together with instant adhesives without melting into a puddle and will take epoxy resin and Bondo with no problems.
Old 10-25-2011, 08:48 PM
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Default RE: Vacuum Mold Help

High Density Urethane works well, Find a sign shop that does dimensional signs and get cut off pieces Comes in 1",1'5" and 2" .  It cuts, sands and carves easily, glue to make larger pieces with epoxy or gorilla glue.

It is 2-400.00 per 4x8 sheet, but there are always cut off oddbal size that they would part with.

For quick forms I just smear vaseline over the raw foam, and vacuum styrene over it, If you are doing a clear canopy, you will have to prime , sand and make a perfect surface, but white styrene is more forgiving than clear.

I f you have trouble finding it, PM me and let me know what size you would like.
ED
Old 10-25-2011, 08:54 PM
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Default RE: Vacuum Mold Help

There are a LOT of good how to videos on you tube. I experimented some with some clark foam. I had an old sailbord I cut up, The foam was great to work with, but after glassing and filling it..I still kept running into heat damage on the plug.. it was pretty disappointing, I would definitely start using wood from here on out...
Old 10-25-2011, 09:18 PM
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Default RE: Vacuum Mold Help

One more vote for wood.....from experiance....
Old 10-26-2011, 06:14 PM
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Mustang Mike
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Default RE: Vacuum Mold Help

I love the idea of wood, but I'm working on a bench that I've built in my college apartment and I don't have a shop.  Space is fairly limited and I don't really have the room required to work with wood.  I'm assuming that you would have to begin by shaping the general form with a band saw? What other tools and equipment would be handy to shape the wood?
Old 10-27-2011, 04:35 AM
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Default RE: Vacuum Mold Help


ORIGINAL: foodstick

There are a LOT of good how to videos on you tube. I experimented some with some clark foam. I had an old sailbord I cut up, The foam was great to work with, but after glassing and filling it..I still kept running into heat damage on the plug.. it was pretty disappointing, I would definitely start using wood from here on out...

One of the first big plugs I made was shaped out of regular white foam, then epoxy glassed, when I pulled the first canopy it collapsed in a little [:@],
What I did is take acetone and melt away the foam, then I filled the plug with plaster-of-Paris. Plug was solid as a rock then

good luck
Old 10-27-2011, 07:09 AM
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Default RE: Vacuum Mold Help

Great tip.
Old 10-27-2011, 07:15 AM
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Default RE: Vacuum Mold Help

You don't have to use power tools to shape the wood. A hacksaw and a sharp carving knife should get the shape done, the the right grades of sandpaper.

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