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fireone

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Is there anyone that uses a hot wire for shaping foam? If so are they easy to build your self or are there commercial ones available? I need big transitions for my next project and wanted to try to do them myself rather than have someone else do them for me. They will be templates for fiberglass to be molded on. I would like to hear some feedback or ideas on how to build one if practical.
 

Micromeister

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They are a little tricky to build yourself as getting the spring tention just right for the size and length nichrome wire is pretty critical....Too thight the wire snaps too loose you get a very wavy cut.
There are several very good, easy to use, hand held and base mounted foam cutters from all kinds of hobby supply and craft stores. www.micromark.com has a couple you might want to look at ranging from about 20 bucks to a couple hundred... Lots out there to choose from. I have one of the cheapy hand helds that work just fine for me... I must have spent 80 or more bucks trying to get a table model working.. finally did but unless your slitting a lot of foam I really don't think it's worth the trouble;)
 

sandman

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I have found that the pink foam from Owens Corning stacked and glued to a wooden face plate turns really nice on a lathe at really low speed.

I just use a rasp...and a vacuum cleaner too!

Messy!
 

SwingWing

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Some foams give off deadly toxic fumes when hot wired and others are o.k. Do NOT hot wire polyurethane foam!
 

stevem

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I built one using the directions on the Vaatsas web site and used it to successfully create my Duck Dodgers rocket.

I got an old Lionel Model Train transformer off of eBay for $5, made the cutter frame out of PVC pipe and used guitar strings (don't recall exact gauge but the B string from a set of medium gauge Martin steel accoustical strings worked the best for me)

Really worked slick!!

pic of cutting set up...
 

stevem

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thanks eugenfl - I don't want to hijack this thread, the original thread I started on how to make a cigar shaped rocket is here

http://www.rocketryforum.com/showthread.php?s=&threadid=6170&highlight=duck+dodgers

Up until last week the Duck Dodgers rocket had been sitting on the unfinished shelf. Last weekend I decided it was time to finish it up so we could fly it this fall. I'll post more info on the thread listed above.

As it pertains to this thread I just want to say that I am happy I decided to delve into foam construction ala Team Vatsaas - I would not have had such success with it without the help here on TRF and the great work of the Vatsaas brothers.

One of the best things in this hobby are all the variations on construction techniques.

Build yourself a foam cutter and have fun!
 

Ozymandias

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If you plan to do any fabrication with foam and composite materials do yourself a huge favor and buy a copy of Burt Rutan's book "Moldless Composite Homebuilt Sandwich Aircraft Construction" it will show you how to build a hot wire cutter as well as any other information you might want while building your own homebuilt aircraft (or rocket, as the case might be). You can get the book from Aircraft Spruce for under $20.
 

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