Hot Wire Foam Cutting ....

[atahoekid]

Looked on the local Craig's list and found none... I agree there's probably thousands in attics and basements sitting around. Just need to let people know that there are willing buyers for things like that.

[wagondude]

Try posting and add in the wanted section. When our Scout troop needed some old skis to build sleds, we placed an add. Had several calls from folks wanting old skis out of the garage/basement. All free offers.

Bill

[allan1]

have found a couple of DIY but require buying a 30V / 5A step down transformer and some wiring. This town is so small I'll have to order one in if I cant think of something to salvage it from. If anyone is interested I'll post the plans I found.

[allan1]

links to diy power unit for hot wire foam cutting. They appear to be similar in construction. My understanding is that wire length and thickness will determine how much 'juice' is dialed up - trial and error? I'm hoping that this unit can power a router type of unit where I can use stiffer wire to bend it to the shape of cutter I want. I saw somewhere that a soldering gun (with 12-14 guage wire) can be used for this. Maybe that's my experiment for tomorrow.

http://www.utahflyers.org/index.php?opt ... view&id=37
http://www.garageofevilnetwork.com/prof ... twire-foam
http://www.instructables.com/id/Hot-wire-foam-cutter/

[GPW]

Allan , the trick is to just heat the wire up to where it will melt/cut the foam , and not be Glowing red hot ... The diameter of the wire and it’s length determine (mostly) the current needed to heat it to the correct temperature... In the past , we’ve used everything from Variacs (variable transformers}, Train transformers , car battery and car battery chargers , with Big ceramic industrial resistors (with taps) ...
The Variacs are dangerous as they are AC and Will shock you if not very careful (that and they’re ridiculously expensive for a hobbyist )
Batteries are unpredictable over a long run of cutting ... Train transformers work the best ... simple DC current , adjustable , all in one package ... Once we found a good train transformer (hobby shop) we cut many foam parts .. mostly wings and fuselages for models ... and a few architectural models too (commercial work) ... Handy tool once you get it sorted...
For small router like cuts , you’ll need something Adjustable so you don’t burn up your small wire cutter or blow a fuse ..


Here’s a drawing of a typical router like cutting fixture .... shape the wire any way you want ... we use music wire for these ... thick enough to hold the shape , but not so much as to require a lot of current to heat up ...

[pete42]

Being a pilot when cutting foam for our airplane build we used safety wire the kind that is used to wire bolts so they won't back out when flying.
the wire and a train transformer worked very well.

for the solder gun I used 14 gage solid wire easy to bend into any shape needed I used a weller 100/140 watt gun but any should work.

I never tried using the gun on a long piece of wire it may work just fine once heated anyone willing to give it a try and report back?

pete

[swampjeep]

ebay has a few transformers with controllers, might be able to get something there cheap,

if you can't wait, here's a brand new one for $28 + shipping

http://www.hobbylinc.com/htm/mrc/mrcaa300.htm

$22 +
http://www.activepowersports.com/model- ... ansformer/

$20
http://www.wholesaletrains.com/Detail.asp?ID=200418130

I also seen a bunch at our local flee market, but didn't look at prices, as I wasn't even thinking about this,

[allan1]

ebay has a few transformers with controllers, might be able to get something there cheap,

if you can't wait, here's a brand new one for $28 + shipping

http://www.hobbylinc.com/htm/mrc/mrcaa300.htm

$22 +
http://www.activepowersports.com/model- ... ansformer/

$20
http://www.wholesaletrains.com/Detail.asp?ID=200418130

I also seen a bunch at our local flee market, but didn't look at prices, as I wasn't even thinking about this,

Homer Simpson moment - Doh, ebay. Thanks also GPW and pete42. I'm going out to find the soldering gun right now and give it a go. Will post results here.

[allan1]

Found my soldering gun and it's a Weller 100/140, 60 Cy and 1.2 amps. I used a 6" piece of 14 gauge copper household wire. At the highest setting it works but leaves a few ultra thin filaments of the polystyrene connected between the piece being cut off - easily removed. It seemed that I was cutting (melting?) about 1" per second. A bit of stinky smoke was given off as I cut (probably another carcinogen to add to my list). Not ever having done this before, I'm not sure what the finished results should look like but the cut felt only a tad bit rougher than the original finished surface. Ohhh, this could be fun.
A 4" piece of wire allowed me to use the low setting on the gun at about 1" per second and the higher setting was cutting faster than that. I think the higher setting gave me less cut control - that it would cut so fast that any minor shake or movement I made was significantly mirrored in the material.

Not really sure of what result I should be looking for so will go to youtube and watch some folks doing foam cutting. With the right jig and cutter, I ought to be able to cut out some nice box joints.

[pete42]

When cutting foam with a hot wire cutter if you feel the wire pulling back you're going to fast,
if the foam is burning bigger than the wire you're going to slow
you will find a happy medium where there are some whiskers left when cutting.
and there will be some smell. I don't know how long a wire can be headed with a solder gun it may take more amps than than the gun can produce.

nice job you'll get it like most anything it's easy once you know how.
a fixed wire and foam pushed through it works great for flat cuts.
on airplane wings where you have to follow a shape it's harder but doable.

Pete

[allan1]

When cutting foam with a hot wire cutter if you feel the wire pulling back you're going to fast,
if the foam is burning bigger than the wire you're going to slow
you will find a happy medium where there are some whiskers left when cutting.
and there will be some smell. I don't know how long a wire can be headed with a solder gun it may take more amps than than the gun can produce.

nice job you'll get it like most anything it's easy once you know how.
a fixed wire and foam pushed through it works great for flat cuts.
on airplane wings where you have to follow a shape it's harder but doable.

Pete

The 6" wire gave me enough length to form the shape I wanted. I figure a slightly smaller gauge wire will get me the performance nedded. I've looked at some video's about using templates to cut air foils so it'll be simple to make up templates for the different joints I want to create.(eg. box joint, dado). I'll have to start building some of the different cutters now. Figure a bow, scroll saw type and a router type and I'll have a flexible system for my potential foamie build. Just bid on a MRC Tech 3 on ebay

[GPW]

Allan, Just don’t get carried away ... It can be addictive ... We would cut up a giant block of bead board in an afternoon ... had wings for months ... FUN !!!
Best turn a fan on .... it does stink and who knows about later ???
I guess next we’ll be discussing gravity cutting ???

[mikeschn]

I'd like to see a picture of a hot wire cutter in action...

Got any pics?

Glenn, you are going to have to design us a roundover wire cutter that runs on 4 D sized batteries...

Mike...

[GPW]

Possible , but it would drain the batteries in 2.5 minutes.... Cut Quick !!!

[mikeschn]

Possible , but it would drain the batteries in 2.5 minutes.... Cut Quick !!!

I use rechargeable batteries...

Mike...