# Hot wire foam cutter



## Gadget (Apr 27, 2012)

I just finished a hot wire foam cutter. I welded the frame and have the wire power hooked up but not totally enclosed yet. Here's a video of the first cut.

[video=youtube_share;WlnFRUMEyHE]http://youtu.be/WlnFRUMEyHE[/video]


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## Rbeckett (Apr 27, 2012)

You can get the foam cutter nichrome wire at Tower Hobbies if you have difficulty finding any.  We have been using Foam and Obechi for ultra strong wing panels for a good while.  Put a little carbon fiber in high stress areas, paint on some resin and vacuum bag the whole thing.  Tougher than titanium and way cheaper.  If you need procedure help or which items work best give me a holler and I will  be glad to hook you up with my info.

Bob


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## bcall2043 (Apr 28, 2012)

Gadget,

Thats a real "cool" hot wire cutter. Great job!

What kind of voltages and transformer are you using?

Benny


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## Gadget (Apr 28, 2012)

bcall2043 said:


> Gadget,
> 
> Thats a real "cool" hot wire cutter. Great job!
> 
> ...



I'm using a transformer out of an old computer UPS. 120v in 12V out. I put a light dimmer on the input side to adjust the wire temp. A lot of people use a 12V transformer from RS but I had this one on hand.


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## Hawkeye (Apr 28, 2012)

That would be really useful for lost-foam casting. No room in the shop for a new station, though. Good post.


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## Gadget (Apr 28, 2012)

Hawkeye said:


> That would be really useful for lost-foam casting. No room in the shop for a new station, though. Good post.



Mike, mine folds flat up against the wall and hinges out over my welding table which also folds down so no lost space there.


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## Hawkeye (Apr 28, 2012)

That implies that you have available wall. :biggrin: One of my belt sanders is already on an old TV swing arm. But you've given me an idea. If I stored it up between the joists and used it in the welding booth...:thinking:


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## bcall2043 (Apr 28, 2012)

Gadget, thanks for the post and build information. I may borrow your idea if you don't mind. I have been planning to put a hand wash sink in the garage/shop but need to insulate it for protection from freeze during the winter since the garage is not heated. I had planned to use the foam insulation board and a strip heater for the sink and enclosure. Original thought was to cut the foam with a bandsaw or sawzall but the wire would be cleaner.

Thanks,
Benny


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## Gadget (Apr 28, 2012)

bcall2043 said:


> Gadget, thanks for the post and build information. I may borrow your idea if you don't mind. I have been planning to put a hand wash sink in the garage/shop but need to insulate it for protection from freeze during the winter since the garage is not heated. I had planned to use the foam insulation board and a strip heater for the sink and enclosure. Original thought was to cut the foam with a bandsaw or sawzall but the wire would be cleaner.
> 
> Thanks,
> Benny



Benny,
I posted this here so others could use it so adapt it to suit your needs and go for it. You can probably use an auto 6V battery charger to heat the wire in a pinch. If you have a rheostat or router speed controller you can plug the charger in that and have a way to reduce the voltage. You could probably use the 12V charge side with the rheostat on the AC side and get the voltage just where you need it.


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## bcall2043 (Apr 28, 2012)

Gadget said:


> If you have a rheostat or router speed controller you can plug the charger in that and have a way to reduce the voltage. You could probably use the 12V charge side with the rheostat on the AC side and get the voltage just where you need it.



Gadget,

I have a variable AC transformer and an old battery charger transformer so I'm set there. How critical is the wire size? Rbeckett suggested getting it at Tower Hobbies but we don't have that store in the middle TN area. We do have Hobby Lobby but I don't have a clue what hobby would use that wire. Any clues where to find it?

Thanks. Benny


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## Gadget (Apr 28, 2012)

bcall2043 said:


> Gadget,
> 
> I have a variable AC transformer and an old battery charger transformer so I'm set there. How critical is the wire size? Rbeckett suggested getting it at Tower Hobbies but we don't have that store in the middle TN area. We do have Hobby Lobby but I don't have a clue what hobby would use that wire. Any clues where to find it?
> 
> Thanks. Benny



Here's a link to some 32 gauge which should be about right for foam cutting. Right now I'm using guitar strings that are about .008  That's pretty close to 32 gauge I think.

http://www.ebay.com/itm/Nichrome-Wi...aultDomain_0&hash=item3a66cf83f4#ht_500wt_969


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## joefroooo (Apr 28, 2012)

That is a really cool Gadget....Gadget, You could make a wood template to trace or follow around. Similar to a pin router. 
Joe


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## Gadget (Apr 29, 2012)

joefroooo said:


> That is a really cool Gadget....Gadget, You could make a wood template to trace or follow around. Similar to a pin router.
> Joe



Joe, that's exactly what I intend to do. I made a template the other day on my CNC router and used it yesterday with good results. I'm still experimenting with the right wire temp and feed. I probably need to get the right tension on the wire too but I'll wait on that till I get the nichrome wire.

Dan


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## Gadget (May 11, 2012)

I took the hotwire bow off the wall and mounted it on my CNC table. The CNC can now perform routing, light milling in aluminum, plasma cutting, and now foam cutting.  I'm designing new bearing skates for the CNC table and made a test cut in scrap foam today. It turned out well but needs a few adjustments. The bearing slots are too long and the opening at the Y needs to be slightly larger. I'm getting close to cutting the final patterns.


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## Johnm (Mar 9, 2013)

That's awesome. What kind of CNC table do you have?


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## Gadget (Mar 10, 2013)

Johnm said:


> That's awesome. What kind of CNC table do you have?



It's a home made table built from plans by solsylva.com. I've replaced that table now with a new all metal table using belt drive using plans from the same company.


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## Hawkeye (Mar 10, 2013)

Good to revisit this thread. I now have a CNC X2 mill. Not much travel (about 6 x 9), but enough for a lot of lost-foam patterns. It would be easy to make up a plywood table that bolts onto the mill table and hangs out to where a hot-wire could reach it. Doesn't have to be over the table. Just added it to the project list.


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## Johnm (Mar 11, 2013)

Thanks. I will check out their site


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