# Using a wallwart for hot wire foam cutter



## Erebus (Jul 28, 2009)

I can't find the power supply I was using for my foam cutter, so I decided to use a wall wart. My problem is that if I leave it plugged in for too long, around 10 minutes, it will get hot, hear a pop, and then it is dead. I try to cut a piece, unplug it for a while, let it cool, then cut another one. Is there a way to where it won't die on me? Maybe using a DC type, I am pretty sure the ones I used are AC. I am just tired of being in the middle of a cut, then the wall wart dies, and I am stuck with my foam halfway cut. Once I get a little money, I am going to make the GOE one, but that is IF I get a better job. Any words of the wise?


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## Otaku (Dec 3, 2004)

Yeah, warts don't like to be running in a dead short condition. I killed a wart once just be leaving it connected to a DMM for a couple of minutes while I verified it's output. Luckily for you, your wart has thermal protection to prevent it being killed outright. A friend of mine uses an old electric train transformer that he got at a thrift store. It has an AC voltage output. He likes being able to vary the voltage according to the material he's cutting.
Perhaps a ceramic power resistor wired in series would help?


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## fritz42_male (May 5, 2009)

Wall warts are usually very cheaply made with low current capability. As Otaku said, try and find a model train transformer - it's an easy one.


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## corey872 (Jan 10, 2010)

I use a variac variable transformer for my cutter, but those can be pretty expensive unless you catch one on ebay. AC or DC should make no difference as it's basically just a big resistance heater. I wonder if a person could use a standard dimmer switch? Those are cheap, usually geared to run from 5% to 95% full power, work perfectly with resistive load such as light bulbs or foam cutters and can usually handle 600 watts. That would be a pretty big foam cutter!

You'd obviously want to take precautions with the mains voltage - such as don't stand in a puddle of water and cut foam, but other than that it should be pretty safe.


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## halstaff (Nov 18, 2009)

I used the GOE how to for mine. Works great and easy to put together.
http://www.garageofevilnetwork.com/profiles/blogs/goe-labs-howtohotwire-foam


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## hpropman (Jul 27, 2008)

Here is how I made mine

http://www.hauntforum.com/showthread.php?t=16712&highlight=foam+cutting+table


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## halstaff (Nov 18, 2009)

hpropman's table design is great! I built my power supply using the GOE design but don't have access to a welder to build their table. Came across hpropman's design and it worked perfectly. Easy and inexpensive to build. The only change I will make to mine is to make a bigger table with a longer arm to cut wider pieces. I used my old router table and it doesn't give me enough clearance for the larger projects.


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## partsman (Feb 26, 2008)

I'm planning on making a hot wire cutter like this one:
http://blog.makezine.com/archive/2009/03/weekend_project_5minute_foam_factor_1.html
This week, I'll post some pics and maybe a quick vid of it in operation, I bought the transformer for it from ebay for 99 cents.


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## halstaff (Nov 18, 2009)

If you are going to use the cutter for larger pieces, you may want to make a longer rod. I will be modifying mine to be able to cut larger pieces.


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## DarkLore (Jan 25, 2009)

partsman said:


> I'm planning on making a hot wire cutter like this one:
> http://blog.makezine.com/archive/2009/03/weekend_project_5minute_foam_factor_1.html
> This week, I'll post some pics and maybe a quick vid of it in operation, I bought the transformer for it from ebay for 99 cents.


lol...I build one just like that a couple years ago. With the exact same train power supply. It didn't take long for me to burn out the supply.


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