# My Hot Wire Foam Cutter



## BioHazardCustoms (Aug 5, 2009)

Well, I finally finished building my hot wire foam cutter. It works great (I'm currently using an "E" string, but I plan to upgrade to a thicker string.)
I used this tutorial:
http://www.garageofevilnetwork.com/profiles/blogs/goe-labs-howtohotwire-foam

It hums a little when the power is all the way up, but it cuts foam clean. I can honestly say that it works a whole lot better with 12V 60W than with 6V 15W. It barely heated up on 6V, but it now gets very hot and slices through 3 inch foam like a hot knife through butter, with barely any drag.

**EDIT** I have pictures, but for some reason my camera is being stupid right now. I plan to set it up and do a short video tomorrow, possibly after upgrading the cutting wire.

**2nd Edit**
I meant to put a pseudo- how to in this thread. 
Step 1: Strip the end of the appliance cord. Mine had a black, white, and green wire. 
Step 2: Connect the green wire from the cord to the green wire from the dimmer. 
Step 3: Connect the black to one side of the outlet, and to one of the black wires from the dimmer.
Step 4: Connect the white to the other side of the dimmer, and to the white wire from the transformer.
Step 5: Connect the other black wire from the dimmer to the black wire from the transformer.
Step 6: Connect one of the blue wires to one side of the guitar string, and the other to the other side. 
Step 7: put the cover on the box, plug in and enjoy!

I marked mine to show the off position, and what I consider the optimal "ON" position (A little less than halfway around the dial). I also marked the outlets as 120V AC, and marked where the 120V comes in and the 12V comes out.


----------



## GhoulishCop (Sep 25, 2009)

Okay, BHC. We've given you enough time to get that camera fixed...show some pictures! LOL!

Rich


----------



## BioHazardCustoms (Aug 5, 2009)

LOL, I keep forgetting to hunt down the cord and hook it up to the computer. I'm off of work with nothing to do tomorrow, so I'll find it and do what I'm supposed to do.


----------



## JustJimAZ (Aug 19, 2010)

BioHazardCustoms said:


> LOL, I keep forgetting to hunt down the cord and hook it up to the computer. I'm off of work with nothing to do tomorrow, so I'll find it and do what I'm supposed to do.


...And it is tomorrow! Looking forward to those pics!


----------



## Uruk-Hai (Nov 4, 2006)

Sounds interesting. Looking forward to photos.


----------



## BioHazardCustoms (Aug 5, 2009)

I'm hunting for the cord now. Pics and possibly video probably this afternoon.


----------



## BioHazardCustoms (Aug 5, 2009)

Pics and video are uploading to the Dragon Lady's computer. She wants to do a little editing, and then it will be up on here and on youtube.


----------



## BioHazardCustoms (Aug 5, 2009)

Hope you all enjoy!


----------



## Copchick (Apr 10, 2012)

Nice demo BioHC!


----------



## fontgeek (Jul 24, 2006)

You might look at a cord saw design. Like a bow saw with the blade, or in this case the wire held far away from the handle or frame, it uses a design that has arms that are a bit longer with the handle/backbone of the saw set in six or seven inches from the non wire ends of the saw's arms. They typically have a chain or even pieces of all-thread running to a turnbuckle in the middle (Between the two ends of the saw's arms) so that you can adjust the tension of the blade, or in this case the wire. A big part of your problem is probably the kind of wire you are using, though almost any wire is going to stretch with use and heat. You might consider using a steel guitar or banjo string (non-wound of course). Think of the whole design as a letter "H" with the cutting wire across one open end of the "H", and the tensioner/tightening device across the other open end. You may have some problems with the long, slim wood arms (Uprights on the letter "H") either bending or snapping with age or if you put too much stress on them. You might look at using some angle aluminum or aluminum channel instead of the wood arms. No splinters, no rust to deal with, and they, by the nature of their design, can take a whole lot more of the stress than the wood versions.
Just some thoughts from the cheap seats.


----------



## BioHazardCustoms (Aug 5, 2009)

Thanks for the input, fontgeek. I have a few design ideas I am going to try out on version 2.0. This was just a basic build for me to proof the concept out. I currently have an "E" string from a guitar on there, but it is so thin that it stretches easily when it gets hot and I run it through thick dense foam. It cuts white beaded foam like hot butter, though. 

I will be working kinks out of this version (going to beef up the arms a little, put a tensioner mechanism on there, and a few other minor improvements I have in mind.) in the near future. I'm also deliberating the idea of building a table that the control mounts to, and the cutting arm can be stored inside. If I do that, though, it will have to be a multi-purpose table. Anyway, I will keep things updated.


----------



## Pumpkin5 (Aug 8, 2010)

:jol:That is just great Bio! I can't believe how quickly it cuts through foam...and no "ball-balls" everywhere and no foam dust! Definitely beats the (you know what) out of the way I've been cutting foam. Excellent!


----------



## hpropman (Jul 27, 2008)

Nice Job looking forward to seeing what improvements you come up with. Love the power indicator will add that to mine.


----------



## fontgeek (Jul 24, 2006)

You might want to look at something like tungsten for the wire. That is what's typically used for filaments in light bulbs as well as for scientific heating equipment (for a lab). It's made to take the heat, so it may have a good bit less in the way of stretching and distorting with the heat. Though be warned, it's not cheap either. It may be that you are better off sticking with the "e" string and just get used to tightening up your tensioner on a regular basis. Maybe using a machine/tuning peg from a guitar to allow you to adjust the tension would help too. That would allow you to adjust the tension while you work.


----------



## BioHazardCustoms (Aug 5, 2009)

I've come up with an idea of how to build a tensioner with a couple of eye bolts, some flat washers, and two wing nuts (which, incidentally, is what I call my dogs when they get hyper) It is basically an eye bolt through each arm of the cutter. The bottom one will be tightened all the way down, and the top one will be used to slowly take out slack as needed. I'm attempting to avoid all shopping areas until after Christmas, but I will probably attempt to add this around the first of the year.


----------



## scareme (Aug 29, 2006)

That's a great video. And I love how you can break it down and use it like a bow saw. I do have to say, I flinched everytime your fingers are near the wire. I know you are a safe guy, but I've seen those things burn.


----------



## GhoulishCop (Sep 25, 2009)

BHC,

I'm not sure if I stole the idea from hpropman (I take all his great ideas) but I used a hanger bolt -- the kind you use to hang drop ceilings with -- as my tension screw. I screwed the bolt into the top arm and ran the guitar string up through a small hole drilled into the end, and then through the hole in the top of the hanger bolt, wrapping the excess around the threads. When too much play came in the wire, I turned the hanger bolt to tighten it up again.

Your minimalist bow saw definitely has its advantages, mainly that it doesn't take up much space and can be stored away easily. That was the one problem with my table, which is why I gave it away (aside from not using it so much) was that it was taking up valuable shop space.

While the guitar wire has limitations, the benefit of it is it's cheap and relatively easy to obtain. Even if you break them because you crank up the power too much (no, I _never_ did that!), you can get a replacement.

I think the indicator light you added was a great addition that should be incorporated on all the tables.

When I built my table, I had also built a smaller hand-held unit out of 1/2" PVC pipe (it looked like a Y-shaped field goal) that allowed the wires to run through the inside of the arms and out the handle. It was about 6"-8" between the arms.

That worked great and gave me a lot of control when freehand cutting and the wire could be shaped to let it perform like a router of sorts. I gave that away too when I gave away my table though.

Rich


----------



## BioHazardCustoms (Aug 5, 2009)

LOL, I get my guitar strings for free. I have numerous relatives who play guitar, and my mother has told them all to save any strings that they break, because I have found a way to recycle them. 

I've been considering building a smaller scale version that will connect to the same power supply, but haven't gotten a chance to sit down and draw out the concept yet. We're working on a shortened staff up through the first of the year, so I don't have much spare time, but at least I am getting overtime.

I'm on the fence about wanting a hot knife, but I bet it would make sculpting a lot easier.


----------



## Lunatic (Oct 3, 2006)

Nice tool Bio. It works exceptionally well!


----------



## hpropman (Jul 27, 2008)

Here is the info on my table that GC was referring to in case anyone wants to see.

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


----------



## BioHazardCustoms (Aug 5, 2009)

Thanks for sharing that, hpropman! That helps support the idea I had.


----------



## GhoulishCop (Sep 25, 2009)

Heh! Lunatic complimented your tool!


----------



## BioHazardCustoms (Aug 5, 2009)

GhoulishCop said:


> Heh! Lunatic complimented your tool!


Bahahahaha! That is so messed up...


----------

