I need to make a quick hotwire to cut some EPS

Any instructions for a REAL basic cutter? What kind of wire, and what can I use to power it? I don’t know what I can use to power it…

Hi tenover, check out the (cutting EPS -train transformer) thread at the bottom of the forum page. Some good tips.

Good luck,


A plywood U (5/8 or 3/4" minumum) big enough for your foam. Buy a 2’x4’ or 4’x4’ "handy piece - $10

2 machine screws through the ends, with nuts & washers on the other side and long enough for wingnuts on top of that. - $2

Stainless steel wire - buy 18 ga, 20, 22, 24, 26, 30. You won’t really know which works until you start to heat them up. About $5 per small roll, so - $30

Car battery charger. Most manual ones now have 5 settings - 6V and 12V and a couple different amperages in each one. - $40.

You’re at $82 and about a half hour of shopping. Another hour for assembly. Another hour to test wire/electricity combinations until you find something that cuts.

And, when you get sick of breaking wires or cutting too slow, you can reuse the bow & wingnuts when you get a $44 variac from Circuit Specialists. I’d recommend that to begin with, but the shipping isn’t as fast as going down to Auto Zone :slight_smile:

a wood 2"x2" and 2 pieces of 18" long (or however long you need) 1/4" steel square stock.

Drill 1/4" (maybe a bit bigger) holes at either end of the 2x2 angled outward. Put the steel into the holes with the end just poking through (now it looks like a bow). Bend the long ends of square stock toward each other and stretch some wire between them. It helps if you file a little notch on the end of the steel for the wire to catch on. Attach battery charger, car battery, low voltage transformer, train transformer, variac, ect. to the ends of the steel poking through the wood and you’re away.

IMO it’s worth it to use nichrome wire - it’s not that expensive - but stainless steel or other steel work for awhile.

Happy slicing.

I have a car battery charger you can borrow if you want.

And I KNOW you have guitar strings…

Used without permission…


Wow - never noticed the detail before in that photo - is that an inline off switch in his left hand?

That is a smart idea. I never like having to look away from the leads to turn off power when a wire breaks…

Once more…


well…i just found the plans for the hotwire i’m gonna make…THANKS!

what’s the total cost for parts and time for assembly???


I didn't keep track of the cost, because I built several of these hotwire harps.  It takes maybe 1 hour to cut, drill, sand, run wire, and install the eyes into the plywood.  The biggest expense is probably for the wire and inline switch and conncetors.  I suspect the whole thing was under $ 30.00 total.  Home Depot special!  The photo used in the post is the first one I made, and seems to work quite well. 

 Good luck!!! 


here’s my hotwire cutter that i made for about 12 bucks. two springs on the bottom with thick wire inbetween them for tension, and i used a high E guitar string for the cutting wire. works pretty well with the battery charger shown.


I admit it. I’m totally useless when it comes to electrical stuff. I was a screw-off in 8th grade electric shop and I continute to pay for it. Can somebody show how the electrical end of the thing is set-up? I can’t tell if the cutting wire continues around to make a complete loop(circuit?) or just terminates on one of the end screws. Pictures or diagrams are the most helpful. Explained as if I was a five year old helps, too. Mike

…yeah, im with Rooster…

…in which way the string is connected to the current…?


Maybe this will help

I’ve cut several blanks using guitar strings and found the wire to be rather weak. The last blank I cut, I broke 3 strings. So I picked up a spool of downrigger wire made by Scotty. Braided stainless steel wire, 150 lb test. I was able to put a large amount of tension on the wire which gave me a cleaner more accurate cuts with no breakage. Worth trying, I’ll never go back to guitar strings.

Updated version of the harp…



hey Mike,

the cutting wire teminates on both ends of U frame. At one end of the frame simply screw in a hook. On the other end of the frame opening screw in several hooks evenly spaced out 1/2" or so apart. Then screw one in up the frames arm towards the top end and attach a spring between the hook you just put in and the next closest hook down the arm. 10" gap? Attach the wire to the single hook and run it across the opening and through all the hooks tying it off the hook attached to the spring at the bottom end. The power source (I use a battery charger) attaches to the single hook and (this is the tricky part) to wherever on the other end it makes the best cut. Put it on the hook the closest to the opening and it might burn to hot and break the wire. Put it up on the spring and it does not get hot enough and you cut at a snails pace. Markssd and I cut out a blank this weekend after Cerritos and it worked ok.

And thanks for the template! I got it Sat. The address to cracked me up. Tim Surf4fins. Guess I didn’t provide my last name!!!

thanks again,

Tim Crays


Hey Drew I have one you can borrow

Jesus L.

Hey Tim,

You mean your name isn’t Surf4fins? Dang. Thanks ya’all. I can make one from what you gave me. Mike