Cutting EPS - train transformer?

will it work for the hot wire?

Yeah it works. That’s how I cut out my foam. They sell on Ebay for $10-$15. Just make sure to get an old one, because the new ones apparently have circuit breakers in them. The only problem I ever had with this was the transformer would stop working after a while, I think because it might’ve overheated. But within 5 minutes it would work again.

I tried with a couple and no go for me. I think the nichrome needs too many amps for the transformers. My wire is 1.5 metres and 7 ohms, needs something under about 20v to get cutting, so thats just over 2 amps. Mine worked for a bit and then cut out too, I figured I was overpowering them, and didn’t want to risk them catching fire, so I stopped trying to get them working.

then what is a good inexpensive way to hot wire?

You can use a car battery charger. Set it to 12V and cut away.


You can make a setup like in this image, using a dimmer switch and a light bulb(for load). Posted originally by one of the guys from France.

Ok. So, I can’t seem to upload an attachment.

Basically it is a dimmer switch attached to a plug box. One plug has a light (60w) in it and the other is connected to your hotwire. The dimmer switch lets you adjust the amount voltage (heat) and according to an electrician friend the bulb is there so the circuit has a load and the hotwire will draw fromit rather than just short-circuiting and popping your breaker.

Hope it helps.

Hey- it just occurred to me that I have a couple Louis & Marx train transformers- I bought them back when I was first learning to hotwire, before I bought my Variac. I paid like 5 bucks for each one- so thats prolly why I still have them. (what a pack rat!) My GF would be stoked if I got rid of a little bit of clutter if someone wants one (or two!) I was using them with 18lb stainless fishing wire… any wire under 12 inches- they work good. Longer wires- not so good. Maybe both of them on the same wire… or a thinner wire? PM me if interested! -Carl

There’s a variac from Circuit Specialists for $44.

I was using a battery charger with minimal success…

Bought the variac

Got DanB to help me suss out the trouble (plastic coating on my wire - D’oh!)

Variac works like a dream at…13 volts. No wonder the 12 V battery charger took a week to make a cut :slight_smile:

BTW, once I scraped off the (trust me, it was invisible:) ) plastic coating, 24" stainless steel fishing leader wire is amazing stuff. $2.99 for a pack of 6 (one guitar string costs that) and it comes with clip swivels on the ends already. One for the eye hook, one for the spring…couldn’t be easier to change wires.

So I had this 8" thick 2# EPS. Wanted to make a 6’ fish - would take 3 pieces or 6 cuts.

When I was using plain ss wire, I broke a wire every 3’ of cut or so. And changing them took a bunch of twisting & screwing. So cutting out 3 pieces of fish would require 12 wire changes! No wonder I quit that & cut EPS with the bandsaw!

But with the variac at 13V and the leader wire, I cut an entire fish out with one wire. All 6 cuts - 36 feet. So I decided to cut another while I was at it - and got almost halfway through that one before the first wire finally broke.

Yes, I’m finally stoked on hotwire cutting.

The lesson is, do it right. Jerry rigs can work, but there’s nothing like the proper tools for the job. And with a $44 variac, a plywood “U” bow, a cut off extension cord, $2.99 in fishing leader, a pair of alligator clips, and a little spring, I’m well under $100.

Well me and my friends just cut out six blanks. We connected two car batteries, You connect one jumpstart cable between the two car batteries from + to - and then just connect two more cables from the remaining poles ( one + on one battery and one - on the other) to Your hotwire rig.

I guess the volts and amps needed also depends on the diameter of your wire and also the length of it. We tried a few other options but the train transformer didnt do it for us not enough amps or volts or whatever.

Good luck


Pics taken this Year by the way…

What I did is buy a toroidal transformer and connect that in series with a light dimmer. I’ve got the transformer and dimmer mounted in the case from an old pc power supply which is earthed. I think I paid about ten pounds for the transformer, 5 for the dimmer.

If you mount a toroidal transformer, you must only have the mounting bolt connected to the case on one side, if it’s mounted on both sides you will get a current running through the bolt.

For a 2ft nichrome hotwire i used a 12v transformer, they usually have 2 coils, so I was able to connect the coils in series and get 24v for cutting my blank in half for the stringer. I got a transformer rated at 100VA, the usage is 24VA (2 amps x 12volts) but I think it’s always best to have a big margin of error.

I used a battery charger as well, worked ok but it was an electronic one so I couldnt vary the power.

That trick with the lightbulb sounds simpler than the things I’ve used though, I would have tried that if I’d heard of it.