The Bacon Slicer (Foam slice hot wire cutter)

I built this little foam cutter to make thin sheets.
It's just a hot wire suspended over a glass sheet ... it can cut foam into very thin slices.



It can also mass produce foam ribs.

that's neat.
clever old stick aint ya.

I just knocked up my own version of a hot wire cutter, (idea stolen from Youtube) for cutting wings. runs off a standard 12v battery charger. I used 0.8 stainless welding wire for it's high chromium content. The heat is controlled by sliding the crocodile clip up or down the copper wire on the side to alter the resistance. I would like to fit a potentiometer instead. Has anyone an idea of what I need ?
It cuts well between 3.5 to 4.5 amps if that helps.

Caveat: If you intend to use a hot wire cutter. It is essential to wear a charcoal filter mask !
Foams produce some extremely toxic gasses, including Hydrogen Cyanide !!!!

wouldn't a dimmer switch handle the amps?

crash happy
A 10A? brushed ESC controlled by a simple servo tester would do the job as long it had sufficient air flow around it.

I do however think your 'copper wire' method has a lot going for it - simple, reliable and easy to fix!

Thanks for all the info. I think Quorneng is probably right, stick with the copper wire. ( KISS)

Just made one small mod to the cutter. Instead of a straight piece of 1.5 mm copper wire, i have changed it for a tight coiled piece of 1 mm. Gives a better variable resistance .

I initially used .8 welding wire when I made one, I found that to keep it taught needed a hell of a lot of tension so it dragged a little too much for me, also once it kinks it's scrap. I changed it for stainless fishing trace which suits me better as I've used PVC waste pipe for mine.

ST "I changed it for stainless fishing trace "
I like that idea. It seems to be cutting really well at the moment, fast & with no hang ups. If I start having problems I will definitely go that route.

Eric. The copper coil being a bigger diameter & with little resistance just gets a bit warm. The welding wire being much thinner & higher resistance is whats generating the heat. As you said it works similar to the old electric fires, only the element got hot not the wiring to the plug. Having said that, I have put it out of the way of any pink bits !

I'd forgotten all about this thread. I originally made this "Bacon Slicer" when I was modding for the RCM&E forum, a friend on there asked me to cut him some foam wings for a BAE Hawk slope soarer.
You need to get the energy to produce heat in the cutting wire, not the connecting wires, for this you need some resistance in the cutting wire.The best stuff I've found is Nichrome Wire. It's readily available on ebay in various resistances per meter, the lower the resistance, the thicker the wire, this means that you can tailor it to suit the length of wire & the voltage you wish to use.
I believe I used to use a 24V supply on my standard 1 meter Hot Wire Bow. I settled on a 48 Watt bow so I needed to put 2 Amps through it, this meant I needed a resistance of 12 Ohm per meter .....
If you use low resistance steel wire ( or guitar strings) you'll need to pass a huge current through it in order for it to get hot .... this then means that any connecting wire will also get hot, unless you use Arc Welding cable.

Pol.

Just a thought Crash, did you not realize that was me in the video?

Pol.

I kind of guessed eventually Pol!