Hot Wire Foam Cutting ....

[pete42]

Ok my leg has been pulled............. .

Allan you said you keep kicking the circuit breaker.
if you are using a small amount of wire it may not be long enough to have any resistance which is what the "load" needs to be
a short piece of wire could be "shorting' the terminals together causing the breaker to trip.
start by using the lowest level of voltage and turn the knob to zero to start
if breaker does not trip turn up knob slowly you should find a sweet spot that cuts the foam and doesn't kick the breaker.
when I was cutting foam the wire would leave "whiskers" I then knew I was cutting at the correct speed
to fast and the wire binds or drags to slow and the foam burns making cuts to wide and rough looking.
you are ahead of most so don't stop now we need your ideas
trials and tribulation only way to learn.

Pete

[allan1]

Ok my leg has been pulled............. .

Allan you said you keep kicking the circuit breaker.
if you are using a small amount of wire it may not be long enough to have any resistance which is what the "load" needs to be
a short piece of wire could be "shorting' the terminals together causing the breaker to trip.
start by using the lowest level of voltage and turn the knob to zero to start
if breaker does not trip turn up knob slowly you should find a sweet spot that cuts the foam and doesn't kick the breaker.
when I was cutting foam the wire would leave "whiskers" I then knew I was cutting at the correct speed
to fast and the wire binds or drags to slow and the foam burns making cuts to wide and rough looking.
you are ahead of most so don't stop now we need your ideas
trials and tribulation only way to learn.

Pete

Electricity is an odd creature to read about, hard to visualize and I think my brain lacks conductivity? Anyways after much resistance here is what I have so far - all comments and suggestions are appreciated ... 16 gauge stranded feed wire (about 10 ft of it) that works with full length guitar strings of .0149, .0141, .012, .011, and .009
Anything thicker won't heat up enough to cut (I'll have to get some NiChrome wire as they say it heats up higher with less voltage /amperage - I'll have to ask if anyone eats toast anymore). If I went to 12 gauge feed wire would this allow me to get more heat and be able to use thicker wire? If I go with longer 16guage? I`d like to be able to end up with a cutter wire that I can easily bend to a shape, similar to what I did with the soldering gun.

[pete42]

number 12 or 16 gage solid wire should work fine for the solder gun
but may be to much resistance for the train transformer to heat.

the guitar strings should heat fairly well with the train transformer
start with a low setting and increase it slowly while trying to cut foam you will find a sweet spot
where the foam cuts and doesn't melt and doesn't drag too much.

Now you have me wanting to do some testing If I can find some foam I'll give it a try.
may have to stop by Lowes and see if they have some scraps.

I'll try airplane saftey wire (not very shape friendly) some 14 and 12 gage solid wire all hooked to my train transformer.

pete

[Papi]

File folder, scrap pine, couple of screws and zip ties, 2 amp printer transformer, and nichrome wire. Cost: free, except for 15 minutes of my time. Works like a wire cutter costing 10 times as much!

[allan1]

File folder, scrap pine, couple of screws and zip ties, 2 amp printer transformer, and nichrome wire. Cost: free, except for 15 minutes of my time. Works like a wire cutter costing 10 times as much!

Good to see. What did you use for the arm that they cutting wire is attached to? Also how are you keeping the tension on the cutter wire? I've been experimenting with springs from a pen. Does your power supply have a dimmer switch or does it run straight current?

[Papi]

The "arm" is the metal from the file folder. I want to add a spring to keep tension on it because it does tend to bow the hotter it gets. No rheostat, it just hooks up to the transformer. I switch it off when the cutter starts to bow and when it cools tension is restored.

[dogeron52]

I started working on splitting my foam sheets in half. Had 3in rigid poly iso foam and wanted 1 1/2 inch sheet. Started a hot wire setup 48 inches wide and 11/2 thick. Had a variable battery charger(6/12 volt up to 10 amps variable) nichrome wire and started the source up and nothing the wire Im sure got hot but only dented the foam. Tried another battery charger and nothing . Tried a different wire. all that did was smoke a little and buzz. So now I am Stuck with too thick foam and a not sure idea how to split this foam. I did try some formular 250 I had sitting around and it worked with my setup. Sooooo any ideas on what to try next?

Dog

[KCStudly]

Just a guess, but your power supply might not have the juice to run a 4 ft long wire. When I used my battery charger to cut scale glider wings it was only about 2 ft.

Diameter of wire makes a difference, too.

[GuitarPhotog]

This calculator will help you figure out how much voltage and current you need to get nichrome wire hot.

http://tinyurl.com/75rscul

<Chas>

[dogeron52]

Thank you for the calculator. Went out and tried 2 12 volt batteries for 24 volts and 22 ga wire with 4 foot length wire. All that was done as to the calculator but I would get just the ends to get hot enough but not the middle. I guess I have to cut the length down to two foot and cut the poly iso down to two foot size. I will keep at this.Thanks again.

Dog

[allan1]

Thank you for the calculator. Went out and tried 2 12 volt batteries for 24 volts and 22 ga wire with 4 foot length wire. All that was done as to the calculator but I would get just the ends to get hot enough but not the middle. I guess I have to cut the length down to two foot and cut the poly iso down to two foot size. I will keep at this.Thanks again.

Dog

I'm a newb to cutting and have no electrical experience nor have 'ripped' foam sheets in half but 20g wire sounds excessive to me. I've read that this gauge wire is used for rigid cutters primarily (similar to a router bit)and that for planing / slicing people tend to use a higher gauge. I've recently played with 27g wire (guitar string #14)at 36" and it took tension well and cut at a rate of about 1" in 1.5 sec and I think that Nichrome wire at this gauge would do be a bit quicker. I'll be interested in how this turns out so keep posting please.