Making a Hot Wire Cutter for Shaping Foam 

A little basic ohms law - 22g nichrome 80 wire is virtually 1ohm per foot, so let's say you're making a 3' wire cutter that's 3ohms, with a 12VDC power supply ohms law will give you the current, I=V/R (I current, V volts, R resistance) so - your power supply has to AT LEAST equal I amps. I amps= 12volts/3 Ohms........ so I = 4amps, so you'll need at least a 4amp power supply. If you want a shorter or longer cutter you can adjust it by either changing the supply voltage which pushes more current through the wire, or the gauge of nichrome wire which changes the resistance per foot of wire. The calculation remains the same I=V/R, and seeing as heat output is generally given in terms of power in watts, P=V*I so in this example Pwatts = 12volts * 4amps which gives you 36watt heater. You can look up the temperature characteristics of nichrome wire on the www but 4amps thru 22g will give you about 700degF, like this guy said don't mess around with other kinds of wire because you won't know what you're dealing with - for example if you tried to make one using 22g copper wire (0.015 ish ohms per foot) you would need roughly a 12V 250amp power supply and god knows what heat you would get from it, and something (perhaps you) will go bang. Nichrome wire is made exactly for this kind of purpose and is a known entity, so don't try making one out of copper, or guitar strings, or a shoelace. Be careful kids, don't burn yourself, and try not to burn your house down either.

Tip: You can salvage nichrome wire from the heating element in an old hair dryer or heat gun.

I'm proud of you for using primer. That pipe will pass inspection and never leak!

After watching your video you've given me a fantastic idea ! ! ! At about time 6:00 you demonstrated "Detailed Cuts" . This is where the idea hit me . If you wanted to make detailed shapes in polystyrene to use as insulation for shipping container homes this would be fantastic ! ! ! Once the shape is cut out with your hot wire cutter it could be placed directly onto the outside or inside walls of a shipping container . This would then fill in that corrugated shape that all shipping containers have in their walls and insulate very well . Thanks for the inspiration .

Model airplane enthusiasts have been doing this for decades . Check out how foam wings are cut . A great addition would be a variable temp control for your cutter so you could use different length wires .It's a game changer

The possibilities for modification and upgrading with additional accessories are endless thanks to the simple and standard design!

Good evening bud, hope you have a wonderful day

Thanks Chris! That was solid brother!

Love the back bow.

Edge templates made from thin aluminum flashing make for precise repeatable cuts.

Thank you for this. I will make one one these fastened to a vertical wood panel. I need to cut a lot of 10cm in half by its thickness. By far the best way to do it. And no snow as with a saw or knife

I think I'd prefer a momentary switch that would automatically turn if off if I let go (as a deadman switch).

Nice! I've been looking for a hot wire cutter, but reviews are hit or miss. Might have to add this to my build list, lol.

Hectic thank you mate unreal

an additional option could be to incorporate a shop vac for fumes into the handle and drill holes strategically to suck in fumes where it's most like.

Wow that was brilliant, so cheap and easy

3:30 I just read today about tinned wires in sockets being a fire hazard. This is done in 3D printers often where they're tinned and assembled snug in the factory. However, tin tends to morph under pressure, so those joints will get loose over time even if they're not moved. Make sure to either get a crimp connection there or tighten them each time before use.

I have put a small spring on one side where the nichrome wire hooks up, it keeps the tension good without stretching the wire so much. I will have to build one like yours because what I have is setup like a miter box.

Just finished making one of these but made like a bandsaw (moving the foam through the wire). An extreme fire hazard, but very helpful. Thanks!

How hot does this get and can I use it to cut PVC Trim board for my home's window trim - what is that/4 inch? Can I cut 3/4" board with this - I'd love to NOT have PVC sawdust everywhere.

Excellent demonstration. Thank you so much!

Thanks!

Very satisfying

an old hire drier can provide the wire as well and is easy to find and cheap

Thank you for the video, helped me a lot!!!!

Good job 👍🏽

That was awesome!!

Nice multi tool! Lol! 🔥🎶 Seems simple enough to build 🤔 lol! Dig your decks on the wall ✌️😎👍

Nice video . Although I used a 3 amp DC output adapter and the wire was almost room temp. Could not cut anything. The cutting wire I used was .009 tungsten and thought that would be efficient enough to work , but I got no where.

Good project. Reduce the length of your cutter (nichrome wire) to half if you want to use that 3A adaptor.

Does this mean that if we strung a guitar with nichrome wire you could play some hot licks? ... ... ... Sorry, couldn't stop myself.

Thank you.

Good video, however connections section make it look like the red and black wires are twiested together so how does a switch work that is shorted at each end by twisting R&Blk wire together. Why? Unless for more current flow?

Just occurred to me that there could be a variation of the design that could accommodate thicker materials.

Cool video dude

thanks ! dope hair btw

I basically made this today. I used 12v 5a Amazon ps 2 screw 12v adapter like yours 12g wire which might be to big but it's what I had. 21g 0.7mm nichrome wire Crimp eyelets with shrink sleeve. On the eye bolts. It will get warm but not hot. I could saw faster with the nichrome bow manually. Any recommendations?

Good stuff subbed

Brilliant

Great video. Definitely subscribed!

Good video , you left out the information that is boring, any fine details someone wants can be looked up online anyway

hello sir can you tell us about the complete materials you use through a message thank you

Nice

Thank you for making this video. My friend made one for me a while ago. He did not use PVC pipe but he made me a wooden frame. It is like 3 by 3 by 3. Unfortunately I packed away the plug and have not been able to find strong enough amperage. But thank you for telling me it's 5 because I think I was buying used computer power plugs that were not working

Why not just take a wood burning tool, attach along thin blade or strong wire to the end. And you have a hand held cutter.

Just asking because I could put it to use immediately. I've got some solid MIG welding wire on site. What do y'all think, could it work in place of the nichrome wire?

Can anyone explain how he wired everything together? I can't tell where the red and black wires are going it's so confusing.

Will this cut very firm seat cushion foam for furniture. I have 6" thick and want to reduce to 4" thick. They are 6x22x21and I want them to be 4x22x21

does the hot metal not melt the PVC at the point where the wire is held by the nut and bolt?

At 3:19, you shouldn't tin the end of wires when clamping with screw connections. This is a known safety hazard because the tin will creep (cold flow) causing the connection to become loose.

Awesome & Thanks :)

It is better to connect the power wire directly to the heating wire. Using the bolt to conduct the electricity will add resistance and cause the bolt to heat, possibly melting the PVC pipe.

Why does the 12 volts, 2 amps? Didn’t work well?

Forgive my ignorance but do the eyebolts not heat up enough to melt the pvc due to their being a larger diameter than the wire ? Do they get hot at all or is the heat concentrated only to the wire?

Would the 2A supply work with a smaller gauge wire

What’s the electric wire gouge ?

Could this be used on memory foam?

I've been using welding wire for years to cut surfboard blanks, I can generally cut a few blanks before it breaks. But that nichrome wire look just that little bit easier to cut with. Have you noticed much stretch when cutting wide?

what type of mask did you and what was the wire again?

does it work on sponge?

ciao scusa dove si compra questo filo x il taglio mi mandi il link grazie

Could this work for shaving thickness of 1/2" off of a 4.5" thick memory foam mattress?

che potenza ha il secondo alimentatore''????

Brillant

You can use a paperclip and rubber band to tension the wire at one end otherwise it loosens when heated.

Do you know if this would work with closed cell foam?

Can I use a Dremel speed control to control current and amps?

What is the red/black wire (gauge) used? I have everything you used to make one except the wire for the switch and want to make sure I am using the correct wire, so it works properly.

Very helpful. I’m looking to making a hot wire to cut 200mm thick insulation foam down to 150mm thick. This is a denser type of foam than polystyrene! The panel widths are around 600mm wide. Imperial sizes 8 inch thick x 2feet wide sheets slicing down to 6inch thick if you see what I mean. My question is, can I use say the 200gm nichrome wire or you are using here or should I use something heavier? And the power source? I wondered if the I would need to use a larger power unit than the one you suggest. I had even thought of setting up the same type of frame and using a 3am fused plug in to the wall socket. I’m used to working with electrics. I’d be so grateful if you’d give me a help. Peter Glasgow Uk

Use two nuts. Put the wire, or lugs, between them.

How to make one with handles and no pvc between

I FABRICATE AVIATION COMPOSITES, COULD YOU LIST THE PARTS. YOU USED IN THIS VIDEO, THANK YOU

Will this cut foam rubber / as in for upholstery? Ty

Do I need to use a switch? Or can I just connect it without one?

i need to cut out the shape ofa guitar pick in foam so i can insert the pick in the hole, and then makeput the pick inside the foam in display case. The thing is I cant cut out the foam cleanley. Any advice?

Can this work on foam for a motorcycle seat

1:10 Whoops or did you mean to put glue on the inside of the pipe for some reason?

Hi there. What kind of metal is the heating wire

Please could you upload a wiring diagram, 😊

Creating guides out of battons is the way forward for straight cuts. Freehand just has too much play and room for error.

Hey man, dunno if you can help me out here, i got the same 12v 5a transformer as you and the same gauge nichrome wire, but my wire wont heat up, what is the lenght of the wire you used?? Thank you. Nice vid btw im trying to follow ur video to make my foam cutter.

no need for the purple primer... you won't have any water leaks

I couldn’t tell how you connected the power supply you did it so quickly. But then my knowledge of electricity ends at flipping the light switch.

Anyone know if I can use Nitinol rather than nichrome?

Do you think you can cut bubble wrap with this?

Charge amp ?

Is it possible for one to use A Gita string?

What is the length of your nicrome sir?

anyone else think this dude looks like matt mercer?

Hmm.. thanks for the video. Is it volts or amps that cut the the foam... I found several laptop adapters laying around at max 2.5A, but at 24-48Volts. I assume a laptop charger should have plenty of juice to heat the wire, no?

Was the high TEMP ever measured ?

What is the dimension of your frame?

Let me know input volt and amp

Your wiring at 2:50 is confusing, you connected the wire on the switch side to the ring hook, then suddenly its no longer wired, and you bypass it. I feel like the most integral part of this is the wiring.

GREAT JOB. $OLD

can I pay someone to make me one?? if so let me know!!

Luar biasa 👍👍👍

Not sure whats was sketchy about that setup, considering the rest of it.

Which wire did you use for the power supply ?

👽👍