wokelliott said...
Definitely need a good spring to tension the wire straight as it expands when hot. A variable low volt power supply (AC or DC) is ideal. If the wire is not dead tight it will give you a hollow section as you follow the profile curve. Good idea is to lift the waste Styrene material away as you go to make life easier for the wire - so another pair of hands needed.

..Wok

Any particular type of power source?

Nikrum said...
As in all things Electric a little Nouse/Comon Sence etc is required. I don't know what you YANKS are using in the way of domestic voltage, it used to be 110v and that was deffinately very dangerouse 240v is bad enough but there is some forgivness in it, again I have experianced it more than once but there again the foolish dare fate..

Gyro

Thanks Ron. Common sense is scarce here, and we still use 110v AC.

These might help

www.instructables.com/id/Hot-Wire-Foam-Cutter-1/
www.instructables.com/id/Hot-Wire-Foam-Cutter-4/?ALLSTEPS
www.instructables.com/id/Hot-Wire-Foam-Cutter-3/?ALLSTEPS
www.instructables.com/id/Hot-wire-foam-cutter/
www.instructables.com/id/Guitar-String-Hot-Wire-Cutter/

Been away for a while, but back now.

Built several of these myself the latest i have been using lately and i'm in the process of a new one.

I'll try and get some photo's later if you want, but i don't want to restrict the improvisation.

Tips;

Use a PC power supply. There cheap, (if it's not free look harder!) and pleantyfull. There are some modifications required, basically most have to have a dummy load on one of the circuits, (I'll have to look that up again later which one). There is several how to, websites, and most get you to wire up the sense circuit to a resistor. However it is much easier to wire it up to the fan in the supply and use that as the dummy load. Couple up several of the 12V output cables to a terminal block, (To ensure you don't set fire to the cable with the current draw).

An old, (or new) guitar string is ideal for the wire, (the one that is about 0.5-0.6 mm diameter is the go) And it will need to be about 400 to 450mm long.

If you need temperature control, i just use an aligator clim on a cable from the top of the wire and move it up and down the cable.

Let me know if you need more info!

Glenn

Thanks for all the responses! There's a lot of info and practical experience here on S.B.

YES for the pictures, please. The visuals will help me a lot.

How do ya know when the wire is hot enough? I'm pretty sure it doesn't need to be glowing red, but is there a visual indicator when it's hot enough?

I used a battery charger for a power source. To control temperature I put a dimmer switch in the box. For a wire I used a stainless steel welding rod. I mounted it on my table saw so I could use the fence. I also made some hand held wands.

I could not load a picture but there is one on page 2 of my build page.

www.seabreeze.com.au/forums/Land-Yacht-Sailing/Construction/Sabydents-Next-Build/

definately not red hot. really only hot enough to cut at a reasonable speed. it will vary depending on thickness. The cooler it is the better the cut, but it needs to be hot enough to cut in a fairly smooth action.

Although in saying that the wire on mine is about 0.55mm guitar string and is 450mm long running off a 12V computer power supply and I normally don't use the alicator clip.

This is what i've got. New one is actually well under way but is a lot more complocated. Will post photo's of that one day!

She's a bit rough. one of those situations where "I'll just knock something up quickly for the moment and i'll build a proper one later!"..... Still in service!

I've noticed my welding skills have improved a bit since then...... Sheesh!

FWIW I have seen one set up that uses a wire put into the chuck of a drill press
and using the spring tension of the drill column to keep the wire taut
I made a couple of years ago a plastic bender using a hot wire and can tell you that the wire expands a lot when heated so a good tensioner is needed

the advantage of a hot wire cutter is the finish you get. the foam is smoothed almost ready to glass onto