[Fergy]

I mentioned the use of foam insulation in an earlier thread on scenery, and touched on the use of a hot wire tool to cut and shape it. If anyone isn't familiar with this method, here's a link to a tool offered by Micro-Mark in the US:

Hot Wire Tools

I'm not familiar with this actual product, and not endorsing it, just putting it out here for general reference.

I think it must be possible to get something more inexpensive. Anyone have any experience in this area with cheaper tools or homemade setups?

 

[Intergrali]

blow torch and scraper method works great on polystyrene, cant see why it wont work on foam?!

Rob.

 

[Fergy]

Might be a little iffy near the MDF track - I glue all the foam in place before contouring any of it. In what situation are you using the torch and scraper?

 

[Intergrali]

well you use the blow torch to heat up the scraper blade and then no nasty squeeking or poltstyrene anywhere as the it just melts thru leaving a nice stright line and "seals" the polystyrene.

Rob.

 

[Fergy]

Got it! Thanks!

Found some good info for homemade hot wire tools after some more net surfing... think I'm gonna build one - should cost me all of $10 or so (in worthless Canadian money)... beats paying US $100+...

 

[Intergrali]

JUST looked at the link now.. thats crazy! and for what we need to cut it for a blow torch and scraper or knife would do fine!!

also, I'm sure a soldering iron would do the same

Rob.

 

[Fergy]

Yeah, the prices are a bit much for what the product actually entails!

Your torch method should work quite well for cutting concave shapes in the foam. The hot wire will be a little simpler when doing convex and straight cuts. Soldering irons (or even wood burning irons) can handle some of the detail carving. I see a plan coming together...

 

[soapy]

Another thing to consider is to throw in a few extra bucks and buy yourself a fan and some furnace pipe and build a little fume hood. Just rig the pipe to the fan and then vent the fumes to the outside. If you plan on doing lots of lead soldering of chassis and spraying paint it is a good idea to vent the nasties outside, not to mention the stink of melting plastic. It is the first thing I am going to build for my new workshop.

 

[Intergrali]

most just open the nearest window

but if it makes you happy

sounds like a good idea, kinda like a hood for the hob in the kitchen..

 

[Fergy]

Soapy, yes, I made one several years ago. I used 4" flexible ducting and a large, powerful, brushless fan (no sparks around paint fumes, please!). The ducting attaches to a filter on the rear of my spray booth or can be located elsewhere as needed. More ducting runs from the fan to a sealed plate that is gripped in a partially opened window.

Inte, you are the master of simplicity.

 

[Intergrali]

I thank you fergy, thats the intention make it simple then confuse you all

so far it hasnt worked

Rob.

 

[JohnP]

Games Workshop sell a battery operated Hot Wire Tool for about £12(UK). The technique works fine and is a lot less messy than cutting with a knife.

You have to bear in mind that the U shaped wire holder limits you to a certain depth of cut. In practice though I have not found this a great problem.

 

[Fergy]

John, I'm fooling around with this as we speak!

Yes, the hand tool versions are good for detail cuts and rough shaping. Major cuts from large pieces are best done on a table-mounted system. If I don't blow myself up today

I may even work out a hand version with a wire stiff enough to hold a shape of its own, rather than just a fine straight wire.

 

[JohnP]

Bah, web access crashed

- seem to be back on air now...

QUOTE I may even work out a hand version with a wire stiff enough to hold a shape of its own, rather than just a fine straight wire.

Fergy, if you do that I've got to see it! You are going to HAVE to buy a digital camera

Do you have any material in mind for the wire? I presume it would have to be stiff enough to hold the shape yet still have the right conductivity. What do you reckon?

 

[Fergy]

Yeah, I'm toying now with some stainless wire. Nichrome, of course, is the norm and easier to use because of its inherent resistance, so there is less demand on a power supply, but it isn't heavy enough to hold a shape. I'm playing with a rather HD transformer right now, and it works with stainless wire up to .015" so far no problem. Next tests will be with .025" and even heavier but I have to go out and buy some... the cupboard is bare...

 

[biggstr6]

I had a friend in the sign business made one with a board ,a couple of nails ,some single strand wire ,and a dry cell battery. Worked fine he just left one end of the wire off when he wasnt cutting ,and when he was ready to cut ,he just wrapped the wire around the other nail and when it got hot (which happened quick) he started cutting.

I guess if you made a U shaped handle (Wishbone shape) you could make a hand held one as well.

 

[Fergy]

Well, I haven't got the rest of the bits I need yet (shop is closed Sun and Mon), but I did accomplish one thing.... I made a 25A arc welder!

What's that dear? The lights upstairs went dim? No, not me, hon! ...Need to dial the output down a little, me thinks...

I'll get a variety of wire sizes tomorrow and see just what it will take. Hoping for .025" or .032" wire for the cutter. That should be stiff enough to hold a shape.

 

[JohnP]

Funny, the lights dimmed here earlier too Fergy

Don't forget to add a welding helmet and safety goggles to that shopping list tomorrow

 

[Fergy]

...Ouch!.... and fire-proof gloves...

The burn marks give the old workbench a nice, distressed look...

 

[JohnP]

hey Fergy, it's Wednesday (I think

). Any more news?