Electric styrofoam knife

[Treeview]

This afternoon I was poking around and found this styrofoam cutting knife.

http://www.sciplus.com/recommendation.cfm/rid/223279

Tom

[IndyTom]

That looks really interesting. I love that website.

I also found something interesting today that qualifies under this thread heading. I was looking around @ Harbor Freight and I found this:

http://www.harborfreight.com/hot-blade-decal-remover-65057.html

I am not building a foamie, but I am going to be cutting foam to insulate the walls and roof of the Bungalette and thought it might work for that.

Tom

[linuxmanxxx]

I got the harbor freight hot knife to try for cutting my sandwich wall foam and it performs horrendously and just reverted back to cutting it with utility knives and just keeping the blade fresh.

[Treeview]

I would bet that a pencil soldering iron could be made into a hot knife.

When I need to hot cut synthetic fabrics I get my pencil. After finding a piece of copper tubing that fit inside I cut the tube in half, shaped the remaining half into a blade and make clean cuts.

[linuxmanxxx]

Yeah the blade is just too wide and has to melt too much foam so it is slow and very aromatic in a most unpleasant manner. If they had put a narrow knife blade on it, I'd bet it would slice the foam like no tomorrow.

[GPW]

The old electric carving knife works Fine ... no fumes ... Even cuts Foam rubber too ..

[atahoekid]

This afternoon I was poking around and found this styrofoam cutting knife.

http://www.sciplus.com/recommendation.cfm/rid/223279

Tom

Bought a similar knife from the hot wire foam factory and it really didn't work too well for cutting straight edges out of the XPS foam. The "blade" flexes too much. But it would work well for finer cuts

[Wobbly Wheels]

I would bet that a pencil soldering iron could be made into a hot knife

The problem I found was that my 40W pencil had to have a short wire in order for the whole thing to heat, which put the barrel too close to the foam. It worked pretty well otherwise (I reshaped a soldering tip) and that problem would just take some tinkering to work out.

[ebutler]

I have used a jigsaw with the teeth ground off and a knife edge ground on the blade. Makes very smooth cuts and no dust, little foam balls or anything.
If you need to cut really tight inside radius just use a thinner blade.
Elmo

[atahoekid]

Thanks for the idea... I've been using a jigsaw with a standard blade and it cuts easily and well but it does leave a somewhat rough cut. So far so good though as that rougher edge just gives the glue something to bite into.

[Papi]

I made this one in about 15 minutes using a piece of scrap pine, a file folder, a couple of screws and zip ties, and the 2 amp transformer from an old printer. And I do mean old!
Cost: 15 minutes of my time. Works like a dream.

[Treeview]

Printer transformer...thanks...off to scour the dumpsters!

Tom

[Papi]

Printer transformer...thanks...off to scour the dumpsters!

Tom

Just make sure the one you get is pretty stout; the first one I tried from an old answering machine didn't heat up. It was measured in milliamps. The next one I tried was a bit stronger, but the solder melted off the inside of the transformer and I had to unplug it in a hurry! I got a big pile of old transformers free, so it didn't cost me anything but time. I bet even a car battery would work.

[GuitarPhotog]

So I agonized over hot wire foam cutters for a couple of weeks, and made a functional straight wire cutter, but couldn't get a low enough voltage at high enough current to drive my "router table" rabet/dado cutter.

I ended up cutting my foam with a very sharp, very thin kitchen knife. It produces very little "foam chips" and leaves almost as smooth an edge as the hot wire. The knife is an 8" filleting (boning) knife that is very thin and flexible.

And it turned out to be about 1000X less work than setting up and adjusting the fence on the hot wire cutter for each piece I had to cut.

I have finished cutting and dry-fitting all the foam panels (1" rigid styrofoam insulation) in less time than I spent screwing around with the hot-wire cutter.

My friend says that I over-think and over-engineer things. She's right, and here is a good example. I spent less time cutting the 10 pieces with a kitchen knife than I spent just trying to get the hot-wire cutter working.

My advice: don't overlook the simplest solution.

<Chas>