In googling for a foam cutter(see 1st thread) I noticed that they basically looked like an Electric solder gun with a different shaped tip.
So, being an inventive soul, I went out to my shop and took some ground wire from some romex and made some tips.
They work!!!
10 gauge is sturdier but cuts slower
14 ga. is faster cutting but will bend if I force it.
12 ga. is in between (imaginary that!!!)
OK, Questions:
A) Am I ruining my sears made in taiwain solder gun?
2) Am I ptting myself in danger? ie: potential tool explosion or meltdown.
III) Any suggestions on different metals/wires to make the cutting “element” out of.
Lemme have it!
Mr T
I can’t afford to be affordable anymore
Replies
Back many years ago I built theater sets and props. We used exactly what you describe to cut foam -- a soldering iron with a bent-up piece of wire in it. The iron we used had clearly been used that way for a long time, and was still going strong. As I recall, the wire we used was a coat hanger, which must have been steel. Steel has higher resistance than your copper, so you'd need a larger diameter than copper to flow the same amount of current. The larger diameter would make it stiffer, which sounds like it is what you want.
Ok, now post a pic of your invention.
I looked at that site and had the same thought you did. I almost never use my soldiering gun, so I won't miss it, if I turn it into a hot knife. (I hate the mess of cutting ICFs with a saw).
Dave
Hammer the wire flat and then tin the wire...
Cut on bro....
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming
WOW!!! What a Ride!
Good Idea!
They gonna let you into the great white north??
Mr T
I can't afford to be affordable anymore
I use an electric kitchen knife for foam rubber. No smoke. Just don't steal one from the Mrs.
Beat it to fit / Paint it to match
As someone else mentioned, an electric carving knife works well, and a regular 14" bandsaw works better...A serrated wide blade restaurant knife works well to cut fiberglass batts...
Let me clarify for those who don't read and comprehend so well!!!
:)
I will be cutting chanels and recesses for outlet boxes in an assembled and poured ICF foundation.
band saw will be slightly problematic here, NO?
Mr T
I can't afford to be affordable anymore
I gotta find mine..I used a guitar string and a coping saw frame and a 40w solder iron mechanism...the string was nickle/silver.
Spheramid Enterprises Architectural Woodworks
Repairs, Remodeling, Restorations.
Ya mean you dont have one of them new minature solid state bandsaws with text messaging and video??? Sorry, did not read it all to well..LOL.
anyway, take a look at the restaurant supply for a serrated knife, those things they sell are amazing..
My dad made soldering gun tips from copper wire for as long as I can remember. Never burnt out a gun.
Like the previous poster I also recommend that you use steel wire instead of copper, pounded flat to give it more stiffness and less drag in the direction you want to travel. Hot copper will just bend. Go up a gauge or so from the copper wire to keep the power up by lowering the resistance.
Actually if I remember my basic Physics/electric. Heat is proportional to resistance.
so more resistance means more heat means better cutting !!
Gonna try tha pounded flat thing with both copper and coat hanger wire today.
As soon as it gets above freezing!!!
Mr T
I can't afford to be affordable anymore
the soldering gun idea is a good one- milwaukee also makes a foam cutting blade that mounts on the business end of a heat gun.
i've had a very long (10" or so), thin blade bread knife stashed in my tool chest for probably 20 years. it gets used for any sort of foam cutting, insulation sheets, you name it. the thin serrated edge cuts with almost no crumbs. just last week i needed to pull a door jamb out of its frame and used the bread knife to very neatly and cleanly saw thru the expando-foam all around it.
m
It's a little trickier than that. At constant current, more resistance means more power, since power equals I^2*R. But your gun isn't a constant current device- it's closer to constant voltage, although that's not a perfect approximation either. At constant voltage, more resistance means less power, since power is also equal to V^2/R. So in short, try to get the DC resistance of your element to be about the same as the original (copper) tip if you want the same output power out of your gun. If you go with steel instead of copper, you'll need to go thicker to account for that, and thicker still to account for the fact that your tip will be a longer loop of wire than the original one (i.e. I assume you want the tip to be hoop-shaped to scoop out a channel in the ICF foam for wires etc.)
All you wanted to do is cut some foam, and somehow physics got into it! Sorry...
Hey, I resemble that remark!
If I remember your post, you simply stated, foam. You didn't say if it was the stuff on top of a Guiness or the innards of a SIP. Right after I posted a reply, I was reading about SIPs and wondered if that was what you meant. Maybe a couple of us pointy head types can come over and butt the panels for you. Unfortunately, we can't read or comprehend your thorough, well written directions.
I pity the fool.
Beat it to fit / Paint it to match
I used my old hand me down weller soldering gun for exactly that this past weekend. I bought a couple extra tips in case, but it worked perfectly well to cut out for the boxes.
A guy two doors down from my old warehouse sold sci-fi type reproductions. He had to do tons of foam cutting, including cutting out a life sized stargate gate. He used car batter charger with a wire between the two clamps, made a pvc pipe handle for it, then shaped the wire to whatever shape he wanted between the two pvc prongs. It worked great, cut through a 2' block of foam like it was butter.
they make a flat wire for what ur doing... if you go to any of the fake stucco sites & supply houses they have this wire and you can see the pretty simple machines they use to cut repete shapes... the old model train transformers that you can "speed up & down" seem to work best ...
i had (got stolen) a commerial hot knife was a ton of fun to play with... but it had a several "blades" to cut flat, V grove, U grove ect...
pony
I did what IMERC suggested with some #12 copper.
Hammered it flat, bent it to a squared U shape and shortened it up some, so the total length is <2"
Works alot better
But I found the manual for my solder gun and it is 20% duty rated.
for every 1 minute on your supposed to let it rest 4 minutes!
Anyone know of an affrodable continuous duty solder gun that wont break the bank?
Gonna check out sears and radio shack.
Mr T
I can't afford to be affordable anymore
You need lots of current at a low voltage. How about an old-fashioned arc welder? You may need more resistance than your 12-gauge copper wire element to make that work, but there'd be no worries about burning out the welder! Even a heavy duty battery charger may not do the job continuously with what you've got- I suspect the current flowing through your heating wire is much more than 10 amps...
Continuous duty soldering irons work on a different method- they've got a more conventional Ni-Chrom element which heats the tip by conduction. You need something which will heat the wire itself by passing current through it.
Just gut an old toaster - don't those elements stay hot for a couple minutes
You asked for a link. Here 'tis.
http://www.wind-lock.com
They sell the foam cutting knife. Gets hotter'n a $2 pistol. Generates RF to do the cutting. No duty cycle. Made to essentially run continuously. Adjustable temp. Comes w/ own tool bag that makes you look like a burglar making house calls. Can't beat it!
Don