Who knows how to regulate the voltage or cobble up a good hotwire for extruded foam?..I’ll need a lot of cuts that are scribed, not slice and dice. I got tons of guitar strings (phosper/broze, nickle/bronze, nickle/silver) from..008 up to .120 any ideas oh great minds?…Car battery and bow saw frame? HMMM?
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made one out of a coping saw frame with small insulators at the ends where the blade attached, then hooked wires to a model train transformer.we used telephone wire or nichrome wire, i dont remember which it was a very long time ago, used it to cut shapes for 1 of my soap box derby cars.
cool idea, but I gotta cut 2" thick foam 8' long and up to about 9'' in depth..coping saw just a little shy..train trans former eh?..HO scale or regular?
If you are try'n to cut 8' long the wire no matter what you'll use will drag... but it's simple to do up to 4' but the right wire... u can usually find it on ebay... but go by the place in ur area that sells the stuff for the fake stuco... they have a ton of sales stuff for hot wire cutting... it will give you an idea of how to make your home made cutter... the model train transformer with the adjustable speed deal works well... a good battery charger will do...
look on ebay under "hot knife" i've seen some stuff go cheap
pony
Get some of the wire used in toasters (NiChrome??) attach it to a dimmer switch, add a piece of extension cord and plug into 120v. Turn on the dimmer and adjust until you can just feel/hear the wire vibrate, this is just before it starts to glow. Use some wood handles to attach the wire to at each end to hold onto. This is what my timber framer used to cut out the foam on SIP panels for splines. It cuts thru the foam like butter and you can make it as long as you need.
Obviously you need to be very careful handling this since you are dealing with 120v.
Robert
That's what I thought a dimmer switch..sounds about right..gonna try a nickle/silver wire..see what happens..worst is I create a lightbulb in my hands right? <G>
better read the post "do you feel lucky today" before you start with the dimmer and 120v...stick to the DC power
Here here! I can see a new Darwin Award. Headline:
MARSHMALLOW MAN FOUND
Authorities find what appeared to be a man made of marshmallows. Upon closer investigation at the scene they found a 110 volt circuit connected to a dimmer that was supposed to lower the current to a guitar wire the man was using to cut foam. Apparently his cat pawed the dimmer and the increased voltage electrocuted the man causing him to fall into a pile of Styrofoam thereby liquefying the foam and encasing him.
Family of the victim said " He always liked fishin maybe we'll take him one last time, use him as a bobber, he'd like that."
ROFLMAO
Thanks, I needed that...
No the wire ain't 8 ' long the cut will be..I 'll surf some more, thankx..I hate ebay tho..
as i recall it was for an ho scale but one of the larger transformers. you could rig it to a table with the wire vertical and a fence,also you need the wire very tight as it will lengthen when the current flows and it gets hot.....cutting curves? or straight strips?if straight you could probably just cut it on a band saw. Ive also used those snap off utility blades about an 1 wide to cut foam. .nice plumb and straight cuts too just keep the blade oreinted.
In fill for a log wall..all curvy, I may just use the band saw but the wire is more portable..and a lot easier than feeding a 4x8 sheet of foam through the saw...yup, DC (car battery) sounds safer.
http://wolfstone.halloweenhost.com/HalloweenTech/fotmak_MakingFoamTools.html#PowerSupply
Thanx Bro, harbor freight is right down the road..gunna go with the solder gun idea.
if you have a good heat gun, they sell adapters that look like little sheet metal swords for cutting foam. milwaukee definitely makes one- not sure who else.
m
Wow! Something else I can help with!
You need nichrome wire for this. Not guitar strings or telephone wire. Nichrome has a specific resistance per foot so, you decide on the length you need, and do a calculation to determine the voltage and current combination you'll need to power it.
You also want a low-voltage transformer to power this thing. The transformer's not going to be a big deal, so don't think complicated!
DON'T mess with 110V, dimmers, and toaster wires! All this stuff puts full, lethal current to all exposed wiring. In the case of a foam cutter, the entire thing is exposed, so you're putting yourself and anyone who tries to rescue you after you weld yourself to the table at risk.
The transformer, properly installed and insulated, isolates you from the AC line, and minimizes shock hazard.
Even if you don't value your own safety, please don't even think of any of these guitar wire/toaster/dimmer monstrosities if there are any children that can come near this thing. They'll surely play with it, and can be killed in an instant when coming in contact with live wires out in the basement or garage science lab where you're cooking this thing up! :)
Wow, yerself..lol. Maybe I'll fix yer doors for a foam cutter? Or, you buy new doors and I will get a case of spray foam..<G>.
Actually, I will ruff cut on the band saw then custom fit with the good ol sawzall blade, MAYBE a solder gun...I don't want saw too much cuz the foam dust is real PITA..sticks like crazy to everything. I guess the fumes are deadly as well..when melted..
Hey, new idea!!!! I will make a bandsaw blade out of wound guitar strings silversolderd together, it will make enough friction to melt the foam, no electricity, and no foam dust..AHA.
I love it, perfect, and who said there is only the proven ways?
You are a riot!
I remember using a "knife" blade in a sabre saw a long while ago to cut foam. It worked better than any regular blade did, though I got decent results froma very fine metal-cutting blade.
I like the bandsaw-blade-made-from-guitar-strings idea. Though I wonder how you'd tune it... :)
How ya tune it, same way I test for tension with a woodblade..pluck it. My guitars resonate at about a 'G' longer length on the saw, about the same tension tho'..gonna do it, just for fun. <G>...Call it the 'Git Saw"..
Will somebody please hurry up and break the suspense as to who gets the family heritage welded to the pavement.....
Who ever invented work didn't know how to fish....
IMERC...Always late, what oversleep?...we already got this dog in a box..the new an improved Git-Saw..(patent pending of course)..can't even cut yersef much less git zapped..Osha will luv it.
Gawd awful work delay...
Who ever invented work didn't know how to fish....
So I guess my hot knife which is powered by a 5K Variac dimmer is a bit of a safety hazzard ?On a hill by the harbour
Well, when I first though of the variac, I would have said that it was ok. But then I thought about it, and remebered that Variac is a brand name for a variable auto-transformer, which varies output voltage with a moving brush that connects to the primary of the transformer.
Given that it's connected to the primary, I'd have said that it wasn't safe. But then I just checked some application notes for a Variac, and they list foam cutters as a common application! So now I don't know what to think!
I would expect any device that connects the output side to the AC line is inherently unsafe for applications where the output side is exposed. I guess I'd have to check the output of the variac to see if it indeed is or is not isolated from the input.
As for the dimmer, I'd expect that it is usually not isolated, so I wouldn't count on it being safe for this application.
Melissa,
The variac in question is a 5 K lighting dimmer ( Motion Picture Lighting)
If I insulated the hot side would it be safe ?On a hill by the harbour
Seems to me I remember long ago someone mentioning they cut foam successfully with an electric carving knife - the type with two serrated blades that slide past each other.
There is a fairly extensive (and probably expensive) list of foam cutting gadgets at:
http://www.demandproducts.com/foamcut.html
Well, as far as I know, the danger is that the primary side (input) is tied to the output. So, potentially the wire can be live with respect to ground.
"Autotransformer" means that one side of the secondary (output) is tied to the primary (input) of the transformer. So that means that it's inherenty dangerous.
I'd test it with a meter, which can be done while it's on (voltmeter) or off (ohmmeter).
If the cutting wire is live, then if you used an isolation transformer on the input, that should fix it.
I'd be interested in what you find if you do test it. Do you have a meter you could use?
You could always use a test light of proper voltage, I suppose, just to give you an idea...
Let us know, OK?
I don't have alot of use for the hotknife so I rent the variac when I need it........ That being said I will definately do some safety research before I flash it up again.
Sidenote: the 5 K makes for a wicked hotknife when used with a proper hot knife wire which I get from my local styrofoam dealer. I would hazard a guess that you had it right with " Nichrome" wire.
Another sidenote: to Sphere your bowsaw thought is exactly how mine is done but it is made with threaded rod & wingnuts for tensioning.On a hill by the harbour
Good plan to check it out before next use.
Interesting that you rent it. I only recently heard of people doing that. I wonder if it's expensive to rent?
Do they know what you use it for? Or do they think you use it for your basement theater? :)
Nope the varivac is a glorified transformer.... isnt it? I know lots of guys into radio controled planes use them to cut foam wings.
bake
Good info.
Now, take all that info and build a frame like a benchtop jigsaw.
Put the wire where the blade would be.
Now, set up a stand, and run the foam through this the same as you would a bandsaw.
Yaaarg !¡!!¡!!! Stand still... While I smite thee !
quittintime
I saw a unit built like that. It was used at a company that made store displays, and they had one they were cutting foam with.
I think they also used a similar setup to either cut or bend plexi or some other acrylic they used in the displays.
I found a link over in KNOTs that was way funny, If I can relocate it I'll show ya..a guy made a CNC hotwire for making casting patterns..thing would just cut away all day..pretty intricate and accurate parts too..I'll do some diggin..
here is one... http://www.8linx.com/cnc/cnc.htm..here is neat thread!! http://www.buildyouridea.com/cnc/hblb/hblb.html
Edited 1/24/2004 9:01:48 AM ET by SPHERE
Edited 1/24/2004 9:13:40 AM ET by SPHERE
I'll do it this way to make sure ya see this..http://www.buildyouridea.com/cnc/hblb/hblb.html
That site is so cool! Are those bearing pictures of your project?
I just bookmarked that site, and I can't wait to look through it all. Now if these kids would just go and make their own breakfast! You'd think that the three-year-old would at least cook some pancakes and eggs... :)
Gawd No..that ain't my site or work..I just stumbled on it..the guy gets a star on his head for perserverance that's for sure!
To start the kid cooking ya need one of them stoves powered by a lightbulb <G>..eazy bake oven I think it is, I still use one and I'm 43..lol..
The Easy Bake isn't good for coffe or soups or stuff like that. Break out the heat gun and you'll have things cooked much faster.
Mapp for the big stuff here..had to swipe the element from the heat gun to cut the foam!
3170867675
This is the wire on Ebay to build your own. $10.50 includes shipping in US.
I have a 10 AMP Radiac, works great.
Joe H
Yo, that is too wild..same stuff thats in a heater or toaster oven..hmm?...the DW don't need the toaster oven till I get the insulation done..seriously I will order a hank , and try it out. maybe play Mr. Wizzard with it.