Foam cutter/ hotwire cutter - RC Groups
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Jun 12, 2010, 08:00 AM
No ceiling for my altitude
Nīmā's Avatar

Foam cutter/ hotwire cutter

I have Searched before but now I can't find a topic about making a foam cutter.
I know I should get woods and a long wire. how can I make a foam cutter?
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Jun 13, 2010, 04:49 AM
No ceiling for my altitude
Nīmā's Avatar
Thank you alot.
Jun 13, 2010, 08:13 AM
Red Merle ALES VI
Curtis Suter's Avatar
Go to and on the Articles/File tab you'll see an article I wrote for RCSD on how to build an Automated Foam Wing Core Cutter.

For more information look at the Videos page "A Beginner's Guide to Cutting and Bagging Foam Wings" will shed a whole lot more light onto the subject too!

All the best.
Jun 18, 2010, 05:28 AM
Registered User
saucerguy's Avatar
Don't kill yourself over it, seriously, they make it way super more complex then what it needs to be "don't look at my wire cutter, it's a spin off of theirs and is more complex then what it needs to be". lol.

Grab a bendable stick, bamboo or a tossed away fishing pole will do. Bend it end to end so you have around 40" of area for the amps and volts I'm showing you which are standard on many power systems, tip to tip, notch the ends of them. String along some stainless steel fishing leader between them, notches will hold the wire in place. Bow is finished "it will look similar to a hunting bow just fyi, done in the same manner for a visual.

Hook up your car battery charger to each end of the wire, keep it at 12v 10 amps and you have the power and are ready to take it to the jigs to cut your foam pieces. You can make smaller ones as well for smaller pieces, it's not at all hard, the plans you'll see look far harder to do then the reality of it all, the wire just needs tension, any way you do it will produce the same results.
Jun 20, 2010, 04:39 PM
"what ever just crash it"
luger007's Avatar
Agreed, a hotwire setup can be as simple or as complex as you like, the main differences are cost and technique to learn how to get the results you want. Here is an example of exactly how simple a wing cutting hot wire setup can be.

Personally I like repeatable results, so I have a gravity feed, drop bar setup. for bows I have everything from a Feathercut bow to a curved, laminated wooden bow, they both work very well.

The two biggest variables I have found for a good cut are wire temperature and speed, but the wire material makes up a little difference too. Nichrome is the standard but I do not like the way it stretches and breaks. Stainless steel leader material, solid strand or multi-strand seems to work well, but I personally use Rene wire and never had an issue with it. (not true of Nichrome or SS leader)

Jun 26, 2010, 04:30 PM


Originally Posted by iruav
I have Searched before but now I can't find a topic about making a foam cutter.
I know I should get woods and a long wire. how can I make a foam cutter?
Make sure you use ni-chrome wire .032"
your bow has to have a tentioner on it,
let me explane, when you heat up the wire
it expands and lengthens so the wire will be
tight when cold and sags big time when hot. It's easy.
picture a straight bar with a bellcranks' central
pivot at each end, the bottom being the ni-chrome
wire pulled tight by the top by having a cable attached
to a tentioned spring that will shorten but won't close up
completely as the wire lengthens.
my top tentioning wire consists of: an eyelet attached to the
top end of the pivoting bar, attached to a cable,attached to a
pretty strong spring (3" long by less than 1/8" thick wire),
attached to a cable shortning gizmo you know, an eyelet on each
end with a way to lengthen or shorten it by turning a middle piece
thus threading itself longer or shorter. (sorry forgot it's name) That
piece simply through bolts through the other pivoting bar with a nut
and washer on both sides of its threaded rod to mount it.

Also, Make sure that you leave enough room between the ni chrome
wire and the bar (length of bellcrank to pivot point) my bow is 12" deep and I wish it was 15" deep. also note that my tensioner cable is only 6" deep (so to speak) and is ample for keeping tension
simply put: the bellcrank is 15" long for wire and 6" long on top for the
tensioning cable (in relation to its pivot point).

Got a little complicated but I hope it helps
Jun 26, 2010, 07:42 PM


Originally Posted by iruav
I have Searched before but now I can't find a topic about making a foam cutter.
I know I should get woods and a long wire. how can I make a foam cutter?
Don't forget to make block holders so you can hold onto and control the
wire, I use 1" dowel stock, drill a hole through it's center, install brass or
copper fuel line into the hole. This makes a great finger hold and doesn't get hot. eventualy it will burn the hole to big to hold the copper but it lasts
a-long time. I do try to keep them in motion when burning off the drops of foam from the wire pre-cut. REMEMBER: install these as you wire your bow or you're screwed, how do you put them on the wire after?
OMG Dang it, I gotta un-do the wire to put them darn things on!!!
Dang!!! and I bent and twisted a loop on it to put it on!!! that's how lol
Don't forget the holders!!! and Good luck

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