Hot Wire Foam Cutting

by FliteTest | April 30, 2013 | (37 Ratings) Posted in Tips


Welcome to Hot Wire Cutting with David and Josh! 

David made his hot wire cutter out of PVC piping and extra RC components, including a Turnigy 30A BRUSHED ESC and a servo driver.You can use building pins to hold down your template.Hot glue also works on very thin parts of the template. The hot wire will cut through the hot glue easliy.When cutting you want to allow the heat of the wire to cut the foam. Try not to pull or bow your wire.This specific project was cut in sections using templates found here.Check out the review of this plane here, and see David's build log of the plane here!

Join in the discussion on this topic in the forum post, CLICK HERE! 

COMMENTS

azgar on May 2, 2013
David, can You please put a wattmeter between Your battery and ESC and try it on wires of different length?
It would give a clue on how much power to count with if alternative powering solutions are used.
Thanks.

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cade861 on May 1, 2013
you guys should sell the formers in your shop im sure there would be a big demand for them!
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Icaro on May 1, 2013
Thanks for the video guys. Looking forward to a build vid of your cutter, especially how you connected your nichrome wire to your PVC tube and applying the correct tension. I threw one together made one from wood connected to an ac adaptor to cut down large polystyrene blocks to put out for recycling a while back. Very unsophisticated with a tendency for the wire to break at the ends. Your variable temperature control is a great touch.
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cade861 on May 1, 2013
icaro if you look at davids ja37 build log added just above this post it has a really good build log of how he made the bow.
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Icaro on May 1, 2013
Oops. I missed the link. Thanks for the heads up. Another great build log from David.
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cade861 on May 1, 2013
no problem and it is another top notch build log by David as usual!
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casehatter on May 1, 2013
Still looking forward to those templates in the store this is on awesome EDF and I usually don't like them and reason is to fast and stalls in turns, but this baby now is a hoot..!! Full up Ele and no stall that's great only the $700 planes with thrust vectoring can do that..!! David can you image that baby with thrust vectoring and controllable canards that thang would 3D..!!
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kooguy123 on May 1, 2013
How would you suggest making the templates if we don't have a means of laser cutting them? The finished product looks fantastic and the build looks like a fun process!

Thanks!
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Willsonman on May 1, 2013
I will be trying to make an article soon with video of how I do this. I do not use wood templates. I use a much more affordable alternative.
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Laynehip on May 2, 2013
It takes a little longer (okay a lot longer), but I have started cutting these using a jewelery saw (I am not sure what they are actually called, its basically just a hack saw with a very fine blade and is smaller overall).
I printed off the template provided using a titled pdf and then cut them out with the saw.
Just cutting out the templates will probably take longer than it took David to build the entire thing but it works well and it is fairly easy.
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kooguy123 on May 3, 2013
Thanks! Can't wait to try this out!
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clivepjamesr on May 2, 2013
Really enjoyed watching this and the maiden video, Search for "rene hot wire" for an alternative. it has less "lag", takes higher temperature for faster speed, or slow depends on your speed preference. thanks FT Team.
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DefekC on May 2, 2013
Question for David and other who had experimented with this in practice:
(X) AWG size nichrome wire is recommended for (Y) size foam cutter.

Recommendations for X and Y values! :D

As far as I am aware it is better to use as thin wire as possible for smoother, faster and therefore more efficient cutting, but trade-of for that is rigidity. Rule of thumb: the smaller the bow the thinner wire can be used and vice versa. Because wire is tensioned it can (or could) be easily snapped.

But where is threshold limits? Most probably it is not recommended to use 32 AWG wire for 3 feet (1 meter) bow as it will most probably snap quite fast (?) and 20 AWG for 5 inch (12 cm) bow would be too bulky.
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liveyourdreamsRC on May 2, 2013
I have one question from the video: Do you leave the formers on after cutting and just glue together or take them off and glue foam to foam? Just seemed wierd how you hot glued them on and that sounds more permenant than taking them off after. Hope you do an episode on airbrushing tips! Great explanation on how to build the bow in the Viggen build, I bet I could make one without a build video, though one would help! Keep it up!
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Driveandairsmash on May 2, 2013
what foam did you guys use?
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RCbacon on May 3, 2013
For the wing and the canards he used dollar tree foam and for the body he used 4" Styrofoam square edge insulation! Hope i helped!
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Madmarl on May 4, 2013
Awesome build David. I never thought to use templates like that!!
There was a C-130 Hercules built years ago that used that technique, but I had forgotten about it...
Thanks for the inspiration!!!
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coffeebean56 on May 4, 2013
I found the Brushed ESC's that he mentioned at Maxford USA
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OutcastZeroOne on May 5, 2013
I made a fairly elaborate hotwire set up a few years ago. Works great and Ive used the same tecnique David shows in the video for years. The only real hard part is making sure your templates are lined up where they need to be.

Heres a link for my hotwire if anyone is wondering.
http://www.rcgroups.com/forums/showthread.php?t=1450332

Ill post to FTs foarum when I start to build my new set up.
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sierra4344 on May 26, 2013
Saludos from Baja mexico... i will try to built te JA 37 Viggen wish me luck
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jab69 on July 12, 2013
HiI like your build.
What do you guys use to glue the parts together after cutting them? I use normal wood glue to glue mine ogether.
I see someone asked about the templates. I use normal cardboard( about 0.4 mm thick.) to make mine.I use a normal scissors to cut them out(wife enjys doing that for me).I can get up to three cuts out of each template.I find that a person tends to push the wire against the template instead of guiding it along the template.
I struggle to get the ideal plans(with the cross cuts in them) to do this kind of cutting.How or were do you guys get your plans.

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jetbuilder on August 21, 2013
could you make a template in english

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RCbacon on May 3, 2013
How shall i print the Viggen plans that David did? If i just print them, they are kinda small :( Please answer!
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Gal 2:20 on September 4, 2013
Use Adobe Acrobat Reader' version 11 (latest one), and take "snapshots" of just the formers while viewing them at full size and print them out "actual size". You can do the same to the wing and rudder and canards then "posterize" them and print onto 12 sheets and tape them together.
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Marker on October 2, 2013
David said that he used 0.4mm thick Nikrothal 80 wire. Did he mean 0.04mm thick? Because I cant find any 0.4mm thick. If he did mean 0.4mm thick where can i buy it?
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mark d on January 2, 2014
Hobby King still sells a brushed esc by the way.
Great article by the way David, I like your design method. The extruded foam you used in the video is extruded open cell polystyrene that can sometimes be found at concrete supplies in the warmer climates like FL and TX. Open cell is great for fuses and wings as long as it won't get contact with water, in that case use closed cell - the stuff that breaks into little beads (Expanded bead Poly Styrene) EPS. I made a boat of open cell once - bad idea, turned into a loofa.
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