Not many people will argue with flying RC airplanes is super fun. One big bummer is when a crash damages a part beyond repair. Sure, the RC pilot could keep buying replacement parts but doing so will add up after a while. RC plane builder and general guy with a cool name, [HuckinChikn], decided to build a hot wire foam cutter so making replacement wings would be quick and cheap.
The actual hot wire part is nothing special, just some wire pulled taut across a frame and a 24 vdc power supply pumping out current and heating the wire so it melts any foam in its path. The unique part of the build is that one side of the hot wire frame is secured in place and only allowed to pivot about that point. The other side of the frame traces an airfoil-shaped pattern. This setup allows [HuckinChikn] to make tapered wings. The difference between a straight wing and a tapered wing is similar to that of a cylinder and cone.
Check out the video after the break for a quick demonstration how easy it is to make a wing when you have the right tool!
Brilliant!
It is clever, but may be a challenge for big wings.
For real airplanes, we use a hot wore template on each end of the wing (one big, one small), have two people with call out numbers, and if the two ends are about on the same number, the wings come out great!
http://cozy.basol.net/chapter19.htm
The cozy and longez have tapered wings.
Not too shabby. Now just upgrade it to CNC and you would have something.
Like this:
http://www.instructables.com/id/Make-a-CNC-Hot-Wire-Foam-Cutter-from-parts-availab/
The jig could probably be optimised so he’s not tossing 2/3 of the material in the scrap bin.
Hey, it’s kinda like that garotte in Johnny Mnemonic!
Experimenting with making wings at home is great fun, cheap too. There are hundreds of airfoils published. https://www.flyingfoam.com/content/online-resources
Short lengths of nichrome wire can be found on ebay. I have a hotwire setup powered by my old red weller soldering iron dimmer.
After cutting the cores, cover with painters paper wet down with 50/50 titebond2 / water. The covering stiffens the wings nicely and makes a paintable surface. I use balsa for the ailerons.
I’m always afraid of the material re-bonding to itself after the cutter has passed, I’m surprised how well it works!
If it rebonds the wire is too hot
I have one of these cutters sitting in my garage that I built a few years ago. It works great. I used fishing leader line, and it heats up nicely. 24v power supply powered by a light dimmer at 110v AC, works great. Maybe I should submit my home made arc welder as a hack. MOT’s FTW :)
I hate to admit it but I went for broke (or dead) when I did it – wired the dimmer direct to the NiCr wire, along with a bungeed lever to maintain tension as it heated. Worked like a charm and still does, but a bit finicky to adjust as you might imagine…
Does anybody else can smell the foam heating just from the video ?
I bet the guy that made this is like WTF as the last post in the build thread was 4 years ago.. must have been a slow stories day ;)