Tips on cutting foam wings with hot wire

[schnellschnell]

My son and I made a hot wire cutter today and started trying to cut some wings. I had the templates for the root and tip on each end. But keeping the wire in sync so that it reached the ends of each template at the same time was really hard. Ended up with some weird leading edges! What happened was one end of the wire was on the top of the leading edge, the other side of the wire was already around at the bottom making for a 'sunken' edge.

Is there an easy way I am missing, or do I just need practice? In my mind it was going to be so easy... :P


j

[volto]

I like to mark the root and tip templates with 10 evenly spaced marks, and try to hit them each at the same time. It's a lot easier with two people, at least with my brother - because we are like the Borg, we operate with collective consciousness.

[IBCrazy]

J - You are pulling too hard on the bow. Use light pressure with a bow as cold as you can stand that will still slice the foam. You also want to be sure your wire is nice and tight. If it isn't you will have a strange impression in the middle of your wing.

The low heat/slow speed allows you to look at both sides and slowly adjust your cut rates without melting the foam excessively due to sloing. The maximum root to tip difference for an even cut is about 2.5:1. That means if your root is 10", the tip can be no less than 4" or the wing will definitely be distorted.

-Alex

[aeryck]

What type of wing are you cutting? rectangular or tapered?

If you're cutting tapered wings, I found this video to be very useful as a how-to... Just ignore the cheesy "Mega Man 3: Snake Man" remix.


View this video on YouTube

[joslynlara]

You can also use the hot wire cutters for similar kind of operations. The weird leading edges have end of the wires on the top part. The bottom part really has a sunken edge. If you practice well, you can easily come up with the difficulties.
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wire cutting

[HugeOne]

FIRST TIP!

Ventilate the smoke out! this stuff is NASTY!

-Hugo

[Derrick]

I recommend starting at the leading edge... Use a two piece template, cut the bottom first, then cut the top. Make sure that you have a lead in and a lead out on the bottom template. This will give you a little leeway for not getting perfect timing. The leading edge is the most important part of the airfoil, the TE can be cut back flus or even cut away to add elevons/ailerons/flaps. Here is a pic I found over at RCG that shows what I mean by the templates.

I also use a weight drop system that I made from a piece of angle, a 36" ruler, and some pulleys.

[chanyote66]

Heres what I do...
But this only works for tapered. (I fly Flying wings mostly...)


View this video on YouTube

[RandallJ]

well that made it look easy... thx..

[chanyote66]

no problem it takes me 1 hour from raw foam to flying fpv...

I use a 24v 2A home built hotwire that can cut up to 12' length

Chris