Monday, May 13, 2013

Soldering Lead Outs

Some guys have asked me about what I use for lead-outs (LOs) saying that is a major reason for not building their own planes. When I tell them I us .021 stainless flying wire the first thing that they say is " I thought you couldn't solder to stainless wire!" Well in fact you can and it is not that big of a deal if you have the right stuff. Here is a quick look at the way I am doing them.

1. The right stuff: I use Superior 78 Stainless Steel flux. With out the right flux the solder will not stick and you will have a single line plane or worse a flyaway. I use  silver solder.

2. Everything has to be cleaned: I use some 600 grit sanding paper to clean the oxidation off the music wire hooks and the end of the LOs.
3. I first attach the LOs to the bell cranks and then measure the total length including the hooks that I need and cut the LO. Also keep in mind that the front and rear LO may need to be different lengths because of the bell crank location. Do this BEFORE installing the bell crank and LOs in the plane.
4. Wrap the hooks to the LOs with thin copper wire. Notice that the wire goes all the way to the end of the hook. The copper holds the hooks in place and lets you slide them for final adjustments before soldering.

5. Time to solder, I have found that using a small or as you see in the picture a big propane torch works best. It is much harder to get the wire up to temp quickly with a soldering iron. BE CAREFUL with the torch not to over heat the wire. You can very quickly damage the wire if you over heat it. I pass the flame over the wire hook for just a second at a time with the solder touching the copper until the solder starts to flow into the copper coils. I suggest a few practice hooks before you work on LOs that are installed in a plane.

6. After the hooks have been soldered bend the LO wires that are past the copper 90 degrees and cut them off with side cutters. Sometimes I go back with the Dremel and a stone to clean up the end.

7. Make sure to clean all the excess flux off the hooks, it is acid based and will cause the music wire hooks to rust  and possibly fail. A stainless steal brush and some rubbing alcohol work great.

All ready to go and only takes a about 5 minutes per plane.

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