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Building Tips and technical articles. => Building techniques => Topic started by: andreas johansson on June 04, 2009, 05:39:43 AM
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Hi all!
As I dont like thimbles for different reasons I have thought of using 1/16 copper tubing as lead-out ends. I thought of pushing the lead out wire trought the tubing and then bend it in a U shape and then wrap the ends as usual. What do you think?
Andreas
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That's been my prefered method for about 35 years. Soften brass tubing with a blowlamp and it bends into a nice horseshoe shape with the .027" cable inside. The partial flatening of the tube is almost enough to secure the leadout, even with wrapping.
I still wrap them, but in scrapping out some old systems, it was virtually impossible the pull the wire out of the tube, even with pliers and a vise. Both ends, bellcrank and wingtip.
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That's how I do mine, but I use annealed brass tubing instead.
Here is a picture of how they look.
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Thanks guys, no more thimbles for me #^
Andreas
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That's how I usually do it. However, I made up leadouts for a plastic bellcrank using the large diameter CA plastic tubing instead of metal tubing. This was a 40-size airplane which I flew a lot over @ 7 years. The outside wing finally blew off and I trashed the airplane. There is absolutely no wear at the bellcrank-leadout interface. I am impressed.
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Hi.
I don't use separate line connectors, just solder a clip directly to the end of lead-out cables. Same thing at the bellcrank end. The piano wire (dia 1mm) overlaps with lead-out cable about 1/2" and it's wrapped with thin copper wire before soldering. It all depends on the shear strenght of solder joint, so it's very important to pre-tin the piano wire and cable ends before wrapping and soldering them together. I don't use stainless lead-outs but it's not a big deal to replace the lead-outs of a fully take-apart plane if I see any problems.
Regards, Lauri
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That looks scary, but, with the new pull test rules I hope it works. DOC Holliday
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Hi.
It's not scary at all, even with your old pull-test rules. Yatsenko's have allways used this method.
But as I said, you must be sure that solder sticks well to piano wire. That's why I pre-tin the parts before assembly. L
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Are you using silver solder on those clips?
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Nope. Just the standard tin/lead stuff. For pre-tinning I use tin/lead paste, that's tin and lead powder mixed with flux.
Also, I saturate the l.o. cable with solder a few millimetres more than overlapping goes and also do the same with copper wire wrapping. this is to prevent a stress riser where piano wire ends. L
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Here's my simple tool for leadout thimble bending. These tool parts were made with a hack saw, drill press and files. The thimble is 1/16 brass tubing.
The pictures show just bending of just the thimble. Flying line of up to .018 diameter can easily be threaded through a pre-bent thimble. For leadouts, I thread the cable through the tubing first, then form the tubing.
Derek Moran
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Derek,
You're always so clever.
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Derek,
You are such a perfectionist..(I mean that in a good way).......I'll be you even keep your shop clean, too ! <grin>
What keeps the brass tubing from collapsing??? Is it just the wheel collar that does the trick?
And do you anneal the brass tubing before you try to bend it?
Good work
Cheers.
Warren Wagner
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Soldering.
Beware of two things...Acid core solder, or Acid flux will really corrode your wire unless treated wit baking soda and water solution. And soldering will also potentially set up a stress riser.
That one doesn't make me warm and comfy. But then, I use solid leadouts!
w.
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Here's my simple tool for leadout thimble bending. These tool parts were made with a hack saw, drill press and files. The thimble is 1/16 brass tubing.
The pictures show just bending of just the thimble. Flying line of up to .018 diameter can easily be threaded through a pre-bent thimble. For leadouts, I thread the cable through the tubing first, then form the tubing.
Derek Moran
Do you use .018 cable for lead outs ?? That seems small to me.
I use .027" which will also fit inside of 1/16 tubing