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Building Tips and technical articles. => Building techniques => Topic started by: Tom Strom on February 22, 2012, 04:58:04 PM
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Hello. I am sure this has been discussed before, but I can't find where. I am just finishing up an aircraft and am ready to do the leadout ends. I used small brass tubing and copper wire at the bellcrank, just wondering what most folks do at the other end. Small brass tubing and wrap, or round eyelets then wrap. Pictures would help, but not mandatory. Thanks.
Tom
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Hello. I am sure this has been discussed before, but I can't find where. I am just finishing up an aircraft and am ready to do the leadout ends. I used small brass tubing and copper wire at the bellcrank, just wondering what most folks do at the other end. Small brass tubing and wrap, or round eyelets then wrap. Pictures would help, but not mandatory. Thanks.
Tom
HI Tom,
Both of your descriptions are used, mainly personal preference. Probably, the small brass eyelet is most in use.
BIG Bear
RNMM/AMM
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I use 1/16" aluminum tubing to make a ferrel and wrap with copper wire. In the past couple of years I started using red and black shrink tube to identify up and down to decrease the opportunity of hooking up lines backwards. Last year after returning from NATS I did it anyway ~^ Shrink tube works well but make sure you put it on before wrapping; don't ask. I terminate this way at both ends.
The picture probably is not to useful. My old camera doesn't have a macro feature.
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Thanks for the replies. Mike, that looks like the way I was going to go, but with brass. Any reaason you went with Aluminum?
Tom
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I think I started using aluminum simply because I couldn't find any brass in that size. That doesn't mean it doesn't exist, just wasn't available when I wanted it. Aluminum however, works real well. That's all I've used for several years, on my leadouts and lines.
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I recently built a Brodak kit thet had brass eyelets for the leadouts. They were too small to use with the leadout wire supplied, so I made my own teardrop shaped thimbles from 3/32" OD copper tubing. They are also easier to hook up to than the round eyelets.
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I have used copper tubing for making the line and leadout ends. It helps hold the cable while wrapping or swagging. There a fuzzy pictoral on this forum some where that I did a couple of years ago. H^^
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Hi.
I don't know what your rules say about this, but here is my favorite method. The cable and piano wire clip just overlap about 1/2" and are wrapped together with thin copper wire & soldered.
To spread the stress in the end of piano wire clip, I impregnate the cable with solder (tin/lead) for another 1/2".
Never any problems. L
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Hi.
I don't know what your rules say about this, but here is my favorite method. The cable and piano wire clip just overlap about 1/2" and are wrapped together with thin copper wire & soldered.
To spread the stress in the end of piano wire clip, I impregnate the cable with solder (tin/lead) for another 1/2".
Never any problems. L
Lauri,
that method is so obvious and simple ........ and yet I have never seen it in use before!
I love it! :D
Thanks.
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Chris,
Actually, it's the godless communists to thank. L
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It is a perfect alternative design if you really know your solder. I love it y1 y1. I always have the lines twisting on the clips and not opening completely... HB~> HB~> Always having to unlock... HB~> HB~> This eliminates the twisting of the eyelets on the clips as you only deal with one pair of eyelets. #^ I would not trust the wire and clip from sliding off the wrapping from a not so good solderer... Perhaps a small 1/16 in. 90deg bend at the wire end of the clip for safety before soldering. Or ridges?
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Chris,
Actually, it's the godless communists to thank. L
VD~ LL~ LL~ LL~ LL~ VD~
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Rafael,
Yes, it's good to know how to solder when using this method. With a good soldering, it's not necessary to make any bend or corrugations but I do understand your concern. Just roughen the piano wire with #400 paper and de-grease all well with acetone. And as allways with soldering steel, it's important to pre-tin the parts before wrapping and soldering.
I use normal tin/lead solder but maybe it would be possible to use stainless cables if I used Staybrite or similar stuff. But with Staybrite/acid flux, I'd be worried about corrosion.
Strenghtwise the type of solder is not important, just calculate the shear strenght of 1/2" overlapping joint and you'll be surprised :)
This method does not fully eliminate the twist/kink of eyelet, just 50% of it. To be sure, I use heat shrink tubing or silicone tubing over the eyelet. L
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Thank you for the info, Lauri H^^
I like this a lot but, y1 would anyone know if this would be allowed at an AMA sanctioned event? The book only suggests methods of ending a stranded or solid wire... I would definitely start using this method due to the better simpler attachment. I believe this arrangement would more that is needed for a pull test.
I remember my first NATS(ever) in P. Carrier (1984, Westover), I showed up with my K&B 5.8, 60-20-20, re-ported & re-timed, etc., everything trimmed and ready to go and at tech inspection, was told that my PERFECT split/slide clips were not AMA approved!!! We all know the gyrations that are performed to get the engine to idle up-down... Nowhere in the book showed the single loop split clips as the only ones approved. (Maybe I missed it)
I had practiced and practiced my slow run to the point that I felt would finish in a decent place. Now, I had to re-trim all my lines and change the clips. Needless to say, Slow runs were atrocious. Not for this to become a sob story (I know, too late LL~ LL~ LL~) but just for information as to how a little detail can create a large problem. Got Rookie of the Year... :-[ (33yr old rookie)
H^^
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Europeans seem to be more solder-minded than we are for leadouts, but I think they use regular steel cable; we typically use stainless.
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Seems to me, and from experience, if it will pass the pull test, it is allowed to fly. I don't like solder, but can't think of any good reason to avoid solder.
Floyd
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Lately, I've been swaging terminations. Carl Shoup makes a fine swage-plier tool that works very well if you take a few seconds/minutes longer to crush the outer tube gradually and evenly. Carl's instructions explain, and this is a case where you should not wait until everything else fails, to read the instructions.
Copper tubing is more ductile than brass - a reason why brass tube sometimes forms cracks in fuel tanks - and aluminum tubing is even more malleable.
(If the terms are unfamiliar - more ductile means it can be deformed more easily than a substance that is hard or brittle. Crushing the tubing is a deliberate deforming process. Malleability is another way of saying a substance can be formed to a different shape easily.)
Carl's swaging pliers can compress copper or aluminum tubing so that it is pressed into the braids of braided cable well enough to stand the pull test. Personal druthers: I'd use aluminum up to a moderate .35 model's leadouts, and copper for something bigger.
Whatever your preference - a bend of tubing to hook onto, or an eyelet, is easy to do accurately with this swaging tool, and it is MUCH more trustworthy than the AMA Rulebook example of crushing two crimps into the line ends.
Plus, neatly done, it is nice in appearance.
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This is mine. I use the same termination on lines and for leadouts at the wing tip.
The wire is a bit small in this example as it was only a test and I would only use it for a .10-size model or smaller. It comes from a length of fishing leader that I bought before I knew how thick the nylon is on the coated wire.
However, the fixing process is—once through the sleeve, almost twice around the thimble, back through the sleeve then loop back through the sleeve and pull up tight. Swage as shown. I then put some coloured heatshrink tube over the ends to tidy up the assembly and identify the up and down lines and leadouts.
At the bellcrank, I use 1/16" tube bent in the 'doghouse' shape and the cable passes through the sleeve three times as shown.
Note the slight flare at both ends of the sleeve. The fishing tackle people stress that you must leave a small amount of the sleeve not swaged to prevent the sleeve chafing and possibly cutting the strands of the cable.
I would only use copper or aluminium sleeves and carefully deburr the inside after cutting to length if I cut my own. Currently, I am using sleeves supplied by a local fishing tackle company to suit the different cable diameters. The wall of the sleeves gets thicker as the diameter increases.
For leadouts, I use a swaging tool from Superflex fishing tackle and for control lines, I use the pliers supplied by Mel Schuette because the Superflex tool does not go small enough. I haven't seen Carl Shoup's pliers but I imagine they are similar to the tool that Mel supplies. The Superflex tool is very similar to the Sava tool.
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Thank you for the info, Lauri H^^
I like this a lot but, y1 would anyone know if this would be allowed at an AMA sanctioned event? The book only suggests methods of ending a stranded or solid wire... I would definitely start using this method due to the better simpler attachment. I believe this arrangement would more that is needed for a pull test.
I remember my first NATS(ever) in P. Carrier (1984, Westover), I showed up with my K&B 5.8, 60-20-20, re-ported & re-timed, etc., everything trimmed and ready to go and at tech inspection, was told that my PERFECT split/slide clips were not AMA approved!!! We all know the gyrations that are performed to get the engine to idle up-down... Nowhere in the book showed the single loop split clips as the only ones approved. (Maybe I missed it)
I had practiced and practiced my slow run to the point that I felt would finish in a decent place. Now, I had to re-trim all my lines and change the clips. Needless to say, Slow runs were atrocious. Not for this to become a sob story (I know, too late LL~ LL~ LL~) but just for information as to how a little detail can create a large problem. Got Rookie of the Year... :-[ (33yr old rookie)
H^^
The rule book says that the tensile strength rating of EACH clip has to equal or exceed the pull test. The big slide clips are rated 49 lbs. If your plane weighed over 2.5 lbs, the pull test in profile would have been over 50 lbs (20G's). So it wasn't the DESIGN of the clips, it was the STRENGTH of the clips that was the problem.