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Building Tips and technical articles. => Building techniques => Topic started by: Rob Killick on May 31, 2008, 04:59:56 PM
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Hi ,
I have finally purchased a Sava T-185 compression crimper and was wondering if swaging (with copper tube) at the bellcrank would be acceptable ,
or is it better to wrap with copper wire ?
I read the article(s) in Control Line World (by Bob Zambelli) , thoroughly , concerning crimping/swaging of lines , but the article doesn't really say anything about swaging the bellcrank side of the lead-outs .
Can anyone add a little (or a lot) concerning my question ?
Thanks ,
Rob K.
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For my line ends I like to use plain round-nosed pliers and sleeves that are just large enough to take three layers of cable. I make them up just like the AMA rule book shows and have not had any problem. Like anything else, take your time to do it right and if anything looks substandard, re-do it.
The above was really for line ends. For the bellcrank end is important to leave enough of a loop that the leadout wire does not bend at the extreme end of control. This applies whether you are using wrapped ends or chimped ends.
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I've never trusted swagging. But that's me. I have a friend that swags his leadouts, lines and the connection at the bellcrank (with proper tools) and has never had a problem. I always wrap mine. I suppose it's a case of personal preference.
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My crimps can hold 200# tuna., I'm not concerned! I use Jinkai sleeves and 90# 7 strand coated cable.No problems.
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I've never trusted swagging. But that's me. I have a friend that swags his leadouts, lines and the connection at the bellcrank (with proper tools) and has never had a problem. I always wrap mine. I suppose it's a case of personal preference.
Full scale control cables use swaging. And on sail boats, anything important is swaged. A proper swage will be stronger than the wire, because there is acutally pressure welding between the wire and the swage.
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But you have to remember that full size control wires and most sailboat stuff is used preloaded in tension. Our stuff can go slack and can be bent at the end of the swage during normal use and most particulaly during handling in between flights. I personally prefer wrapping but there are those who have success with swages. "Each to his own", said the old lady as she kissed the cow!
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I too have all my leadout connections swagged, both at the bellcrank and at the outboard ends using coated cable from which I strip the coating at the connection points. I've never had a failure of either, but I don't fly as much as a lot of other guys. I agree that it seems to be a matter of personal preference.
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But you have to remember that full size control wires and most sailboat stuff is used preloaded in tension. Our stuff can go slack and can be bent at the end of the swage during normal use and most particulaly during handling in between flights. I personally prefer wrapping but there are those who have success with swages. "Each to his own", said the old lady as she kissed the cow!
Full scale mostly, but sailboats have things get loose a LOT. Every in full scale aircraft, things like throttle and mixture adjustment are not in tension all the time.
Cut apart a good swage sometime and you will be convinced. You can't tell where the swage ends and the wire begins. It is all one mass.
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Where can I get a set of the round nose crimping pliers and or, is there something different to use when crimping?
Thanks, Terry
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Terry, I don't believe the round nose pliers will do the job. Go to member index and contact Carl Shoupe as he makes and sell the pliers and line connector tools. So far I have not had any trouble with mine that I got from him. If you had looked at my handle and lines in Topeka you would have seen the results. Great to have different length connectors on the hard point handles. DOC Holliday
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I usually crimp leadouts with a piece of copper tube and round nose pliers. Occasionally I wrap them. I wrap lines because I feel less confident of my crimps on the more delicate lines. I do think a crimp sets up a stress riser, but there is very little bending on leadouts, particularly at the bellcrank. I've used nylon coated leader material with no problem.
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I have the same swaging tool you have, Rob, and I now swage everything except ½A lines. (I'd do those, too, except it requires a different swaging tool!) The copper tube/roundnose plier prodecure can easily create a stress riser which can become a failure point because it concentrates the holding force in a very small area; the swaging tool does not do this.
Once you make the investment in the tooling, you may as well use it!
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Hey, Ralph,
Can you be so kind as to discribe for me some detail as to your swagging process (i.e. size tubing, dia wire and how many passes thru the tubing..). I have a T-185 swagging tool, but haven't figured out all the details as how to swage small dia wire (i.e. .012 - .018).
Thanks
Happy Father's where appilicable and a great weekend.
All the best.
Angelo
earthboundmisfit@bellsouth.net
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General reply -
I picked up my swaging pliers from Carl Shoup at a VSC a few years ago. Excellent, for the sizes of lines that suit it!
Carl stressed that technique is important. It is not a one squeeze job. Of course, the copper tubes must be deburred, first - twirling a #11 blade inside to shave a slight chamfer works well.
Then, when you have the length, eyelet and lines set up correctly, Carl recommends taking at least a dozen squeezes, from different positions around the copper tube to draw the 'crimp ferrule' you'e creating down evenly, centered and straight. Actually, I think he said more like 50 separate, small presses. It's a thing to do until it's done right, not until you count to any arbitrary number.
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What about the crimping tool, used with pliers, that came with the old Pylon Brand C-D leadout kit? I have never had a failure with this.