The right size crimp tubes for .015 lines

[RknRusty]

I need to cut a .015" line set a little shorter and want to make sure I use the safest crimps. My HS has K&S 3/32" OD copper tube, but I'm thinking 1/16" might be best. I have brass, is that grippy enough, or is it too hard? Should I heat either metal red hot with my mini torch first?

I also have some black colored 1/16" tubes for fishing tackle. They are soft, slightly magnetic, and I think have nickle in them.

I need to pass a 20 pound pull test as well as be as safe as possible.
Thanks,
Rusty

[Steve Helmick]

Everybody I know uses 28 ga. copper wire and bind their lines per the AMA rulebook. I like to put two pieces of heat shrink tubing on each end of the line. A very small piece and one that's just big enough to cover the bindings. Both about 1" long, they shrink together to avoid a stress point at the end of the binding. The stress points are much worse with crimps.

Jim Lee Machine sells a neat little binding tool that makes it much easier and quicker.  See in the Vendor's Forums below.  Steve

[RknRusty]

Thanks, Steve. I like the looks of the wrapped connection better too.

Rusty

[Steve Helmick]

Rusty, about the shrink tubing...some like to color code their lines to their leadouts...red or black, etc.  I just make them all the same color, so that I won't fall into the trap of relying on color codes to hook up the lines correctly.

Whatever procedure you decide on, think about it, and repeat it faithfully. I take my handle off first, roll up the lines, leaving both clips on the handle and a clip on the rear leadout. All goes into a quart Ziplock Freezer bag. The handle is roughly color coded to the plane, and the line spools are marked for the plane. When I hook up the lines, I hook the lines onto the leadouts first...one clip on the plane and one on one line...can't mess that up too easy. When I get the lines out, I pull on the lines to find the "up" line, and hook it to the "up" side of the handle. If I get that right, the rest is automatic. Then, I hold up on the handle, look at the elevator, and then look at the handle...back to the elevator and then the handle. This has prevented me from never ever hooking the lines up backwards, starting from Jr. Highskool. So far, so good!  Steve

[RknRusty]

I usually paint the clips at each end of the Up line with a black Sharpie. Can't find any fault with your method though. So far I only have one plane that uses these steel lines. Hopefully that will change soon though. The Shoestring leadout repair and general checkup put the Yak build on the back burner for yet another few days.

[john e. holliday]

If you are using solid wire lines, yes, follow the wrapping method in the AMA rule book.   You, in my opinion, never want to crimp or swage a set of solid lines.   Now for cable I do the swaging method.

[RknRusty]

My lines are stranded. I don't think I could ever bring myself to trust solids. But now, after talking more with an experienced flyer, I've decided to go with wrapped. I don't have swaging or crimping tools. I've used everything from needlenose to dulled cutters in the past, but it's time for me to graduate toward both rules and safety now.
Thanks for the tips.
Rusty 

[Garf]

I have been crimping lines since the beginning and have had very little trouble. I use fishing leader crimping sleeves. You need to get in the habit of examining the lines at the crimp when hooking up the lines to the airplane.  It only takes a few seconds.

[RknRusty]

I have been crimping lines since the beginning and have had very little trouble. I use fishing leader crimping sleeves. You need to get in the habit of examining the lines at the crimp when hooking up the lines to the airplane.  It only takes a few seconds.

Hi, Garf. Me too, I never had a failure except one where I only made two passes through the tube with Surflon 7 strand nylon coated steel. When I recovered in flight with a yank, the nylon sheath broke, allowing the unbroken wire to slip out, throwing my plane into about 5 spectacular tight but widening outsiders. It's been in the shop getting a complete physical ever since then. If I only had an x-ray machine.

[Dan McEntee]

    I just lost a nice profile Oriental that I had bought from a friend, due to a broken up line. The lines were a new, old set of Pylon brand lines that had crimped terminations. The up line broke up inside the copper tube, right where the crimp was. This is the absolute last time I ever use a set of crimped lines, and I'm embarrassed that I was lazy enough to trust them, I know better that that!
    Wrapping is the only way to go.
   Type at you later,
     Dan McEntee

[RknRusty]

Yep, these planes are too precious to cut corners on simple things. Especially when one(like me) doesn't have a backup plane.

[Garf]

After I crimp a set of lines, I subject them to a torture test. I have lost a couple of sets during the torture test, But I figure it's better to lose them then than when flying.

[Brett Buck]

After I crimp a set of lines, I subject them to a torture test. I have lost a couple of sets during the torture test, But I figure it's better to lose them then than when flying.

    The initial load is not the issue. The problem is the fatigue.

    Brett

[RknRusty]

    The initial load is not the issue. The problem is the fatigue.

    Brett

And the rare but punishing yank.

[Randy Cuberly]

I have used crimped stranded lines for 50 +years and never had a failure at the crimp site.  I use red brass tubing or Thick wall copper tubing.  3/32 OD is the correct size for the copper tubing for .015 lines.
Many years ago I made a crimping tool from one of the electrical connector crimping tools that are common, by simply grinding a small amount of material from the closure of the tool to get a complete contact inside the copper tubing.  I use 1/2 inch long tubing with two crimps approximately 1/8 inch from each end of the tubing.  The crimps should be a complete closure of the tubing but only in a dimple...It's the extremely high unit loading of the dimple that makes the joint completely slip proof.   Using a pair of wire cutters or standard pliers to make a crimp across the copper tubing doesn't achieve the high unit loading of a dimple and should not be used.

Crimping lines in this manner is in keeping with AMA rules and is shown in the AMA rule book for stranded lines.  Wrapping lines is tedious and I've seen more wrapped line failures than crimped ones.  Particularly from corrosion caused by using shrink tubing that traps moisture and epoxy to glue the wire ends down.

Next time you're around heavy equipment like a big crane take a look at the cable terminations...they will be crimped or bolted clamp terminations...not wrapped with anything.

I will agree that the crimping process is perhaps more demanding and people that can't handle that are probably better off wrapping thier lines and replacing them often to overcome the potential for corrosion.

Randy Cuberly

[Larry Fernandez]

It's been in the shop getting a complete physical ever since then. If I only had an x-ray machine.

If only you had properly wrapped them.

Larry, Buttafucco Stunt Team

[Jim Thomerson]

I prefer to wrap lines.  I do it like the AMA rule book shows, except that I go up the single line five or six turns before starting wrapping back toward the eyelet.  I think it helps soften the stress riser.  I crudely crimp leadouts with round nose pliers.  I'm afraid I would injure control lines if I crimped them, but the leadout wire is substantial enough that I think it is OK.  I use the nylon coated leader, and have never had a problem with it. 

[RknRusty]

...I crudely crimp leadouts with round nose pliers.  I'm afraid I would injure control lines if I crimped them, but the leadout wire is substantial enough that I think it is OK.  I use the nylon coated leader, and have never had a problem with it.  

Jim, what sort of round nose pliers do you use on your coated leadouts, something you made from an old pair or is it a tool you bought? I'm using 60# 7 strand coated Surflon fishing leader for now until I get the .027" wire from somewhere that has reasonable shipping charges. I'll try RSM, Tom Morris, or one of the other vendors that serves the SH community.

[Jim Thomerson]

I bought the round nose pliers to make round bends in small diameter wire. I put three hard squeezes on the crimp tube.  I usually use copper tubing. I bet you can get a good pair of crimping pliers where you got your leader. 

[RknRusty]

Okay, now I'm gonna make y'all laugh... either at me or with me.
I was flying the other day when my loops were jumpy. Turns out the thick cables on my Sullivan Insta-Just were all bent up and jumping around. So I wanted to shorten and try to straighten them. This is my version of round pliers, two bits of 1/16" music wire superglued into opposing grooves in my pliers. Temporary, for Tuesday's upcoming outing, but it passed a lengthy 35# pull test. I'm going to order a new hardpoint handle next payday.

 

Preparing to be piled on.

Rusty