servo lead extension tube !

[Stuphedd]

For channelling  long servo leads I tend to use drinking straws, I just undo the plastic plugs on both ends, servo and extension , plug the leads together, a bit of heatshrink on each separate wire and thread   them down the straw!

I t means that you dont have large holes in wing ribs , extension plugs getting caught on "structures" or even coming undone. and it looks neat . 

and you can get straws  up to 70cm long !

[Gary Manuel]

I'll give them a go. ?

[Stuphedd]

found an "old" wing so made up the aileron tube and took some photos which should make things easier to figure out !!   

[Allan Bennett]

That's an interesting alternative to soldered extensions.  With the heat-shrink nicely shrunk they should be quite secure -- have you tried a pull test out of interest?

[Stuphedd]

if you pull hard enough you can get anything to come apart .Soldering would be more "Positive " but I have done this many times  and not had any failures yet .  There is one  definite advantage , when you need the servos anywhere else , just put the plugs back on ,no soldering !

cheers  

[Phil McCavity]

Looks like a good solution. A problem with soldering is that when the solder runs up the wire it creates a fatigue point between the solid wire and the flexible wire where the insulation starts. 

[Gary Manuel]

Extra long straws arrived this morning. They are verrry looong ?

 

When I first put them to use, I'll try using just heatshrink as @Stuphedd has suggested above and give them a good tug test. If they fail the tug test, I'm thinking of solderring the two parts of the crimp together and then adding heatshrink tubing. This will avoid the fatigue problem mentioned by @Phil McCavity. I have crimping gear, so can easily replace the soldered crimps as required. Obviously only useful for straight runs although straws might be tempted into a gentle bend.

 

In the past, I've tried rolling my own tubes by wrapping and gluing long lengths of paper around carbon tubing, large enough diameter to take the servo plugs and sockets held together with strong thread - works well but only on straight runs. I've more recently been using spiral wrap around the entire extended servo lead - also works well and can be glued to the airframe regardless of bends etc, but time consuming, adds weight and not easily replaced if servo needs replacing.

 

We can never have too many options at our disposal!

Edited April 16, 2021 by Gary Manuel
Typo

[Allan Bennett]

I don't believe the "fatigue problem" is really a problem if the soldered joint has a good heatshrink covering extending a few milimetres each side of the solder.  Wouldn't there also be a fatigue problem where a lead exits the crimp, if it weren't for the crimp housing limiting its movement? 

 

The point about being able to reattach the servo plugs is a good one but, like Gary, I crimp my own plugs anyway.

[Gary Manuel]

Allan. The fatigue issue is real. Soldered connectors have been prohibited for many years in Railway applications, in favour of crimp connectors. I believe that the same applies in the aviation and automotive industries. 

The crimp connection allows the wire to remain flexible right up to the crimp, whereas the solder connection results in an abrupt change between flexible and solid. This is the weak point.

[Nigel R]

20 hours ago, Gary Manuel said:

same applies in the aviation

 

Correct, to best of my knowledge.

[Basil]

Good idea, but how do you get the metal plug parts out of the plastic surrounds, without damge to the metal 'Pins', is there an easy way?

Bas

[extra slim]

yeah, get a pin, lift up the plastic and just ease the pins out... really really easy

[Chris Walby]

Sorry, don't agree with the don't solder it argument. If the soldered wire connections are lying in a tube (straw) then flexing will be very minimal where as relying on a connection that is not accessible or not frequently connected/disconnected to wipe the contact surfaces is prone to poor contact.

 

I have had far more servo plugs that are not exercised give issues that I have had supported soldered connections fail.

 

PS some heat shrink and a thermosetting glue and some does not, but I would not rely on either for a pull test as for good practice we used servo locks.

 

Tin hat on and each to there own in the end.

[Nigel R]

Vibration rather than flexing is the problem, I believe.

 

As ever, YMMV.

[Basil]

4 hours ago, Chris Walby said:

Sorry, don't agree with the don't solder it argument. If the soldered wire connections are lying in a tube (straw) then flexing will be very minimal where as relying on a connection that is not accessible or not frequently connected/disconnected to wipe the contact surfaces is prone to poor contact.

 

I have had far more servo plugs that are not exercised give issues that I have had supported soldered connections fail.

 

PS some heat shrink and a thermosetting glue and some does not, but I would not rely on either for a pull test as for good practice we used servo locks.

 

Tin hat on and each to there own in the end.

Chris, surely if they are gold plated dirty metal contact should not be a problem!!!!!!