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-   -   Easy way to create long servo extensions (http://www.Wattflyer.com/forums/showthread.php?t=73092)

ServoCity 01-30-2014 04:10 PM

Easy way to create long servo extensions
 
http://www.servocity.com/assets/images/ServoCity.jpg
This tip is from our Tech Tip Archive. Find all kinds of helpful project tips here: http://www.servocity.com/html/tech_tips.html

Create Longer Servo Extensions
Here is an easy way to put ends on your wire and create a longer servo extension to your specifications.
When using bulk servo wire, cut a short servo extension in half and splice the pieces onto the bulk wire.
Links: Servo Extensions and Leads, Bulk Servo Wire
http://static.rcgroups.net/forums/at...hExtension.jpg

For questions about this tip, email tech@servocity.com or call 620-221-0123...we're happy to help!

Rodneh 01-30-2014 08:15 PM

Even better is to just cut the lead on the servo in two and solder the needed length of wire in. No extra connectors required and much more reliable than extensions are. Extensions that do not get repeated use tend to become intermittent and troublesome.

fhhuber 01-30-2014 08:30 PM

For high vibration environments I recommend against soldering the wires in the middle. These solder joints are just about guaranteed to fail over time. (more of a problem with gasoline power than electric)

The solder makes a hard section of wire and the heat changes the metal's "grain" making it easier to break by making repeated small bends (fatigue fracture or brittle fracture) The part of the wire right beside the solder joint is weakened and subject to rapid repeated bending forces amplified by the hardened (solder filled strands) joint.

If you want to do the method of lengthening the servo's lead... replace the whole wire and crimp a new end on... or cut the end off an extension. Do the soldering at the servo's circuit board using a very fine tip iron. Avoid heating the wire more than necessary.

tr4252 01-30-2014 10:11 PM

I just bought 5 packs of servo connectors from A Main Hobby for a similar purpose. With these I can shorten servo leads without splicing, but not lengthen them unless I make a new wire. I don't need longer ones though, just want to get rid of the excess wire.

I hate splices passionately. Nothing wrong with them per se, it's just a personal thing.

Tom

kyleservicetech 01-31-2014 01:43 AM

Quote:

Originally Posted by Rodneh (Post 938508)
Even better is to just cut the lead on the servo in two and solder the needed length of wire in. No extra connectors required and much more reliable than extensions are. Extensions that do not get repeated use tend to become intermittent and troublesome.

Yeah, we ran into that at work years ago. Check your servo connectors. If they are not gold plated, DON'T use them with extensions that are seldom taken apart.

Connectors that are not gold plated in this type of application can lead to problems after several years or so.

kyleservicetech 01-31-2014 01:46 AM

Quote:

Originally Posted by fhhuber (Post 938511)
For high vibration environments I recommend against soldering the wires in the middle. These solder joints are just about guaranteed to fail over time. (more of a problem with gasoline power than electric)

The solder makes a hard section of wire and the heat changes the metal's "grain" making it easier to break by making repeated small bends (fatigue fracture or brittle fracture) The part of the wire right beside the solder joint is weakened and subject to rapid repeated bending forces amplified by the hardened (solder filled strands) joint.

If you want to do the method of lengthening the servo's lead... replace the whole wire and crimp a new end on... or cut the end off an extension. Do the soldering at the servo's circuit board using a very fine tip iron. Avoid heating the wire more than necessary.


Yeah, very good point.
Any soldered extensions absolutely have to be protected by one or two layers of shrink tubing. What I've done is first shrink a piece of shrink tubing perhaps an inch long over the soldered joint. Then shrink a second piece of shrink tubing about two inches long over the same joint.

This will work well, provided the shrink tubing size is appropriate for the soldered connection used.

cyclops2 01-31-2014 02:04 AM

I cut in the center of the servo leads. Cut 1 wire. The move away from that cut. About 1 to 1.5 ". cut that wire. Move 1.5" again & cut the third wire. Carefully strip & solder in the length you need to lengthen.

Tape each solder joint SEPERATELY. Has never failed in 76 years.

You can also SHORTEN cables the same way. Same warranty. :)

pmullen503 01-31-2014 03:52 AM

Quote:

Originally Posted by cyclops2 (Post 938559)
I cut in the center of the servo leads. Cut 1 wire. The move away from that cut. About 1 to 1.5 ". cut that wire. Move 1.5" again & cut the third wire. Carefully strip & solder in the length you need to lengthen.

Tape each solder joint SEPERATELY. Has never failed in 76 years.

You can also SHORTEN cables the same way. Same warranty. :)

Done that too. Makes it easier to pull through holes in ribs and former.

Siberianhusky 01-31-2014 12:41 PM

http://www.servocity.com/html/hitec_...emale_set.html

Do them right the first time! A pair of these and your wire = custom length extension.
You can also get Futaba plugs.

Rodneh 01-31-2014 02:41 PM

As long as you add some strain relief (like shrinktube or tape) around the soldered connection to minimize any bending at the stiffened joint, no problem. I have never had a solder joint fail when protected with some form of strain relief in some 40 years of flying models. And yes, I also agree with one of the comments above that even gold plated connectors that do not get exercised (demate/mate) occasionally will corrode enough to cause a high impedance problem. That is why I NEVER bury a connector where it can not be readily cycled.

solentlife 01-31-2014 03:16 PM

You can buy extension leads in various lengths and with LOCKING tabs too secure connections. No need to solder ... cut ... join .... just plug together and let clip lock all together ...

Even without the locking clip ... I have used extensions via plug / socket for decades with NEVER a failure.

If I want to make a really long extension - then I use multi-core Telephone cable - this allows me to run extension to cover more than 1 servo with single run. All you need to do is have one each of + / - and all other leads are the signal wires ... a 9 core Tel cable can extend 7 ... yes 7 servos !

Nigel

Rodneh 01-31-2014 10:38 PM

Quote:

Originally Posted by solentlife (Post 938615)
You can buy extension leads in various lengths and with LOCKING tabs too secure connections. No need to solder ... cut ... join .... just plug together and let clip lock all together ...

Even without the locking clip ... I have used extensions via plug / socket for decades with NEVER a failure.

If I want to make a really long extension - then I use multi-core Telephone cable - this allows me to run extension to cover more than 1 servo with single run. All you need to do is have one each of + / - and all other leads are the signal wires ... a 9 core Tel cable can extend 7 ... yes 7 servos !

Nigel

I think the wire gage is much to small using Tel cable for servos drawing much power. When you parallel two or more digital servos and run any length of Tel wire, you will get a significant voltage drop.

hayofstacks 01-31-2014 11:04 PM

I was on a car forum where someone posted pictures of his race car wiring. I was shocked that not a single connection was soldered. I asked him why, and he said that solder joints fail quickly because his car launches at 1.6 g's.

Personally, i know i hit more then that when i do loops and rolls on my mini ultra stick repeatedly and i haven had a solder joint fail on me yet.

cyclops2 02-01-2014 01:46 AM

Acid cored solders ??

Use Rosin cored solder only.

kyleservicetech 02-01-2014 02:31 AM

Quote:

Originally Posted by Rodneh (Post 938685)
I think the wire gage is much to small using Tel cable for servos drawing much power. When you parallel two or more digital servos and run any length of Tel wire, you will get a significant voltage drop.

Not directly familiar with tele wire, but the servo wire we use for our equipment is made from many many very fine strands. There is a reason for the use of this much more expensive wire. That would be work hardening of the wire due to severe vibration.

Think of a piece of 1/2 inch flexible copper tubing. Bend that back and forth several times, and it becomes extremely hard to bend. Bending it is likely to kink it.

We don't have a lot of vibration on our electric models, but glow and gasser powered models is a whole different ball game.

At work years ago we had a lot of field failures of 12 conductor control cables that were connected to high voltage circuit breakers located on the top of telephone poles. This was very expensive cable material. The failures were completely open conductors inside the rubber jacket around each conductor. Turned out the wind was causing these cables to flutter in the wind, and after awhile we had failures. Solution was to print a statement in the installation manual that these $500.00 cables HAD to be secured against wind damage.

cyclops2 02-01-2014 03:02 AM

Good thought.
But our electric company has lots of the 4 wire spacers sliding to 1 end. What a waste of everything.

kyleservicetech 02-01-2014 03:07 AM

Quote:

Originally Posted by cyclops2 (Post 938712)
Good thought.
But our electric company has lots of the 4 wire spacers sliding to 1 end. What a waste of everything.


Yup
Before retiring, the company I worked for had a cable assembly department. That department completely filled a 55 gallon barrel full of wire cut offs every day. That wire got sent to the recyclers, at pennies on the dollar.

And, every so often they'd throw out 1000 foot spools of wire for no apparent reason. I'm still working on three #24 gauge wire rolls of them, after being retired for 5 years.

One day, they threw out a $2000, 5000 volt electronically controlled hipot unit, completely in working order, looked brand new. We were still using that thing in the department where I worked when I retired. (The shop could hipot stuff to over 110KV.)

solentlife 02-01-2014 09:12 AM

Quote:

Originally Posted by Rodneh (Post 938685)
I think the wire gage is much to small using Tel cable for servos drawing much power. When you parallel two or more digital servos and run any length of Tel wire, you will get a significant voltage drop.

I understand your comment, but the proof of the pudding is that I have several models with extended systems that work and show no signs of any distress or problem. My F16 has 1m long such cable extending 5 servos to provide control. The cable I use is the main installation cable - not the soft 'fly-lead' style you have at the telephone. The cable is the one that comes from the distribution box to the house and then fed to where consumer wants first point. The leads are usually solid copper core insulated and inside a round outer tube insulator.

http://i6.photobucket.com/albums/y24...onecables2.jpg

http://i6.photobucket.com/albums/y24...onecables1.jpg


Remember that a telephone is not just the short bit you have in your hand ... it can be significantly long and is good enough to run extra around houses without any problems.

The only time I would not use a single + / - set-up for multiple servos would be in servos over 10gr ... where we could be pulling higher rates ... but the cable is still good ... we just select leads for sets of servos dividing the load.
The beauty is of course is that the cables have leads all different colours - so you can note what is what and connect up accordingly.

One point I missed of in my previous post - if no locking tab - I use tape to secure plug to socket that are buried in model.

If you want a really light extension system - remove outer insulation and just use the inner cores. With long extensions - the weight difference is surprising.

Seriously - the Tel Cable works a treat ...

Nigel

fhhuber 02-01-2014 11:20 AM

Telephone uses an extremely low current.
Wire gauge needed is related to current, length and composition of the wire.

Depending on the aircraft the wires may be under very low current demand or it can be substantial. Many larger models can have several servos demanding 2 amps average EACH with much higher peak demands.

The high power buss RXs by Spektrum allow for input directly to the RX using 2 14 gauge inputs (defaults with EC3, I change mine to Deans for LiFes that I use for RX power on the large models) These RXs are capable of feeding over 30 amps of current to the servos... if the servo leads are up to it.
Obviously the telephone wire won't be handling that.

Sure, its probably fine for the relatively low current demands of the foam aircraft where you use it.
If I tried to get away with it in the plane in my avatar pic it wouldn't survive take-off.

kyleservicetech 02-01-2014 08:24 PM

Quote:

Originally Posted by solentlife (Post 938739)
I understand your comment, but the proof of the pudding is that I have several models with extended systems that work and show no signs of any distress or problem. My F16 has 1m long such cable extending 5 servos to provide control. The cable I use is the main installation cable - not the soft 'fly-lead' style you have at the telephone. The cable is the one that comes from the distribution box to the house and then fed to where consumer wants first point. The leads are usually solid copper core insulated and inside a round outer tube insulator.


Remember that a telephone is not just the short bit you have in your hand ... it can be significantly long and is good enough to run extra around houses without any problems.

The only time I would not use a single + / - set-up for multiple servos would be in servos over 10gr ... where we could be pulling higher rates ... but the cable is still good ... we just select leads for sets of servos dividing the load.
The beauty is of course is that the cables have leads all different colours - so you can note what is what and connect up accordingly.

One point I missed of in my previous post - if no locking tab - I use tape to secure plug to socket that are buried in model.

If you want a really light extension system - remove outer insulation and just use the inner cores. With long extensions - the weight difference is surprising.

Seriously - the Tel Cable works a treat ...

Nigel

IMHO, that solid copper wire wire would be a real big NO NO on any model with a piston type engine up front. Vibration issues can lead to the wire work hardening, and fracturing inside the insulation jacket. Yeah, at work we had this happen.

Also, it again a real big NO NO to crimp any terminal onto a solid copper wire lead. Unless the terminal is designed for crimping over solid wire. Otherwise, any such connection must be crimped, then soldered. And, the terminal must be crimped over bare copper strands. Do not crimp over solder tinned copper strands. That solder can cold flow, and cause problems months, or years later. At work, we had some assembly guy dip all of his stranded wires into a solder pot before securing them into a screw type terminal block. And, after a month, every one of those screws were only finger tight. Every one of those solder dipped wires had to be cut out and redone. There were over a hundred of them. (Yeah, I was the guy who had to do it.)

As for locking tabs, I do have a mfg supplier part numbers that makes very good locking tab types of connectors in pin counts from two to over 20 pins. They are reasonable in cost, and gold plating is an option. If anyone is interested, I can provide more details. (www.digikey.com stocks them)

hayofstacks 02-01-2014 10:40 PM

There is a reason why they use solid wiring in housew, but not any other application, including to a house. Grab a metal clothes hanager and bend it back and forth till it heats up and.breaks. Braided wiring will last much longer and does not heat up.

solentlife 02-02-2014 03:59 PM

This is Wattflyer.... so I answer based on E models.

On wet-fuel models then braided / stranded cable is called for.

My models have survived all sorts of abuse and time. No failures. Any joints if made are soldered with the above cables. Another no-no according to some, but never failed on any of my models.

Nigel

solentlife 02-02-2014 04:53 PM

This is Wattflyer.... so I answer based on E models.

On wet-fuel models then braided / stranded cable is called for.

My models have survived all sorts of abuse and time. No failures. Any joints if made are soldered with the above cables. Another no-no according to some, but never failed on any of my models.

Nigel

kyleservicetech 02-02-2014 11:47 PM

Quote:

Originally Posted by cyclops2 (Post 938701)
Acid cored solders ??

Use Rosin cored solder only.

Yeah
I even clean off all of the rosin cored solder flux with pure alcohol after soldering any RC equipment. (Not that drug store stuff, that's 20% water) After a year or three, that flux turns different colors, and looks like heck.

Plus, we had a real serious issue at work with that solder flux on circuit boards that were encapsulated for weather resistance. That resulted in a very expensive recall. Seems after several years, that flux residue caused resistive bridges between integrated circuits. That encapsulation sealed everything inside. Probably would have been OK if the circuit boards had not been encapsulated. (Think shrink tubing!)

Rodneh 02-03-2014 04:34 PM

The flux (if it is not the acid type--usually a rosin flux for electronics) is not in itself bad, it is just that it collects most things that contact it and will build up a conductive/possibly corrosive coating that will cause problems. Always a good idea to clean it off after soldering. Alcohol or acetone works great but hot water does almost as well. If acid flux you MUST clean it and neutralize it to prevent corrosion.


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