# Wire splicing techniques

Discussion in 'Workshop Tips and Secrets / Tools' started by brian, Apr 3, 2009.

1. Apr 3, 2009

### brian

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I've been using a wire splicing technique that I think works very well. As part of doing a bunch more splicing recently, when I added my SDS ECU into my STi engine wiring harness, I took pics & just created a new page that shows the products and techniques used. Any feedback from it, please let me know.
www.meyette.us/crimping.htm
brian

2. Apr 5, 2009

### Midniteoyl

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That'll work, though I'm alittle concerned with the amount of 'crush' you have going there. The proper way for that kind of connector is one that squeezes in a 'ring' or trapaziod. This grips the wires, and forces the two together as apposed to apart and splayed you have. Remember, electrons flow on the outside of each strand, not through it.

These are cool little connectors also.. Multilink™ Sealed Crimp and Solder Butt Splice Wire Connectors and Ring Terminal Kits

One of these days I'll either scan or post pics of the way we did it in the Navy. Very strong and no extra heat at the joint. Involves splitting the strands and some solder.

3. Apr 5, 2009

### Rom

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The electrons flow within the conductive material. It is the electromagnetic forces that appear outside of the conductor.
The clamp would act the same as though it were a bus. Now the field lines outside of the connector may have a geometry which could interfere with nearby electronic equipment. Further analysis would be needed.

4. Apr 6, 2009

### kent Ashton

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Nice pics but why not just twist together, solder and shrink-wrap?

5. Apr 6, 2009

### bmcj

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A crimp sleeve gives more protection against the splice pulling apart when loaded in tension.

6. Apr 7, 2009

### JMillar

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I read somewhere that soldered joints were to be avoided for reasons of cracking under vibration? Or am I misremembering completely?

7. Apr 7, 2009

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8. Apr 7, 2009

### wally

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Yes that is true. Many years ago with Airman stripes on my sleeve, one job I had was replacing relays in aircraft. these relays were 6 or 8 pole relays with 22 gauge wires and soldered to hooks on the relay base. A tedious job.

The instructions were to use enough solder to attach the wire but not allow the solder to wick up the wire and go under the insulation. There is to be a little gap between where the solder ended and where the wire insulation started. This allows the wire to flex but not flex or bend the soldered area. The completed joint is then covered with a piece of insulation sleeving. If the solder wicks up the (stranded) wire, it doesn't take too much bending/vibration for it to break.
The way I remember it.
Wally

9. Apr 7, 2009

### bmcj

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That makes sense Wally.

10. Sep 8, 2009

### LArzfromarz

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There is a place for every technique. The trick is knowing when to use the appropriate technique. As an A&P I find the FAA Advisory Circulars a great place to find what is acceptable and approved in certified aircraft. If a need arises to deviate I try to meet or exceed the FAA standard. The Circulars are a great guideline for home builders.
My point here is don't use the China Harbor Freight, 1000 for a Buck crimp connectors for ANYTHING.
Buy Mil Spec connectors if you have to use crimp connectors.
Biggest tip is to leave yourself service loops and strain reliefs- everywhere you can.
Also if you can afford it don't use automotive PVC grade wire in your aircraft- it out gases when on fire- but hell so do I.

My 2 pence for today
LArz

11. Sep 8, 2009

### djschwartz

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A wiring harness should be built such that there is no way a splice or connector can be loaded in tension. All forms of splices become unreliable over time when loaded. Always use a strain relief loop (doesn't have to be a full circle) in your harnesses.

12. Sep 23, 2009

### skeeter_ca

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Why don't they make a different terminal size for each gauge of wire? One terminal fits two gauge sizes. I use alot of auto style connectors and it always seems i have to use the terminal size one size up and it makes for a sloppy crimp. It's like the wire is too small for the terminal.

skeeter

13. Sep 23, 2009

### djschwartz

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Are you using one of the inexpensive auto/hobbyist crimpers or a good, heavy duty, ratchet action tool? If you're using the cheap one, that's your problem; throw it in the garbage. A good crimper with cost $30 to$50 depending on where you get it and is worth every penny. It will give you good solid crimps every time.

14. Sep 25, 2009

### vortilon

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15. Sep 26, 2009

### skeeter_ca

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So your saying the terminal end/butt splices used in the autos should not be used on an aircraft or just use high quality crimpers to crimp them?

skeeter

16. Sep 26, 2009

### djschwartz

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Always use the good crimper. I use a $30 one from Chief Aircraft. Certified crimpers are nice but not neccessary http://www.chiefaircraft.com/airsec/Aircraft/Tools/TerminalCrimper.html The aircraft grade terminals are best; however, I have perfectly good success using the auto grade splices. Note that there are now two grades of terminals available in the auto parts and hardware stores. One has the traditional vinyl plastic insulation, the better ones have nylon insulation. It's easy to tell the difference. The nylon is thinner and translucent. The vinyl is thicker and opaque. I use the better nylon ones for all applications, even in my truck. And always remember to include strain relief and provide support for cable harnesses. No terminal or splice will be reliable under tension, and vibration will eventually weaken them or fatigue the wires. When making a harness that goes from something moving or shaking, like the engine, to the rest of the airframe, use an adel clamp to hold the harness to the moving part. Provide a large loop with no splices to get to the airframe, and then use another adel clamp to secure the harness to the airframe. Last edited: Sep 26, 2009 17. Sep 29, 2009 ### LArzfromarz ### LArzfromarz #### Well-Known Member Joined: Aug 17, 2009 Messages: 98 Likes Received: 0 Location: Sunny Central FL Skeeter- I know we all have to economize, its just a fact of life. But just ask yourself "what would I do if my wife or childrens' lives depended on XYZ?" Will the pennies you save on cheap automotive grade stuff be worth it? When the panel is on fire and you are declaring an emergency with your SO in the right seat will it be worth it then? Most of us will readily sacrifice ourselves, but our loved ones? The question is so much bigger than "should I cheap out and buy xyz?" Buy the BEST you can afford and if you can't afford it WAIT until you can. If you can't wait then get out of the hobby/business/industry. Sorry I don't mean to be rough but I also don't want to be the one to talk to your "next of kin". Larz 18. Oct 2, 2009 ### vortilon ### vortilon #### Well-Known Member Joined: Jul 7, 2009 Messages: 453 Likes Received: 5 Location: Marana AZ USA I prefer aircraft grade wire and terminal ends and good quality crimpers. It is expensive but hey smoke in the cockpit really sucks, been there done that. 19. May 23, 2010 ### bobm4360 ### bobm4360 #### Member Joined: Mar 13, 2009 Messages: 16 Likes Received: 8 Location: Oak Harbor, WA Over the cost of the plane, what's$100 for milspec crimp connectors and \$100 for the proper wire?

Cheap insurance.

20. May 23, 2010

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