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Crimping or Soldering and Crimping?

rockitdoc

Well Known Member
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I know I may be entering the minefield here, but since I am getting ready to add ring terminals and Fast-On QD terminals in many locations, what is the consensus?

Crimping only: No stress concentration due to solder but a chance of wire coming loose if not crimped correctly (I suppose this means getting the proper crimper so every crimp is the same and tight)

Crimping and soldering: Said stress concentration could lead to fatigue failure at the interface of solder and no solder (unless supported well) but the chance of wire coming loose is nil.

OK, let me have it!
 
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Crimping only: No stress concentration due to solder but a chance of wire coming loose if not crimped correctly (I suppose this means getting the proper crimper so every crimp is the same and tight)

...

Bob Nuckolls makes a great case for crimping. There are times when solder is needed, but it's very rare in aircraft. If I recall correctly, I'm 100% crimped, and with the exception of some thermocouples that came loose, all good after about 18 months of flying.
 
Crimp, but with heat shrinkers

I am a fan of the crimped on (properly) ring terminals, but the ones with the thick, translucent heat shrink, that the little bit of “hot glue” looking stuff oozes out of when heating to the right temp. They are very secure, and help smooth out the stress where the wire comes out of the crimp and could break. In addition, you should never have any corrosion down in the wire inside the crimp, so in the future you just need to clean the terminal itself. Little bit more work, but they are way dressier than the sloppy crimping I see a lot, that with a good tug let go and fail.
 
Get ahold of NASA-STD-8739 and the accompanying Workmanship Pictorial Reference if you really want to do it right.

Crimping is an efficient and highly reliable method to assemble and terminate conductors, and typically provides a stronger, more reliable termination method than that achieved by soldering.
(Pictorial Reference section 2.01)
 
Crimping is good.

Soldering is better - BUT - requires excellent (not good - EXCELLENT) strain relief beyond the ends of the solder area. This is beyond the resources of most shadetree mechanics and the majority of home builders in my opinion, from my experience.

Crimping is easy to be good at. Soldering is better, but is very difficult to do correctly for the mainstream. We're talking about a difference between 98% and 99.5% here. Stick with what you know.
 
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I am a fan of the crimped on (properly) ring terminals, but the ones with the thick, translucent heat shrink, that the little bit of “hot glue” looking stuff oozes out of when heating to the right temp. They are very secure, and help smooth out the stress where the wire comes out of the crimp and could break. In addition, you should never have any corrosion down in the wire inside the crimp, so in the future you just need to clean the terminal itself. Little bit more work, but they are way dressier than the sloppy crimping I see a lot, that with a good tug let go and fail.

I think that is the type of terminal I have. When looking at the Steinair website I found a kit that looks a lot like mine (https://www.steinair.com/product/terminal-kit-450-pieces/). I couldn't find the receipt for what I have, so I don't know if it's from Stein. Their website doesn't indicate if their kit is the type of terminal you described, either. But, when viewed from the wire side of the terminal, I can see something white inside that will surround the wire after insertion. Not sure if this is the heat shrink material or something else. I guess I will sacrifice one with some heat to see if the white stuff inside melts along with the red/blue insulation on the outside. If so, these terminals might be the ticket. IF not, I will get some. Seems like the optimal solution. Thanks for posting your response, cuz I forgot these things existed, and will be more surprised if what I already have are these beauties. I guess I should take better notes.
S
 
Get ahold of NASA-STD-8739 and the accompanying Workmanship Pictorial Reference if you really want to do it right.

(Pictorial Reference section 2.01)

I looked at that yesterday and was mighty impressed. Not sure this shade tree wrench has the resources to implement, however.
 
IF you use the correct tools, there is no need to solder the crimp...

I've got a Pros kit CP366 with the dies for red/blue/yellow sizes of terminals. Works fantastic. Squeeze it until it releases the terminal, and the same perfect crimps come out every time.
I looked at the Stein website yesterday and see they offer the Pros kit CP371. That one looks very similar to mine, but with a bit of a bend. Mine is straight. Not sure if they crimp the same.
 
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I decided to get some of the heat shrink crimp terminals. I may already have some, but just in case mine aren't, these will do the trick (https://www.delcity.net/store/Heat-Shrink-&-Crimp/p_804390.h_7920420

I usually put heat shrink over my crimped connections, but these terminals with the heat shrink already included makes the job way simpler and faster and best of all, leaves the connection translucent so you can see that the wire is properly crimped. And, the connection is sealed from moisture. Very cool. The only disadvantage I can see is higher cost. But, in the scheme of things aeronautical, not too high for convenience, efficiency, safety, durability and piece of mind.
 
I recently had to replace my roll servo and in the process insert a noise suppression capacitor. This required installing new db9 connectors. I used these https://www.amazon.com/gp/product/B076F6X8WJ/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1 d-sub connectors that have a PCB with screw terminals. A bit bulky & pricey but well worth it. I doubt I will ever go back to crimping pins. Particularly helpful when you have to get into an inverted yoga position to finish the job.

Yes. Those look way easier than crimping those tiny pins, but unfortunately, not applicable to ring or push on terminals. Crimping still needed there.
 
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