Jim Devine

Found this- they seem to favor crimped connections
and also warn against crimping tinned wire.
Looks like it's time to buy a quality crimping tool.

http://workmanship.nasa.gov/lib/insp...uirements.html

brutus

Perhaps more important is using good quality terminals in that tool.

Jim Devine

Good point. Anyone have a source for military grade connectors & ends instead of the cheap junk that's common?

dr bob

There is a lot of discussion available. Consider that the NASA standards generally look at relatively sanitary use environments. Same as what we see in the auto environment? Crimp connections are much easier to QC visually, compared with soldered and shrink-protected connections. So what works best for spacecraft may not be what's best for automotive connections outside of the passenger compartment

For engine bay and undercarriage/wheel well areas, I have good luck with ABYC standards. This is the marine builders standards. Cable is tinned and soldered. Someplace in my dark past I took a mil-spec soldering course, with standards that are a bit more stringent than the average DIY solder-slinger might presume. Biggest difference are in cleanliness and connection prep, then materials and technique, then cleaning again, inspection, and possible protection. Generally, if you'd be comfortable dipping the connection in your soup at any time in the process, and the connection is mechanically sound before solder is introduced, you are good to go.

Downsides to soldering include possible solder creep up inside the cable, moving the flex point up inside the insulation where you can't see failures. Also contamination with flux that isn't removed prior to sealing. Lots of possible failure modes if you aren't careful.

My too sense.

hacker-pschorr

That is the #1 reason why most of us "shade tree mechanics" should be using a quality crimper instead of the soldering iron.

Yes it's easy to screw up a crimp job but it's pretty obvious when that happens. A crappy soldering job can look good to the untrained eye at first and cause issues down the road.

I bought one of these and I get most of my terminals from the local Wurth supplier:

http://www.kaboodle.com/reviews/s-g-...kit-5-piece-10

GregBBRD

None of the "offroad" wiring harness builders, that I'm aware of, would ever solder a wire...only crimp. Same with any racecar. The solder connection is stiff and will break from vibration, whereas the crimp connection will flex for a much longer period of time.

dcrasta

Ok question (from an amateur solder guy)..

I usually crimp then solder . I have a ratcheting crimping tool that has interchanging jaws (used for CatV cabling etc) and usually after crimping I flow a drop of solder into the terminated end for 'a more solid connection'. Is this over kill ? I have done this in the past however I have yet to touch the 928 with my irons yet.

Before I get started is this over kill, bad practice or ok ?

danglerb

Assuming you made a good crimp, there is nothing for the solder to due but coat the outside, not the electrical contact.

Solder can't improve the electrical contact of a crimp, metal to metal beats metal solder metal.

That kind of leaves does the heating and soldering degrade the connection, and that could be a maybe.

Crimp and use a good heat sealing shrink.

jcorenman

The operative word in the NASA spec is "solder-tinned", in the same section that prohibits crimping solid wire. A solder-tinned wire-end is basically a solid wire, and is not happy being crimped.
There's nothing wrong with crimping tin-plated stranded wire, i.e. marine-grade wire, and the tin-plating helps avoid corrosion. West Marine is a good source of good-quality wire and terminals, not cheap though.

I don't think soldering a properly-done crimped connection adds anything, and some folks have said that the heat changes the temper and weakens the crimp. I do not know if that is true.

Mike Simard

Dr Bob gave the main problem with soldering, creating a flex point that can fatique.

That's also why it's important to restrain connectors, especially underhood ones subject to wind.

One good use of solder are the little solder/heat shrink wire splices. Those are very good and used by pros.

Andre Hedrick

Typically I do both to back fill the gaps, sometimes left by crimping.

blazing928

What about large wires like 2,4,0 guage. I crimp and then with a small blow torch, or larger soldering iron, melt solder into the crimp.
In car audio this is common for the power connectors.

>> metal to metal is better than metal Solder metal <<<

Isn't solder metal, so why is it less conductive. Wouldn't solder fill the small air gaps around the wire and connector giving a greater contact area. I would also put forward the theory that with the crimp filled with solder there would be no air gaps that cause oxidation?? Any thoughts?

I agree that a solder only joint can fail, look at all the dry solder issues with our cars, but crimp and proper soldering must be better IMHO and secured so it doesn't move. Plenty of crimp only connections can crack and break at the crimp, not much difference to solder.

WallyP

Building aircraft is an area where performance is much, much more important than cost. Harness connections are crimped, period. If adding solder made the crimped connection more secure, they would be soldered. They aren't.

yardpro

i also use the marine standars for crimping.

the crimpers i bought were well over $50 if i recall correctly.

he real marine grade crimps have heat shrink sheathing that you heat to seal the connection.

Solder makes a rigid point that will eventually break.

danglerb

A decent guide for all things electrical, electronic, and acoustic could be made by gathering together all the common practices of car audio and adding the word DON'T at the front.