Crimp Good/Crimp Bad

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Crimp Good/Crimp Bad

Postby BchrisL » Sat Jun 07, 2008 2:20 pm

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Postby Unity » Sat Jun 07, 2008 2:22 pm

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Postby R4R&R » Sat Jun 07, 2008 11:06 pm

Personally, I like to 'tin' my wires before crimping them. This usually eliminatesstary strands. 8)
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Postby echo » Sun Jun 08, 2008 9:06 am

R4R&R wrote:Personally, I like to 'tin' my wires before crimping them. This usually eliminatesstary strands. 8)


Major no-no.This will increase the diameter of the wire also make the wire not deform under the crimp as it usually does. Likely to crack the terminal. (thats what they tell me) When I am crimping wire harness to NASA specs every so often one has to be pull tested. Wire and crimp goes into a machine that pulls the wire out of the crimp and measures the force required to do so. This is considered the ultimate test of whether or not the crimp is good. Then you must document it! I have learned QC doesnt care so much about whether or not the pull test is done. What they want is DOCUMENTATION. ie CYA.
If done properly crimping is considered superior to soldering for hi-rel NASA assembly. Which shows how much they know!
PS If you tin the wires before crimping they pull out of the crimp on the machine much easier.
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Postby BchrisL » Sun Jun 08, 2008 11:36 am

R4R&R wrote:Personally, I like to 'tin' my wires before crimping them. This usually eliminatesstary strands. 8)


We found that the lead/tin solder was higher in resistance and in a crimped connector would heat under load more than a conductor without tinning. The constant heat/cool cycle would lead to failure of the connector due to metal fatigue brought on by the repeated expansion contraction of the joint.
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Postby Ted » Sun Jun 08, 2008 1:56 pm

What about a bead of solder after the crimp is done?
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Postby BchrisL » Sun Jun 08, 2008 2:05 pm

Ted wrote:What about a bead of solder after the crimp is done?



Not sure...insufficient data...
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Postby jskene » Sun Jun 08, 2008 3:41 pm

A solderless crimp is better than a soldered, uncrimped joint because the heat generated by high current through the connection can melt solder, resulting in a failed joint.

It's best to use a ratchet style crimper, never the combination crimper/wire cutter, if you want a reliable joint.
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Postby BchrisL » Sun Jun 08, 2008 3:52 pm

jskene wrote:A solderless crimp is better than a soldered, uncrimped joint because the heat generated by high current through the connection can melt solder, resulting in a failed joint.

It's best to use a ratchet style crimper, never the combination crimper/wire cutter, if you want a reliable joint.


Image

+1 ( the ratchet style is expensive though, but it will "git 'er done" right.
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Postby echo » Sun Jun 08, 2008 4:57 pm

A long as you remember that excellence is the enemy of good enough.
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Postby R4R&R » Mon Jun 09, 2008 12:45 pm

echo wrote:PS If you tin the wires before crimping they pull out of the crimp on the machine much easier.

Personally, I've never had a tinned, crimped wire connector come undone. My previous bike seemed to have 'issues' with some of the OEM crimps in the rear tail section of the harness. This seemed to affect the brake light, tail light, and turn signals. Vibrations from the engine (only speculation) seemed to cause the wires to break just outside of the crimps (from vibrations?). I replaced them quite a few times, and the final time I tinned the wires before crimping. That last fix lasted the remainder of the bike's life for me (over 15k miles). The previous standard crimps lasted between 7k and 10k miles before failing.

My current bike has over 60,000 miles and I've added an accessory fuse panel with tinned wires/crimps supplying the power for my accessories (GPS, iPod, Sirius radio). They've been on at least 45,000 of those miles. No failures (yet). If solder causes higher resistance, my connections aren't causing anymore than what's used on the PC board that's inside the car lighter adapter.

I have a question about tinned wires/higher resistance/more heat: Would this be the case regarding low power lighting (brake/turn signal)? I'm getting ready to re-wire my trailer and was planning on tinning/soldering the connections and sealing with heat-shrink. The crimps that came on the trailer when it was originally built are failing. No, they weren't tinned.

I'm not trying to say tinned and crimped connections are better, I'm only saying that they have been very reliable for me. No, I don't work for NASA, nor am I leaving our atmosphere anytime soon so the risks I'm taking are acceptable. I wonder how much NASA spent on testing different ways of crimping to find the best solution for their use?
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Postby echo » Mon Jun 09, 2008 1:40 pm

R4R&R wrote:
echo wrote:PS If you tin the wires before crimping they pull out of the crimp on the machine much easier.

Personally, I've never had a tinned, crimped wire connector come undone. My previous bike seemed to have 'issues' with some of the OEM crimps in the rear tail section of the harness. This seemed to affect the brake light, tail light, and turn signals. Vibrations from the engine (only speculation) seemed to cause the wires to break just outside of the crimps (from vibrations?). I replaced them quite a few times, and the final time I tinned the wires before crimping. That last fix lasted the remainder of the bike's life for me (over 15k miles). The previous standard crimps lasted between 7k and 10k miles before failing.

My current bike has over 60,000 miles and I've added an accessory fuse panel with tinned wires/crimps supplying the power for my accessories (GPS, iPod, Sirius radio). They've been on at least 45,000 of those miles. No failures (yet). If solder causes higher resistance, my connections aren't causing anymore than what's used on the PC board that's inside the car lighter adapter.

I have a question about tinned wires/higher resistance/more heat: Would this be the case regarding low power lighting (brake/turn signal)? I'm getting ready to re-wire my trailer and was planning on tinning/soldering the connections and sealing with heat-shrink. The crimps that came on the trailer when it was originally built are failing. No, they weren't tinned.

I'm not trying to say tinned and crimped connections are better, I'm only saying that they have been very reliable for me. No, I don't work for NASA, nor am I leaving our atmosphere anytime soon so the risks I'm taking are acceptable. I wonder how much NASA spent on testing different ways of crimping to find the best solution for their use?


Well think of this too. When you tin the wire, you have a very vulnerable place where the wire ends and the tin begins. If you bend the wire a few times at this point it will break. I put a piece of shrink sleeving on the wire at the connection to the terminal to give stress relief for this reason. (its true to a lesser extent of even non soldered connections)
Remember with NASA/military stuff you are talking about writing specs to eliminate the one in ten thousand chance of something failing. (HA!) If that happens lots of money goes up in smoke/people die. Heres a trip Ill lay on you. NASA/military doesnt want flux on the solder connections. They have VERY high cleanliness standards for circuit boards. Why? Corrosion over decades of use. So they make us clean everything in a high pressure soponifier solution in a special machine. The high pressure solution can get into sealed parts and ruin them! And the thing is, its only old fashioned acid fluxes that corrode things. Rosin fluxes if reasonably cleaned wont hurt a thing. Ah but it gets deeper! Acid fluxes actually give a better solder joint than rosin fluxes! Acid flux is easily washed away with low pressure soap and water! So theres NO CHANCE of it getting into sealed parts! I know this because I work on a bench every day for 30 years soldering things. But...the ding dong people who sit behind a desk all their lives and write the specs dont have a clue. They make us use rosin flux (which wont hurt a thing) make us wash the boards in a high pressure cleaning machine (which can ruin the parts) which produces an inferior (but adequate) solder joint!
But you do it the way you want. The most important thing is the care and skill the worker puts into his work. (but you can still have a kaboom)
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Postby IAMBOB » Mon Jun 09, 2008 3:35 pm

I just spit on em, and twist them together.. lil electrical tape and done!

It's only a motorcycle, I'm not landing Tom hanks on the moon..
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Postby Hello Kitty » Mon Jun 09, 2008 4:11 pm

BchrisL wrote:
jskene wrote:A solderless crimp is better than a soldered, uncrimped joint because the heat generated by high current through the connection can melt solder, resulting in a failed joint.

It's best to use a ratchet style crimper, never the combination crimper/wire cutter, if you want a reliable joint.


Image

+1 ( the ratchet style is expensive though, but it will "git 'er done" right.


Jerry, Chris, as part of my cruise control research, I talked to a guy who mentioned "rolling" crimpers which he said were better than traditional crimpers. Do you know what he's talking about and is it true?

Thanks!
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Postby R4R&R » Mon Jun 09, 2008 4:15 pm

echo wrote:NASA/military doesnt want flux on the solder connections. They have VERY high cleanliness standards for circuit boards. Why? Corrosion over decades of use. So they make us clean everything in a high pressure soponifier solution in a special machine. The high pressure solution can get into sealed parts and ruin them! And the thing is, its only old fashioned acid fluxes that corrode things. Rosin fluxes if reasonably cleaned wont hurt a thing. Ah but it gets deeper! Acid fluxes actually give a better solder joint than rosin fluxes! Acid flux is easily washed away with low pressure soap and water! So theres NO CHANCE of it getting into sealed parts! I know this because I work on a bench every day for 30 years soldering things. But...the ding dong people who sit behind a desk all their lives and write the specs dont have a clue. They make us use rosin flux (which wont hurt a thing) make us wash the boards in a high pressure cleaning machine (which can ruin the parts) which produces an inferior (but adequate) solder joint!

That's hilarious! Typical suits thinking they're doing things more efficiently!
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