Electrical basics

[Ken Streeter]

Originally Posted by Al Skierkiewicz

We use screw mount push on connectors on Victors and Jaguars.

These sound neat. I don't think I've seen these before. Can you provide a pic and/or a supplier/part number?

Thanks!

[Al Skierkiewicz]

http://www.digikey.com/product-detai...7866-ND/293277
We buy one hundred at a time. When needed we use the APP 35 and 45 amp contacts. Crimper is available from West Mountain Radio (outside Milwaukee) as well as other places.

[RonnieS]

Will you still be doing this with the limited length of leads on the new speed controllers? Or splicing in on the PD board side?
-Ronnie

[Al Skierkiewicz]

We will likely add APP connectors to the new speed controller output wiring. I don't like that but we will adapt. I hate adding another point of failure.

[JamesCH95]

Here is a good thread to read if you're having issues with your wiring connections: http://www.chiefdelphi.com/forums/sh...d.php?t=119549

There is absolutely no need to both crimp and solder every electrical connection. Crimping is just fine when it's done properly. I would strongly encourage you to do rudimentary tension testing on a couple crimped fittings. They should be able to sustain far more force than one can every apply by tugging on the connection by hand. Ratcheting crimpers are key to ensuring consistent and strong crimped connections.

[Al Skierkiewicz]

James,
We crimp then solder for one very good reason. We lost a World Championship to Beatty when one of our crimp connections let loose. We have vowed that will never ever happen again.

[JamesCH95]

Originally Posted by Al Skierkiewicz

James,
We crimp then solder for one very good reason. We lost a World Championship to Beatty when one of our crimp connections let loose. We have vowed that will never ever happen again.

What would you have done if it was a cold or improperly soldered joint to blame?

[SteveGarward]

Final soldered connections for the competition robot are often checked by a mentor, and usually at the request of the student. It's not a lack of trust (on our part) or confidence (on theirs), but a matter of quality assurance by all to ensure we are building the best that we can.

In any case, I would want to be able to say we did everything we could to ensure a good mechanical connection.

[Al Skierkiewicz]

James, we crimp first and then solder. We have had a stunning run of zero electrical failures.

[JamesCH95]

Originally Posted by SteveGarward

Final soldered connections for the competition robot are often checked by a mentor, and usually at the request of the student. It's not a lack of trust (on our part) or confidence (on theirs), but a matter of quality assurance by all to ensure we are building the best that we can.

In any case, I would want to be able to say we did everything we could to ensure a good mechanical connection.

What we (on 95) have done to ensure a good mechanical connection is to adjust our ratcheting crimping tools and then test the crimp connections that they make. We get awfully close to mil-spec pullout strengths with these connections (around to 130lbs on 10awg connectors, almost 300lbs on 6awg connectors) and dissecting these connections shows nearly continuous metal through the crimped cross-section due to deformation and micro-welding. This qualifies as a "good mechanical connection" in my book at least! Two robots and counting on this process (plus pre-season drives and other projects) with zero failures. The two robots before that used soldered connections, also with no failures.

Soldering relieves all of the cold-working from crimping making the crimping process pointless. Most solders only begin to melt at around 200C (depends on formulation), and copper will start to stress relieve around 150-200C (depends on alloy).

I'm not saying that soldering can't work, or doesn't work; my team and I have used numerous soldered connections with great success. Both soldering and crimping are perfectly valid methods of joining connectors to wires. What I am saying is that it is pointless to do BOTH to the same terminal. It is simply a waste of time because soldering essentially undoes crimping.

[Al Skierkiewicz]

James,
Loosing a World Champs to four time winner Beatty Machine is not pointless. We would be the only four time winner instead of the other way around. Since that loss we have won three times by crimping and soldering. You are never going to convince us otherwise. Sorry...

[JamesCH95]

Originally Posted by Al Skierkiewicz

James,
Loosing a World Champs to four time winner Beatty Machine is not pointless. We would be the only four time winner instead of the other way around. Since that loss we have won three times by crimping and soldering. You are never going to convince us otherwise. Sorry...

Well, I am disappointed to see a sound and technically-valid argument fall on completely deaf ears, especially in FRC.

[Al Skierkiewicz]

I didn't say it was unsound, I am just saying don't fix what ain't broken.

[JamesCH95]

Originally Posted by Al Skierkiewicz

I didn't say it was unsound, I am just saying don't fix what ain't broken.

Al,

I guess I am not being clear here. Saying "you are never going to convince us otherwise" shows a remarkable amount of close-mindedness, something that I would not have expected. I would think that when presented with a compelling argument and data that anyone in FRC would be open to changing their mind. Perhaps your are not convinced now, and that's fine, but saying that you will never be convinced... that is what disappoints me.

[Al Skierkiewicz]

James,
I don't want to mislead anyone. NASA does not allow soldered connections for the reasons that you have mentioned. The auto industry swears by them. In my heart I know you are right and I use crimped contacts everyday as often as I use soldered contacts. However, in our case, the team will not accept loosing another Championship to Beatty or any team because a of a failed crimp. It's a choice, and that is all it is. We take a lot of pride in our solder jobs and insure that a minimum of solder is used so as to not wick solder into the wire under the insulation. We also make an effort to correctly strain relieve all wiring and to tie it down so that it can't fall off or be pulled out. It is not always pretty but it always works.