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Critique the Crimp

R

RidiculousM

Well Known Member
I'm currently crimping terminals onto the 2 gauge battery wire. I did a few practice runs using the hand crimper I bought from Stein Air. From what I have read, I believe I am doing it right with one crimp in the middle per terminal but I could not find anything definitive on which side the crimp should be on, the seam side or the non-seam side.

Any info, critiques, tips, etc... would be helpful.

Thanks,
Mike

Seam Side
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Non-seam Side
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Non-Seam side

The seam side of a crimp connector always goes towards the simple, curved portion of the die. The "nail" side of the die goes on the non-seam side of the connector.
 
Seam side

I may be wrong, but i think Stein Team used the indent on the seam side of the crimps for my work. Since the seam is beam welded, it probably does not make an electrical or physical difference, but look at the deformation of the connector. It seems to work better on the seam side for an indent style tool.

Here is a primer on crimping by Molex. It contains a pull test table. The battery terminals (#2) are 550 lbs proof test for pull out.

If in doubt, now that you have two opposing answers, call Steins guys and ask them. You could also post a poll to get the crowd vote on the process. :rolleyes:
 
For the larger wires, I am a fan of the Tyco/Amp diamond crimp which is a confined crimp that offers a lower resistance and higher physical strength crimp. The forces developed with this tool are quite high and actually result in cold welding the strands and terminal. This prevents moisture intrusion over time also. The tool is has a different head for each wire size and is somewhat more expensive however. The Molex document referenced by Bill L refers to the confined crimp also.
 
Disclaimer up front: It's been a while, and I don't remember exactly how or where I originally learned the "proper" technique, and I also can't really speak to the "why" without speculating.

In a former life, I was a mobile electronics installation technician and spent about 7+ years professionally installing car audio systems, remote starters, alarms, overhead video systems, etc. I've crimped a pretty wide variety of connections for vehicle wiring, from 0 awg power cables to 22 awg wires. I haven't had a chance to do much wiring on our plane yet, but am excited for that phase because it is one of the few areas of the build I will have some prior experience in :)

I believe the expression we used is "saddle the seam" or "seam-to-saddle", in other words the curved part of the crimper goes over the seam, and the tooth on the crimper should penetrate the back (non-seamed) side of the terminal.

There is also some debate, not unlike with primers, over what kind of crimper to use, and when to use it. For instance, some say not to use a "toothed" crimper on insulated terminals, or not to use them on sizes larger than x-awg. Personally I've always had good luck with toothed crimpers, particularly on smaller connections, but there are some gotchas you have to be careful of especially with insulated terminals.

An even better way to crimp large-diameter wire, though, is going to be with a hydraulic crimp tool that uses a hexagonal die. The tool you are using is definitely adequate, but the way the terminals "squash" they will only hold the top and bottom very well, and be relatively loose by comparison on the sides. Also, it's harder to make every crimp perfect every time. After making all the heavy-gauge crimps necessary to do your whole plane, you're going to be pretty worn out from doing them all manually, and they may not all be 100% consistent.

In my opinion even a cheap hydraulic crimper with the proper die will do you good. I'd recommend this one, or something similar to make higher-quality and consistent crimps on your power cables:
http://www.amazon.com/TEMCo-Hydraulic-Cable-Crimper-TH0005/dp/B00HJXG3KM

Cheers and happy crimping!
 
Or, you could just (GASP!) solder it. (Yes, a crimped connection has a stress riser, too. Right at the crimp.)

Charlie
 
I'm not a big fan of crimps, for the stress riser mentioned. Most production large wire connections are swaged and that's what I did with mine, as well. I applied solder over the wire end after the swaging just for extra corrosion resistance. Looks brand new after eight years on my RV-6A.
 
flion said:
I'm not a big fan of crimps, for the stress riser mentioned. Most production large wire connections are swaged and that's what I did with mine, as well. I applied solder over the wire end after the swaging just for extra corrosion resistance. Looks brand new after eight years on my RV-6A.
Click to expand...


I agree with Mikey and Flion. Seam in the saddle with a classic crimping tool. And, I agree that either soldering or swaging is far superior to crimping for larger connectors. You need a good swaging tool with the proper dies though and those tools can get a little pricy. Soldering works too but it's a pain.

Regardless of the method, technique is what's important. There are plenty of YouTube videos out there with good examples of each. Stein has some nice videos up too though I couldn't find one on that discussed bigger, battery size connections.
 
DonFromTX said:
I was very unhappy with my crimps, found a hydraulic crimper and that was the secret. I removed all my cables and remade them. I am very happy with them now, you can see them here:
http://www.mykitlog.com/users/displ...TX&project=2429&category=0&log=200611&row=157
Click to expand...

I bought the HF crimper and it did not include dies large enough for the starter cable size. I took it back and ordered a larger one from eBay. I like the one mikeyj350 posted, it won't yawn like the "C"frames. Be careful with the chinese crimpers, the dies are powdered metal and some are poor quality, dimensionally. They don't mate squarely. The one posted looked pretty good.
 
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