Bantam Tools Blog

Factory Friday: The Importance of Crimp Tools and Test Jigs

Posted by Owen Smithyman on Jan 16, 2015 12:30:00 PM
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Hey guys! I’m Owen, a Hardware team member at Other Machine Co. For those of you who don’t already know, we build the Othermill right here in our San Francisco office/factory. As we continue to refine the processes for assembling Othermills in-house, I’m learning more about how important it is to use the right tools and to find creative ways to catch errors. Why? Because timely error correction can mean the difference between limping along and zooming ahead. It can mean the difference between a successful product, and a returned one.


These are crimp tools. They attach metal terminals to the ends of wires, which then go into connector housings as part of making wiring harnesses. Wiring harnesses are basically cables that connect one component to another, and each Othermill contains 12 of them.

The blue crimp tool costs $36, and the red one costs $380. They both can crimp the same kind of terminal, with close to the same consistency. Why use the red one, then? If the $36 crimp tool produces a bad crimp, or makes the user more likely to make a bad crimp, even one percent of the time, $380 doesn’t seem so bad. A bad crimp will result in the product malfunctioning. The product will then need to be returned, fixed, and sent back — costing us time, money, and reputation, not to mention customer frustration — all of which immediately adds up to more than $380.


This is a custom-made QC (quality control) test jig that we use to inspect our most complicated wiring harnesses. I simply plug each end of the harness into the jig, then twist the dial and make sure each row of lights turns on. This indicates that the connections are good and that the terminals are in the right places. Joachim, another member of our Hardware team, made it in a single afternoon using the Othermill — and it immediately paid for itself when it caught the first few errors. Yes, we use the Othermill to both make new Othermill parts and test Othermill assemblies.


Before using this test jig, every once in a while, a machine would malfunction while we were testing it and then we’d have to run a diagnosis to figure out why. Once the issue was isolated to one of the wiring harnesses, we’d need to disassemble the machine to varying degrees, take out the harness, sort what was wrong with it, fix the problem, and put the harness back in.

Sometimes the issue was a bad crimp, which we solved by getting the $380 brand-name crimp tool mentioned above. The rest of the time, the problem was that the assembler had swapped two of the pins when building the harness, so we made this test jig to catch both of those errors — the bad crimping and the pin swap.

It turns out that there’s a big difference between building five of something and building 100 of that same thing: with more quantity comes more variation, and that variation includes mistakes. We haven’t had a single issue with those wiring harnesses since we bought the crimp tool and made the test jig. Our efficiency has dramatically increased because we can now address errors immediately and without any question of what the problem is.

Topics: Manufacturing, Inside OMC, Factory Friday