Let’s talk about lever nuts!
Edit: pics are generally pretty hi-rez, if you open them in a new window/tab you can see a lot detail.
Lever nuts, specifically the Wago 221 Inline Splices for REV Robotics are a simple and effective method for doing large portions of FRC robot wiring. We used them almost exclusively on our robot this year and were quite happy with the results. However, there are some minor pitfalls to avoid for successful use of these connectors.
For these photos I used what some consider the most difficult wire to use with a lever nut: the super-fine leads from a SparkMAX.
Strip the correct length of wire! Conveniently, you can sight this in by using the back of the lever nut. You want to trim enough to fit past the funnel portion of the lever nut (blue) and metallic contact portion of the nut (green), plus a little bit.
That’s it. Stop. Don’t twist the strands, don’t tin them, try to avoid bending the wire at all until it’s in the lever nut. Basically ANYTHING you do to the strands will make installation harder.
As-installed it should look like this, with just a bit of strand poking past the contact and the insulation bumped up against the funnel section.
This connection should take significant effort to pull apart by hand, and result in numerous strands being damaged along the way.
What NOT to do: strip too much insulation and twist the strands together. Stripping too much makes the strands less resistant to bending and buckling during installation. Twisting the strands makes the conductor bundle shorter and wider, often making it impossible to properly fit into the lever nut contacts.
Starting with this…
Results in this…
Or at best this…
Note that despite the extra stripped length there are very few, if any, conductors visible past the electrical contact area.
The fatter twisted strands just jam in the funnel portion of the lever nut, preventing proper installation. The extra-long strands bend and buckle when you try to force them in. Sad times all around. These poorly-made connections nearly fall apart when tugged.