I am interested to hear if other teams are having issues with power and motor wires becoming detached from the HiTechnic motor controllers (usually at the most inopportune time).
It seems to me that a better design for the motor controllers would be to make them more like the servo controllers which have plugs for connecting the servos. Why do the motor controllers have to have wire ports with bolts to hold the wires in there?
It is our experience that if the wires going into the MCs have any angular stress on them, they will eventually become detached. Not very robust in our opinion.
Our current solution is to build a “motor controller containment box” which will have holes in the side directly across from the MCs, that we will pass the MC wires through. We then have an Anderson Power Pole connector mounted at that spot, connected to those wires, physically attached to the side of the “motor controller containment box”. The idea is that we will keep the wires from moving at the point where they connect to the MC. Sort of like this…
Tetrix wires come with tinned ends which is a huge no-no when using screw terminals. After tightening the solder will creep and a few days later the wire will be loose. Bare wire is considerably better but better still are ferrules. Since we started using them the only loose wire we’ve had has been self-inflicted.
The crimping tool is of medium quality–perfectly adequate for what we do but there are much nicer ones.
On the same topic, the Tetrix power switches come with connectors crimped onto tinned wires–this is absolutely the wrong way to get a reliable connection. Crimp on connectors should only be used on bare wire.
A very poor design. We’ve attempted to mitigate
this by attaching anderson powerpole pigtails to
the terminal and then using ziptied strain relief to
an acrylic board that all controllers are mounted on.
The number one reason wires pull out of the controller is because the wire is not stripped to the correct length. When not enough insulation is removed, tightening the screw simply pushes the wire out of the terminal.
Al
@Al, I have to respectfully disagree with you. I know that you are correct with regard to wires falling out that are not stripped enough, but that is not the issue we are having. Also, with regard to the post about tinning the wire ends, we are not doing that either, so that is not the problem.
The main issue is that if the wires do not come straight out of the MC, and remain straight, then they tend to work themselves loose.
Again, I simply can not understand why the MCs are not designed with plugs for the motors. If anyone can post some logical reason for the current design, and tell me why they can’t be designed with plugs for the DC motors, I am very interested to hear it.
There are 2 common types of PCB terminal block available, spring wire protector and rising clamp.
Unfortunately the HiTechnic controllers use spring wire protector type which for the miniscule saving in cost just isn’t worth it. If you try to use these with bare or tinned wires you’ll run into trouble as noted simply because it’s really only the screw end that’s applying any pressure holding wires in and once you over tighten them (trying to stop them falling out…) it just gets worse because the wire protector gets deformed.
Rising clamp terminal blocks have far more solid construction and will clamp the wire over a much larger area.
We’ve always used wire ferrules with the HiTechnic controllers and never had an issue with them falling out. That said please HiTechnic add $0.50 to the product cost and give us decent rising clamp terminal blocks! We’ll pay the extra $1.00.
Totally agree with aklego - all these tinned wires are really bad and we don’t actually use any of the supplied wires or crimps at all as a result.
As others have described, there is a piece of metal between the screw and wire opening. This does not automatically push out of the way when you insert a wire and may need a little help from a small screwdriver. When yo insert the wire, the end musts extend beyond the screw prior to tightening. If it does not, the screw will push down on the metal tab forcing the wire out of the terminal. The ferrules described above work well in this application as they will force the metal tab out of the way when inserted. But here comes a big caveat, do not use these for the FRC PD. The PD is designed for a very particular WAGO ferrule that is available from WAGO suppliers. Any other device is not designed to handle the current due to the unique design of the WAGO PD terminals. In general, these terminals and the PD are intended to be used with bare copper (not tinned) or specific ferrules.
The proper way of tinning for this type of a screw against pivoting clamp bar connector scheme is to tin only the very tip of wire, and then cut most of the tinned end off, leaving mostly only bare copper to mash down at the point directly under the screw and further out, but with a short zone of tinned remaining at the far tip of the wire.
This produces a reversed wedge effect, such that the tinned tip of the wire is the big end of the wedge, and the clamp piece then squeezes tighter as the wire gets pulled, since the tinned tip will not flatten out as much or as easily as the bare copper did when connection was tightened. Thus, the clamp bar grips the wire at an angle, tighter at the exit and looser further inward, and this effectively locks the wire inside the clamp.
