Motor on Claw Frying Ports

Hello all,

Our team has a major static problem. As you can see from the image, we have a claw motor mounted to the front of our 4 bar. Occasionally, when using the claw, the motor port light blinks red, and it no longer works. We assume that the port on the brain has been fried, and we change the port of the motor so the claw works again. We have killed 7 ports on the brain so far from this problem.

To attempt to mitigate this, we have sprayed the bot and the field with anti static, rubbed dryer sheets on the claw, and grounded all aspects of the bot with copper wire. However, with these modifications, the motor still burns through ports like no tomorrow.

The occasion when the port burns out is inconsistent. Sometimes we practice for 10 minutes straight and the port is fine, or the port is killed during a single round robin match.

Is there anything else we can do to preclude this issue?

Currently, the brain is mounted to a metal plate with screws, but none of the other ports have burned out beside the brain. We are going to mount the brain using plastic, but are there any additional fixes to reduce ESD?

Another thing you should check is the wire as if it is a bad wire I can cause the ports to burn out. As well as check different motors (only as a last resort) as the motor could also be causing it to short out(very rarely but still a possibility)

How does a wire become “bad?”

We will try replacing both.

  1. Lookup my post history… and look for the static electricity thread.
  2. put a metal shaft collar between the motor and aluminum it’s mounted to. this will help ground the shaft to the frame directly, instead of going THROUGH the motor.
  3. ground the lift to the chassis… i guess you could use an old motor wire, strip the ends, and put the bare ends under a good tight screw.
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usually when a particular motor keeps burning out your ports, that means that static charge is able to build up differently on one end of that smart cable than the other. In your case, that’s the end of your lift building up a different charge to wherever your brain is mounted.

To prevent the difference in charge from building up, try electrically grounding these parts together so that the charge can safely be dispersed instead of building up and then surging through the cable.

To do this, you need to make sure that there is a clear and conductive path for the static to flow from the claw area to the rest of the robot. When you have parts of metal which are isolated (through bearings, spacers, or other non-conductive components), this cuts that connection between the parts. One theoretical solution is to use some sort of conductive cable (like steel or copper) to electrically ground parts of your robot. Metal cables under 1/8" thick are legal under the definition of “string”.

You may also want to try things like anti-static spray.

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I have found that I a wire has gone bad if either of the ends have been damaged or gotten dust or other debris in it or if the ends were not crimped correctly.

Time, wear & tear, flexing, kinks, etc.

Generally speaking, you don’t want to bend ANY wire less than a certain portion of its diameter. I would need to look up the actual amount. But short version… sharp bends are bad.

I’ve seen bad wires which will physically break the inside of ports when plugged in by bending the internal pins and whatnot. But this sounds distinctly like a static issue, not a bad cable. A bad cable won’t make the port blink red like they do when fried in my experience.

From my static testing… anti static spray usually drops static levels WAY down.

If you are having troubles despite this… are you dragging anything (especially plastic/nylon) across the field as you drive? This will create massive static levels VERY quickly. Is part of your bot rubbing the field as you drive? Gears maybe?

Are there plastic/nylon parts on the bot that are rubbing, creating static? Maybe add spacers/etc so they don’t rub.

Edit: we may be looking at this backwards. The goals might be the charged items… and they discharge through the clamp/motor/bot when you touch them. That said… usually static spray solves this problem.

I do notice your ground wire in the top right of the picture. I would ground my shafts using the metal lock collars so they lightly touch the frame.

Edit (again): aluminum has an oxide later which is actually a quite good electrical insulator. You need to lightly sand where the wire is contacting the frame, insert a bolt/nylock and place a round of wire under the head… creating a good TIGHT mechanical/electrical connection between the assembly.

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[quote=“turbodog, post:9, topic:98482, full:true”]

Nothing drags across the floor. Only 6 wheels touch the ground normally, but whenever the lift is all the way down the goal touches the ground.

We also use white nylon spacers for everything, do these create static?

I had a similar issue on our cap claw for turning point. I think we went through three or four motors and as many brain ports. What helped me the most was putting a ferrite core on each end of the cable (in this case the motor end is the more important one, but both would be good). You can get 5mm clip-on ferrite cores for very cheap in amazon.

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Not from themselves… but plastic that slides/rubs can create static.

Example: If you’ve got a gear next to a 1x2 ‘c’ channel that’s rubbing as it rotates, then this can make static. A simple washer on the shaft would make some space so the gear doesn’t rub.

You can also drag a ground wire underneath the chassis. That will dramatically lower the static charge on the bot.

You can’t NOT have plastic/nylon washers, spacers, etc so you have to use them in the right way… build up advantages and minimize disadvantages.

I’d really recommend looking at my static thread.

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That’s the prevailing wisdom, but testing… with a meter and actual hard data, showed it to not be accurate. Static electricity seems to have zero problems forming on subcomponents regardless of their electrical isolation with one another.

I suspect your grounding wire did less about equalizing that charge than it did at providing a path to ground that DIDN’T flow through the motor, motor wire, and brain port.

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