Hello CD!
We were finishing our new ball control today and I mounted it by putting a rather large bolt through the motor. Now, I know what you’re thinking (:eek:), but it was the only wait I could do it.
The new motor replaces the old FisherPrice and I’m not sure whether it’s the bolt or something else causing the motor to stall. It turns freely by hand, but skips at a regular interval.
Any advice?
Could you post a picture of the mounting?
It could be the bolt. Or something else could have been broken inside either by the bolt or inside. When you were turning it by hand the debris inside could be out of the way. However when you have it mounted it could have shifted in a place where it is stalling the motor.
Almost definitely the motor is hitting the bolt. You’re going to have to shorten the bolts. The factory mounting points allow bolts to hit the armature/fan inside the motor can if the bolts are too long, I’ve done this before.
Putting a bolt through a motor (as in by drilling a hole through it, not by using the Mabuchi’s mounting holes!) would change its performance and make it not so FIRST legal anymore.
We tested the robot today and if we enable the motor while driving, the robot stops responding to input until we release the trigger, making the motor stop receiving current.
i would guess that when the electromagnet in the motor is turned on it causes something to strike the motor in a way that shorts it or jams it.
The bolt is either shorting it, or causing it to stall, both drawing too much current, and causing the system to stall.
This could be indicative of either a software or a hardware problem.
Try unplugging the motor controller and pressing the same trigger, does this cause the same loss of control?
In almost every case of drilling into the motor case, shavings will be attracted by the internal magnet and find their way between the magnet and the armature. When you apply current, those shavings will then stand up and align with the magnetic field between the armature and the magnet usually causing some kind of mechanical friction. It is also likely that you have dislodged the magnet or cracked a piece off internal to the motor. Either way that will also produce significant internal friction when current is applied. The robot rules prevent modifying the motors (among other things), for just this kind of damage.
Thanks everyone. I’ll go check out the motor this weekend when the mech lab’s open. Oh and there was no drilling involved, it was just a bolt through the mounting holes.