ORIGINAL: TOMAPOWA
ORIGINAL: JimDrew
I think you misunderstood my intentions on timing. If you time the duration and subtract a certain amount you can use that as a reference point of where to slow down the motor to finish the remainder of the cycle. This eliminate potential damage if a bind were to occur at the end of the cycle, and this completely removes the need for spinning the motor the opposite direction to ''relax'' the threads. Running full tilt until the current sensor kicks in is too late, and the reason you are having to back it up right now. If this process is repeated over and over again, something is definitely wearing out quicker. Just a suggestion...
Thanks Jim, I see what you are now saying... I thought you were trying to eliminate the stall current sensing all together...
I could certainly try that... but I have a feeling that even if the motor was slowed down a little, it would still have to experience a specific stall (i.e. torque) before shutting down. Maybe slowing it down like you said might not bind it as much.... I'll have to test.
I also found something out interesting late last night. I was pausing a little (200ms) before backing up the motor after sensing a stall condition... and in doing so, the mechanics would work 20-30 cycles until it would bind and not move when under control. What I did was then remove the pause such that it would immediately back up a little just as the stall conditions was sensed. I have since cycled the gear 40-50 times with 100% success! Go figure!
No, actually this makes sense (and the reason why I suggested the slow down just before the end). When you pause that 200ms with the motor power off, the motor is still spinning down and the gear train is still moving for another 200ms (which makes the it turn quite a bit). When you immediately back up the motor, you are preventing it from going too far by halting the movement and changing directions. Slowing down prior to the end will prevent any possibility of binding because of this "overlap" due to the gear train spinning down.