DaddySam

My Feedback: (9)

I have one of the new servo programmers that can interface with the PC or be used as a field unit. I was learning the software and had a question. Sometimes when I attach a servo arm it will not be right at 90 degrees to the case, so I was planning on setting the center point. When I do this it wants me to set left and right end points. It seems like one side will be a number like 84 and the other will be much greater. When I then cylce the servo in the test mode, it will swing way to one side and less to the other. So my question is, if I set the center point, what value do I want to set the endpoints at? Do I want to set them both to the same number on either side of center?
Thanks for any assistance. I'm programming some 5645's.
Sam

mglavin

My Feedback: (31)

Daddy,

What’s your reasoning for centering the servo arm to be perpendicular to the case? In a perfect model where all things are equal this may make sense, but our model specific linkage geometry is anything but perfect. That said many believe it’s necessary to center the servo arm as you mention providing for equal surface deflection in either direction, unfortunately this is rarely realized. There are methods which can be used to realize equal surface throw with equal arm/control output; but almost always its a mechanical linkage thing verses the short cuts many use with programmable transmitter and servos.

That said, if you center the servo arm perpendicularly to the servo case and you want equal throw either side of center with regard to the servo arm only you’d program the travel arcs equal offsets in each direction, i.e., the servo centers at 1510us, you’d want to program equal numbers in each direction say 1510 + 300 in one direction and 1510 – 300 in the latter. Your actual numbers will vary dependent on how much servo arc or t ravel you want for the specific model.

Again all things are not perfect and the electro-mechanical variables of transmitters and servos may in reality skew these numbers a little, best way to insure you get what you want to is to use a simple photocopied protractor enlarged to suit your needs centered over the servo output shaft, follow the servo travel arc with respect degrees in both directions and program accordingly. Generally speaking servo travel arcs are 60 degrees either side of center (but you may require/want less or more).

DaddySam

My Feedback: (9)

Thanks Mike. I was hoping for perfection but will have to settle for less. Even when I recentered a servo, when I plugged it into the rx it went off center a bit. Not sure why as the others were all okay. I really bought the programmer for the convenience of being able to change rotation direction and also slow the servo down, for flap deployment. In those cases it has worked wonderfully. Of course, I do like gadgets too , but I could never bring myself to part with the $130+ for the other programmer.
Sam