Folks,

I am installing the servos in a plane I am currently working on, and When installing the servo arms on the servos I noticed that the arms don't sit perpendicular to the servo (I have already centered the servos using the transmitter, problem seems to be with all of them.) The servo gears are positioned such that the arm is not quite perpendicular to the servo, and when I remove the arm and put it back on the adjacent gear, it is still off but in the other direction.

I was going to proceed and finish the installation any way, but thought I would ask the question: is this something that happens regularly, and can it somehow be fixed?

It sounds like you just have some weak servos. First off, what brand are they? If they are Futaba, you can rotate the servo arm to get it centered (See Diagram)

But regardless of that, if they don't return to center, first check your pushrods to make sure there is no excess pressure or binding. If not, then you might want to consider replacing the servo depending on how bad it is.

You can always keep those servos for use on a non-critical control, like throttle, or flaps

There is nothing wrong with your servos some types of output arms but not all, will minimise this by rotating the arm on the output shaft Use your subtrim to center the arm when one tooth change or 180 degree changes won.t do it.

On the multiple prong arms or on the srvo wheels, there are numbers close to the hub where they mount on the servo. These indicate the relationship of the output arm to the splines on the servo output shaft. You can select a different radial to find one that is centered.

You can buy new servo arms from Tower or Horizon if you mess them up

I remember reading here in a recent post that it's more important that the servo arm be 90 degrees to the push rod or cable termination than 90 degrees to the servo itself. I don't know from experience.

Bill

Both should be close.

Neither is so critical that it will hurt anything if it's off a little

Having the control rod 90* to the servo horn (tangential to the arc) ensures equal travel in both directions. The benefit of having the rod 90* to the servo is to use minimize movement of the servo in the plane by having the forces act along the length of the servo instead of across the servo. I would argue that having the rod 90* to the servo horn is more important for precise control.

All - thanks for the replies and the suggestions. I agree that it would be important for the geometry to be correct for things to work properly - also that things being a little "off" is not a huge deal unless we are talking about precision plane.

To answer some of your questions:

- The brand of servos is... ehm... the "el cheapo" type (they look like HS-55 knock-off). Before you go on saying you get what you pay for, I know! I specifically left this detail out to see if this was a problem that also occurs with brand servos, and didn't want an automatic attribution to the quality of the servos
- The servo arms I am using are single-prong so rotation is not an option

I like the option of using the sub-trim to center the arm, I hadn't thought about this. I can then adjust the travel through the transmitter to ensure equal travel.

if the servo always returns to the same spot that is center..as said above 1 spline off is no big deal

that was the answer..........