Originally Posted by
JohnBuckner
OK two different issues as far as I can tell from your description: First excessive travel of the control surface and binding, second differential travel of the control surface (traveling further in one direction than the other).
I will address the excessive travel first. Since you posted this in the beginners forum I will respond with the suggestion that with you first airplanes it is best to always use the hole on the servos arm closest to the center of the arm and on the control surface horn that you use the hole that furthest out from the control surface. This will give you the least mechanical throw and any further reductions/fine tuning can be done electronically with the transmitter if available.
Now to the differential, the servo horns must be (in the case of the fuselage servos) must be ninety degrees to the fuselage centerline. Next and here is where folks tend to screw up when they assemble an ARF is to position the control horns improperly on the control surface which induces a mechanical differential. The control surfaces horn must be positioned when installed with the hole that is to be used for the pushrods clevis or S bend directly even (fore and aft) with the hingeline of the surface. This is a very common mistake and will introduce a differential every time.
John
Thank you for your detailed reply. After trying everything recommend and scouring for more info over the past two days I am still having the same problem but I do not think it is entirely a servo problem but more to do with the range of motion with the rudder itself. After powering off the Rx and disconnecting the push rod from the rudder control surface completely I manually move the rudder and discovered it moves 1" more to the left than it does the right. I really do not understand why. The manual calls for equal 2 -1/2" of throw in both directions. I think the servo buzzing is caused by the servo trying to move the rudder further than it can physically travel. I can adjust the throw down but I will still have unequal travel and will not be at the manual recommended throw setting. I know that the prop rotates counterclockwise and that more left rudder may counter this but I still comeback to fact the servo (which is analog) buzzes and right rudder deflection cannot get to the factory suggested throw.
Is there anyway to compensate for this or should I replace the rudder?