Hi All, I have a few questions:

1) Why are servos always mounted with the spline at the end farthest from the control surface? To reduce the angles of the push rod? Does it make sense, or is it a bad idea, to install with spline at the surface end to reduce push rod length and weight?

2) What is the best method to properly align and temporarily secure the servo for marking/pre-drilling?

3) What is the best method to mark/pre-drill the servo holes?

4) When and where is HD servo extension wire really needed?

...Ryan reminded me of:

5) I usually use 2 extensions on the ailerons; one from the servo to wing root, and one from the Rx to exit the fuse. Is there a better method?

Thank you,
Joe

1. It often has to do with how long the pushrod will be. If given the opportunity, I try to install servos such that the pushrod is the shortest that it realistically can be. Geometry should remain unaffected as pushrod length has no bearing on geometry, even reversing a servo it will remain the same.

2. I've actually gotten in the habit of measuring the holes on the servo and measuring them out on the surface. You can also shim with some relatively solid material (hard balsa, for example) to block the servo in place. I find this more difficult and time consuming to achieve, therefore I measure for one-off circumstances. If I am doing something like an IMAC airplane that has all identical-sized servo boxes and servos, I will build a dummy servo that's the same size as the opening to mark the holes, but it's not very effective for an airplane with different sized servos, or one off work. With you trimming your servo boxes back on your Integral, you may end up with slightly different sized openings anyway, so this will render that further useless.

3. A good eye and a pin vise. If you have a snap punch, that can help, but they generally have so much spring tension that you can cause damage to the surface before it snaps. I use a pin vise to drill the holes, run a screw in the hole to cut threads, and then wick thin CA in the threads to harden them.

4. If you are using really high torque servos. You lose more through the connectors than you do with the wire. If you are sharing common power leads for dual elevator servos, it may be a good idea to run the HD servo wire, but for most other purposes, standard 24 AWG wire should be fine.

2 or 3 wraps of masking tape on the servo will center it nicely and hold it in place while drilling.

My opinions on 1 and 4-
1- I have spent a great deal of time understanding and perfecting geometry on my setups (obssesive). on a set up like the elevator where the horn and servo arm swing in the same plane pushrod length has no effect on throw symmetry assuming the rest of the geometry is correct. on a perpindicular plane set up like the ailerons excessive angles from short pushrods should be avoided. a longer pushrod also affords less wasted force, less angle error and  generally speaking is easier to setup for throw symmetry (if thats what youre after). an extra couple of inches of carbon tube pushrod length adds a negligable amount of weight too. There are more important factors to linkage setup than pushrod length and a lot of "rules of thumb" that are just not true.
4- the rudder may require most of the servos capacity but the typical twin servo elevator or ailerons having low friction, with the typical throws and proper ratios will likely never need more than 1/4 of the servos capacity.