I was setting up the throws on my aircraft the other day and I noticed a line in the manual for my radio that said I should keep the EPA as close to 100% as possible. Can anyone explain the reason for this?

End point adjustment controls how much total arm movement occurs, or the total travel, of the servo. Limiting the EPA to less than 100% doesn't allow full travel of the servo, and might limit travel on your control surfaces.

I think they mean you should mechanically adjust your linkages so that you get the throws you want with 100% EPA. This will give you the max torque from your servo for a given throw, and give you the most resolution for controlling it over that throw. If you dial your EPA way down, you loose a large amount of your resolution, and the smaller servo movement for the same throw means you have much less torque than if you mechanically adjusted...

Using excessive electronic endpoint adjustment will reduce servo resolution and increase the deadband at neutral (poor neutral centering). This will have the effect of say in the elevator for example, symtoms very similar to an aft CG when in cruze or high speed flight. The airplane will tend to hunt up and down now matter how much you mess with the elevator trim. Never quite able to trim.

John

The last two posts sum it up perfectly