just about anything other than balsa wood. although I have used that too,...with no problems at all as long as it's not the very softest, lightest grade. there really isn't that much stress involved in running control surfaces, the main consideration is that the throws are properly adjusted so that the extent of control surface travel is not what is stopping the servo arm's travel. even the most dense hardwood is not too heavy considering the sizes of the pieces needed for mounting a servo.
I think there is an awful amount of overkill and "much to do about nothing" when it comes to the torque of control surface servos. it is only since the hobby got infiltrated with young "techy types" with their scientific calculators and the internet, needing something to post about, that servo torque became such trendy concern. in all my 40 plus years of being around rc, there was never any concern beyond "having a decent servo", until recent years. 90 oz. is aprox. 7-1/2 lbs of force . no model control surface of any plan is anywhere near big enough to require that much force to move in the air stream. the association between plane weight and servo torque is a false equation, made up simply to have something to compare numbers ....a 7-1/2 lb. plane doesnot need servos with 7-1/2 lbs. of torque to move a control surface.
Last edited by r ward; 07-01-2018 at 09:41 AM.