[NSRCA-discussion] Metal Servo Arms

[Earl Haury]

The nylon servo arms are quite adequate when used with a clevis that applies the force in line with the plane of the arm (typical pin clevis). Pushrod ends that bolt to one side of the arm move the force off the plane of the arm and thereby impart a twisting force to the arm. (DuBro type ball links are the extreme.) Add a bunch of vibration to the normal loads and the nylon arm may eventually fail - a wheel is a much better choice if one uses the nylon accessories. In addition to better withstanding the twisting forces of offset linkage, the aluminum arm is more substantial for screw mounting the ball / ball bearing end.

Jim is correct regarding the H9 arms on JR servos - there seems to be more variation in the spline of the output than the spline of the arm. (An arm tight on one servo may fit nicely on another.) OTOH, I've found the H9 arms to fit Futaba servos consistently well.

Earl
  ----- Original Message ----- 
  From: vicenterc at comcast.net 
  To: NSRCA Mailing List ; NSRCA Mailing List 
  Sent: Friday, August 31, 2007 7:28 AM
  Subject: Re: [NSRCA-discussion] Metal Servo Arms


  For pattern I always use the nylon servo arms that comes with the JR servos.  I am not sure why you need the metal servo arms.  Usually I use the round one for aileron and elevator.  For rudder I use the heavy duty arm that JR offers (comes in the 8611 servo).  I never have problems with the nylon servo arms in pattern application.

  Regards,
  --
  Vicente "Vince" Bortone

    -------------- Original message -------------- 
    From: Bob Richards <bob at toprudder.com> 

    I've used the H9 arms and the SWB arms. No comparison, I will continue to use the SWB arms.

    Bob R.


    Kelly Regan <kelly.regan2 at verizon.net> wrote:
      Not an answer to your question but I find the SWB arms much nicer
      since they are split. They use a a 2/56 clamp screw and nylon locking
      nut to draw the clamp tight around the spline of the servo shaft.

      twtaylor wrote:
      >
      > I bought some Hanger 9 alum servo arms and when I put them on they are 
      > VERY hard to get to pull down on to the servo. Is
      >
      -- 

      ________________________________
      Kelly Regan
      Home Page: www.reganspace.com
      ________________________________

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