Servos

[David Lockhart]

Nat,

I am pretty sure the 9411sa comes with a metal output shaft.  I am basing this on the spec weights of the 9411 and 9411sa - they are the same.  I can't tell you 100% because all my 9411s started as 9411 and I retrofit them to 9411sa's long before the 9411sa was a production item.

In general, all of the JR servos have a metal pinion gear on the motor, then 3 intermediate gears, and then the final gear/ouput shaft.  If you change the 3 intermediate gears from metal to nylon, you will save about 0.01 to 0.03 ounces depending on the servo.  Changing the final gear/ouput shaft from metal to plastic will save around 0.10 to 0.15 ounces depending on the servo.  As has been noted, removing/installing the BB on the output gear is a real pain.

FWIW - Within a couple months of JR introducing the 8417 and 8411 digital servos (both with metal gears) in 1999 (?), I had retrofit nylon gears.  I've done the same thing with 9411s and 3421s and have not had a problem with gear breakage in any of the servos - thousands of flights in pattern planes and various sport/funfly planes.

Regards,

Dave Lockhart, Team JR
DaveL322 at comcast.net



  ----- Original Message ----- 
  From: Nat Penton 
  To: discussion at nsrca.org 
  Sent: Wednesday, February 04, 2004 2:39 PM
  Subject: Re: Servos


  I still dont know if the 9411SA comes with a plastic output shaft. I do know that the metal output shaft has a plastic "bushing" that is inserted (pushed with some difficulty) into the bottom of the metal output gear and the bearing is installed on this bushing.
    ----- Original Message ----- 
    From: Henderson,Eric 
    To: discussion at nsrca.org 
    Sent: Wednesday, February 04, 2004 12:06 PM
    Subject: RE: Servos


    I remember that the reason you left the metal output shaft in place is that you can't get the bearing out of the bottom of the gear. Does the 9411 SA version come with a plastic output shaft?  It is not shown on the Horizon site.

    Also, is Troy back on the list. I only see his posts if someone lese replies to one and includes his notes.

    Regards,

    Eric.


    -----Original Message-----
    From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org]On Behalf Of Nat Penton
    Sent: Wednesday, February 04, 2004 12:45 PM
    To: discussion at nsrca.org
    Subject: Re: Servos


    On one servo I replaced all but the motor gear with the returned metal gears and ,like Troy says, it was somewhat difficult replacing the servo arm gear and, Jerry, everything "feels" ok. The two smaller intermediate gears had missing outer teeth. The other servo I replaced all but the motor and servo arm gears with the returned metal gears and , Jerry, it feels super . The inner gear on one of the intermediate gears was missing a tooth or two. It seems to me this is the logical way to go on future conversions and I believe this is what Troy said.
      ----- Original Message ----- 
      From: Troy Newman 
      To: discussion at nsrca.org 
      Sent: Tuesday, February 03, 2004 10:09 PM
      Subject: Re: Servos


      Nat,

      The conversion is to leave the metal output gear in place. So the gear that the servo wheel attaches too is still metal all other gears are nylon. And the standard servo comes with a Nylon gear off the motor already and this gear is left in place.

      I have been running these servos converted for 2+ years now and I have tons of flights on them...We are talking over 2000 flights on these servos converts....Lots of snaps and lots of abuse.

      I have never had a gear strip in the setup....Servo pots wear but not a gear go bad...I don't think you can convert the output gear easily to nylon because of the way it is attached to the pot and the bearing. I'm sure you can get the bearing off the shaft on the output gear and then it might work out..I also will add a little white grease like the servos use...Also in a  pinch I have used petroleum jelly too....Probably not the best choice but it worked.


      My question is what gear(s) stripped?

      I am very curious as I have had nothing but superb luck with this setup. My opinion this is the absolute best aileron servo setup I have ever used. They are fast strong and light just over 1.25oz each.

      Let me know if I can help you out.

      My email offline is 

      troy_newman at msn.com


      Regards,

      Troy
        ----- Original Message ----- 
        From: Nat Penton 
        To: discussion at nsrca.org 
        Sent: Tuesday, February 03, 2004 8:28 PM
        Subject: Servos


        I had two DS9411's coverted to SA . A gear , or gears, stripped in both with relatively no torque by hand. They could have easily crashed an airplane. Does  the stock SA have all plastic gears, or only one or two ? These were converted to all plastic.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.f3a.us/pipermail/nsrca-discussion/attachments/20040204/1f3378b5/attachment.html