Rack and Pinion Gear sets for scale modeling?

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  • wlambing
    SubCommittee Member
    • Feb 2003
    • 842

    Rack and Pinion Gear sets for scale modeling?

    Well, now I'm looking for a source for a teenie-tiny rack and pinion set up, suitable for use in only 3/16" of space. The smallest control horn I have still will not clear the hull side and pivot the rudder stock (1/16" brass rod). I could cut a slot in the hull, or manufacture "blisters" for each side with a slot underneath for horn arm clearance, but that would destroy the fine lines of this racy looking subject. She's one of the RPM Tech 1/72 Foxtrot hulls, and a production hull that seems to differ greatly from the one HWSNBN built in some areas. Can anyone share a source for really small rack and pinion sets? Such info could be of benefit to us all for actuating little features. TIA.

    Bill

    PS- I did look at the Servo R&P Bob Martin has, and it is too big also.
  • scott t
    Member
    • Feb 2003
    • 879

    #2
    Would LEGO rack and pinion work?
    Click image for larger version  Name:	s-l500.jpg Views:	0 Size:	28.6 KB ID:	148866

    I also thought about using a zip tie for the rack.

    Click image for larger version

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    Last edited by scott t; 07-22-2022, 04:34 PM.

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    • wlambing
      SubCommittee Member
      • Feb 2003
      • 842

      #3
      Scott,

      Thanks for the thought, but Lego looks to be way too big, though the rack could maybe run down the side. Do you have any dimension info??

      Take care,

      Bill

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      • feet wet
        Member
        • Mar 2003
        • 210

        #4
        Bill,
        I had some small racks, but they were1/8" square, whcih with the gear, would not fit your needs. I remember Loran Prry doing some great stuff, many years ago, with watch gears. You might consider that route. MicroMark sells them by the batch, but your local watch man would probably give you a load for lot's less. Anothor option ight be to try a linear servo and a short arm.
        Jonathan

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        • crueby
          Member
          • May 2015
          • 323

          #5
          Or a cable wrapped around a small pulley, another pulley back where the hull is wider so it could take a normal crank arm.

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          • feet wet
            Member
            • Mar 2003
            • 210

            #6
            "Or a cable wrapped around a small pulley, another pulley back where the hull is wider so it could take a normal crank arm." Great Idea. Take it one step further and use a toothed belt...or an O-ring.

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            • wlambing
              SubCommittee Member
              • Feb 2003
              • 842

              #7
              Thanks for ideas, guys! I'll keep digging around until I can find something. Not so easy to find things that are in the sizes we use! Like really small pulleys!

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              • cheapsub
                Member
                • Feb 2011
                • 196

                #8
                Have you look in to these type of servo ?

                Wishiot Tiny 1.5g servo Micro Linear Digital Servo Lightweight Mini Size for Indoor Aircraft Small RC Plane (Pack of 4) https://a.co/d/4Dw2Axt

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                • wlambing
                  SubCommittee Member
                  • Feb 2003
                  • 842

                  #9
                  Thank you, but I have the servo end of things covered. The problem is at the rudder stock bellcrank/control horn pivot point. Way back in the stern.

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                  • m. munger
                    SubCommittee Member
                    • Feb 2003
                    • 71

                    #10
                    Curtis Lee made the rudders in his tiny Trumpeter Alfa work, very well. I believe he used a couple loops of thin brass rod (offset and perpendicular) to the tiny wheel collar he made to fit to the shaft. Gotta be pictures around here somewhere....

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                    • wlambing
                      SubCommittee Member
                      • Feb 2003
                      • 842

                      #11
                      Matt,

                      You have given me an idea: convert 2, 1/16" wheel collars into a small pullies. Add support as necessary for the driver and rig from there until it works. Thanks!!! I have many o-rings to chose from for use as a belt.
                      l'll let you guys know how I fare! It will be a while yet, as I'm currently engaged in cleaning out 30 MBT flood ports in another hull.

                      Take care,
                      Bill

                      Comment

                      • wlambing
                        SubCommittee Member
                        • Feb 2003
                        • 842

                        #12
                        I found some small plastic gears amongst the materials from Bob Harris' estate. I'm back in the game! A package of 75 assorted gears and pulleys, source unknown. Maybe Micro-Mark? Coulda been Amazon, too. Found a good pinion and with have to modify the rack piece, but it'll work and more importantly, actually fit!!! Yayyyyyyyyyyy!

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