The world of model and hobby engineering

Subscribe

The Modelling Hub Logo

The world of model and hobby engineering

Subscribe
Buy Latest Issue

Forums

Help

Register

Log in

Gear Cutting Problem

Advert
New Replies
Report Bug
Help/FAQs

Gear Cutting Problem

Home › Forums › General Questions › Gear Cutting Problem

Viewing 5 posts - 1 through 5 (of 5 total)
  • Author
    Posts
  • 26 February 2025 at 05:58 #785898
    Alan Charleston
    Participant
      @alancharleston78882

      Hi,

      I have a problem with a gear train I am building. The part causing the problem consists of 4 gears, A, B, C and D. Gear A meshes with gear B which is screwed to gear C which then meshes with gear D which is on the same shaft as gear A.

      Gear A is specified as 22 teeth, gear B as 106 teeth, gear C as 56 teeth and gear D as 73 teeth. All the gears are module 1.0. The problem is that the total number of teeth in gears A & B is 128 while C & B are129. This means that either gears A & B are barely meshing or gears C & D lock up.

      If I made gears A & B to be module 1.008, the sum of the pcds of gears A & B would be 129mm, the same as gears C & D.

      My question is, can I use a module 1.0 gear cutter to cut a module 1.008 gear? I can’t imagine the gear form would be too much different.

      Regards,

      Alan C.

      Advert
      26 February 2025 at 07:28 #785916
      JasonB
      Moderator
        @jasonb

        It will depend slightly on the application – loads and speeds but provided you do it to both gears in the pair it should not be a problem. I might be inclined to make the 56/73 pair a bit smaller, as they are not at the extreams of the cutter ranges they change in spec of the two will be similar.

        I’ve used 32DP cutters to cut gears sized to MOD 0.8 which is a similar fiddle and they did what I wanted.

        26 February 2025 at 07:41 #785921
        Diogenes
        Participant
          @diogenes

          ‘Technically you shouldn’t but practically you probably can’ – falling into the same category as ‘fiddling’ the full depths / OD’s to achieve the engagements / clearances you need – which more-or-less results in the same thing.

          A couple of ‘prototypes’ and your inner monitor will tell you whether the idea has legs or not..

           

          26 February 2025 at 08:27 #785937
          HOWARDT
          Participant
            @howardt

            Reduce the pcd rather than increase to achieve to required centres. Reducing gives a better tooth form, do not reduce by more than half a the module on the pcd.  I design gear trains on a daily basis for thirty years of my working life, mostly simple spur gears and never increased a pcd.

            26 February 2025 at 11:13 #786021
            John Haine
            Participant
              @johnhaine32865

              Depending on the tooth form and application…

              I made a clock train where I achieved what you want to do by using different moduli on two pairs of gears.  However the gears were profiled out by CNC from dxf files generated by this web page:

              https://hessmer.org/gears/CycloidalGearBuilder.html

              …where you can specify what module you want for each gear pair.

            • Author
              Posts
            Viewing 5 posts - 1 through 5 (of 5 total)
            • Please log in to reply to this topic. Registering is free and easy using the links on the menu at the top of this page.

            Latest Replies
            Report Bug
            Code of Conduct
            Help & FAQs
            Advert

            Latest Replies

            Home › Forums › General Questions › Topics

            Viewing 25 topics - 1 through 25 (of 25 total)
            Viewing 25 topics - 1 through 25 (of 25 total)

            View full reply list.

            Advert

            Latest Issues

            Subscribe
            Buy Latest/Back Issues

            Newsletter Sign-up

            Latest Replies