Announcement

Collapse
No announcement yet.

Change gear backlash

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Change gear backlash

    I haven't been happy with the backlash of the gears in the change gear group non my lathe. I have just been setting them by feel. I had a look around the net and found a method that sounded good to me to I gave it a try this morning. I went to the Boston Gear engineering information and found a chart of outline drawings for the different diametrical pitch sizes. By printing it off and comparing one of my change gears to the outlines the closest I could see was 16 D.P. so I took that and went to their backlash table which gave me a backlash of .003. Now from the method I found you take a piece of paper 1/2 that thickness and cut a strip to lay between the gears. 1.5 thou paper was a little hard to find but fortunately my wife is and artist and had some tracing paper that measured close to that dimension. I took a strip and worked through the gear train by running the strip between the gears, pushing down on the moveable gear then locking it up in that position. 1.5 thou on each side of the gear tooth should give you the 3 thou clearance. Then just roll it back and take the paper out. After I finished I ran the lathe up again and the gear train sounded a lot happier.
    Larry - west coast of Canada

  • #2
    The old guys I worked with years ago used a cigarette paper to do that with. Supposedly, a cigarette paper was 0.001" thick.----Brian
    Brian Rupnow
    Design engineer
    Barrie, Ontario, Canada

    Comment


    • #3
      Yes, I've used the cigarette paper method, it works well. These days though, I've been doing it so long, I just set them by feel.
      'It may not always be the best policy to do what is best technically, but those responsible for policy can never form a right judgement without knowledge of what is right technically' - 'Dutch' Kindelberger

      Comment


      • #4
        Do you thread in both directions in a single set up?

        If not lash has no effect.

        Comment


        • #5
          Originally posted by Bented View Post
          Do you thread in both directions in a single set up?

          If not lash has no effect.
          I wasn't worried about threading, more the gear noise. Because the drive gear is mounted on the hollow spindle it seem to amplify the gear noise through the spindle. Once I got the backlash correct it appears to be noticeably quieter.




          Larry - west coast of Canada

          Comment


          • #6
            Grease.. lots of grease..

            Comment


            • #7
              Just on a whim I sprayed the gears with motorcycle racing chain lube. Quieter, smoother- worked great.
              I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

              Comment


              • #8
                Atlas (yeah, I know) actually suggested the paper method in their version of "how to run a lathe".
                CNC machines only go through the motions.

                Ideas expressed may be mine, or from anyone else in the universe.
                Not responsible for clerical errors. Or those made by lay people either.
                Number formats and units may be chosen at random depending on what day it is.
                I reserve the right to use a number system with any integer base without prior notice.
                Generalizations are understood to be "often" true, but not true in every case.

                Comment


                • #9
                  Standard, household aluminum foil is very close to 0.0007" thick. And very uniform. Better specs than the shim stock assortment I purchased. So two thicknesses of aluminum foil will be just about 0.0014" thick. If that is not enough, add a third thickness.

                  And aluminum foil will not turn to mush when it is exposed to oil.



                  Originally posted by Cuttings View Post
                  I haven't been happy with the backlash of the gears in the change gear group non my lathe. I have just been setting them by feel. I had a look around the net and found a method that sounded good to me to I gave it a try this morning. I went to the Boston Gear engineering information and found a chart of outline drawings for the different diametrical pitch sizes. By printing it off and comparing one of my change gears to the outlines the closest I could see was 16 D.P. so I took that and went to their backlash table which gave me a backlash of .003. Now from the method I found you take a piece of paper 1/2 that thickness and cut a strip to lay between the gears. 1.5 thou paper was a little hard to find but fortunately my wife is and artist and had some tracing paper that measured close to that dimension. I took a strip and worked through the gear train by running the strip between the gears, pushing down on the moveable gear then locking it up in that position. 1.5 thou on each side of the gear tooth should give you the 3 thou clearance. Then just roll it back and take the paper out. After I finished I ran the lathe up again and the gear train sounded a lot happier.
                  Paul A.
                  SE Texas

                  And if you look REAL close at an analog signal,
                  You will find that it has discrete steps.

                  Comment


                  • #10
                    Originally posted by Cuttings View Post

                    I wasn't worried about threading, more the gear noise. Because the drive gear is mounted on the hollow spindle it seem to amplify the gear noise through the spindle. Once I got the backlash correct it appears to be noticeably quieter.
                    It's got to be easier on the gears as well.
                    in Toronto Ontario - where are you?

                    Comment


                    • #11
                      Good question. On my emco v 13 I just throw a piece of standerd printing paper between the gears. Seems to work fine.
                      But what I dont do is use oil on the gears. Or grease. I am worried swarf travelling along the spindle will drop on the gears. I cant see any notable wear on these gears. Am I doing it wrong.?

                      Comment


                      • #12
                        Nice going Brian, I remember my first lathe many years ago (Busy Bee 12x36) had change gears and after swapping them out the first time I inadvertently got them too close. I learned real quick how a few small gears can bind up a 1.5hp motor 😲
                        Ontario, Canada

                        Comment


                        • #13
                          I set change gears so that I can see or hear a clearance when they are meshed, by holding one gear and rotating the other back and forth. On a lathe it doesn't matter much at all except for the noise aspect but on my gear hobber I aim for the minimum of backlash or it will clatter a bit when cutting.
                          Peter - novice home machinist, modern motorcycle enthusiast.

                          Denford Viceroy 280 Synchro (11 x 24)
                          Herbert 0V adapted to R8 by 'Sir John'.
                          Monarch 10EE 1942

                          Comment


                          • #14
                            Hi Plunger. I have never in all my years seen swarf to be a problem In the back gears or the few times I have run a lathe with change gears. I would think that running them dry would be a lot worse for the gears then an occasional fleck of swarf. Just my opinion. On my SB heavy and Monarch they run a lot quieter if I keep them well lubed. That noise is coming from somewhere.

                            Comment


                            • #15
                              I just set a little backlash and give the gears a spin, if they are too tight, they tend to growl. I use the German Wurth HHS2000 thick spray synthetic oil on gears, leadscrews and mill ways now.
                              Plunger, if you use the gears a lot, you might try a little WD40 dry PTFE spray, it won't attract swarf.

                              Comment

                              Working...
                              X