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16 x 1.5 MM and the Atlas lathe

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  • 16 x 1.5 MM and the Atlas lathe

    I have a few projects on hold because I need to single point some 16 x 1.5 MM threads. While my primary lathe is an elegant old gal, a 14.5 inch Monarch, along the way I have managed to pick up and a hand full of Atlas lathes. The problem is that I don’t have the transposing gear set that is needed for Metric pitches for any of them. Atlas lathe 3, a nice little 6 x 18, is the only one that came with a full factory gear set and a Manual. I have heard for years that the Atlas will do metric, but of course any lathe can do metric with the correct gearing. As I said, I had looked through the gear set and definitely no transposing gears.
    Haunted by my dilemma, I did the unthinkable, I looked at the manual. On the last page of the threading chapter it stated that, while the lathe would not cut true Metric threads with the supplied gear set, it would come damn close and it even had a chart for the close counts, wanabee, Metric threads. I re geared the lathe and checked the pitch. I got a pitch error of .0001 inch per thread or .001inch accumulative error over 10 threads, Outstanding! And to think that I have only been using Atlas lathes since my first job, some 44 years ago.
    With any luck at all, this information will be helpful to someone.
    No excuses now, the threads came out perfect.
    Have a good one, Mike
    Last edited by mf205i; 11-10-2017, 01:53 PM.

  • #2

    Now you've added another reason to complete my Atlas refurbish. It's been on hold since my wife became ill, but she's improving now and I'm starting to get some shop time.

    More tools than sense.


    • #3
      The South Bend 9A standard quickchange can not do any pitches close the the standard metric ones.

      I have the 'poor man's" conversion for it which is a 63:64 tooth compound gear.

      This does not give perfect ratios for metric pitches,
      however the main pitches I need {0.5, 0.75, 1.0, 1.5, 2.0} are all within 7 micrometre
      and most within 5 micrometre (0.0002 inch)
      I have made a few metric threads mainly for cameras and they work OK.

      Here is a screenshot of a spreadsheet I made for the 9A gearbox with the 63:64 in the train.


      • #4
        It is amazing how close you can get with a consumer grade lathe. Even the ubiquitous 7x10 lathes get very close. shows the 1.5mm pitch can be cut as 1.501 mm, 0.061% error, with an error of 0.009 mm over 10 threads.

        At the end of the project, there is a profound difference between spare parts and left over parts.

        Location: SF East Bay.


        • #5
          I think I did 1.5mm pitch threads on my Atlas 618 for my ER25 collet chuck. I think I just used what someone else online had used, then ages after someone else pointed out that they're in the manual I think some metric pitches need a 3rd gear on the banjo, but I'm not 100% sure if that's correct and if so which.


          • #6
            For some strange reason I have a full set of change gears for a 9" South Bend including a 100/127 tooth transposition gear even though both of my lathes have a quick change gear box. So far I haven't needed to single point cut a metric thread.
            Location: Saskatoon, Saskatchewan, Canada


            • #7
              I have the print outs for gearing up the atlas for 1.0, 1.25, 1.5, and 1.75mm thread pitches by my lathe. I did the conversion from change gear to qcgb on my atlas so I had the complete set of change gears which came in handy.


              • #8
                How long are the threads, and how precision. .
                Cuz I am thinking 16 tpi may work.... not perfect , but may work.


                • #9
                  Anyone have a link to a chart or cheat sheet? My manual doesn't cover metric threads. Thanks--Mike.


                  • #10
                    So many years ago I don't know the link. It isn't so much a chart but a drawing of what change gears to switch to while using a qcgb to get metric.


                    • #11
                      Try here



                      • #12
                        Here is a video too setting up change gears for metric.

                        There are 17 videos in this series on the ATLAS/CRAFTSMAN 12" Lathe. Be sure and watch them all. Tips #220 thru #239


                        • #13
                          If you have a android phone, the appstore has a few decent changewheel calculation apps. You put in what gears you actually own (and the ratio's on the leadscrew gearbox if you have one) initially during setup into the one I found, then every time put in the pitch you want, and it chews through and comes out with a drivetrain position for each one, and what the final error in pitch will be.
                          I've got a cheap android fire tablet screwed the wall for music in the shop, so I just installed it on that.