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  • Lathe speed

    I am building an overhead drive system for my 1930 9" lathe. I thought I read somewhere that the proper speed for the countershaft with the step pullys should be around 300 rpm. I have mine setup with a 2 1/2" motor pully driveing a 12" countershaft pully. The motor is 1725rpm reversable capacitor start single phase and should give about 340rpm by my calculations. As I get a little further along I will have some pictures.

    Skip

  • #2
    I thought about doing that at one point, as a way of isolating the motor and countershaft vibration from the lathe. I'll be interested to see your pictures.
    ----------
    Try to make a living, not a killing. -- Utah Phillips
    Don't believe everything you know. -- Bumper sticker
    Everybody is ignorant, only on different subjects. -- Will Rogers
    There are lots of people who mistake their imagination for their memory. - Josh Billings
    Law of Logical Argument - Anything is possible if you don't know what you are talking about.
    Don't own anything you have to feed or paint. - Hood River Blackie

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    • #3
      Originally posted by skipd1
      I am building an overhead drive system for my 1930 9" lathe. I thought I read somewhere that the proper speed for the countershaft with the step pullys should be around 300 rpm. I have mine setup with a 2 1/2" motor pully driveing a 12" countershaft pully. The motor is 1725rpm reversable capacitor start single phase and should give about 340rpm by my calculations. As I get a little further along I will have some pictures.

      Skip
      Actually I didn't really word my thread correctly as I am asking is this speed is correct??? Or what is the correct speed for the countershaft??

      Skip

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      • #4
        I think your looking at this from the wrong direction.
        What is the the lowest and highest speed range you want your lathe to operate at ?
        Use that to determine the pulley size & desired rpm of your ceiling mounted countershaft at the lathe end,
        And then use that to determine the pulley sizes at the Jackshaft/ motor end.
        Machinery's Handbook States that the maximum speed for a flat belt drive to be 6000 fpm, so you need to stay below that, If it were me, I'd shoot for about 1/2 that or less.
        I cut it twice, and it's still too short!
        Scott

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        • #5
          Even more to the point, what is the highest speed the lathe is designed to run at? My 10K with essentially the same bearing technology has a top speed of 1475 rpm.
          Lowest speed with backgear etc. is 60 rpm.
          ----------
          Try to make a living, not a killing. -- Utah Phillips
          Don't believe everything you know. -- Bumper sticker
          Everybody is ignorant, only on different subjects. -- Will Rogers
          There are lots of people who mistake their imagination for their memory. - Josh Billings
          Law of Logical Argument - Anything is possible if you don't know what you are talking about.
          Don't own anything you have to feed or paint. - Hood River Blackie

          Comment


          • #6
            Don't know if this info will be of use to you...

            I converted my late 1930s 10" Sheldon from horizontal to a home brewed overhead version [sorry, no pics posted yet] and isolated motor from lathe as much as possible. Bronze "shell" bearings.

            Stock was 2.5" to 10" pulley (at the counter shaft), with a 1725 rpm motor this yields 431 rpm of the shaft.
            When the two cone pulleys are taken into account, the speeds became 819 rpm, 431 rpm, 226 rpm [4.75" and 2.5"; 3.5" and 3.5"; 4.75" and 2.5"].
            Once refurbed I took slightly more exact measurements, of what I hope is the "effective" diameter of the initial train pulleys, those are 2.75" and 9.75" [the 10" original is still in use but more accurate measurement gets to 9.75"]
            This means speeds become 924 rpm, 486 rpm, 255 rpm.

            I can't give exact speeds in back gear now...that's part of the plan towards completion for tomorrow

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