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Proper drawbar torque?

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  • Proper drawbar torque?

    I saw a related thread on automatic draw bar closers and it brought up a question. What torque value should I be aiming for on a machine with a NT50 spindle? The drawbar is 1" x 8tpi, and the machine is a Kearney Trecker S-12 307, 7.5 hp spindle motor.

    In the couple of times I have mounted a tool I just went for what felt tight with the wrench I was using. If I had to quess I would say that is around 50 to 60 ft. lbs., maybe up to 75.
    James Kilroy

  • #2
    Now if I was faced with the situation your in .
    I would take off the automatic thingy put in a normal drawbar........put a torque wrench on drawbar......tighten to what you feel is right ..and noting the torque required to do this on your wrench.
    then it's just a matter of appliying this to your auto drawbar.......hope this maybe gives you different fresh aproach to the problem.......if it dont .well at least I tryed to help.
    all the best..mark


    • #3
      50-60 ftlbs should be fine,afterall it just holds the arbor in the drive keys take all the actual torque.
      I just need one more tool,just one!