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Thread: double start thread

  1. #1
    scott113 Guest

    Default double start thread

    machine is a hankook 9n running fanuc 21iTB CONTROL
    does anyone know of a parameter to change or any other way to set chuck rotation from zero to 180 degrees..
    i am trying to cut a 2 start thread on a 1"taper per foot(external pin thread) using G76 problem is that both starts must be on "Z" zero,
    any help woud be appreciated.

  2. #2
    Join Date
    Dec 2009
    Thanked 0 Times in 0 Posts

    Default Re: double start thread

    It sounds like your lead is off remember if I recall you need tomultiply your lead by number of starts. a 4start would be 90 degrees for every start 2 start would be 180. a 3/8-16 2 start would be .0625 x 2 .125 lead. try this I think it will work. be careful good luck let me know if this worked.

  3. #3
    Join Date
    Jul 2009
    Columbus, ohio
    Thanked 19 Times in 18 Posts

    Default Re: double start thread

    Quite a long time ago, in the days when Fanuc had the 10-11-15T controls, there was a method to specify the angle for multiple starts. I never liked it and always used this simplified method:
    Lets say you want a double lead thread of 10 TPI.
    The feedrate for a double lead is F.2.
    Start the 1st. thread at Z.3 and run the G76.
    Move to either Z.2 or Z.4 and run it again.
    It should put another thread exactly between the last threads.
    Good luck, I don't think I have a double lead example on my website below, the question comes up once in a while, I should probably put an example on there.

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