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Thread: Use of the Hardinge TT Tapping Head??

  1. #1
    Join Date
    Aug 2006
    Location
    Harrisburg, PA
    Posts
    445

    Question Use of the Hardinge TT Tapping Head??

    Hello,

    I just bought a Hardinge TT Tapping head and have been having a problem. (The lathe is a Hardinge DSM 59.) I can tap the hole fairly well, however, I have to stop the machine, grab ahold of the part of the tapping head that spins, turn the spindle backwards by hand, in order to get the tap to start backing out. After a few turns, I can back it out under power.

    I think I am doing something wrong. Does anybody have any instructions, can point me to some instructions, or can tell me how to properly use this thing? (I have already searched this forum...and may have missed the thread, if it exists.)

    Thanks,

    Brian
    There are only 10 types of people in the world: Those who understand binary and those who don't.

  2. #2

    Default

    is the ratchet set for the right rotation of the spindle. you should be able to reverse the spindle and the tap will back out. to change the ratchet take the unit out of lathe and there is a screw in the end of the shank undo the screw and the collet holder assy. comes out the front clean and oil the assy. flip the little dog around to go the way you want and put it back together. Ken

  3. #3
    Join Date
    Jan 2003
    Posts
    2,901

    Default

    I've used those and others for years. They all work pretty much the same.

    Feed the tap in under power. When the turret hits it's pre-set depth stop the tap will self feed a bit, then the tap should spin freely with the part. The drive dog in the head has been dis-engaged at this point.

    Reverse the lathe spindle. Almost instantly the drive dog in the head for unscrewing the trap will engage and the tap feeds out.

    A couple thoughts on your problem....

    Some heads have to be mounted right-side up because the dogs are gravity acting. Don't remember if the Hardinge is.

    The Hardinge heads have a spring that gets damaged. Unscrew the bolt showing on the inside of the back end of the shank to see if the spring is scrunched up. The springs are available from Hardinge, I've had to replace a couple. Once the head is apart you'll get a better idea of how it works.

    WARNING: take the head apart slowly/carefully in a clean environment. There are some tiny springs under the driving dogs that are easily lost. In fact, it's possible one of those is missing which could be causing your problem.

    Another common thing to look for, not related to your problem, is a little pin that engages the tap collet. The back of the collets have two slots. The little pin in the collet seat engages one of those slots so the collet can't spin in it's mount. If someone inserts and tightens the collet nut without the pin in the collet slot, the pin gets pushed back. This is something you won't even know about until you notice you can't tighten the nut enough to stop the collet from turning in the body. It's simple to push the pin back where it should be. You'll see what I mean when you have the head apart.

  4. #4
    Join Date
    Aug 2006
    Location
    Harrisburg, PA
    Posts
    445

    Default Fixed and working!

    Hello,

    Thanks for all of the input. The tapping head was missing the ratchet pawl spring. I shortened an old pen spring and used that and it works perfectly.

    Regards,

    Brian
    There are only 10 types of people in the world: Those who understand binary and those who don't.

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