Broken live center in lathe crash
Close
Login to Your Account
Results 1 to 8 of 8
  1. #1
    Join Date
    Dec 2011
    Country
    UNITED STATES
    State/Province
    Illinois
    Posts
    479
    Post Thanks / Like
    Likes (Given)
    117
    Likes (Received)
    151

    Default Broken live center in lathe crash

    We had a crash today that broke the shank of a MT4 live center. I was hoping to get some help figuring out what happened. It appears that the live center loosened up and was hanging out of the tailstock when the drill came in and smacked it. I just can't figure out how the live center could have loosened up. We've made probably thousands of parts since this center was put in the machine. There's a bolt used to eject the center from the Morse taper. I thought it might have loosened up and pushed the center out, but it's tight. The machine has been holding close tolerances without issue. If the center was even a little loose, I would have expected sizes to be moving around. I'm stumped on this one. Pics are below.

    img_0493.jpgimg_0494.jpgimg_0495.jpgimg_0497.jpgimg_0498.jpg

  2. Likes Ox liked this post
  3. #2
    Join Date
    Jan 2003
    Location
    Posts
    692
    Post Thanks / Like
    Likes (Given)
    172
    Likes (Received)
    237

    Default

    Morse tapers will do that sometimes. When you want them to come out they will stick like crazy. When you need them to stay put they tend to fall out, usually at worst possible time too.

  4. #3
    Join Date
    Dec 2011
    Country
    UNITED STATES
    State/Province
    Illinois
    Posts
    479
    Post Thanks / Like
    Likes (Given)
    117
    Likes (Received)
    151

    Default

    Quote Originally Posted by mmurray70 View Post
    Morse tapers will do that sometimes. When you want them to come out they will stick like crazy. When you need them to stay put they tend to fall out, usually at worst possible time too.
    Thanks. I had never seen it happen before, but I was afraid of that being the case. I had considered using some retaining compound to keep it from coming out. I don't think I could ever remove the center without heating it up, though. And I don't think I could heat it up without cooking the grease in the bearings.

    Surprisingly, the center still spins fine despite being nearly broken in half. Just stick it back in and run it, right?

    Also, props to Riten for giving me a discount on a replacement by sending my broken one back. Their trade-in program is a nice deal.

  5. #4
    Join Date
    Feb 2021
    Country
    UNITED STATES
    State/Province
    Pennsylvania
    Posts
    23
    Post Thanks / Like
    Likes (Given)
    11
    Likes (Received)
    5

    Default

    You better check your machine. That takes some serious force to break that in half like that.

  6. Likes Chris59, doug925, Fancuku, BT Fabrication liked this post
  7. #5
    Join Date
    Dec 2011
    Country
    UNITED STATES
    State/Province
    Illinois
    Posts
    479
    Post Thanks / Like
    Likes (Given)
    117
    Likes (Received)
    151

    Default

    Quote Originally Posted by vw_chuck View Post
    You better check your machine. That takes some serious force to break that in half like that.
    Yeah, I'm about to go do an alignment on the machine. I expect the turret and the tailstock to be have moved. Thankfully, the Morse taper socket where the center plugs in to doesn't show any signs of damage. That part must have been hardened.

  8. #6
    Join Date
    Jul 2006
    Location
    Hillsboro, New Hampshire
    Posts
    14,797
    Post Thanks / Like
    Likes (Given)
    3227
    Likes (Received)
    9873

    Default

    Quote Originally Posted by wmpy View Post
    Yeah, I'm about to go do an alignment on the machine. I expect the turret and the tailstock to be have moved. Thankfully, the Morse taper socket where the center plugs in to doesn't show any signs of damage. That part must have been hardened.
    What I'm wondering about is the fretting damage (or whatever that is) on the surface of the live center Morse taper. That alone might have been a cause (or result?) of a poor fit to the tailstock, and could have directly contributed to the loosening prior to the crash.

    Was that center used on other machines, or did it live in that specific lathe?

  9. #7
    Join Date
    Dec 2011
    Country
    UNITED STATES
    State/Province
    Illinois
    Posts
    479
    Post Thanks / Like
    Likes (Given)
    117
    Likes (Received)
    151

    Default

    Quote Originally Posted by Milland View Post
    What I'm wondering about is the fretting damage (or whatever that is) on the surface of the live center Morse taper. That alone might have been a cause (or result?) of a poor fit to the tailstock, and could have directly contributed to the loosening prior to the crash.

    Was that center used on other machines, or did it live in that specific lathe?
    I did notice the marks on the shank. They didn't look that bad to me. I wouldn't expect the shank to look pristine, so I don't know... I chalked it up to normal wear marks. You might be on to something. I'm just not sure how to investigate it further.

    The center was not used on any other machines, but we do take it out if we don't need it to avoid crashes.

  10. #8
    Join Date
    May 2020
    Country
    UNITED STATES
    State/Province
    Ohio
    Posts
    296
    Post Thanks / Like
    Likes (Given)
    199
    Likes (Received)
    197

    Default

    Check the Morse taper in the tailstock with another tool and Prussian blue to ensure it has full contact.

    A precision Morse taper master would be ideal but in the real world; anything in good shape should work.

  11. Likes wmpy, Dan from Oakland liked this post

Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •