Lathe Taper when boring/turning - Page 2
Close
Login to Your Account
Page 2 of 2 FirstFirst 12
Results 21 to 28 of 28
  1. #21
    Join Date
    Feb 2004
    Location
    peekskill, NY
    Posts
    24,687
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    4717

    Default

    I'm suprised that nobody's chimed in yet with the standard three solutions:

    1) buy an expensive test bar.

    2) buy an expensive starret super-duper level, and

    3) use a laser to align it!

  2. #22
    Join Date
    Sep 2018
    Country
    ALAND ISLANDS
    Posts
    65
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    22

    Default

    In all likelihood the headstock isn't aligned with the ways.

    To check you don't need a proper indicating rod, we're looking for a tough measurement here. Hold a reasonably straight piece of stock in your Chuck and put a indicator in your toolholder. If there is runout at the point you're indicating at, spin the chuck by hand and take the average of your measured runout.

    You will want to check for misalignment in the horizontal and vertical direction as both can cause taper. If you can find the error, we can be much more helpful in correcting it.

    Sent from my Pixel 2 using Tapatalk

  3. #23
    Join Date
    Sep 2018
    Country
    ALAND ISLANDS
    Posts
    65
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    22

    Default

    Quote Originally Posted by Jim Kobe View Post
    Tell me, how in the hell can you bore a hole between centers?
    Stay in your lane

    Sent from my Pixel 2 using Tapatalk

  4. #24
    Join Date
    Sep 2018
    Country
    ALAND ISLANDS
    Posts
    65
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    22

    Default

    Read this:

    https://www.google.com/url?sa=t&sour...l8vWjaDrzjtqgy

    Sent from my Pixel 2 using Tapatalk

  5. #25
    Join Date
    Sep 2011
    Country
    UNITED STATES
    State/Province
    Virginia
    Posts
    28,788
    Post Thanks / Like
    Likes (Given)
    7561
    Likes (Received)
    8936

    Default

    Quote Originally Posted by jim rozen View Post
    I'm suprised that nobody's chimed in yet with the standard three solutions:

    1) buy an expensive test bar.

    2) buy an expensive starret super-duper level, and

    3) use a laser to align it!
    *yawn* or even better levels, three test bars, not one, lasers, and even three Davison D600 differential collimators with proper mirrors and even the optical "wedges" to calibrate them, Mahr Millimess and Hamilton DI's graduated in millionths, not just half-tenths?

    Guilty as charged.

    OTOH, I have a sneaking suspcion that I'm dealing with higher-grade machine tools that pay-back such insanely anal attention to detail ....and the OP has-never.

    Any experience hand wuddua simply groked the cause in matter of a minute or three, corrected what could be quickly corrected, compensated for what could not, got the effing job DONE arredy.

    That's why they call us "experienced machinists" rather than "all-beef hot dogs".


  6. Likes tdmidget liked this post
  7. #26
    Join Date
    Sep 2018
    Country
    ALAND ISLANDS
    Posts
    65
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    22

    Default

    Quote Originally Posted by thermite View Post
    OTOH, I have a sneaking suspcion that I'm dealing with higher-grade machine tools that pay-back such insanely anal attention to detail ....and the OP has-never.
    Within reason, good work can be done on a machine that isn't perfect. It just takes more time. Like everything: good, fast, cheap, pick two.

    Sent from my Pixel 2 using Tapatalk

  8. #27
    Join Date
    Sep 2009
    Location
    barcelona, spain
    Posts
    2,436
    Post Thanks / Like
    Likes (Given)
    549
    Likes (Received)
    1453

    Default

    My guess is the saddle is turning in the horizontal plane.

    Due to wear and looseness on the V ways, the saddle twists a bit, horizontally, when turning towards the chuck, but does not when turning away from the chuck.
    Adjusting the gibs on the z axis should reduce the problem, a lot.

    It is also possible that you cannot totally eliminate the problem, quite, because tight gibs in the center that are just right will bind at z-- and z++ ends.

  9. #28
    Join Date
    Jan 2008
    Location
    McKenney, Va
    Posts
    706
    Post Thanks / Like
    Likes (Given)
    152
    Likes (Received)
    69

    Default

    Probably something only a rocket scientist can figure out. Like maybe a burr on one side of the tailstock center taper letting it rock one direction and be in line the other. Maybe not a burr, a corona virus bugger or a ciip in the bore.

    For me it's always something stupid like that. Good luck with it. Check the simple things first.

    Ben

    The centering bolt on the back side, or front of the tailstock might not be tight...maybe
    Last edited by lazarus; 03-13-2020 at 01:56 AM. Reason: just another thought


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
  •