lathe drilled hole not concentric - Page 2
Close
Login to Your Account
Page 2 of 2 FirstFirst 12
Results 21 to 35 of 35
  1. #21
    Join Date
    Aug 2002
    Location
    West Unity, Ohio
    Posts
    25,097
    Post Thanks / Like
    Likes (Given)
    5345
    Likes (Received)
    7841

    Default

    Quote Originally Posted by Delw View Post
    ^^^^
    This

    but i'd be more concerned on how he is checking it. I am guessing Calipers
    I can tell the diff between .432 and .438 with a calipers.
    ABS value not a concern.
    Calipers could have .010 worn tips and been dropped 2 yrs ago and be .025 off.
    As long as they repeat good, we are looking for a differential value. (Incr?)


    Crickey - Robert snucked in there ....


    -------------------------

    Think Snow Eh!
    Ox

  2. Likes Bobw liked this post
  3. #22
    Join Date
    Jan 2019
    Country
    UNITED STATES
    State/Province
    Arizona
    Posts
    553
    Post Thanks / Like
    Likes (Given)
    39
    Likes (Received)
    190

    Default

    Quote Originally Posted by Bobw View Post
    What is wrong with calipers to make sure he is within .010" of center, so that the part works.

    Are you one of those people that build a fixture for everything and refuse to use a vise?
    Nothing wrong with calipers I never said that. he is checking less than .010

    it pretty hard to use a vise on a Lathe

    as far as fixtures and vise's this is a lathe part he chucked it in a chuck and spun it.
    I think I would be checking with a V-block and a indicator to see what the runout is, but then again thats just me

  4. #23
    Join Date
    Jan 2019
    Country
    UNITED STATES
    State/Province
    Arizona
    Posts
    553
    Post Thanks / Like
    Likes (Given)
    39
    Likes (Received)
    190

    Default

    Quote Originally Posted by Ox View Post
    I can tell the diff between .432 and .438 with a calipers.
    ABS value not a concern.
    Calipers could have .010 worn tips and been dropped 2 yrs ago and be .025 off.
    As long as they repeat good, we are looking for a differential value. (Incr?)


    Crickey - Robert snucked in there ....


    -------------------------

    Think Snow Eh!
    Ox
    I agree with that

  5. Likes Ox liked this post
  6. #24
    Join Date
    Dec 2008
    Country
    UNITED STATES
    State/Province
    New York
    Posts
    10,037
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    2610

    Default

    many machines need either a mechanical alignment adjustment
    or a electronic grid shift adjustment (cause distance from zero return has changed)
    .
    some places check parts and if a problem calibrate or align machine
    other places check monthly
    other places check daily
    .
    i have seen many a cnc lathe or mill needing adjustment. for some its a maintenance people do it and for other shops the operators do it first and if for some reason they have a problem then they call maintenance. sometimes the adjustment is explained in the maintenance manuals and not the operator manuals
    .
    saw where a M0 was added to a program to check a part at a spot where part often failed inspection. then operator often saw the problem quickly rather than part go to inspection and find out days or weeks later.
    .
    kind of a weakness with mazak conversational in sure you can add a M0 but not so easy to leave a comment in the program. some use a desktop computer with a setup sheet procedure or work instruction and there the M0 is explained what for
    .
    i have seen many a part on a cnc lathe where the hole in center of part is not on center. its actually a fairly common error. amounts can vary. even with soft jaws just bored if chuck dirty you also get random chucking error or chucking runout on top of machine alignment errors from the rest of machine. obviously if thin walled part and your chucking pressure too high you can squeeze part triangular distortion and when unchucked you can see or measure the triangular distortion if 3 jaw part. chucking pressure distortion obviously more a problem with tight tolerance thin walled parts
    .
    i have also seen where machine grid shift adjusted to .0002" and when zero return or homing done grid shift was off again.
    .
    when machine repeatability not happening often its a call maintenance thing. it could be something worn out mechanically or a electronic scale or encoder is dirty (coolant or oil is common). a sign you got a problem is when grid shift is adjusted more than one or two increments. after all why would you need more than a fine adjustment.

  7. #25
    Join Date
    Jan 2006
    Country
    UNITED STATES
    State/Province
    New York
    Posts
    1,597
    Post Thanks / Like
    Likes (Given)
    681
    Likes (Received)
    781

    Default

    It's a frikin hole in the center of a turned part.

    spot drill, then drill. problem solved (and the op got all the the info he needed to get him going in the right direction)

    summa you guys really know how to beat a dead horse.

    man, how do you guys deal with "real" problems
    Last edited by chip_maker; 08-11-2019 at 12:55 PM.

  8. Likes mc3608, Derek Smalls liked this post
  9. #26
    Join Date
    Feb 2005
    Location
    Hatch, NM Chile capital of the WORLD
    Posts
    9,018
    Post Thanks / Like
    Likes (Given)
    13662
    Likes (Received)
    10663

    Default

    Quote Originally Posted by chip_maker View Post

    man, how do you guys deal with "real" problems
    alcohol...

  10. #27
    Join Date
    Jan 2006
    Country
    UNITED STATES
    State/Province
    New York
    Posts
    1,597
    Post Thanks / Like
    Likes (Given)
    681
    Likes (Received)
    781

    Default

    Quote Originally Posted by Bobw View Post
    alcohol...
    That's one way lathe drilled hole not concentric.

    Sent from my SM-G930V using Tapatalk

  11. #28
    Join Date
    May 2008
    Country
    UNITED STATES
    State/Province
    Minnesota
    Posts
    684
    Post Thanks / Like
    Likes (Given)
    352
    Likes (Received)
    232

    Default

    I got a chance to work on this again this morning. Put in a 120 degree 1/4" shank solid carbide spot drill and that is ending up perfectly on size and perfectly (for as well as I can measure) concentric.

    My initial reason for trying to avoid spotting is that I only have room for a single drilling tool available in the setup. So now I am going to be spending some money with Maritool for a few more tool holders and will have to change tools to do the second half of the part.

    Thanks guys.

  12. Likes chip_maker, Ox, Mtndew, malkey liked this post
  13. #29
    Join Date
    Sep 2011
    Country
    UNITED STATES
    State/Province
    Virginia
    Posts
    26,222
    Post Thanks / Like
    Likes (Given)
    7561
    Likes (Received)
    8257

    Default

    Quote Originally Posted by Ox View Post
    Seen a fella at Booger King last night that had a "Fighting Machinists" T-shirt on.
    I asked him about it.... ???

    Seems it'a all about inter termoil.
    CNC crowd got skimmers for rebicycling that.

    Tee-shirt about fightin' may indicate he's gettin' holes off-center, anyway. To-home, if not also on the job.

    Lot 'o that going "around" lately, just not on concentric askis-ease.


  14. #30
    Join Date
    Oct 2007
    Country
    SPAIN
    Posts
    3,208
    Post Thanks / Like
    Likes (Given)
    1706
    Likes (Received)
    1132

    Default

    You say it's repeatable and more "out" left to right.
    Which would assume the x axis?
    So clock your drill, or move your x shift by half the amount it's out?

  15. #31
    Join Date
    Jan 2014
    Location
    Coventry RI
    Posts
    1,132
    Post Thanks / Like
    Likes (Given)
    1359
    Likes (Received)
    897

    Default

    Quote Originally Posted by barbter View Post
    You say it's repeatable and more "out" left to right.
    Which would assume the x axis?
    So clock your drill, or move your x shift by half the amount it's out?
    The part is round, and spinning in a lathe chuck. Exactly which side is the "left"?

    Someone tried to explain this early on in this thread, but it fell on mostly deaf ears it seems. When measuring position error between two round features, the error can always be expressed as being in only one axis, or any combination of x and y you want, just rotate the part! That's why it's typically thought of as runout and expressed as TIR, not position error, but, what ever floats your boat I guess.

  16. #32
    Join Date
    Jan 2006
    Country
    UNITED STATES
    State/Province
    New York
    Posts
    1,597
    Post Thanks / Like
    Likes (Given)
    681
    Likes (Received)
    781

    Default

    Quote Originally Posted by barbter View Post
    You say it's repeatable and more "out" left to right.
    Which would assume the x axis?
    So clock your drill, or move your x shift by half the amount it's out?


    Quote Originally Posted by Derek Smalls View Post
    The part is round, and spinning in a lathe chuck. Exactly which side is the "left"?

    Someone tried to explain this early on in this thread, but it fell on mostly deaf ears it seems. When measuring position error between two round features, the error can always be expressed as being in only one axis, or any combination of x and y you want, just rotate the part! That's why it's typically thought of as runout and expressed as TIR, not position error, but, what ever floats your boat I guess.
    I'm thinking that was an expert level troll right there.

  17. Likes barbter, Ox liked this post
  18. #33
    Join Date
    Sep 2011
    Country
    UNITED STATES
    State/Province
    Virginia
    Posts
    26,222
    Post Thanks / Like
    Likes (Given)
    7561
    Likes (Received)
    8257

    Default

    Quote Originally Posted by chip_maker View Post
    I'm thinking that was an expert level troll right there.
    Aye. Termoil will float a boat,

  19. #34
    Join Date
    Jun 2012
    Location
    Michigan
    Posts
    4,603
    Post Thanks / Like
    Likes (Given)
    4210
    Likes (Received)
    2768

    Default

    Pop in a center drill and go .01" - .03" deep. Just enough to put a tiny spot for the drill.
    Then drill the part and tell us the concentricity.

  20. #35
    Join Date
    Nov 2014
    Country
    UNITED STATES
    State/Province
    Florida
    Posts
    3,444
    Post Thanks / Like
    Likes (Given)
    1483
    Likes (Received)
    1627

    Default

    Post #28 says he has fixed the problem.. Not sure what the additional comments are for (except this one LoL)

  21. Likes Mtndew, Matt_Maguire, Ox 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
  •