OT- small diameter turning
Close
Login to Your Account
Results 1 to 10 of 10
  1. #1
    Join Date
    Nov 2014
    Country
    UNITED STATES
    State/Province
    Florida
    Posts
    6,185
    Post Thanks / Like
    Likes (Given)
    2451
    Likes (Received)
    3074

    Default OT- small diameter turning

    I just asked our manual lathe guy if he could turn a piece of 1/2 hard brass .012" dia x .13 long. He said "yep, no problem, done them before" !!

    Anyone else doing turning that small?

  2. #2
    Join Date
    Feb 2014
    Location
    FL
    Posts
    4,194
    Post Thanks / Like
    Likes (Given)
    13436
    Likes (Received)
    5001

    Default

    Quote Originally Posted by Mike1974 View Post
    I just asked our manual lathe guy if he could turn a piece of 1/2 hard brass .012" dia x .13 long. He said "yep, no problem, done them before" !!

    Anyone else doing turning that small?
    With no tolerance on straightness, roundness, or diameter, sure I can make it.

  3. Likes Bobw, Straightedge, Bill in PA liked this post
  4. #3
    Join Date
    May 2019
    Country
    UNITED STATES
    State/Province
    Michigan
    Posts
    2,522
    Post Thanks / Like
    Likes (Given)
    1403
    Likes (Received)
    1920

    Default

    Quote Originally Posted by TeachMePlease View Post
    With no tolerance on straightness, roundness, or diameter, sure I can make it.
    With a belt sander..??


  5. #4
    Join Date
    May 2017
    Country
    FINLAND
    Posts
    2,450
    Post Thanks / Like
    Likes (Given)
    663
    Likes (Received)
    1144

    Default

    Quote Originally Posted by Mike1974 View Post
    I just asked our manual lathe guy if he could turn a piece of 1/2 hard brass .012" dia x .13 long. He said "yep, no problem, done them before" !!

    Anyone else doing turning that small?
    0.012" ?
    Ha, that qualifies as a bar stock

    This was about 14 micrometers or 0.00055 inches in diameter:


    Any smaller than that and you need damn electron microscope to set the tool center height

    rest of the thread if someone is interested: Digital microscope for lathe work

  6. Likes DrHook, jz79, sfriedberg liked this post
  7. #5
    Join Date
    Feb 2006
    Country
    UNITED STATES
    State/Province
    Indiana
    Posts
    13,812
    Post Thanks / Like
    Likes (Given)
    792
    Likes (Received)
    4579

    Default

    Any watch repair person, the kind that can make balance staffs, not just replace batteries, can turn and polish hardened steel to around .005 inch diameter. Smaller diameters would seldom be needed, but I never did a ladies' wrist watch staff, so I don't know their dimensions.

    The trick is to have a good lathe that turns at high speed. A Hardinge lathe with a 5C spindle and 3500-4000 RPM can do surprisingly small work. Hardinge makes 5C collets with stock size order holes as small as 0.016", 1/64" or 0.5 mm. But watch lathes are much smaller and faster and watch lathe collets are made with order holes as small as 0.1 mm.

    Turning brass to .012" x .13" is a trivial job for a watch lathe with a slide rest. I will explain that most watchmakers never use a slide rest because most watch work can be done with hand-held tools faster and maybe even better.

    Larry

  8. #6
    Join Date
    May 2019
    Country
    UNITED STATES
    State/Province
    Michigan
    Posts
    2,522
    Post Thanks / Like
    Likes (Given)
    1403
    Likes (Received)
    1920

    Default

    I calculated the RPM needed to run that part at 1000 sfm.

    314,000...!!

  9. #7
    Join Date
    Mar 2001
    Location
    Switzerland
    Posts
    2,710
    Post Thanks / Like
    Likes (Given)
    3024
    Likes (Received)
    1266

    Default

    I routinely do balance staffs for very small high end watches, length around 2.2mm is common (.087"), sometimes as short as 1.6mm (.063"), pivots on those are typically .065mm or .0026". 2 pivots, one at each end, largest diameter on the part would be 1.5mm typically with about 4 other diameters and a critical taper.

    That's in steel, would be tricky to do in brass but .012" in brass a piece of cake.

  10. Likes L Vanice liked this post
  11. #8
    Join Date
    Nov 2003
    Country
    UNITED STATES
    State/Province
    Texas
    Posts
    5,862
    Post Thanks / Like
    Likes (Given)
    208
    Likes (Received)
    2010

    Default

    And that is why smaller lathes, with higher spindle speeds, are generally used for such work. In my shop I would use my Unimat instead of my SB.

    But then, I consider such calculations as guidelines, not rigid dictates.



    Quote Originally Posted by ChipSplitter View Post
    I calculated the RPM needed to run that part at 1000 sfm.

    314,000...!!

  12. #9
    Join Date
    Feb 2004
    Location
    peekskill, NY
    Posts
    26,686
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    6089

    Default

    Heck I can do that job with my harding 5/9 lathe. Key is to start with 1/4 inch stock and take it all off with one whack.
    Dead sharp tool, too.

  13. Likes JST liked this post
  14. #10
    Join Date
    Feb 2004
    Location
    peekskill, NY
    Posts
    26,686
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    6089

    Default

    OK I cheated a bit, I used the antique lathe for this, also I screwed up and made it
    too long. Have to get a heavy duty set of cutters to short it to 0.130 inch long.
    Attached Thumbnails Attached Thumbnails small_brass_2.jpg   small_brass_1.jpg   small_brass_3.jpg  

  15. Likes old_dave, TeachMePlease 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
  •