Concentricity vs. Runout - Page 2
Close
Login to Your Account
Page 2 of 2 FirstFirst 12
Results 21 to 25 of 25
  1. #21
    Join Date
    Feb 2016
    Country
    UNITED STATES
    State/Province
    Washington
    Posts
    89
    Post Thanks / Like
    Likes (Given)
    240
    Likes (Received)
    53

    Default

    Quote Originally Posted by JNieman View Post
    If you only meant for the hexagon to illustrate how concentricity can be perfect while form is horrible (like it was /supposed/ to be a cylinder but you ended up with a hexagon for hypothetical reasons) then sure, you've got it spot on.
    This is what I was going for. I was mainly expanding off Halco's comment earlier.

  2. #22
    Join Date
    Mar 2012
    Location
    Southern Wisconsin
    Posts
    539
    Post Thanks / Like
    Likes (Given)
    70
    Likes (Received)
    176

    Default

    Concentricity is an absolute term, runout is a relative term.

  3. #23
    Join Date
    Mar 2015
    Country
    UNITED STATES
    State/Province
    Pennsylvania
    Posts
    7
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    1

    Default

    Quote Originally Posted by Halcohead View Post
    There are important differences between runout, total runout, and concentricity:

    Concentricity is how well a shape is centered on a theoretical axis, regardless of roundness. So a hexagon can theoretically be perfectly concentric to a datum axis while having huge runout due to the fact that it isn't round.

    This is technically incorrect. Concentric is a geometric term, not a machining term. "Cone Centric" means circles made by slicing a cone with planes perpendicular to a line running through the focus, thus making circles with the same focus, but differing diameters.

    A hexagon cannot be a cone, only a six sided pyramid, so therefore cannot be concentric.

  4. #24
    Join Date
    Aug 2011
    Location
    Tampa Bay, FL
    Posts
    14
    Post Thanks / Like
    Likes (Given)
    1
    Likes (Received)
    2

    Default

    Quote Originally Posted by genther View Post
    This is technically incorrect. Concentric is a geometric term, not a machining term. "Cone Centric" means circles made by slicing a cone with planes perpendicular to a line running through the focus, thus making circles with the same focus, but differing diameters.

    A hexagon cannot be a cone, only a six sided pyramid, so therefore cannot be concentric.
    How about I add the term coaxial. Isn't this the same thing as concentric?

  5. #25
    Join Date
    Nov 2011
    Location
    Missouri, USA
    Posts
    2,782
    Post Thanks / Like
    Likes (Given)
    1353
    Likes (Received)
    2710

    Default

    Quote Originally Posted by genther View Post
    A hexagon cannot be a cone, only a six sided pyramid, so therefore cannot be concentric.
    7.6.4 Concentricity
    Concentricity is that condition where the median
    points of all diametrically opposed elements of a
    surface of revolution (or the median points of correspondingly
    located elements of two or more radially
    disposed features) are congruent with a datum axis (or
    center point).
    "Surface of Revolution" means you're technically correct. However, the hexagonal example given previously was a purely hypothetical deviation from a circular shape. It's just showing how a control on form and location can differ. Nominally it should've been circular. The hexagon was an exaggerated example of deviation-of-form.

    Examples of other exaggerated form variations can be Figures 7-60 and 7-61 in the 2009 standard.

  6. Likes J Gilles 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
  •