DRF & Alignment Questions (Job Specific)

  • Filter
  • Time
  • Show
Clear All
new posts

  • DRF & Alignment Questions (Job Specific)


    Hi all,

    Never really come across an alignment like this, just had a few questions and wanted to seek some advice:

    Part set-up vertical, working in the Z plus workplace:

    • Primary datum a small cylinder constraining 2 translation, 2 rotation (Level Z+, then Translate to XY)

    • Secondary datum constraining remaining degrees of freedom so no tertiary required? How with a 2nd cylinder can I constrain translation/rotation of Z? Sample hits and trig a line for rotation between the cylinders?

    I'm working to ISO1101 as I'm UK based.

    Have a good weekend all

    Last edited by EdenG; 10-17-2020, 08:53 AM.

  • #2
    The datums shown do not constrain translation in Z and for the GD&T callouts shown, they do not need to. The only callouts I can see in your screenshot are concentricity of the Ø28.50/28.60 cylinder to datum A and concentricity of the Ø16.40/16.60, 45° cone to datum B. These are separate callouts that are completely independent from each other and from any of the other information shown on the print.
    Neil Challinor
    PC-DMIS Product Owner

    T: +44 870 446 2667 (Hexagon UK office)
    E: [email protected]


    • EdenG
      EdenG commented
      Editing a comment
      Hi Neil,

      Thanks for getting back to me. It seems I didn't interpret the drawing correctly at all, It kind of felt like an epiphany when I read your reply (I had a mindset that one datum had to follow another and all are connected). Based on what you've said, I can establish the part using features of greater size (Disregarding the DRF temporarily) and then treat A & B independently as local alignments?

    • neil.challinor
      neil.challinor commented
      Editing a comment
      Yes, that's correct.

Related Topics