Results 1 to 6 of 6

Thread: Slot with Basic location and size tolerance but no Positional

  1. #1
    New Member
    Join Date
    Apr 2023
    Posts
    2

    Slot with Basic location and size tolerance but no Positional

    In the sample image is the slot fully constrained in both directions? We have multiple and differing opinions depending on whether we talk about the vertical or horizontal direction. (Datum A is not shown but is the large flat mutually perpendicular face). If it is what are the extremes of geometry that it allows?
    Image corrupt
    Please excuse my use of powerpoint as CAD software!
    Last edited by Kelly_Bramble; 04-20-2023 at 04:48 PM.

  2. #2
    Technical Fellow Kelly_Bramble's Avatar
    Join Date
    Feb 2011
    Location
    Bold Springs, GA
    Posts
    2,609
    You need to reattach image - it was corrupt
    Last edited by Kelly_Bramble; 04-20-2023 at 07:31 PM.
    Tell me and I forget. Teach me and I remember. Involve me and I learn.

  3. #3
    New Member
    Join Date
    Apr 2023
    Posts
    2
    Reposting the image. Hopefully not as corrupt.
    gdt.png

  4. #4
    Technical Fellow Kelly_Bramble's Avatar
    Join Date
    Feb 2011
    Location
    Bold Springs, GA
    Posts
    2,609
    1) Circle P is Projection Tolerance Zone, there should be a Position or orientation geometric characteristic in the first horizontal frame. So, the specification is nonsensical as it is presented.

    2) the 10 +/- 0.8 is a size control

    3) the 30 +/- 2 is a size control

    4) Assuming that the intended geometric tolerance is position (in place of the circle P), and the feature control frame associated with the oblong hole is attached to the 30 +/-2 size dimension the location of that feature is only controlled/specified left and right or horizontally. Measurements would made and the derived center plane from the radius's would need be as-manufactured within two tolerance planes separated 1.2 and oriented vertical and symmetrical about the 40.2 basic dimension.

    See ASME Y14.5-2018, Figure 10-35 and associated paragraphs for an example and detail overview of the "Boundary concept".
    Tell me and I forget. Teach me and I remember. Involve me and I learn.

  5. #5
    The drawing is not the best but basically yes, it's fully defined. Well, I at least understand what they're getting at. The slots position can get larger in proportion to how much larger the slot size moves away from MMC. Also, if the overall length and width of the part gets smaller you can shift the part around within whatever the remaining tolerance allows to try and get the slots position to fall within tolerance.

  6. #6
    Associate Engineer
    Join Date
    Jan 2024
    Posts
    5
    Here is a resource to how to use GD&T to define a slot:

    slots-precision-location-Article.pdf
    Last edited by Kelly_Bramble; 01-04-2024 at 05:16 PM.

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •