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  1. B

    Perpendicularity callout with curved datum

    Although your advice was directed to the original post, I extrapolated it as: Define appropriate datum A for the hole perpendicularity condition. Add datum B, C to fully constrain that part & support Dtm A. This Dtm A could be a datum target as suggested, but can also be another surface from...
  2. B

    Perpendicularity callout with curved datum

    Thanks everyone for the discussion & comments. It looks like there are some "trade-off's" for each solution. I think these 2 may work a) Using Position to control the hole, and also controlling R10 to similar datums. (3DDave). b) and Pmarc's suggestion. 🙏
  3. B

    Perpendicularity callout with curved datum

    Actually yes, this part is fixed from the curved surface, and this surface is allowed some free play, then a bolt goes thru the hole. Hence this perpendicularity relationship.
  4. B

    Perpendicularity callout with curved datum

    Someone else created this and I'm trying to improve/correct it. "Have fun figuring out where this axis is in your inspection lab." - it's because I was having too much 'fun' figuring this that I thought it was abnormal.
  5. B

    Perpendicularity callout with curved datum

    I re-created this drawing for illustration purposes. All the flat sides/surfaces are actually not flat (so cannot be used as datums). The intention is for dia4 hole to be perpendicular to curved surface (R10). But is this FCF correct? (whether by ASME or ISO) If Datum A was re-defined as a...
  6. B

    How to convert linear dimensions to GD&T

    Thanks for your feedback & confirmation. Will check about the center cut end mill idea. Using drop indicator will be convenient.
  7. B

    How to convert linear dimensions to GD&T

    Dimension 25 indicates the depth of the pin, so this method reflects it (slightly indirectly). The remaining wall is important, but more difficult to measure. Hence dim 25 was created as an indirect way to control.
  8. B

    How to convert linear dimensions to GD&T

    Sorry for my laziness :D, refer below for measurement setup. This checks Go & No go (i.e. pin height must be within the step). This only checks Go. Stepped ring looks something like this (copied from internet):
  9. B

    How to convert linear dimensions to GD&T

    Thanks for the input. I've answered about the spot face in my reply to 3D Dave. I agree that using theoretical dimensions to specify a part is not ideal, so I'm trying to see how i can change it. We have many parts in similar conditions; but because we also design the appropriate gauge...
  10. B

    How to convert linear dimensions to GD&T

    3DDave, thats a lot of questions, I'll try to clarify: What does the mating pin/rivet do? Primarily it allows the mating part (of dim 18) to swivel. If the mating part has a flange, why isn't there a spotface to properly stop it? This rivet has a knurled surface at one end for interference...
  11. B

    How to convert linear dimensions to GD&T

    Thanks for the suggestion. Profile of surface can be applied to Left flat profile, but for right conical end, I don't know how to measure it. Its difficult for CMM probe to access. Current similar parts are being measured with a combination of gauges & pins (method is easy but has a small stack...
  12. B

    How to convert linear dimensions to GD&T

    3DDave Thanks for the alternative ideas, i'll see how to use it. I've been wondering for some time how to apply FCF to theoretical intersections. There was a similar topic here long ago, but was finally resolved using Position spec.
  13. B

    How to convert linear dimensions to GD&T

    I'm on ISO, but I've found ASME to be quite similar on surface. This part shown is actually a section of a larger part. Basically this part connects to another part which will swivel around the rivet. Dim 18 is important to ensure clearance, dim 25 is to ensure sufficient depth yet not too deep...
  14. B

    How to convert linear dimensions to GD&T

    Hi all, I have 2 dimensions which I hope to change to GD&T control. In the dwg represented below, dim 18 is meant to control the minimum width excluding root radius. Another part will fit in here. (a) I'm thinking this can be controlled by Profile of surface (with unequal tol). Please advise...
  15. B

    Can I omit Basic dimensions?

    We use JT-PDF which requires JT2Go viewer. This can measure 3D features very roughly. (can measure point to point, but not plane to plane). It is really meant for general purpose usage. For detailed purposes, user needs a dedicated 3D software. It can also display adjustable cross sections. For...
  16. B

    Can I omit Basic dimensions?

    As I mentioned, I will have geometric controls for key features. The main idea was to omit what I thought was unused basic dimensions.
  17. B

    Can I omit Basic dimensions?

    Haha, this is my experience as well, using JT-PDF as our format. But we are trying to push it through regardless. I think our push is mainly based on positive MBD reports from (US) aerospace & automotive industries. Just how much "value" MBD can create vs "cost up" is probably the big question.
  18. B

    Can I omit Basic dimensions?

    It is a parametric model, and I have mostly GD&T spec's to define/control critical profiles. For these GD&T spec's e.g. True Position, there will be accompanying basic dimensions, which I will show (because True Position requires the basic dimensions for CMM measurement). However for others like...
  19. B

    Can I omit Basic dimensions?

    Thanks everyone for the input, you've helped to give a clearer picture. Sorry for the confusing terms, as we are transitioning from 2D to MBD, we still use "drawing" & "MBD" interchangeably. (actually we say 3DA instead of MBD). 3DDave: You are right about recipient of MBD, unfortunately they...
  20. B

    Can I omit Basic dimensions?

    Hi, the MBD shows non-general tolerances for specified profiles. E.g. Diameters, linear dimensions, but mostly GD&T spec's. Thanks, I think 5.1.1.2 (b) will be useful for me.

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