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  1. Viper555

    MMB calculation

    Would it be correct to say that only orientation controls (including location and profile) dictate the MMB calculation along with the size? If there are multiple tolerance controls to the higher order of precedence, would you just use the one that has the largest effect? For instance when...
  2. Viper555

    MMB calculation

    It's where I see examples with tertiary that gets me tripped up. I've also seen examples of just primary at MMB which yields the MMC. Does the MMB tertiary calculation affected by a feature that has secondary at MMB and same primary vs secondary RFB and same primary?
  3. Viper555

    MMB calculation

    I was hoping someone could help me with the MMB concept. I understand VC and RC, but the respecting datum precedence for MMB has me a little confused and I don't feel like the standard does a great job in explaining this. Scenario 1: Suppose you have a block with a call out of pin #1 with...
  4. Viper555

    RMB for width as tertiary

    Thanks for the helpful answers! It's just an example from a workbook.
  5. Viper555

    RMB for width as tertiary

    I'm having issues with a concept in particular that I was hoping someone could shed some light on (Y14.5-2009). Part in question: Slender bar with hole in center of larger face (through thickness) and one hole on each side mirrored about the center hole (on same face). Larger face is primary...
  6. Viper555

    Datum shift

    So if you are indeed shifting the part, then I guess I'm still confused. Before the shift scenario: The upper cylinder feature is produced exactly at MMC .45 away from the fixed Datum A and the lower cylinder is produced at LMC at true position. Shift scenario: The lower cylinder (and entire...
  7. Viper555

    Datum shift

    Ah. So it's just the feature that's shifting and not the entire part. Thanks!
  8. Viper555

    Datum shift

    I'm still not sure I understand the final measurements in that figure. Suppose that both cylinder features were produced at LMC and that the upper cylinder was at its maximum positional deviation of .45 from Datum A. Since Datum A is always fixed, wouldn't any radial shift of the part, and by...
  9. Viper555

    Datum shift

    Hello, I'm trying to understand an illustration which uses datum shift to show one possible "means this". I'm referring to Fig 7-58(c) in the 2009 standard. The illustration shows the VC for both cylinders, but it's the location of the three vertical lines relative to each other that I don't...
  10. Viper555

    Datum Modifier Effects - Planar Surface

    Wow! Thanks! I think it makes sense now. The conflicting illustrations between the revisions (and the bit talking about the extremeties was throwing me off). Just to make sure...you are saying that no matter what the scenario is, the entirety of Datum Feature B still must fall within the...
  11. Viper555

    Datum Modifier Effects - Planar Surface

    This is at the heart of what I don't understand. In reference to Fig 4-29(b), the last sentence of 4.16.2 states "Datum Feature B may rotate within the confines created by its departure from MMB and might not remain in contact with the datum feature simulator." The same verbiage is stated as...
  12. Viper555

    Datum Modifier Effects - Planar Surface

    Thank you Thank you for the assistance and yes I meant Fig 4-31 (a), (b), and (c). Not separate figures like in the 2018 revision. I'll try to clarify my question 3. Suppose that Datum Feature B comes in with perfect form and orientation at 4.9 in both illustration (b) and (c). What requires...
  13. Viper555

    Datum Modifier Effects - Planar Surface

    Hello, I have been studying for the GDT Senior level exam (2009) and I'm really struggling to wrap my head around a concept laid out and exemplified in Fig 4-31 through Fig 4-33 (equivalent is Fig 7-34 through Fig 7-37 in 2018 (Reaffirmed 2024)). The first example, Fig 4-31/Fig 7-34 makes...

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