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  1. Belanger

    Y14.5 Drafting

    Studying for the Y14.5 certification exam would be an excellent way to learn or review some of those topics. People think that the test is all about GD&T, but the exam covers those early chapters where some of the things you're talking about are detailed. (Granted, it's based on the older 2009...
  2. Belanger

    Unilateral tolerances-why?

    Chris, just a small nit-pick... While I agree that the tolerance range is .145 - .150, the target value is not .150 (according to ASME Y14.5). In the standard, paragraph 4.1(q) says "UOS by a drawing/model note or reference to a separate document, the as-designed dimension value does not...
  3. Belanger

    Reference Point System

    I simply said I don't know offhand (without digging up the doc and finding a quote). It was in reference to your saying that "simultaneous requirement is not default in ISO." Since that's not the immediate topic, I just punted and said that we should assume my first sketch to be ASME...
  4. Belanger

    Reference Point System

    Greenimi, I don't know if that's true about ISO. Perhaps you're thinking about size dims, which don't serve as location (unless the modifier CT is shown). But to be safe, let's just say I meant the first pic to be ASME style. Pmarc, yes I purposely left off a secondary and tertiary datum to...
  5. Belanger

    Reference Point System

    A very interesting thread. I've seen CZ used is several capacities, but I never thought much about the perpendicularity application. Garland23, does the attached picture sum up your question? (Assume datum feature A is the main face, and TEDs would be given, etc.) John-Paul Belanger...
  6. Belanger

    Datums on thin part

    Most likely, a single datum isn't sufficient. As Burunduk suggested, you'd probably want to identify one of the large faces as the primary datum feature, and then yes, the current datum feature A (perhaps rename it as B) should be qualified to the large face with a perpendicularity control...
  7. Belanger

    Perpendicularity Stack-up

    The question pertained to the sketch that was provided. Datum B plays no role in that stack; it's all about how the two main faces interact with each other. John-Paul Belanger Certified Sr. GD&T Professional Geometric Learning Systems
  8. Belanger

    Perpendicularity Stack-up

    I was referring to the amount of leaning, but actually both. Notice that datum feature B is the left side. What would that have to do with stacking the parts in the manner shown? Nothing -- so the stack for leaning is really about parallelism. That's controlled by the perpendicularity...
  9. Belanger

    Perpendicularity Stack-up

    But... if the height tolerance (±y) is smaller than 0.02 total, then it would control the leaning-tower stack result, rather than the perpendicularity numbers (because that becomes an implicit parallelism control). John-Paul Belanger Certified Sr. GD&T Professional Geometric Learning Systems
  10. Belanger

    ASME promotional material on GD&T - does this look professional?

    I didn't watch the entire vid yet, but I notice a total runout tolerance with the MMC modifier. Ouch -- good luck with that. John-Paul Belanger Certified Sr. GD&T Professional Geometric Learning Systems
  11. Belanger

    The term Drill

    If you're asking about using that term as a specification on a drawing, the answer is that it's usually discouraged. According to the ASME Y14.5 standard: "The drawing should define a part without specifying manufacturing methods. Thus, only the diameter of a hole is given without indicating...
  12. Belanger

    Parallelism between coaxial cylinders?

    The options you propose all sound valid, but they will have significant differences. That's because parallelism is merely an orientation control; it doesn't control form (roundness/circularity/cylindricity). If you go with cylindricity, that's merely a form control (doesn't control parallelism...
  13. Belanger

    Inspection of keyway in bore

    It depends on whether the callout is the symmetry symbol or the position symbol (you used both terms). Also, it might depend on which tolerancing standard the drawing subscribes to (ASME or ISO). John-Paul Belanger Certified Sr. GD&T Professional Geometric Learning Systems
  14. Belanger

    Datum targets and their form and orientation errors controlled

    Greenimi -- yes, that certainly would apply (and Rule #1 would control form, if nothing else). But he might not even like the general profile idea, if he's that stuck on the notion that any tolerance on the surface is illegal! John-Paul Belanger Certified Sr. GD&T Professional Geometric...
  15. Belanger

    Datum targets and their form and orientation errors controlled

    If a part's function means that it's only being contacted at selected regions (thus the datum targets), then it's plausible that there need not be any explicit form or orientation tolerance to supplement those surfaces. But it's a HUGE stretch to say that an explicit form or orientation...
  16. Belanger

    Datum targets and their form and orientation errors controlled

    Greenimi -- even though the standard's graphic doesn't have size dimensions, Rule #1 would indeed control the flatness of that surface (assuming it's a rigid part). John-Paul Belanger Certified Sr. GD&T Professional Geometric Learning Systems
  17. Belanger

    Datum targets and their form and orientation errors controlled

    Let's go with his idea and take it to its extreme -- if the surface where A1, A2, and A3 are is not toleranced for flatness (because somehow it's "forbidden"), then what controls it from being crazy bumpy? Rule #1? Your colleague is simply making stuff up. If a regular-style datum surface can...
  18. Belanger

    Datum targets and their form and orientation errors controlled

    For your two questions for me... I would say it's not illegal. For Figure 4-42, it seems that B1 and B2 are on a very small surface that is toleranced by profile. Is that illegal? Or is it OK because it includes datum B in the callout? John-Paul Belanger Certified Sr. GD&T Professional...
  19. Belanger

    Datum targets and their form and orientation errors controlled

    I might say the burden is on him to prove things (why does lack of a picture equate with the standard forbidding something?). But here are two more thoughts: --Since the datum plane is created just from areas A1, A2, A3, a flatness tolerance on the overall surface is not doing much to the...
  20. Belanger

    Datum targets and their form and orientation errors controlled

    I was looking at 2018. In 2009 it would be Fig. 4-2. But my point is that if your colleague is fine with the figure I gave, why would having targets change things? John-Paul Belanger Certified Sr. GD&T Professional Geometric Learning Systems

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