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  1. AMontembeault

    Tapered Datums

    Y14.5 specifies the use of a conical taper as a datum candidate, arresting 5 degrees of freedom - 3 translational, 2 rotational. It makes me wonder, why couldn't the same apply to a wedge shaped, extruded feature - a dovetail, for example. Such a feature would also constrain 5 degrees of...
  2. AMontembeault

    Profile of contour

    I have a cylinder (actually a "pipe"), from which I establish datum "A" as the axis of the OD of the cylinder, datum B as an end of the cylinder, and datum C from a hole drilled into the side of the cylinder. On the OD of the cylinder, I have to machine a grooved contour, one that presents...
  3. AMontembeault

    Profile on a unit basis

    ASME Y14.5 - 2009 specified in section 8.3.3.2 that profile could be specified on a unit basis (as a note to the section). In the 2018 version of the standard, this reference has been omitted from the comparable section and there is seemingly no reference permitting profile on a unit basis...
  4. AMontembeault

    Multiple Single Segment Positional Tol and Datums

    Got a bit of an oddball question I have a series of different sized features for which it would be beneficial to control via multiple single segment positional tolerances. It has been proposed to turn one of those holes into a datum reference for controlling one or more other holes, also with a...
  5. AMontembeault

    Assembly level dimensioning

    Having a bit of a philosophical debate at work, and I was curious what a broader community might think. ASME Y14.5-2018 Section 4.1 (p) states "Dimensions and tolerances apply only at the drawing level where they are specified. A dimension specified for a given feature on one level of drawing...
  6. AMontembeault

    Thin Datum Surfaces

    I have a sheet metal part, which is more or less square, with a bilaterally symmetric, sinusoidal contour cut on one side. I set my primary datum "A" at the large planar surface of the part, secondary datum "B" as the midplane of the part, and tertiary datum "C" as the edge opposite my contour...
  7. AMontembeault

    Datum Translation application

    Can a datum translation modifier be used when the datum is a planar surface? I can't see anything in the standard which seems to explicitly prohibit this, but every example out there I can find typically only demonstrates this concept using a datum derived from a feature of size (typically a...
  8. AMontembeault

    Surface Profile and Size

    I'm looking at a series of prints which detail a round feature of size, controlled by a datum-less surface profile. My question is, should the diameter be basic, or limit toleranced? My inclination is that it should not be basic - that a datum-less surface profile is just a form control (in...
  9. AMontembeault

    Profile without Datum reference

    Referencing this thread: https://www.eng-tips.com/viewthread.cfm?qid=314750 It was discussed that a surface profile without a datum would essentially just be a form control on a singular surface. However, based on that discussion, I believe, based on the context of those discussions, that's...
  10. AMontembeault

    GD&T for small features/non-features

    I have a number of parts for which vendors supply scribe lines on surfaces, used for the purposes of alignment at the assembly level. These scribe lines are typically called out as having a maximum depth and width, but could be produced with no discernable dimensions (for example, a scribe line...
  11. AMontembeault

    Design Best Practices - Rolled Cylinder

    I have a rolled, right cylinder, approximately a meter in diameter (inside) and 1.5 meters in length,with a wall thickness of about half an inch. The problems with dimensioning this are: 1) its not really rigid in the free state 2) To constrain it adequately, on a mandrel, for example, would...
  12. AMontembeault

    GD&T Interpretation - Perpendicularity and Limits of Size

    I reccently had to check a drawing of a right cylinder, with a length tolerance of +/-1 and a perpendicularity requirement on each flat end of 1.5 with respect to the axis (Datum A). I rejected the drawing, on the basis that if each end has 1.5 perpendicularity at the same time, then rule 1 is...
  13. AMontembeault

    Fastener/Hardware Specifications - ISO

    We're looking at revamping our methods of controlling hardware in our CAD modeling and drafting processes. As we're going through this effort, we've been digging into the relevant standards (typically DIN, Iso, etc.) to understand tolerances, naming conventions, and so on. Reccently, when...
  14. AMontembeault

    Application of Scale

    Hello everyone There seems to be some confusion in our design/drafting department regarding the application of scale in drawings. We know that its generally not a good practice to take a detail view from a section view, however, due to the nature of our product, its often the cleanest and...
  15. AMontembeault

    Surface Profile Between 2 pts.

    I have a part drawing which is nominally symmetric about 2 planes, which we might think of as 4 quadrants. I would like to use a surface profile tolerance between 2 points (call them A and B) in one of these quadrants - not exactly rocket science. Now, my question is, because this part is...
  16. AMontembeault

    Standards help

    I remember, waaay back in the day when I was first learning how to draw, my instructor defined how borders needed to be drawn - specifically how far from the edge of the sheet (something like 8mm if I recall correctly). I also seem to recall that inside the border, views, dimensions...
  17. AMontembeault

    Quantity callouts

    Hello, I was wondering if some of you all might be able to clairify or perhaps share some "best practices" with respect to calling out quantities on engineering drawings when it comes to features (lets say holes) in a pattern. Here is the confusion: In the GD+T standard, sections 1.9.5 and...
  18. AMontembeault

    Surface Profile with respect to datum

    Good Morning There is some confusion in our design department regarding the interpretation of using surface profile w.r.t. a datum as it may (or may not) control size/orientation/location. Numerous reference materials we've pulled up have all said some flavor of "Surface must be at true...
  19. AMontembeault

    Common Datums

    We're having a bit of a debate here at work. Suppose I had a piece of plate with 2 holes in it. Each hole is specified as a datum (in this case, datums B and C, where datum A is the large flat face of the plate). I have another feature with a positional tolerance with respect to A and a common...

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