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  1. AndrewTT

    Help! Can't find English term for GD&T concept.

    At my company we have the part drawing and sometimes there is an accompanying drawing that we call the "process print". The process print can have different dimensions/notes than the part print. The process print dimensions/notes are based around measurements that can be taken quickly...
  2. AndrewTT

    Would this valid callout bother you

    We use FDMP with MMC bonus tolerance all the time on "flat" shaped parts stamped from coil stock. It allows for a "pass-through" gage to be employed to check the flatness of the part. It fits our design intent and works great for us. My rash usually stems from the note "no burrs allowed".
  3. AndrewTT

    MMB / LMB sizes

    (2009) 4.11.6.3 - Clarifying Applicable MMB - In cases where the boundary is not clear, or another boundary is desired, the value of the boundary shall be stated, enclosed in brackets, following the applicable datum feature reference and any modifier in the feature control frame. 2018 covers...
  4. AndrewTT

    implementing/enforcing a different drawing standard

    My experience in implementing ASME Y14.5-2009 at my company. 1) I second what The Tick states about passive resistance. Get ready. 2) Watch out for people who claim they already understand the standard because we "used GD&T at my old job". If they are not certified or have not read the...
  5. AndrewTT

    Rule #1 envelope question

    Rule #1 (ASME) requires perfect form at MMC for Regular Features of Size. It does not required perfect orientation or perfect location. A RFOS can have perfect form and still be less than perfect for its orientation and/or location.
  6. AndrewTT

    Moveable Datum Target Question

    Along with using the new moveable datum target symbol, figure 4-47 from 2009 added a 2X basic 45° and a basic 9 dimension when compared to figure 4-38 from the 1994 standard. Otherwise, these two figures are identical. I have seen at least one GD&T author show their interpretation of a fixture...
  7. AndrewTT

    material selection for load bearing screw (compression)

    Thanks EdStainless. Would passivation with Citric acid also be acceptable?
  8. AndrewTT

    material selection for load bearing screw (compression)

    I have a compression screw that has a conical tip that terminates in a spherical radius. In assembly the tip of this screw sits in a very shallow dimple. The assemble must pass many tests but the two I am here to discuss are a 30-day salt fog exposure (20% by weight sodium chloride) and a...
  9. AndrewTT

    Does this use of multiple datum features make sense?

    For what it is worth, a reputable company once published the attached as an approach to defining a similar part (per ASME Y14.5-1994). https://files.engineering.com/getfile.aspx?folder=3f4a21f9-51f5-445c-a7c9-a6f06977d8d4&file=similar_part_per_ASME_Y145-1994.pdf
  10. AndrewTT

    GD&T Datums from two Holes

    EDIT - Sorry, just noticed that you are using ISO and not ASME. I am not very familiar with ISO but maybe some of the below still applies. for standard compliance: The perpendicularity FCF is missing a dia. symbol in front of the zero tolerance value. for clarity: Add the all around symbol to...
  11. AndrewTT

    Datum on angular slab centerline

    If you use Profile to describe the non-parallel surfaces you open the door to using MMB modifier on that datum in subsequent FCFs. I'm not sure is this is answering the OP's second question or not.
  12. AndrewTT

    Position tolerance of a sphere with respect to Taper datum feature axis

    How can you verify if the position of the sphere is correct if you don't know where its true position is? You will need a basic dimension from the datum point that is generated from the datum feature A cone. If you stick with positioning the sphere feature you will need to add an "S" in front...
  13. AndrewTT

    Tricky Datum Reference Frame

    Does the stock material have a standard governing its form? If not you may be underdefined for the form of datum feature A.
  14. AndrewTT

    Datums Features Symmetrical part

    If you employ the same datums, in the same order, with the same boundary conditions for all of your profile FCFs the rule of simultaneous requirements will allow you to avoid the use of a clocking datum feature (section 4.19 ASME Y14.5-2009). If you are following ASME Y14.5 for this part there...
  15. AndrewTT

    Similarity of LMB (Least Material Boundary)

    The below is written with respect to the ASME standard (ASME Y14.5). If you are just starting to study GD&T then I recommend you make it a priority to understand the terms and their definitions, as written in the standard. Learn the difference between LMB and LMC, and the difference between...
  16. AndrewTT

    How To Dimensioning Internal Features of a Shaft

    ASME Y14.5-2009 Section 1.4 Fundamental Rules Fundamental Rule (g) : Dimensions should be arranged to provide required information for optimum readability. Dimensions should be shown in true profile views and refer to visible outlines.
  17. AndrewTT

    MMB Calculation - Special Case

    ASME Y14.5-2009 4.11.6.3 - Clarifying Applicable MMB In cases where the boundary is not clear, or another boundary is desired, the value of the boundary SHALL be stated, enclosed in brackets, following the applicable datum feature reference and any modifier in the feature control frame. I think...
  18. AndrewTT

    Controlled Spherical Radius (ASME Y14.5 2009, 2018)

    Thanks for the input everyone. I agree that the CR and proposed CSR have their own issues. I am putting together a list of options for defining a critical feature. CSR is going to be one of them ...... followed immediately by "do no recommend", lol. feature: hemispherical concave feature...
  19. AndrewTT

    Controlled Spherical Radius (ASME Y14.5 2009, 2018)

    Does anyone have a reason why a controlled spherical radius could not be invoked as an extension of principles (extension of the principle of a controlled radius)? Thank you.
  20. AndrewTT

    ISO 13715-2019 - figures 21 & 22

    ISO 13715-2019 Edges of Undefined Shape - Indication and Dimensioning What does "t=3" signify in figures 21 & 22? If there is language in the 13715 standard pertaining to it, then I am entirely missing it. Is this a symbol that is described in a different ISO standard? Thank you very much...

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