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True position of... length?

Erikir
I have a round slot, 17 mm from edge of radius to edge of radius and 4mm wide.

My drawing says
17 +/- 0.3
|TP|0.5 MMC |A|B|C| (length)
Boundary

4+/- 0.3
|TP|0.2 MMC |A|B|C| (width)
Boundary

How do I report that?
  • I create two separate dimensions and only report out the axis of the feature. I have a few two way locators that have similar callouts.
  • I create two separate dimensions and only report out the axis of the feature. I have a few two way locators that have similar callouts.
    This way you are only reporting center point of the slot. What "Boundary" part is trying to cover is rotation of the oblong slot around its axis.
    Lets say this slot is located at nominal, but rotated 45 deg. about center. You would show good results on report, but you wouldn't be able to assemble it to mating part.
    I used to report both ends of the slot as circle for both TP's, so 4 dimensions total. Or you could report inside boundary profile of the surface (which is harder to explain to your costumer)
    Inside boundary of this slot is 17mm-0.3mm-0.5mm=16.2mm X 4mm-0.3mm-0.2mm=3.5mm and it may not be violated by the surface of the slot

    From Tec-Ease BOUNDARY
  • This way you are only reporting center point of the slot. What "Boundary" part is trying to cover is rotation of the oblong slot around its axis.
    Lets say this slot is located at nominal, but rotated 45 deg. about center. You would show good results on report, but you wouldn't be able to assemble it to mating part.
    I used to report both ends of the slot as circle for both TP's, so 4 dimensions total. Or you could report inside boundary profile of the surface (which is harder to explain to your costumer)
    Inside boundary of this slot is 17mm-0.3mm-0.5mm=16.2mm X 4mm-0.3mm-0.2mm=3.5mm and it may not be violated by the surface of the slot

    From Tec-Ease BOUNDARY

    I face this same kind of problem ALL THE TIME! Engineers wanting true position of a distance. I finally got one of them convinced to use a profile call out. Quite frustrating when the only thing you can do given that kind of call in a FCF is to report position of a midpoint. Not what they want at all.
  • I use that method as that is what is asked for. In my particular example, these are reported back to my main (car) alignment. As for beign out of rotation, that would be caught when this is used for an sub-alignment for other features. I wouldn't pass these features to the new datum structure utilizing this slot if it was out of location. In addition, I have a hard gage for this alignment, which was part of my launch verification (gage studies & cmm verification).
  • I use that method as that is what is asked for. In my particular example, these are reported back to my main (car) alignment. As for beign out of rotation, that would be caught when this is used for an sub-alignment for other features. I wouldn't pass these features to the new datum structure utilizing this slot if it was out of location. In addition, I have a hard gage for this alignment, which was part of my launch verification (gage studies & cmm verification).

    On your report what do you report for BOUNDARY?
  • You should use the vector of the slot as tolerance zone for the TP. Depending on how the leader lines are connecting to the slot, they also depict the tolerance zone for you to use (at least thats the way it's done in ISO-land). Often these leader lines are connected either parallell or perpendicular to the slot, meaning that the direction of the slot tells you the direction of the tolerance zone. Extra important when there is a TP in one axis (non-Ø tolerance zone).
  • On your report what do you report for BOUNDARY?

    In my case, we are assemblers. Our sister plants create our stampings. Boundry was covered during the stamping phase, spent many hours reviewing dimensionals related to this product. (Large product, 90+parts to assemble a rear frame for a GM vehicle). GM supplies their own large stampings (yeah our customer is also our supplier Disappointed ). I wanna go work for them as all the data I ever get from them is a scan of the part that is best fit, not the gd&t assigned datums. GM hasn't questioned my PPAP sumbissions in the 3 years I have been here.
  • You should use the vector of the slot as tolerance zone for the TP. Depending on how the leader lines are connecting to the slot, they also depict the tolerance zone for you to use (at least thats the way it's done in ISO-land). Often these leader lines are connected either parallell or perpendicular to the slot, meaning that the direction of the slot tells you the direction of the tolerance zone. Extra important when there is a TP in one axis (non-Ø tolerance zone).

    Same here in ASME land. Problem is word Boundary under FCF, which controls inside boundary of the slot (profile) but they want it reported as TP. Thats why I reported each end of the slot and not centroid of the slot. See link for Tec-Ease in my post
  • I create two separate dimensions and only report out the axis of the feature. I have a few two way locators that have similar callouts.

    +1
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