Considering that Garland's assumption about the figure numbers is correct, I would add the following:
4.31 (b) and (c) work essentially the same way, except the fixed location of datum feature B simulator from datum axis A is at 5 mm (basic) for case (b) whereas it is 5.1 mm for case (c).
In...
There are ways, not implemented in the OP's image, to indicate that the entire hexagon shape is to be treated as a single geometric entity (feature or a pattern of features) to control and derive a datum from. The datum would be an axis and a plane, since the shape qualifies as a "linear...
A hexagon could be Irregular.
The irregularity could be per-design, at a level that is not visually detectable. Since there is a single dimension over flats without indication such as 3X, the definition is lacking.
The datum feature symbol is aligned with the .753+.000/-.002 width of the irregular hexagon. So, if this drawing is to be interpreted by any internationally known standard on dimensioning and tolerancing such as the ones by ASME or ISO, datum C is the center plane of this specific internal...
Question 4 - yes that position boundary in the right hand corner is the Virtual Condition boundary. The Resultant Condition envelope has the dimensions of the LMC of the cutout enlarged by 1.2 (profile tol. as a "bonus") +0.5 (stated position tol.) = 1.7 mm. For example, the vertical dimension...
Question 3 - had the feature been cylindrical, then the most similar scheme would be size (diameter) limits within +/-1.2 (not +/-0.6) and position within 0.5 at MMC (and not 0.25). Think of two opposed faces of the cutout each allowed to dislocate 0.6 mm from true profile either in opposite...
Regarding question no. 2 - no that would not attain the same goal. The second segment of profile within .85 U .85 would simply override the possible variation that the first segment would provide by the 1.2 mm wide tolerance zone. It would mean the total usable space for size, form, orientation...
Regarding question no. 1, I'd say MMB is a mistake and it should have been MMC. It is shown on the part of the figure that describes the profile control, which only limits the size and form of the opening. MMC is a size related term, while MMB takes into account also the location (and/or...
Why do you want to use any of these redundant standards?
Just apply the tolerances that will make it work.
What are the functional considerations?
Does the flat surface locate the part in the vertical direction or the hole? The one that does should be a datum feature of some order, probably not...
mfgenggear,
At free state you may still need to support or hold the part in some manner, by devices used as datum simulators, but not only.
Datum simulators could be a granite slab, angle block, v-block, centers, etc. However, you don't clamp to them by force at free state. If the part deformed...
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For example, if a hole is specified with a free state tolerance for perpendicularity, the tolerance would apply even if the hole deforms slightly due to a clamping force. "
This is wrong. If the tolerance is applied at free state, there must be no clamping forces or elastic deformation when...
The answer for you is the one you like better:
a) They do a half-assed job because they don't get paid for it.
b) Well, at least they don't get paid for that lousy job. Thank God!
But seriously speaking, If I'm not mistaken, the rule that a circularity FCF can't be attached to the dimension is new in 2018, while the figure is a carryover from previous versions.
If we go all the way with those speculations, maybe the purpose is to have the user scratching his head and doubting his understanding, until an ASME-affiliated training provider tells him there is an error in the standard? 🙂
I hope I'm not outside the context of your statement, but <CF> with plus minus size definitely works. That's fundamental, and there are as many as 3 figures in section 5 of Y14.5-2018 that show how it applies Rule #1 simultaneously to the FOS segments seperated by interruptions. It is also my...
Is it far from any sense of reason to say that a basic dimension that locates a surface for a profile control applies to the surface?
Yet we are not supposed to attach a profile FCF to any basic dimension, it should be attached or pointing to the surface or surfaces.
Perpendicularity...
They should've just written one clear, simple rule for the whole topic of placing feature control frames. I've seen drawings where position or profile FCF was attached to a basic locating dimension. The rule should have been straightforward: attach it to a dimension only when the tolerance zone...
