So, you are asking about RMB (the datum feature material boundary modifier), not about RFS (for the mutually locating position tolerance specification).
ASME Y14.5-2018 states:
" 7.12.4 Pattern of Features of Size RMB
When RMB is applicable in a feature control frame to common datum features...
greenimi,
RFS would be interpretable.
In terms of the requirement it's two dia. 0.15 mm coaxial cylindrical tol. zones in which the two unrelated actual mating envelope axes must fit. In terms of the measurement It's two measured zones fitted over the two unrelated measured mating envelope axes.
mfgenggear,
Yes, I'm not sure why there is the basic dia. 39, maybe OP was thinking to control it with a general profile? Anyway I'd simply specify a larger direct tolerance as in my above suggestion in post #7 (+/-.xxx where .xxx is just loose enough to still not cause any trouble).
Limited length or area dimensions are a lot like datum target area dimensions. You don't control their variation on the part drawing that uses them, but that's also why you should specify them as basic ("theoretically exact") - you assume that they are exact and someone's job is to make sure...
greenimi,
A cylindricity tolerance zone, whether per unit length or full length, is always 2 coaxial cylinders.
Suppose a measured zone that is as long as the full length of the actual cylinder is best fitted over the actual 100 mm long cylinder and it should measure up to 0.4 mm. Then a 10 mm...
mfgenggear,
I think there could be a go gage fixture as 3DDave described: two recesses of diameter 20.53 and a saddle of diameter 23.1, following the sections and bends of the tubing. I suppose it's not a cheap fixture, but if enough parts are to be manufactured, it should be worth the...
As 3DDave mentioned, most of those requirements can be verified with a functional go gage.
That is because datum reference A(M)-B(M) is specified at MMB, and the positional tolerances referencing it apply at MMC.
If you delete the datum feature qualifying feature control frames, your datum features A and B will be left uncontrolled other than for size.
If you keep those controls, the datum features A and B are controlled relative to a datum reference frame with all 6 degrees of freedom locked, so their...
Why not establish a datum reference frame from datum features or datum targets and then apply simultaneous profile requirements to the left flat surface and to the right conical end of the hole. Also, a positional tolerance for the interrupted hole in the same DRF. Then do the tolerance stack to...
SEP REQT doesn't require two separate set ups, it just means that the unconstrained degrees of freedom in a single set up can be used to allow variation between the two features or patterns in a way that ignores their mutual basic location/orientation. One way to think of it is the act of moving...
mfgenggear,
Sorry, I'm not sure I follow. Possibly I wasn't clear enough with the question too.
I'd like the inspected profile to be based on both dimensions 35 basic and 105° basic, not just 105° basic which is leveled to horizontal condition by the sine bar set at 15° (or that would only be an...
mfgenggear,
One more question if possible:
How would you make sure that the location of datum axis A is repeatable for all measured parts, and independent on the variation allowed in the diameter of datum feature A (Dia. 20+/-0.05)? Note that in my illustration the axis location is approximately...
"All I wanted to accomplish with my question was to hear that an optimization would be needed..."
And it's good that you did 🙂
It's a good and important point.
pmarc, that's why I said "unless I'm missing something critical" :)
But speaking seriously, I think that the unconstrained degree of freedom makes it OK to optimize the rotation of the part around the datum axis for having the "best-fit" to a horizontal condition. Although on second thought, it...
