Figure 4-16 in the '2009 version vs. figure 7-22, 7-23, and 7-24 in the '2018 version

[3DDave]

How fun. I hadn't looked until now but the figure that was 4-16 in the '2009 version and now 7-24 in the '2018 version no longer uses the virtual condition. I wonder why.

It still fails to mention that for the 3rd condition the maximum dimension only applies in one direction, but still, that's quite a change. Converting it to RFS means that there's less point in making that calculation as whatever the size the mating datum simulator has to collapse to meet it. Since D is referenced to arrest rotation the radial component of the RFS feature reference doesn't matter; the tangential one does and that is limited by the perpendicularity. Starting from a cylinder when only the width centered on datum feature B is important is not useful.

As I recall, the combined effects in the first example produced a dimension in a slightly diagonal dimension that was greater than the simple calculation showed so it is still wrong, but just in a different way. The addition of the straightness tolerance is a nice touch, but I don't understand why most values are changed. Change the text, change the test perhaps.


Edit: Title fix.

 

[Burunduk]

Implied was the point of my question.
Having it explicit may help you get it:

The communicated requirement by a customized datum reference frame explicitly stating the constraints of degrees of freedom as shown in figure 4-19, would be exactly the same as the implied constraints of degrees of freedom by the datum references shown without any modification or customization in the related figure, 4-9. Therefore, It would impose the exact same datum simulation method shown in the "means this" portion of fig 4-9, with the basic spacing of 57.4 mm between the B and C datum feature simulators. It would in no way be equivalent to what is shown in the "means this" portion of figure 4-19, covering the special datum simulation method allowed by the use of the translation modifier; the adjustable spacing between the datum feature simulators.

 

[3DDave]

You shift the argument from the one you lose to the one I didn't make. I understand why you do that.

Years ago I played against a chess program. When it got to the point where the only moves it could make would be forced moves, it claimed that those moves I would make to do that were not allowed. However, when I told the software to play from my position it immediately performed the move(s) it claimed were not allowed.

I've seen what your tactic is already.

 

[Burunduk]

I think you could benefit from being less focused on argument tactics, and more on the topic.

You've been saying all along that the translation modifier is redundant and everything it does could be achieved by the customized datum reference frame.
You've been just shown again that the translation modifier is not "a special case of a customized datum reference frame" but here we are again with you not willing to learn.

 

[3DDave]

You haven't shown that.

 

[Burunduk]

I have.
But I guess "explicit" doesn't always work, either.

 

[Burunduk]

So apparently the explicit explanation (11 May 22 17:06) didn't work, although by saying "you haven't shown that" you don't point out what exactly you disagree with.
Nevertheless, you could try to look at it from another angle; the translation modifier is like the movable datum target symbol applied to datum features identified by only a datum feature symbol and not the datum target symbol. Is the movable datum target symbol redundant too?