I believe everything above is correct. There is no difference between the two. However, I do not see the need for the word INDIVIDUALLY in this case. It is superfluous in its meaning.
Is there a possibility this can mean something other than what it says without the word 'individually' being...
But what if you are more than .4, and the parallel jaws of a caliper tell you that you are within +/- .2. That parallelism will never be checked if you don't call out a parallelism control.
Which is fine if it is not important to you. But in reality, yes you could be more than .4. And it all...
And if that's the case, then DR CADD must have been a man before his time! Back then you see, we didn't even know what the term CAD meant!
But he did actually show me how to use CAD. That was - drawing a line, and a circle successfully, on an IBM 8086 Personal Computer, and actually running one...
Sorry folks!
I'm out of it too. And yes it really did end up in the weeds. And that's not constructive.
Better to keep it to one question, and one answer. But it is a complicated subject!
And thank God I don't know any evil Dr CADD. Because if I was his student, then he would have to be a...
But, Can a cylindrical feature establish a datum axis? Yes. And can a feature control frame somewhere in that drawing reference that datum at say MMC? Now, what does that mean, say you?
Now why can't I just go ahead and refine that feature to be within a cylindricity tolerance (in most cases, I...
New Post powerhound (Mechanical)
4 Dec 13 23:01
Well it looks like the big misunderstanding is what you were responding to. The original question was if perpendicularity was a refinement of CONCENTRICITY, not cylindricity. This explains what appeared to be an unrelated tangent. I was wondering...
And now just imagine, that you are charged with the task of designing an absolute/ practical absolute guage, just to measure all this nonsense! Where would you start?
New Post powerhound (Mechanical)
4 Dec 13 11:23
In both the 1994 standard and the 2009 standard fundamental rules 1.4(i, and j) clearly define the implied 90 rule. So that means there IS such a rule.
Great!
But only for a theoretical datum reference frame is this true (chapter 4). And that...
And remember datum axis B was established by the cylindrical feature. We just happened to call out a cylindricity for it. But we never said how perpendicular it needed to be to datum feature A.
Wrong, and very wrong!
There is no 'implied rule'. The perpendicularity of datum feature A must still be controlled wrt datum axis B. Your cylindricity requirement does not specify that.
That is why you need the refinement. Because if you never specify how A is related to axis B, then you...
Sorry, fsincox,
This was a drawing I found on another post. I meant to reply to the post but it didn't let me for some reason. I will find out who sent it so you can see the thread.
Here is the drawing. I have seen too many drawings like this in my time. And then have to listen to crap like -...
