Surface profile questions

[d.evans]

THANK YOU ALL!!

for your responses. I think I've got a good handle on this now.

[kbotta]

You could do a scan, and check the 'to points' box.
But I prefer to capture each point ind'ly...
Might just be my personal pref.
KB

[J Temmen]

I hate using "FEATURE SETS" due to the favt that if all points are equally shy or heavy the centroid of the set will report as perfect when it is not, in this case I would take enough points to ID each surface without going overboard,( i.e. are the surfaces finished or just roughed?),and report the individual "T" values.

[kbotta]

D.Evans,
Ask your eng why the arrow is directed to the chain line.
Is it part of the piece (a phantom line?), or as George is suggesting - a tolerance zone (chain line).
I think that will clear this all up.

In any case, here is how the different profile tolerance zones should be shown.

HTH,
Kevin

[d.evans]

I'm not an "automotive" guy.
I'll ask again, is there an automatic way of collecting all these vector points for the purpose of dimensioning a surface profile? Could I do a UV scan, and use it? or will PC-DMIS treat it as one feature?

[george frick]

checked with our engineering group. the consensus is: your print calls for a UNILATERAL tolerance as i originally stated. suggested that we hold gd&t classes in the parking lot after work for you "automotive" guys.

[d.evans]

I think he was surprised that I asked. I don't think he respects the job I do very much. In fact, he has dubbed my CMM "the NCR Machine" (NCR=Non-Conformance Report). I think I caught him off guard a little, and he HAD to be right.

[kbotta]

Which begs the case "why the chain line"?
Is it a part outline (does not look like it to me...but it's your part).

He should fix that. After I 'zoomed' in on it, the arrow is directly pointing to the chain line. Very unclear.
KB

[d.evans]

Yes it looked clear to me, but I asked anyway. I was surprised the answer he gave me.

[kbotta]

As many as you need to accuratley define the area (I know it is a canned response - but the right one...)
Kev

[kbotta]

Just because the arrow is pointing there, does not make it a valid unilateral. I would agree that it is 'unclear' as to the intent - with the chain line and all. In any case (bi-lateral, or unilateral) I believe the designer should have been more clear.
And just think. Soon this will be different (circle U...Maybe).

KB

[d.evans]

How far apart should I space the V points? I am currently spacing them approx .5" apart. I'll be here all day typing in X, Y locations. Is there a quicker "automatic" way of doing theses Vector Points?

[george frick]

interpret the dwg

I checked with the engineer on that one, and he intended it to be +/-.005. We both went back and looked at the y14.5 1994 spec and it had a drawing with two arrows pointing to both ends of a unilateral callout tolerance zone. He's only got one arrow, which to him, means bilateral.

the machinist probably interpreted as unilateral (to the inside of the pocket) as shown on the print. if you are showing .0005 o/t he machined it right on nomimal .0055. LOOK AT SECTION
A-A clearly unilateral

[kbotta]

Pg 164 illustrates this very well (asme Y14.5) top of fig. 6-11
And I believe your eng would be correct.
kev

[d.evans]

I checked with the engineer on that one, and he intended it to be +/-.005. We both went back and looked at the y14.5 1994 spec and it had a drawing with two arrows pointing to both ends of a unilateral callout tolerance zone. He's only got one arrow, which to him, means bilateral.