Reporting Profile from only 1 or 2 axises

[Gary Fitzgerald]

Have a callout "Profile of .007 to A" and another "Profile of .016 to A & B"
How does one isolate only one or two datums when reporting in this situation?? Under Surface Profile in Pc-dmis we don't have the option to select where from. Please see attachment with snapshot of Drawing callout.

Thanks a Million for help or feedback.

[kbotta]

I cannot exactly see your -A- datum so:
Assuming -a- is 90 deg perp to -b- and -c- (roughly)
1st Profile to -A- is controlling orientation and "form" only, of that surface.
2nd is orientation and location (and form of that surface) to -a- and -b-.
kb

[cmmguy]

Would you use Best Fit and restrain the freedom represented by the datum?

[kbotta]

I don't like to use BF unless forced (composite's - hole patterns, etc..)...
But - yes, restrain DOF according to DRF. This is a qualification of the datum features exercise...
Kev

[cmmguy]

If you dont use BF, then how are you going to allow DOF to change to accomodate the datum structure?

Even when datums are not set, DOF are still fixed. Yes? Or, if you select Form Only in the Control Options, the DOF are allowed to adjust - and if they do, isnt that Best Fit?

[kbotta]

If you dont use BF, then how are you going to allow DOF to change to accomodate the datum structure?
Let's define best fit. I am speaking as to a "best fit alignment". I am not totally understanding this question "allow DOF to change to accomodate the datum structure". DOF do not change. There are always 6. A planar feature will restrain 3 of those, as it is "un-bounded". Leveling a plane in this case will suffice as a primary DF.

Even when datums are not set, DOF are still fixed. Yes?There are always 6. they are the same. There is a "machine alignment" from the CMM, is this what you are ref'ing to? Or, if you select Form Only in the Control Options, the DOF are allowed to adjust - and if they do, isnt that Best Fit?
Form only report's the "form" of the set to known nominals (assigned). Again, the best fit i am ref'ing to is for initial inspection alignment, not an algorithm used for calculation purposes (i.e. cheby, lst sqs, etc...)
kb

[cmmguy]

Let me try again...

(I was referring to the Best Fit that is in the Profile tolerance window.)

How does PCDMIS handle a profile tolerance with no referenced datum - only the tolerance band. Under the control options there is Form Only and Form and Location. Then there is Best Fit when you check Form Only.

I think I did a crappy job of explaining my original question.

[Gary Fitzgerald]

Thanks ~ One more for clarification

I do an alignment > Best Fit > Select only A and B (B = Feature Set surface).
I then select surface profile, select B and enter my tolerance. This sounds good to me so far because it's only A & B in the mix.

Sound good so far???? If so 2 more questions?
1)Do I use weights in the alignment to favor A or leave alone?
2)Now it's Form and Location or Form Only for the profile?

Thanks for the Help

[John Riggins]

I do an alignment > Best Fit > Select only A and B (B = Feature Set surface).
I then select surface profile, select B and enter my tolerance. This sounds good to me so far because it's only A & B in the mix.

Sound good so far???? If so 2 more questions?
1)Do I use weights in the alignment to favor A or leave alone?
2)Now it's Form and Location or Form Only for the profile?

Thanks for the Help

for the .007 to -A- tol it should be Form Only.
for the .016 to -A- and -B- it should be Form and Location.

[Gary Fitzgerald]

What about the weight Question

Use weights or not?

[John Riggins]

Use weights or not?

If your results are very close but still out of tolerance then maybe weights will help.
But, I am not real familiar with using the bestfit routine that way.
Maybe someone else can chip in here.

[Gary Fitzgerald]

Thanks John