Using note callouts for holes with positional tolerances
Using note callouts for holes with positional tolerances
(OP)
Our company has always called out hole patterns for flanges using leader notes such as:
1.25 DIA THRU
8 HOLES ON 8.00 DIA BC
EQ SP AT 45 DEG APART
That was for directly toleranced dimensions, but now we're switching to positional tolerancing for these. It seems to me that the dimensions for the BCD and angular spacing would be best shown directly in the drawing view as basic, but our management still wants to use the same notations but with basic symbols added. This means the 8.00 DIA and 45 DEG would have boxes around them within the existing leader notes (and of course a positional tolerance control frame added).
Is this acceptable practice?
1.25 DIA THRU
8 HOLES ON 8.00 DIA BC
EQ SP AT 45 DEG APART
That was for directly toleranced dimensions, but now we're switching to positional tolerancing for these. It seems to me that the dimensions for the BCD and angular spacing would be best shown directly in the drawing view as basic, but our management still wants to use the same notations but with basic symbols added. This means the 8.00 DIA and 45 DEG would have boxes around them within the existing leader notes (and of course a positional tolerance control frame added).
Is this acceptable practice?





RE: Using note callouts for holes with positional tolerances
EQ SP should be EQLSP per ASME Y14.38a-2002 if you care.
BC means specifically Bolt Circle per ASME Y14.38a-2002 if you care - Pitch Diameter (PD) may arguable more correct for a hole pattern.
Saying Equally Spaced & 8X 45 is arguably dual dimensioning, and I've got a feeling the meaning of Equally Spaced isn't explicitly supported in the dimensioning spec but I can't recall for sure.
Maybe something like:
8X Ø 1.25 THRU
[Ø 8.00] PD
[8X 45°]
[] is meant to be the box as in basic dims.
I assume you have a FCF with appropriate datums or some such to indicate what the PD is centered on.
I think this or similar has been discussed before you may be able to find a previous thread.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Using note callouts for holes with positional tolerances
Will the dimensions in your note be associative to the actual feature?
Practise in ASME Y14.5 is to apply dimensions directly to the pitch circle and to the angle. Not everyone knows what BC, BCD and PC mean. The directly applied dimensions are clear, unambiguous, associative, do not require good knowledge of English initialisms, and they can be boxed as per ASME 14.5.
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JHG
RE: Using note callouts for holes with positional tolerances
RE: Using note callouts for holes with positional tolerances
RE: Using note callouts for holes with positional tolerances
What is wrong with boxing 6X 60°?
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JHG
RE: Using note callouts for holes with positional tolerances
If:
1.25 DIA THRU
8 HOLES ON 8.00 DIA BC
EQ SP AT 45 DEG APART
You don't need "45 DEG APART" if they are EQ SP.
Should be one or the other.
Chris, CSWA
SolidWorks 13
ctopher's home
SolidWorks Legion
RE: Using note callouts for holes with positional tolerances
Tunalover
RE: Using note callouts for holes with positional tolerances
As for circular patterns of holes, in North America, in my experience, this is typically called a bolt circle or a circle of centers. But on drawings originating in Europe, I commonly see pitch circle, and the abbreviation PCD (pitch circle diameter) in leader notes.
RE: Using note callouts for holes with positional tolerances
PD= Pitch Diameter - this would be on screw threads etc. as you say.
PC = Pitch Circle - this is what I meant to suggest.
both are in ASME Y14.38 I just looked up and posted the wrong one - sorry.
8X Ø 1.25 THRU
[Ø 8.00] PC
[8X 45°]
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Using note callouts for holes with positional tolerances
Tunalover