The response is incorrect in referring to maximum material condition. The feature frame description did not reference M in a circle as it did not reference L in a circle (minimum material condition) or S in a circle (regardless of feature size). I'm not a GD&T expert, but an assumption is being made when one refers to maximum material condition. The feature frame is what it reads. I agree that the feature control frame referenced appears to be lacking in information. Without reviewing the entire drawing, it is difficult to make additional comments regarding the intent of the dimensional call out.
Don Vischulis
-----Original Message-----
>From: Randy Morrison <[log in to unmask]>
>Sent: Jul 10, 2006 11:05 AM
>To: [log in to unmask]
>Subject: Re: [TN] Geometric Tolerance
>
>Yes, the tolerance zone is a circle. The hole can be anywhere within
>that tolerance zone diameter. So if your hole is closer in the "X"
>direction, it can be further off in the "Y" direction, etc. Maximum
>material condition means that at the smallest allowable diameter of the
>hole, you have the given positional tolerance. So, for example, every
>.001" that the hole diameter exceeds its minimum, you can add .001" to
>the positional tolerance.
>
>Just a marketing guy now, but I did spend many of the worst years of my
>life in Quality in precision machining and sheet metal manufacturing....
>
>
>Thanks,
>
>Randy Morrison
>Marketing Manager
>Pentagon EMS
>
>
>
>http://www.pentagon-ems.com/bio/randy.html
>[log in to unmask]
>Tel: 503-924-2747
>Fax: 503-924-2744
>
>
>
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of Donald Kyle
>Sent: Monday, July 10, 2006 8:10 AM
>To: [log in to unmask]
>Subject: [TN] Geometric Tolerance
>
>We are having a little debate here as to the interpretation of a
>Geometric statement evolving the tolerance of holes on a PCB.
>
>The geometric statement reads from left to right:
>Position (symbol)
>Diameter (symbol)
>.005 (tolerance)
>X (datum)
>Y (datum)
>
>Some say that this statement means a positional tolerance zone within a
>circle.
>
>Others say that this is just another way of stating a bilateral
>tolerance zone within a square.
>
>How do you interpret this?
>
>If you have IPC-D-325A you can read about this on page 28 and appendix B
>for more information.
>
>Because I don't know how to insert a geometric symbol for POSITION and
>DIAMETER you will need to use your imagination here.
>
> Geometric Geometric Tolerance Datum
> Symbol for Symbol for Reference
> Position Diameter
> __ __ .005 X
>Y
>
>
>Thanks for your time
>
>
>Donald Kyle C.I.D.+
>
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