Here is a link that might help explain true position,

http://listserv.ipc.org/scripts/wa.exe?A2=ind0112&L=technet&P=31804

Ray Johnston
Lead CAD Designer
Rane Corporation
425-355-6000
rayj@rane,com

----- Original Message -----
From: "Denis Lefebvre" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, April 25, 2006 8:17 AM
Subject: [DC] Diameter True Position


>I must admit, this is a drawing callout that I have never fully
> understood. Back in the early days, per MIL-STD-275 I'd callout Diameter
> True position at 0.010", then at some point in time it was reduced to
> 0.008". Now I have someone telling me it should be 0.003". Huh?
>
> Can someone help me understand what this (Diameter True Position) means
> and how dropping the value to 0.003" might be a good thing or a bad
> thing?
>
> Denis Lefebvre, CID+
> Sr. PCB Designer
> Finisar Corp <http://www.finisar.com/index.php>
> (408) 542-3832
>
>
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