One more reason for dimensions:

Assembly inspection.

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Pete Houwen
Sent: Monday, March 09, 2009 7:03 AM
To: [log in to unmask]
Subject: Re: [TN] To Grid or Not To Grid

Dated, indeed.

Why dimension fab features?  Dimensions on a fab drawing have become 
nothing more than reference information as actual dimensions are handled
by 
CAM files.  Sometimes reference for the fabricator, sometimes the
assembler.

So defining dimension requirements ought to be a result of understanding
what 
those dimensions wil be used for.  It has nothing to do with grids.

ref: I do use grids for parts and vias, but only to maintain good
routing 
channels.  Drill and pick and place programming doesn't really care
where the 
features end up, they're just numbers in a file.

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