At 05:20 AM 12/2/2010, you wrote:
On Wed, 01 Dec 2010 19:38:32 -0500
Ethan Swint <eswint.r...@verizon.net> wrote:
> Sorry for my late reply - but have you tried the BOM export (File ->
> Export Layout->BOM). One of the output files from that is an XYRS
> (X, Y, Rotation, Side) text file.
>
> http://archives.seul.org/geda/user/Feb-2009/msg00351.html
Yes, but as I pointed out earlier, it doesn't do what I want. It averages the
coordinates of the pins/pads, and it is not good when you working with
asymmetric element such as SOT223.
My experience is that there are two points on a pick and place
package. There is the centroid, which I understood to be the center
of the outline of the part and is used to define the orientation
point on the part for positioning. There is also a pick point which
has to be in a spot where the vacuum nozzle can lift the
component. This are mostly the same spot, but on unusual parts, not
always. I can't imagine the XYRS file generator is not capable of
outputting the appropriate centroid position. Is it possible that
you are seeing the pick point thinking it is the centroid?
The feedback from my assemblers is that I should give the X and Y
coordiates of the centroid of the part for placing it on the
board. The rotation is nice for them to have, but they mostly don't
trust them and so always go through a process of verifying both
placement and rotation of each part as it is placed on the board for
the first item. It may actually be a virtual dry run using the
machine display. But they have told me they ignore all other info
such as glue spots and pick points. They know where they want the
glue spots and pick points and have no reason to trust your data for that.
If the XYRS file output does not output proper centroids, I see this
as a major issue. If they are not outputting the correct value for
asymmetric parts, how do you see the centroid being defined exactly?
Rick
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