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Re: gEDA-user: new footprint guidelines
Rick Collins wrote:
At most you might want to verify that the data in the XYRS file
matches the Gerber files for a small number of representative parts.
Why do you think you need to verify the results by reverse engineering
the code??? That is the stuff I am talking about "over thinking the
problem". All you need to do is look at the output.
Looking at the output is a precondition to verifying anything. You tell
me, that I shouldn't
look at the input.
But it's one of the iron rules of computation: garbage in -> garbage out
Having to verify the output on each and every design is rediculous. It's
like a
marksman determining his hold-off on every target by trial. This is not very
common nowadays because the bear wins.
E.g., where is the centroid of a 3-leged part? Is it:
a) the center of the bounding box of the pads
b) the center of the bounding box of the pad centers
c) the center of gravity of the pad centers (each weight 1)
d) the center of gravity of the pad areas
e) (0, 0) in the footprint definition file (or a designated vector
inthere)
...
When you find out what PCB does, a through e, what will that tell you?
It will tell me, whether what PCB does, conforms to the standard or has
a chance
to conform to the standard with correct libraries.
If you don't know what the standard is, how will you know if your
design is correct?
If there is a standard and I don't know it, it's my fault - and of
course I will never know
until the assembly house told me, that I screwed up.
Maybe for the series you do, the cost is negligible. At my present state
of business
€250 for the setup compared to €950 for assembling 30 boards is a
considerable
cost factor. If I can get rid of this or reduce it to €50 because the
assemblers knows
they can trust my data, this is a huge competitive advantage.
Maybe the savings generated by this discussion here never hit my wallet.
But I'm not writing for me alone, as I use others work for free.
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