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Thread: metric Eagle question!
www.piclist.com/techref/pcbs.htm?key=eagle
picon face BY : Spehro Pefhany email (remove spam text)



At 02:08 PM 12/12/02 +0000, you wrote:
>Hi,
>
>I would tend to agree with Werner on this.  Having attended school in the
>post UK decimalisation era, I've grown up with metric and generally use
>metric in every "units of measurment" scenario.  In my case there are only
>two exceptions to this rule.  The first is road distances (where I'm just
>used to seeing signposts written in miles) and the other is PCB layout.  I
>too use Eagle for schematics and board design and soon realised that
>metric measurements were not really the way to go, given that electronic
>components are generally sized for an imperial world.  My own advice would
>be to use a grid measurement half the size of your smallest pitch - that
>will give you enough flexibility to do 80% of your layouts (unless they're
>hideously complex).  For the other 20%, keep halving the grid measurement
>until you get the required resolution.  For example, any 0.01" pitch
>boards that I'm working on my default grid setting would be 0.005".  For
>more detailed track layout I take this temporaril

We're still using Imperial measurements for PCBs, but I find that many or
even most components and virtually all *new* component footprints are now
hard metric. It takes more digits and is less accurate generally to enter a
metric measurement in Imperial units than the other way around (because
2.54 is exact and 1/2.54 is a repeating number). But, if they are within a
mil (thou) that's good enough, usually.

Does anyone have a clever way of automatically placing and orienting many
sequentially numbered parts from a spreadsheet or other similar data? If
so, what PCB package and how? I *think* there is a way using Protel's
reverse pick and place file capabilities, but it looks messy and seems not
to be well documented, at least in my demo version. This is to prevent the
necessity of manually keying in scores or hundreds of 5 digit
random-looking numbers with perfect accuracy.

Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speffRemoveMEspaminterlog.com             Info for manufacturers: http://www.trexon.com
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