Re: gEDA-user: Arc to line connections?

[DJ Delorie <dj@xxxxxxxxxxx>]

> The manual says I can just switch tools in the middle of a trace
> using the right keys (F2/F3 in the lesstif HID).  This works when
> going from a straight line to an arc, but when I try switching from
> arc to line it does not work properly.

Whenever you switch tools or layers, you always click on the LAST
point, then switch tools.  So, you should be finishing up the arc,
"starting" a new arc, switching that to a line, and drawing the line.

> I gather the idea is mostly to reduce trace lengths by using truly
> straight paths,

It's to make the board look pretty, nothing else really.  However, if
you're also using the teardrop tool, the puller gives you more room on
that initial segment on which to put the teardrop.

> Of course, I can use all-direction lines for that, so the main
> advantage of the puller seems to be in avoiding sharp corners.

I originally wrote it to help with BGA breakouts, because sometimes
you can get two arcs between pads where two 45-degree corners won't
fit.

> Professional boards seem to use only 45-deg increments -- just
> judging by what I see when I open up computers and consumer
> products.

"Professional" boards used to have lines going in all directions,
because they were more reliable to fab and offered better signal
quality.  These days it doesn't matter as much, and the autorouters
are good at routing 45's.  However, the new topological autorouters
won't be limited to 45's any more, so we may start seeing more any-way
lines.

Besides, look at your motherboard in your PC.  The autorouters seem to
care more about matched trace lengths than how pretty it is; traces on
my MB wiggle all over the place to keep trace lengths consistent
across busses.


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