gaussmarkov: diy fx

Finally, click on the RATSNEST button or enter “rat” into the command line. Because I entered the command “set polygon_rat on” at the beginning of this tutorial, the RATSNEST command causes Eagle to fill in the ground pour and I get this final result:

The distance between the ground pour and the pads and traces of other nets was determined by the “ch iso 40″ command at the beginning of the tutorial. I will show you how to fiddle with this and some other characteristics of polygons further on in this tutorial.

Note that the upper right-hand corner is bevelled again. Eagle did not fill this in. You may have to experiment a bit to discover how to get Eagle to fill in the areas that you want. But I can pass on this hint: if a polygon does not contain a pad or the corner of a trace on the same net (in this case, GND) then Eagle will not fill in the polygon. Instead you will only see the highlighted outline of the polygon. Otherwise, you would never see it again, even though the polygon is there.

Here’s a trick that comes in handy sometimes: enter the ground pour polygon on the TOP layer and then change it to the BOTTOM layer. When you do this, it’s easier to see what’s going on. Here’s what I mean. Before starting the POLYGON command, type in

ch layer top

Now start the polygon as before and you will see something like this instead:

The TOP layer is red, instead of blue, so that the outline is easier to see as you make it. Once you have completed the rectangle and run the RATSNEST command, you will see this:

Now change the polygon to the bottom layer and you will have the final result shown at the top of this page. To change the layer of the polygon, type

ch layer bottom

and then click on the edge of the polygon. If you end up selecting something else first, keep right-clicking until the red outline is highlighted and then left-click. Presto! The ground pour turns blue and does not touch the other traces and pads.