Page 122 - Make Your Own PCBs with EAGLE from Schematic Designs to Finished Boards

• Layer. Copper on the top or bottom of the board.

• The next eight icons represent different styles of track bend. To get the hang of these, you will
experiment with them when we try laying out the bar-code example.
• There is then a “Miter” dropdown that allows you to select a curve radius for bends in the

track. This used to be important for certain chemical etching processes where tight bends could
cause the etchant to collect and overetch the track. Unless you are home etching your PCBs, this
feature is largely down to personal preference.

• Finally, there are two selection buttons that allow you to choose between square and curved
miters.

Ratsnest

If you are routing a PCB by hand, you will probably find yourself hitting this button frequently. When
clicked, it recalculates the shortest routes for all the air wires. Remember that these air wires indicate
where there is more routing to do. When all the connections have been made, it will display the status

message Nothing to do!
If there are still connections to be made, this command will recalculate them, indicating the
shortest routes between existing tracks. Thus, having done a bit of routing, clicking Ratsnest will tidy
everything up and recalculate the air wires for you.

Copy

If you remember from the Schematic Editor, Copy is actually more like “duplicate.” It is another
command that should not be used with parts. Switch to the Schematic Editor if you want to add or
duplicate parts. It is, however, useful to copy board-specific items that do not appear on the
schematic, such as holes or text.

Rotate

This rotates the part through the angle specified in the Parameters toolbar. This is normally 90

degrees. However, you can use other angles by

• Clicking the Rotate command
• Typing the angle into the dropdown (say, 45) and hitting “Return”

• Clicking Rotate again

• Selecting 45 in the dropdown
• Clicking on the part to rotate

This can be useful for unusually sized PCBs.

Add and Replace

Adding a part is another operation that is not permitted from the Board Editor, and while replacing
parts, if they have compatible pins, it is much better to go back to the Schematic Editor and make the
change there.