Removing Layers in Eagle


Eagle PCB is weird. It’s kind of like Democracy:

“Democracy is the worst form of government, except for all those other forms that have been tried from time to time.” -Winston Churchill

Eagle is not great, but it’s better than all the other forms I’ve tried for the general PCB hacker such as ourselves and our friends. I used the non-profit version for a stint, but when we started to sell our designs we took the plunge and purchased the professional version.

If you do decide to shell out the money, you’ll get the opportunity to layout a board up to 16 layers! Really? You should rarely need more than 2-layers. But if you spend the big bucks on Eagle, it will by default assume you want to layout a 16-layer board.

http://www.sparkfun.com/tutorial/Eagle-Layers/Eagle-Layers1.jpg

Look at all that noise! 16 layers is great for a motherboard, but that’s really not me. And all those extra layers cause lots of problems when I’m tying to route between layers.  While routing, I like to use the mouse and keyboard to quickly drop a via and jump to the opposite layer (either top or bottom). This is how I route between layers:

http://www.sparkfun.com/tutorial/Eagle-Layers/Eagle-Layers6.jpg

With a design open (this is the layout for the XBee Explorer), start routing (I use the F9 shortcut).

http://www.sparkfun.com/tutorial/Eagle-Layers/Eagle-Layers7.jpg

As you’re routing, hold Shift. Now when you click, because you’re holding shift, it will drop a via on the board. Neato.

http://www.sparkfun.com/tutorial/Eagle-Layers/Eagle-Layers8.jpg

Now after you’ve dropped the via, click the middle button on your mouse - it should be the scroll wheel. If you have more than 2 layers, Eagle will pop open a window asking which layer you want to go to.

http://www.sparkfun.com/tutorial/Eagle-Layers/Eagle-Layers5.jpg

Wait! I just have a two layer board. Why is it asking me which layer I want to go to? I want to go to the opposite layer obviously! This can be really annoying. If we can convince Eagle we only want to route two layers, Eagle will switch to the opposite layer. So how do I remove those annoying inner/extra layers in Eagle? It’s completely wild, but not too hard:

http://www.sparkfun.com/tutorial/Eagle-Layers/Eagle-Layers2-M.jpg

Open up the DRC menu by clicking on Tools->DRC. Click on the ‘Layers’ tab.

http://www.sparkfun.com/tutorial/Eagle-Layers/Eagle-Layers3-M.jpg

Checkout the ‘Setup’ box. This is where you can create an entire stack up of layers of various thicknesses and complexities. It’s all very fancy, but if you 2 layers, it’s overkill. To remove the extra layers (and just have a two layer board) remove the parentheses from “(1*16)” in the Setup box. Then click apply.

http://www.sparkfun.com/tutorial/Eagle-Layers/Eagle-Layers2-M.jpg

Now add the parentheses back. Yes, put them back. Now click Apply - this will cause the changes you just made stick. Then click Select - this will close the DRC window and return you to the Eagle PCB window.

http://www.sparkfun.com/tutorial/Eagle-Layers/Eagle-Layers4.jpg

Now if we look at the layers again, you should see only Top and Bottom. Yippee! We can now route quickly using the mouse wheel button to switch between layers. Enjoy!

Comments 4 comments

  • Does anybody know how to write a script for eagle that would do this automatically, of any settings to change to get eagle to do this automatically on startup? It’s kinda annoying doing this every time I design a new board.
    Thanks a ton for the tutorial!

    • you can change/update the script named [eagle.scr] which is launched at startup and configures most of the GUI.

  • Thank You!
    Thank You!
    Thank You!
    -BB

  • “Eagle is not great”….
    That is the nicest thing I have heard anyone say about eagle in a long time. I have never commented on anything posted here before however, I feel very passionate about eagle. eagle is not a cad program, it’s a time wasting machine. It’s a sick joke masquerading as CAD software.
    Try DipTrace,..I find that to be the way to go.
    It defaults to 16 layers,…just another eagle cad failure…
    Nate..your a good guy. None of this is directed towards you.