Trick to draw circular PCB outlines in Eagle

December 26, 2017

If you haven’t used the Eagle PCB design tool lately, you will be surprised to learn that it has underwent a major update since it was acquired by Autodesk.

Eagle’s license model has been switched over to a subscription service and I am liking the experience so far. I am able to get the latest updates of the software (unlike earlier, the updates are quite frequent). I am currently using Eagle 8.5.x and it comes with the “Push and Shove” feature that automatically pushes signal traces while routing your PCB.

PCB Outlines

I was working on a circular PCB for building something like a fidget spinner. I assumed that I could draw circular PCB outlines by drawing a simple circle.

Circle_snapshot

Circle feature in Eagle PCB

Being able to draw circular outlines can make your life easy. For example: You could draw a random circle and specify its radius, center etc (similar to Mechanical CAD tools).

Circle_Radius

It turns out that the software considers this an error. When I started to route the PCB, the automated DRC check ignored glaringly obvious errors.

eagle_2017-12-26_19-54-44

Errors resulting from the Circular Outline

In the above snapshot, you will note that I am able to route traces over PCB pads and the cursor indicates bad news.

After wasting some time, I found out from this forum thread that I need to draw my outline using arcs.

In Eagle, drawing an arc is a three step process:

  • Specify the starting point
  • Move the cursor to specify the arc radius
  • Draw the arc

It is definitely confusing and imagine drawing a “closed circle” using arcs. It can be frustrating.

I eventually managed to find a simple solution that involves combining arcs to draw circular outlines. Check it out!

I am no video expert. I made this video using basic screen capture tools. I look forward to hearing your tips on improving the video.

I really hope Autodesk simplifies creation of non-standard outlines. Did you have a similar experience? Drop your thoughts in the comments section!

My design is off to OSH Park. What manufacturing house do you use for your designs? I will share my build in upcoming blog posts.

 

 

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