Eagle BRD - Double sided how to? Hi all, am taking my first steps,

Eagle BRD - Double sided how to?

Hi all,
am taking my first steps, trying to get a doubled sided PCB milled. Am using the latest eagle BRD v5.8 with a TinyG v8.

Can anyone please point me at a “how to”, video or text. I’ve looked at the videos for single sided but am missing something here and can’t seem to get the two sides aligned. It wants to mill the top layer to the right of the Y axis and the bottom layer to the left.


I flip wood parts often. It takes 3 operations. The first is to drill alignment holes. Then place the part on a fixture with locating pins. Now when you flip you know where the part sits on the table.

Make sure that your machine X and Y axis are both perpendicular, otherwise you won’t be able to fit into alignment pins locations.
Engrave a square or rectangle (the larger the better) and measure diagonals - equal length = you are good to go.

You need to be highly accurate to mill PCBs.

Other option: there is a tool I used in the past to adapt gcode to machine inaccuracy called ‘gskew’, downloadable from the Internet. But later on I mechanically aligned my machine.

Once you are happy with machine setup, just follow Colin’s recommendation, the widget is quite intuitive and straightforward. Good luck.

Early in my efforts to produce two-sided PCB’s, I realized my x and y axis were not quite perpendicular, with the result that although holes would align well where y was 0, they aligned increasingly poorly as y values grew. I concluded (perhaps wrongly) that mechanically re-aligning my cnc would be a hit and miss process, and that I would never get it exactly right. So I ended up writing an excel spreadsheet to correct my g-Code. I wish I had the skill to fork chilliPepper to make a widget to adjust the code. (And I am working on it, having “learned” javascript and CSS on CodeAcademy.) The algorithm behind it is pretty simple.