Here’s where my lack of experience really starts to show. I spent the better part of saturday trying to fine tune the router. I attached a dial indicator and ran the router along each axis with a carpenters square clamped to the bed. I found several major problems with the way the router was configured and solved them one by one but couldn’t get everything to run true. I’d get it to run square in the X direction and it would be way off in the Y.
After nearly pulling out all my hair I thought to check the squareness of my square. Surprise!
You check the square by drawing a line, then flipping it and checking the match. You can also tune it a bit by using a punch a to spread the inside or outside of the line across the thin arm at the corner.