My gantry router is working great except one problem. When I route a square, the corners are not square. The straight sections are good but when I approach the corner there is a bump out.
I'm not sure if it is a backlash problem or flexing in the router bit. I don't think it is a backlash problem because when I mill a circle it is perfect.
I'm using a Bosch Colt router with a 1/4" spiral bit. I've tried slowing down my feed rate to 20ipm and depth of cut of 0.1". The problem still show up.
Here is a drawing what the corners look like. You do you guys think?