Author name: I'm no expert, but

Squaring and Tramming a DIY CNC Mill

When you’ve built your own mill, you need to square it up beyond what most mill owners need to do. […]

The X axis bearings constraining the lead screw failed in an odd way. I replaced one with a double angular

Parts list is here: https://pastebin.com/raw/qTwZPJzE Note that the base width in the video isn’t what I used. My base is

Milling aluminum angle brackets on my modified Openbuilds Minimill. source