Since I find it asinine to cut 28 linear feet of plywood in straight lines with a 6mm bit, I resolved to find a way to do what I wanted. Thuis is what I’ve come up with, based on examples in this forum.
The first image shows a wooden bump stop which I’ve attached to my Y-slides on both sides. I am intending to put one on the X-slide as well, since these work so well. In practice, I manually bring the carriage to its home position in the lower left corner of the table before I turn power on to the stepper motors. This seems to ensure that the machine is set to (0,0) in the same place relative to the wasteboard everytime I fire it up.
The 2nd image is a fence that I machined out of cheap plywood which establishes X and Y stops for my dimensioned stock which are relative to the (0,0) point. Since I am using a 6mm bit for the project I’m working on now, I jogged the machine +3mm in the X and Y directions before I machined the fence faces.
I’m finding that this setup is working extremely well and with great accuracy, despite the somewhat low-tech nature of the implementation.