The Shapeoko 5 pro 2x4 comes with 3 base frames. The left and right sides where they attach each have 4 sets of holes. The instructions tell you to expect 4 base frames and to attach 4. If only 3 are to be attached then which set of the 4 sets of holes go unused? The instructions apparently are for a 4x4 only and are of no help in figuring this out.
The first three holes (from the front) are used for the basframe — the back half is the same as on a 4x4, so the furthest back baseframe is a bit in from the back edge of the machine.
I had the same question when I was assembling my 4x2 last week. I emailed support and got the same response, word for word. I searched both the PDF and the “printable PDF” for that note and couldn’t find it. You might want to make the “note” a wee bit larger for us dumb-dumbs