More progress. Still having fun. I've got almost the whole carriage put together minus a few bearings. When I went to slide the steel rails back into the carriage, they didn't fit. I guess I didn't use enough cardboard on the rails when I was spacing everything out. I loosened the 4 bolts that hold the carriage together, and then clamped it to the rails again, but this time without the cardboard because now the bearings were installed. I used calipers and measured end to end over and over again, making small adjustments in the set screws in order to position the bearings and make the carriage pieces parallel. Once both sets of the carriage pieces were parallel, I had to make the two sets perpendicular... again. This is easy with a digital angle finder. I just tilted the whole assembly approx 45 deg and held it with a vise. I set the angle finder on one of the horizontal carriage pieces (part #16) and zeroed the angle finder. I then placed it on the vertical piece (part #23) and made small adjustments until I got 90 degrees.
It's coming along. I still don't have any electronics (other than the Super PID), or any of the base parts yet. I'm working out all the metal issues before I continue. However, I better get that base done soon because it doesn't seem like it will be long before I need to mount the gantry to something.