Sometimes I wonder if I should do fewer but less incremental updates - not sure which you guys would prefer?

Anyway, for now a little extra work done today.

I've done a few tweaks to the Z-axis design after having a long think about how it's going to be assembled and aligned on the machine. To that end I've added an eccentric bushing to the top of each carriage mount and a 6mm dowel pin at the base to act as a pivot point. The idea being that I can install the backplate on the machine, lining it up square to the gantry arm. One dowel pin will provide a hangar while installing and ensure its central on the slider.

Then I can use a dial indicator to align the right carriages to a machinist square based off the bed, which will ensure the rails are aligned 90 degrees to the bed in X, then use those to dial in the left carriages.

Only had time to do one side of the carriage mounts today but It came out very nicely and for once I managed to make a part without messing anything up. When it cam to reaming the dowel pin hole I just had a very low feed rate and span the spindle by hand... I'm thinking there must be some sort of cunning arrangement I can come up with in future to spin the spindle slowly using a separate motor and some HTD belt/pulleys for things that need super low rpm like reaming/thread milling.

Anyhoo:

Top side finished




Flipped and bottom side done (used dowels to align with Y, then probed the reamed hole to determine zero)










I also designed a top seal for the motor mount, took a few prints to get it perfect as the CAD model of the motor mount isn't entirely correct in the non-critical dimensions: