Trimmed roughly a quarter inch off the end of the ballscrew to make the entire Y-axis motion assembly fit in the frame interior (barely). Installed the stepper motor bracket in the proper location and then installed the stepper itself. Determined that 18mm of shimming will be required below the ballscrew support blocks. I have various aluminum stock thicknesses that together stack up to that value, and I can cut and drill those this week.
Calculated, measured, marked out, drilled and tapped holes for the Y-axis motion control on the X gantry plate. Installed the linear rails. Because space is tighter than I anticipated, I'll need to saw off a bit from the ballscrew and possibly even some from the drive shaft on the stepper. Not ideal but it should work. I'll also need a different stack of spacers between the ballscrew follower thingamajig and the XY gantry plate since the stepper mount is different, again since space is so tight. 
Put final counterbores into X-Y gantry plate and test-fit the linear rails and ballscrew ball nut carriage block. Somehow miraculously everything is aligned. I do still need to put in tapped M5 mounting holes for attaching things. 
Began to drill and counterbore mounting holes for the X-Y gantry plate. These slotting counterbore bits are really nice but get gummed up quickly and stall the motor of my weak drill press. Also have to use a cordless drill to reach the central holes. Would be nice to make a nice drill press. 
Took inventory of CNC mill project after long hiatus. Updated CAD model to reflect length of installed collet and bit and migrated to organization repository. Marked out the drill and tap locations for the X-Y gantry plate. 
