As for the Y axis.

First I machined a new plate to mount to the table, designed to accommodate my new shaft bearing.

It has a bigger opening to the top to provide better clearance so that I can slide T nuts easily into the centre table slot.
It also has holes on both sides for a the braces.



I removed the table and glued some steel inserts into the slots under the table. I will use these to ground the braces. I glued these in only after I had pre-assembled the whole thing with the braces in place so everything lined up- initially I used a little epoxy putty to hold then in place.



Finally, I could assemble the whole lot. It makes the Y axis more rigid under load (I think). The eagle eyed amongst you will notice that I notched the side braces onto the front plate to help make the joint more rigid. I didn't feel the bolted joints under the table needed notches because of the loads on them.