New Z axis couplers and hot bed mount

So the PLA Z rod/motor couplers didn't work quite right.  The PLA is a bit brittle and as I tightened the screws, I heard a bunch of cracking.  It seemed to hold for a bit, but then later the couplers just slid off of the Z motor shafts.  You can see the cracking in the couplers in the following pics.

I milled out new couplers from some aluminium stock I had on hand.  I drilled through at 5mm and then drilled half way through at 8mm.  Then I cross drilled some 3mm holes for set screws and tapped them for m4 threads.  You can see the couplers on the machine in the following pics

And I've gotten a method for hot bed mount done.  I'm using plywood and have the heat bed attached to one sheet and have made it so I can detach the heat bed easily if I need to.  The attachment method allows for easy adjustment to level the bed to the nozzle.  You can see it in the following pics.

I still need to find connectors with sufficient ratings to connect the bed to the electronics.  Also need to decide on how to attach to the electronics.  And then I need to attach the endstops so it can auto home and stop the +Z motion before the belts hit the frame.  I hope to have things done and printing any day now.