The next step is to mount the beds for the X and Y axes (that is, the two horizontal axes). This is probably one of the hardest parts of the construction process. I used tapered (countersink) screws to keep the hardware beneath the bed surface, but if I had to do it all over again I would have used a regular low profile machine screw and milled a flat spot into the bed plate to provide a little more adjustment. As it stands now, the screws have to be tightened in stages and in pattern to get the to just the right position.
The Z axis rails are then bolted to the Y axis bed plate. The holes for mounting are tapped directly into the aluminum.
And the same process again for mounting the Z plate- shown here with a 1/4" high speed router attached.