It's 10 days later and time for an update. I have what appears to be a usable Rev 1 of the two piece X-axis end cap.
This is a half inch thick piece mounted on top of another half inch piece, and held together by the two black SHCS screws at the 2 and 10 o'clock positions of the big bearings. It's an easy mod to do in any CAD program to copy the hole pattern and then flip it; when you do so, the top hole overlaps the bottom edge, so I deleted it. Of course that leaves only two screws to hold the parts together. The stack-up of two bearings with a shim between them fits perfectly, and stand slightly proud of the top surface (didn't measure). The next part is a motor mount and stepper motor support that mounts on top of this. The motor mount's bore is considerably smaller than the bearings, sized 0.800" while the outer bore at the bearings here is 1.024". The motor mount compresses the bearings to help control backlash.
I started with the Hoss DVD drawings that I purchased for the end cap, and then split them in two. One became the small top piece while the other became the 7x2 (-ish) bottom. I partitioned features between them so that when the two pieces are joined, the result should be the same as the one piece end cap. For example the original part had a dual diameter bore for the bearings: 1.024" that went down 0.638" and the rest of the hole is 0.875". I split that into the top and bottom pieces, so the top is all 1.024 diameter and the bottom piece has 1.024 for 0.138" depth and 0.875" the rest of the way through.
There's a goof up here - in those three holes around the bearings you can see in the top piece. Those are not threaded and are sized to clear an 8-32 screw. The base of the end cap has those holes threaded. That's wrong. The top piece should be threaded. I moved the threaded portion down from the top piece without it registering in my mind that the screws need to thread into the bottom piece but can't because they're not long enough to make it to the bottom piece. What I missed is that motor mount I mentioned that goes on top of this piece. The stack up looks like this (the parts are just stacked - no fasteners - just sitting on the Grizzly with my boring head still mounted.
The motor mount is 3/8" thick, the top of the end cap is 1/2", so a screw has to go through 7/8" of metal before it gets to the threaded holes, and you'd want some engagement there, like another quarter inch (1 1/8). So instead of 3/4" screws, I need three longer screws. No big deal, but if I was starting again, I'd just thread the holes in the top piece and not drill them into the bottom piece at all.
There's another problem lurking in this piece, which is that when I transferred the base (7x2 piece) from the Sherline, where I drilled all the holes, onto the big mill for boring the holes, I flipped it upside down! So the "top view" you're seeing has the two mounting holes left and right of the 1" thick area counterbored on the bottom - backwards. I think that's also going to be fixed by two new screws.
This part doesn't have the stylish tapers that Hoss' part has. I'll have to see if I can figure out how to add those without barfing anything up.
Getting close to time to take the Grizzly apart and add all this stuff.
Bob