Thanks so much for the insight. I value the wisdon gained from experience. I checked out your site, looks like a lot there. I will have to visit when I get some time to absorb it.
I realized that I needed to set it up to define the extents of the machinable volume (including corners) of the rotary space as defined by the ability of the tool to reach all necesary areas. The problem was I defined that 'necessary' area based on the upper, inboard quadrant. I never thought I might want to cut beyond the verical plane defined by the rotary axis.
Of course once you enlightenend me it made sense. I really do appreciate that input.
Being able to lower the rotary table was built into the design at the concept phase.
Part of the reason I concentrated on that upper inboard quadrant is my idea was to have the best of both worlds, albeit in a limited way. I figured that if I could sacrifice a foot of X axis when the rotary was in the raised position, then that would leave me with a useable cutting area of 24"x36" on the table. If I need the whole table the rotary can lower out of the way and I can slide the table over (ingnoring for the moment the potential need to resurface the table).
The lowering of the rotary table would also allow larger project to be mounted, but I was only thinking of surface embellisment on a piece I turned on the manual wood lathe, or platter edge treatments.
I see two options. Make allowance for the tool to travel outboard of the rotary axis (at least to achieve an acceptable balance between outboard travel and remaining usagle cuttion area in the XY plane).
Or, chane the rotary axis orientation (B to A I believe), to be down the X axis. The XYZ Gantry Kit I'm using comes with extrusions between the X rails (along Y) so that it sits on the frame. I suppose It would be possible to either use braces on the ends (which would make stock loading/unloading uncomfortalbe) or use some angle stock and mount the X rails to the extrusions of my frame. I don't know if that will maintain rigidity though.
Anyhow, I will think about it some more and when I get furthur along I will have the frame finished and the XYZ stuff mounted (at least temporarily) and I can better envision the options I come up with.
You've give me a lot to think about, and once again, I appreciate it.