OK, I've been working hard on this, following everyone's advice and ideas, and here's what I have learned: First, bolting a 3/8 steel plate to the gantry has helped immensely. You can't get any flex out of it now with a crowbar. Secondly, I cut circles (as per Bill's suggestion), squares, pockets and profiles, and I tried all kinds of different offsets. What I discovered is this -- when you do an offset, you are left with the original vector and the new one, and unless you magnify the area, you can't see that there are two vectors there. You need to delete the outside one. This, of course, doesn't explain why the profile is still coming out bigger than the pocket, but I have used all the slightly oversized veneers I made by making them smaller on the spindle sander. Tomorrow I will generate a new design and, starting from ground zero, see if the same thing happens. BTW, all the circles and squares measured out exactly as they should have. I am sure that the machine is cutting accurately.
Rich, I am not aware of the compensation technique you mentioned -- how do I do it?
Thanks again, Bob