I tried a new technique. Instead of squaring the vise before I put a part it, I put a part in and squared the vise with the piece. ordinarily, that wouldn't be a bright idea, but the part was a precision ground squared block:

(I squared it at 12")




So these blocks are the "saddle joints" since I don't have a better word for them:





They create space for larger ballscrews, and they give something for the large saddle plate to bolt into (instead of the linear guides themselves. Not to mention, keeps the spacing of the blocks. I will use a few bolts, and pins to hold the solid plate to the joints (if i ever have to take it apart in the future). Somehow, I have to fit this already 100 lbs beast on my Tormach build to drill the holes through the saddle plate into the joints.