You can use all 4 holes on the inner sets of bearings, so gusset(s) there would work. However, the outer bearings that carry the R&P can only be attached with the inner holes.

I have been contemplating building some plates that I could use to 'pin' the inner and outer bearings together without using any screws, but I haven't found it to be necessary. The two bolts on the outer bearings seem to be enough to hold them in place. Having extra attaching points on the inner bearings just adds redundancy.

Just my opinion.

Jay

FWIW, here is a link to my gantry design. Hopefully it can help you in some shape or form.

http://www.cnczone.com/forums/897949-post116.html