IIRC the ribbing under the bed gives more clearance than the last 3/4" at the ends, so you can fit the larger X nut if you don't mind removing the tapered Gibb completely everytime you want to get at it. The table would need to tilt.

The Y screw nut fixing runs in a horrid-zontal, U shaped slot. Obviously the nut extends beyond the nut fixing and has to fit under the ironwork. Lengthening the slot would weaken it substantially. This required a bit of angle grinding from below for even the 16mm nut. You may need to deepen the Y screw entry hole on the front of the mill so you can fit the screw a bit lower down.

I found the screws securing the Y nut collided with the column, thus limiting the rearwards Y travel a tadge. Mount the nut further forwards and you may limit it in the other direction. Compromise and lots of measuring required. I got an extra couple of mm by using button heads. Durned difficult to get the angle grinder in there to relieve the iron.

I preloaded all the screw mounts and double nuts to around 1/4 ton, well within the capability of a 16mm screw, but that does set my top load limit for zero backlash.

The accuracy limitation seems to be the head rotating around the centre axis of the round column. My Y axis cuts to better than my digi-calipers can measure, 5um. X leaves a 25-50um excess depending on the final cut. You can't remove 25-50 microns if the head can shy away and rub, you could go round until Dooms Day and it would still be there :naughty:

Robin