The bolts for mounnting the X travel rails are too long. As is, they bottom out in the extruded aluminum approx. 3/32" before the rail meets the aluminum. In the "Rail Hardware Pack" bag there are what I imagine thin plastic shims but no where near enough to do the job. There is no mention of these shims in the assembly manual. The gap is large enough I could stuff a 1/2" flat washer in-between the bottom of the rail and the top of the aluminum and that will take up enough space so the bolts tighten and hold the rail firmly in place. Grind the bolts? ShopBot not open until 9:00 Monday :-(