I corrected the X-axis nut holder on Thingiverse to make room for the screws that tie top and bottom together. Since the nut holder is larger than the original, there is some overlap with these screws. 

Hi Marco 64 

 Where did you buy t12 nuts? I bought the t12 TR 12X6-P3

 but the nut is 28mm in diameter, and your part has an 18mm hole

Thanks for your answer