I am working on a beltless printer so i modified the x ends from hugo originsals to fit in place a 6mm rod 33cm long to hold 5 modules of herringbone rack and the carriage to fit a nema 14 stepper.
Inspired from http://www.thingiverse.com/thing:22475 (resolved the rack from exiting the printer area), and http://www.thingiverse.com/thing:37787 (i intend to use this on y axis).
Printed the parts with no support material but have not tested them yet so i don't know how they work.
I will say more after i finish the printer. Hope it is a good contribution.
Print the parts with no support material.
5 herringbone rack
1 x end left
1 x end right
1 x carriage
Use 7 lm8uu
Use 2 8mm smooth rods 33cm long.
Use the 5 rack pieces with 6mm rod 33 cm long.
When you mount the rod on the left and right ends be carefull to maintain the right distance between the 2 ends.