The original extruder wasn't efficient and reliable. So I replaced it by a home-designed holder + a Geetech extruder.
The new holder has been designed with OpenScad and was the las piece printed with the original extruder.
This thing is available on thingiverse :http://www.thingiverse.com/thing:604586
To improve the rigidity of the X axis, I have added a second Z axis (screw+nut+stepper).
The printer and the second Z axis are fixed to a MDF plate. See details on my blog :http://www.astrokraken.fr/2015-01-24-un-double-axe-z-pour-imprimante-3d-qu-bd-twoup-a114396206
Last modification : a "shell" to give to the printer
Do anyone have solutions to improve the rigidity of the Y axis ?
You will find on my blog ( http://www.astrokraken.fr/2015-01-24-un-double-axe-z-pour-imprimante-3d-qu-bd-twoup-a114396206) some pictures showing the Z axis.
The TwoUp is fixed on a MDF plate.
I did 3d-print a stepper holder. The stepper (nema17) is placed in the holder which is fixed to the MDF plate.
I baught a 3/8-12x12 inchAcme screw + flange nut. I fixed the screw to the stepper with a flexible connectior.
I fixed the flange nut to a 3d-printed holder, that is fixed to the X axis.
The additional stepper is wired in parallel with the original Z axis stepper.
If you need it, I can add to my "Things" the files related to the holders.
how did you mount the Z axis