Makerfarm Prusa i3V 12" Lead Screw Upgrade

After accidentally bending one of the Z screws I decided it was time to upgrade them to something higher quality and ideally more accurate.

I found some Lead screws with bearing blocks that looked perfect.
from here
http://www.qtecstore.com/pages/screwdrives/8mm_495_1_screwdrive/page.html

It took 3 weeks to get them once ordered but they look great! really solid and smooth.

I made a new Bracket for the Z Steppers and also a plate to mount onto the X rails.. plus a top support for the bearing.

I used a shim for set up in the pictures. but I have updated the parts so this shouldnt be needed anymore.

had to update the steps in marlin from 4000 to 2560 to adjust for the difference in Z height per rotation

I also added a backup Z endstop, incase the Nozzle one day decides it wants to go down or my ABL Servo doesnt deploy.
I feel this is necessary. as there is no more nut trap safety mechanism as on the stock makerfarm setup.

I also re-added springs to the hotbed. (prevously removed) for the same reason.