Dual Z Ender 3 Complete System

A complete dual-z motor modification for the Ender 3 and Ender 3 Pro.
! Requires removing the PSU from its location to accomomdate the second leadscrew!

Required hardware:

• 3 M5x40mm screws to replace the existing M5x30mm screws holding the X gantry on the PSU side
• NEMA17 motor ( with or w/o leadscrew)
• 300 to 400 mm leadscrew (your choice)
• T8 lead nut (the one that slides on the leadscrew)
• shaft coupler 5 to 8mm (if you buy yhe leadscrew and motor separately)
• 4 M3x10mm screws for fixing the T nut
• 8 M3x10 screws for mounting the motor to the holder and the holder to the frame.
• 2 M3x10 screws for mounting the leadscrew holder to the frame.
• 8x22x7mm bearing
  Just get a bag of mixed M3 screws. They are always handy to have.

There are 3 main printed components:

1. The motor holder - holds the nema17 motor to the 4020 frame, where the PSU used to be
2. The X gantry holder - mounts on the 3 M5 screws that replace the 3 M5 screws on the PSU-side of the X gantry (see photos)
3. The leadscrew holder - a bearing holder designed to stabilize the leadscrew rod.

Printing:

1. Easy print. 0.2mm, use more perimeters than usual.
2. Needs support, print with the screw holes up. 0.2mm, use many perimeters.
3. Easy print, 0.2mm.
   I used PETG, I wouldn't recommend PLA since it is brittle.

Installation:
First, install the motor and holder to the frame using 3D printed T nuts that take M3 screws. (https://www.thingiverse.com/thing:3050607 like these)
Then, remove the 3 screws that hold the right side of the X gantry. insert the new screws in and position the triangular holder over them. Make sure it sits with no tenstion, then tighten the bolts.
Last, mount the leadscrew holder and insert the bearing.

The extra motor will be run off the first motor's cables. You will have to splice the cables and solder the wires going to the second motor. They will run on the same stepper driver obviously.

I found a nema17 motor that has an integrated leadscrew, and so I used that one. I would recommend having them separately and an elastic coupler between them to reduce tension, but this is ok too.

There you go! You now have dual Z leadscrews on your Ender!

!NOTE!
Be careful about the 2 Z motors desynchronizing. This can happen if you manually move the Z axis like you are used to. DON'T move the X gantry by hand! This will introduce skew in the X gantry. Just use the Move Z Axis printer feature. I found this out the hard way - my BLTouch was thrown off balance.

For alignment, just use 2 items of a fixed length, place them below the X gantry, and press the X gantry on top of them. Do this with all the screws loosened. When properly seated, tighten the screws. It should all be ok now. Or you can simply measure the distance with a caliper or smth and adjust each lead screw manually.