Ender 3 Dual Z-Axis Upgrade

Let me begin by saying that it may not be especially cost effective to add a second lead screw without a purchased kit unless you just happen to have a spare 350mm lead screw, stepper motor, coupler, brass nut, and additional metric hardware for doing so.  This model does however correct a problem inherent to Creality's original design.

I tried to use Egco's “Ender 3 V2 Dual Z-Axis Upgrade” on a pair of Ender 3 Pro's I'm working on, but it didn't quite fit.

I found the holes for mounting the brass nut to be 5mm too far from the vertical extrusion and 4mm too far left on the right for the lead screw to be parallel.  I had previously edited mknet's “Ender 3 / Pro / V2 Z axis motor mount” piece Egco linked to so that it could actually work on the right side of the machine, so I've added that edited file as well.

The things I liked most about Egco's design is that he's properly attaching it to the X axis extrusion with a long screw and spacer leaving the camnut and axle on the right side connected only to the inside plate.  I'm not sure why the Creality dual Z kits aren't set up that way, nor do I understand why Creality incorporated the same design flaw on the left side of the machine.  The left side can be corrected by replacing the long axle screw with a shorter one and omitting the standoff.

I added two holes to the 4mm base plate of Egco's design.  The hole on the right allows head-on access to the screw holding the steel plate on the outside.  The hole on the left is there to allow for the use of a 40mm screw to hold the camnut and pom wheel, although I still recommend using the original 30mm screw that came with the Ender 3.

The raised portions around the two screw holes for the outside pom wheels, combined with the 4mm thickness of the printed plate means the standard 40mm screws that Creality would use for a second lead screw are just a bit too short to make good use of nylock nuts, so I recommend picking up two M5 x 45mm button cap screws for those wheels.  The 45mm screws allow for adding flat washers before the nuts to prevent the nuts from digging into the plastic while tightening.

As for the 27mm spacer, I'm using a M4 x 50mm screw with both a split and flat washer for maintaining tension without cutting into the plastic plate.

The cut version of mknets motor mount can be used on either side of the machine now with T-nuts.

The brass nut I'm using for the 2nd lead screw is an Anet style round 4 hole nut, which is what Egco intended for his original design, simply because those are what I have handy.  The Creality style nuts with two flat sides will not directly fit this model.  Without taking one of my machines apart that uses the Creality style nuts, I'm unable to take proper measurements.  If there is any interest in using the other style brass nut with this design, drop a comment and I'll revisit this design adding a second version of that part that accepts those nuts.

I print all these parts as oriented in the STL with 100% infill and no supports.

UPDATE 12142024:  I added a version 2 of the carrier bracket for use with the flat sided brass nuts that come stock with Creality machines.

UPDATE 01122025:  I added two new versions of the right side carrier.  When I recently overhauled the designs for both rear carriers on my Tronxy XY-2 Pro, I added a large wide round opening to the under side of the carriers to eliminate clearance issues with couplers for those using taller stepper motors on the Z axis, and shaved some material from the very bottom of the carriers to prevent them from bottoming out against the stepper mounts.  Because those changes improve compatibility with more machines and different configurations, and because I needed to reprint the right side bracket for color matching purposes on my Ender 3 Pro, I decided to add those same changes to my Ender 3 right rear carrier design.  Version 3 is the model I'll be printing and installing on my Ender 3 Pro since I'm retaining the round Anet style brass nut.  The Version 4 file has all the same changes, but is for using the Creality style flat sided brass nut.  I currently have no intention of creating a left side rear carrier for the Ender 3 as I'm using the original steel bracket for anchoring my cabling to the direct drive toolhead on that machine, but if somebody needed a rear carrier for the left side of the printer without the Bowden extruder mount, I suppose it wouldn't be too difficult to tear down an Ender 3, take some measurements, and make the necessary changes to the left rear carrier I designed for the Tronxy XY-2 Pro.  

Where the “Z Axis Carriage.stl” is concerned, I didn't so much remix it as I remodeled it from scratch, simplifying the design.  I relocated the brass nut openings 5mm towards the front and 4 mm to the right of the machine as mounted and reduced the profile of the part by 5mm.  I recessed the hole for the brass nut and resized the retaining nut cut-outs to properly fit M3 fasteners.   I'm calling this a remix because I used so many of Egco's design elements…

Where the motor mount is concerned, I removed the bottom 12.5mm of V-slot material to allow for the use of M4 T-nuts to mount this part.