A dual Z axis upgrade with a single stepper is in my opinion a must have for the Ender 3 because this increases the accuracy and reliability of the machine. I have designed one which uses standard parts which don't need to be modified and it is combined with the frame braces I have designed earlier https://www.thingiverse.com/thing:3719799
I have added corner pieces without the frame braces if you are just interested in the dual Z axis. I have designed the bracket to be as stiff as possible and therefore it has this odd shape which I am quite happy with. I have made a video about this upgrade in which I show the process https://youtu.be/nBVrcIZ095Y
I have bought all parts from RepRapWorld and it happens to be that the 696 mm closed loop timing belt together with the two 60 teeth pulleys have a center distance similar to the two vertical beams. All holes are slotted so it can be adjusted a bit.
The power supply must be placed somewhere else and I have seen that there are some mods which enable you to do this. I will make an enclosure soon and this will have impact on the power supply placement so I have not created a solution for this.
EDIT: I have created a solution for this: https://www.thingiverse.com/thing:3773553
Please consider buying me a coffee if you liked it or helped you :) http://ko-fi.com/properprinting/
I have added a picture of the orientation of the two upper corners which proved to be successful for me.
I have used the existing screws for mounting the bracket, but I think slightly longer screws work better. I'll get back to that.
- Remove the power supply and Z-axis motor (leave the existing lead screw in)
- Remove both top end caps
- Place the top left corner piece (the one above the Z-motor)
- Press both bearings in
- Press the existing lead screw through the lower bearing and add the pulley together with the timing belt
- Press the lead screw through the pulley, the upper bearing and far enough for the Z-motor and coupler
- Place the Z-motor and mount it to the lead screw
- Fasten the pulley
- Add the top right corner piece and press both bearings in
- Add the bracket with the 300mm lead screw and nut (use a 10mm drill to widen the hole for the lead screw nut if necessary) and do not press the lead screw nut in yet
- Press the 300mm lead screw through the lower bearing and add the second pulley together with the 1mm shim and timing belt
- Press the 300mm lead screw to the right height (just above the upper bearing) don't fasten the pulley yet
- Press the lead screw nut in the bracket by rotating it downwards and mount it
- Adjust the height of the gantry so that both sides are at the same height. This can be done by rotating the 300mm lead screw and holding the pulley still
- Once the gantry is horizontal you can fasten the second pulley and enjoy printing
If you have any questions or suggestions, don't hesitate to leave a comment or contact me.