Summary There are a few modification available to address the misalignment of the Ender 3 z axis motor from the leadscrew nut. This version: brings a 4.5 mm misalignment closer to true uses the original screws and includes a gauge for checking the size of the gap. The Ender 3 must be capable of printing obviously to create the model. X, Y and Z axis dimensional accuracy all need to be reasonable to print an accurately fitting part. The model addresses misalignment in the Y direction which is by far the worst and after fitting the Z axis was free to turn by hand with the leadscrew nut securing screws tightened. The Z axis still moved more freely with leadscrew nut screws loose indicating misalignment in the X direction between the motor and the leadscrew nut and/ or the two misaligned in their Z axis. Given the mechanical setup misalignment between the Z axis motor and leadscrew nut is probably inherent in the design. A flexible coupling and backlash prevention nut is probably a suitable option. For practical purpose this is probably not an essential modification. Measured misalignment on assemble was approximately 4 mm. Creating 4 mm of plastic shim proved pointless as the stock screws only accommodated 1 mm of shimming. 1 mm of shim and loosening the lead screw nut securing screws was sufficient to free the z axis from binding and allow accurate, repeatable and reliable operation. Using the gap gauge the misalignment was measured at 4.5 mm and the size this model is made to. Print Settings Printer Brand: Creality
Printer: Ender 3
Notes: Print with small holes (stepper motor screws) toward the bed to avoid the need for supports inside the small holes. Post-Printing Power off and disconnect Power off and disconnect the Ender 3 for commencing fitting. Disconnect the Z Axis motor connector at the motor. Ensure the two screws securing the lead screw nut are loose. Remove the two counter sunk hex head screws securing the stock motor mount bracket to the vertical extrusion. Position the X Axis gantry approximately half way up the Z Axis. Insert the gap gauge between the exiting stock motor mount and he vertical extrusion. Turning the Z axis motor coupler travel the X Axis gantry to up and down the Z Axis three times allowing the gap gates to self position in the gap. The stepper motor will need to held lightly to remain parallel with the vertical extrusion. Ensure that the gap is 4.5 mm +/- 0.5 mm. The gap gauge is in 0.5 mm step between 0.5 mm and 5mm. Measure the gap gauge step that fits if in doubt. If the gap is less or greater than 4.5mm +/- 0.5 mm either modify the model or request a different size in the thingiverse comments. Remove the two pan head, hex head screws securing the stepper motor mount to the stepper motor. Fit the new printed part to the stepper motor. Secure the mount to the vertical extrusion. Check the travel by hand and ensure no resistance or binding is present. If the travel is free, try tightening the lead screw nut securing screw. If no increased resistance is felt, the securing screws can remain tight. If an increase in resistance is few, loosen the screws until the lead screw turns freely (a flexible coupler is probably required) Reconnect the Z Axis motor connector and power on the Ender 3. Test Z Axis motor drive from the Ender 3 control panel. How I Designed This Creality Ender 3 Open Source Design Models Fusion 360 Creality Z Axis Motor Mount model. The model was split and separated but the required gap. Hole tool was used to counter bore the counter sunk holes by the required distance to allow the original screws to still be used.
Addendum A Better Way https://youtu.be/xnzNd_FIMKY The use of a spacer seems like the solution everyone come-up with when building the Ender 3 and that conditions thinking toward building better spacers. The video by Ronald Walters in the attached link seems drastic but is without question the better solution. The E mount bracket is actually aluminium and bends very easily. I found it difficult to get it perfect but easy to get much better than original. Once the bracket is closer to square very light downward pressure on the x axis gantry will cause it travel downward and the z axis leadscrew and stepper will turn without any assistance. I found a bit more resistance in the upward direction but lifting does the same in the upward direction. A flexible coupling takes out what misalignment remains, this is one of the better one's I've found. https://www.makerstore.com.au/product/5mm-x-8mm-flexible-coupling/?yotpo_token=65ac1d59890b024012d58d0b07b25ab17b0312bd&utm_source=yotpo&utm_medium=email&utm_campaign=map I've found leadscrew manufacturers are not specific on lubrication type. They do recommend lubrication for steel lead screw on brass nut. Most seem to recommend oil but usually as a constant flow, that's not practical for most 3D printing requirements so they suggest gel or grease as an alternative an in dusty environments recommend a dry lube such as PTFE or Silicon spray on. https://www.altronics.com.au/p/t3122-white-lithium-grease/