The MGN12 Linear Rails Y-Axis Kit is designed for the original Creality Ender 3 3D Printer. It is Intended to replace the stock v-wheel rollers, offering high precision and smooth motion.

Package Contents

Before Starting

Hex Wrenches

The installation will require 2.5mm and 3mm hex wrenches, found in the Ender 3 toolset.

Alignment Guide

Download the alignment guide from our STL library. It's recommended to print this before starting the installation.

Drill Template

If you have NOT purchased our Modular 3-Point Y Carriage, download the drill template from our STL library. This can be used to make the necessary mounting holes.

Prepare MGN12H-300 rail for installation by pre-installing M3x8 screws and T-slot nuts as it is shown here, keep t-nuts slightly loose - ready to be mounted.

1. Remove Heated Bed

Unscrew and set aside the heated bed and mounting hardware. Take care not to lose the springs during disassembly.

The heated bed will later be re-installed on the new carriage plate using the original hardware.

2. Remove Belt

Tools Required: 3mm Hex Wrench

Loosen the 3x M4 mounting screws (1) on the belt idler. Slide the idler back to loosen the belt, then remove clipped belt ends from the carriage slots. Completely remove the stock belt from Y axis assembly.

3. Remove Belt Tensioner

Tools Required: 3mm Hex Wrench

Loosen and remove the stock belt idler from the Y axis.

4. Remove Carriage Plate

Remove the stock carriage plate by rolling it off of the Y axis extrusion. The carriage will not be reused for the MGN12 conversion.

Leave the v-wheels attached to prevent small parts from being lost.

5. Mount Endstop Switch Lever

Tools Required: 2.5mm Hex Wrench

Mount the Y axis endstop switch lever from package (A) to the new Modular Y Carriage Plate (D).

6. Install Belt Tensioner

Re-install the original belt tensioner back on the Y axis extrusion. Finger tighten the screws to keep the tensioner in place.

7. Install MGN12 Linear Rail

Tools Required: 2.5mm Hex Wrench

Install the MGN12 linear rail from package (C) with included hardware. The rear should sit flush against the Y axis motor mount as shown.

Use the printable alignment guide to ensure that the MGN12 linear rail is mounted straight on the top left v-slot channel.

8. Install Adapter Block

Tools Required: 2.5mm Hex Wrench

Mount the adapter block (B) to the MGN12H carriage using the included (4x) M3x6 black oxide screws.

9. Install Modular Y Carriage Plate

Tools Required: 2.5mm Hex Wrench

Mount the Modular 3-Point Y Carriage Plate (D) to the adapter block. Use the (3x) M3x8mm stainless steel screws from package B.

10. Install Belt

Re-install the timing belt and tension as needed.

12a. Install Heated Bed (4 Points)

Mount the heated bed on the Y Carriage Plate using with stock springs and adjustment wheels.

Important! Please Read:

Many Creality 3D Printers come with warped heated beds. This is a well known issue. The heated bed manufacturing process (PCB etching) causes the bottom side of the bed to expand and deviate from flatness.

3-Point bed leveling is an optional modification that will enhance the bed leveling process, but it cannot improve the flatness of the bed. Before converting to 3-Point leveling, carefully check your heated bed's flatness after it has been removed from the 3D Printer. Place a metal ruler across the surface, or lay it on a granite countertop to roughly gauge any deviations in flatness.

If you find that the heated bed is deformed and not flat, you can try manually bending or twisting it back to a flat shape. This procedure is not for everyone, but aluminum is malleable and can sometimes be corrected using this approach. If that does not work, you may need to purchase a new heated bed. We suggest a CNC machined bed with silicone heater to replace the etched PCB aluminum bed. The Ender 3 Heated Bed Kit is available for purchase in our store.

If your Ender 3 heated bed is reasonably flat, and you decided to go with 3-point leveling adjustment for your Y axis MGN12 upgrade - use the cross bar and hardware from package (F) to make the bed modification as it is shown on this drawing.

12b. Install Heated Bed (3 Points)

This is an optional assembly step. Complete it if you decided to use 3-point leveling as described above.

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