MGN12 Linear Rail Kit Assembly Guide
Ender 3 S1 and S1 Pro (Y-Axis)


The MGN12 Linear Rails Kit is designed for the Creality Ender 3 S1 and S1 Pro Printers. Intended to replace the stock Delrin v-wheel rollers, it offers high precision and smooth motion on the Y axis.

  • High Positional Accuracy
  • Complete Y axis replacement
  • Precision machined CNC components
  • Lightweight Modular Y Carriage

Package Contents

Ender 3 S1 / S1 Pro Y axis linear rail kit package contents

Required Tools

hex wrenches thumbnail

Hex Wrenches

The installation will require the 2.0, 2.5, 3.0 and 4.0mm hex wrenches, found in the Ender 3 S1 / S1 Pro toolset.

medium threadlocker thumbnail

Medium Threadlocker

While optional, we recommend the use of a medium strength thread locking compound, used to secure threads on all metal-to-metal connections.

1. Remove Heated Bed

Loosen and remove the bed leveling thumbwheels, then lift the heated bed and set it aside.

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

step 1 - part 1 - remove heated bed
step 1 - part 2 - remove heated bed

2. Remove Y Axis

Tools Required: 4mm Hex Wrench

Loosen the (6x) mounting screws that hold the Y axis extrusion in place. Take the complete Y axis extrusion off the S1 base.

step 2 - part 1 - remove Y axis
step 2 - part 2 - remove Y axis

3. Remove Belt Tensioner

Tools Required: 2mm Hex Wrench

Detach the GT2 belt from the Y Carriage by sliding it out of the notches on each side.

Loosen the (2x) M3 screws on each side of the belt tensioner, then remove the belt tensioner from the Y axis extrusion.

step 3 - part 1 - remove belt tensioner
step 3 - part 2 - remove belt tensioner

4. Remove Belt

The GT2 belt is routed through the center channel of the aluminum extrusion. Carefully remove this and set it aside.

The belt will be re-used after installation of the MGN12 linear rails, adapter blocks and new carriage plate.

step 4 - part 1 - remove belt
step 4 - part 2 - remove belt

5. Remove Motor Assembly

Tools Required: 2.5mm and 3mm Hex Wrench

Detach the Y axis stepper motor assembly from the extrusion by loosening the (2x) M4 button head screws.

Remove the M4 screw and washer from the carriage plate and set these aside. They will be re-used at a later stage.

step 5 - part 1 - remove motor assembly
step 5 - part 2 - remove motor assembly

6. Install Brackets

Tools Required: 2.5mm Hex Wrench

Place the Tensioner Bracket (A) on the front, and Motor Bracket (B) on the rear of the Y Beam (C), then secure in place with the included hardware.

step 6 - part 1 - install brackets
step 6 - part 2 - install brackets

7. Install Motor Assembly

Tools Required: 2.5mm Hex Wrench

Slide the stepper motor assembly on to the rear of the Y Beam, attaching it with the original M4 screws.

step 7 - part 1 - install motor assembly
step 7 - part 2 - install motor assembly

8. Install Belt

Insert the GT2 belt through the center of the Y Beam, then route it up and through the stepper motor assembly.

step 8 - part 1 - install belt
step 8 - part 2 - install belt

9. Install Belt Tensioner

Tools Required: 2mm Hex Wrench

Route the GT2 belt through the belt tensioner, then slide it on the front of the Y Beam.

Use the original (2x) M3 screws to fasten it on each side.

step 9 - part 1 - install belt tensioner
step 9 - part 2 - install belt tensioner

10. Install Y Beam

Tools Required: 4mm Hex Wrench

Place the complete Y Beam assembly on to the S1 base, aligning it with the original holes.

Use the M5 mounting hardware included in the package (C) to secure it. (2x) M5x6mm screws in the front and (4x) M5x18mm screws in the rear.

step 10 - part 1 - install Y beam
step 10 - part 2 - install Y beam

11. Install Linear Rail

Tools Required: 2mm Hex Wrench

Place the MGN12 linear rail (D) on the Y axis beam tube, aligning it with the center set of mounting holes.

Use the (6x) M3x6mm screws included in the package and mount it as shown.

step 11 - part 1 - install MGN12 linear rail
step 11 - part 2 - install MGN12 linear rail

12. Install Y Carriage

Tools Required: 2mm and 3mm Hex Wrench

Mount the new Modular 3-Point Y Carriage Plate using the (4x) M3x6mm screws included in the package (E).

Install the stock M4 screw and washer from Step 5.

Attach the GT2 belt to the front and back of the carriage plate, then tension the belt as needed.

step 12 - part 1 - install Y carriage
step 12 - part 2 - install Y carriage

13. Install Heated Bed

Install the heated bed with the stock springs and bed leveling thumbwheels.

step 13 - part 1 - install heated bed
step 13 - part 2 - install heated bed

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