Overview
The MGN12 Linear Rails Kit is designed for the Creality Ender 3 S1, S1 Pro and S1 Plus 3D printers. Intended to replace the stock Delrin v-wheel rollers, it offers high precision and smooth motion on the Z axis.
- High Positional Accuracy
- Complete Z axis replacement
- Precision machined CNC components
- Lightweight components
Package Contents

Required Tools

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 / S1 Plus toolset.

Open Wrench
The installation will require the 8mm open wrench, found in the Ender 3 S1 / S1 Pro / S1 Plus toolset.

Needle Nose Pliers
A pair of small to medium sized needle nose pliers will be called for several times.

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.

Grease
White Lithium, Super Lube 21030 or similar multi-purpose synthetic grease is recommended to lubricate linear rails.

Alignment Guide
Download and 3D print the MGN12 linear rail alignment guide from our STL Library.
Installation
1. Disconnect Wiring
Rotate the 3D printer to access the rear side.
On the left, disconnect the Z axis stepper motor, LED light and filament sensor plugs.
On the right, disconnect the X and Z axis stepper motors, as well as the X axis endstop.
2. Disconnect Ribbon Cable
Detach the ribbon cable from the Sprite extruder by releasing the clamps on each side. Pull it from the black plastic connector housing to avoid damage.
3. Remove Sprite Extruder
Remove the Sprite Extruder assembly by loosening the (4) M3x6mm screws on the right side of the mounting bracket.
4. Remove Gantry
Loosen the (4) M5x45mm bolts from the bottom of the printer base, two per side. Carefully lift the gantry off to separate it.
5. Remove Bearing Holders
There are two bearing holders at the top of the frame, one per side, each held in place by (2) M4x18mm socket head screws.
Loosen the screws to remove the bearing holders, taking care not to lose any of the small parts. Set them aside as they will be re-installed at a later time.
6. Remove Leadscrews
Loosen the (2) clamping screws on each coupler. Turn the lead screws counter-clockwise to back it out of the coupler and through the nut.
7. Remove Z Stepper Motors
To separate the the Z axis stepper motors from the frame extrusions, first slide the couplers off the motor shaft, then remove the (2) M4x20mm countersunk screws securing it to the frame.
8. Remove X Axis
Remove the X axis from the gantry by rolling it off the bottom.
9. Remove Belt
Loosen the tensioner knob on the right side of the X axis, turning it counter-clockwise until the belt goes slack.
Disconnect the crimped belt ends from the carriage by sliding them out of the rear notches.
10. Remove X Axis Motor Cover
Loosen the M3x8mm screws on the top and bottom of the X axis motor cover to remove it.
11. Disassemble X Axis
The Idler and Motor side brackets are secured to the X axis with (2) M4x16mm screws each. Loosen these screws from the back side and completely remove both assemblies.
12. Separate X Idler Assembly
To separate the X Idler assembly, loosen and remove the (3) M5x40mm screws which hold the front and back Idler plates together.
Only the front plate will be re-used. The back plate, v-wheels, spacers and hardware will not be kept.
13. Remove Idler Lead Nut
The T8 brass leadscrew nut from the X Idler will be transferred to the new Z axis kit back plate.
While holding the M3 nut with needle nose pliers from the bottom, loosen and remove the rear most M3x18mm screw and screw cup.
Loosen the front M3x18mm screw, then slide the leadscrew nut back and out of the keyhole.
14. Separate X Motor Assembly
To separate the X Motor assembly, loosen and remove the (3) M5x40mm screws which hold the front and back Idler plates together.
Only the front plate will be re-used. The back plate, v-wheels, spacers and hardware will not be kept.
15. Remove X Motor Lead Nut
The T8 brass leadscrew nut from the X Motor will be transferred to the new Z axis kit back plate.
While holding the M3 nut with needle nose pliers from the bottom, loosen and remove the rear most M3x18mm screw and screw cup.
Loosen the front M3x18mm screw, then slide the leadscrew nut back and out of the keyhole.
16. X Idler Sub-Assembly
To prepare the X Idler assembly for linear rails, install (2) hex stand-offs from Package C and (1) hex stand-off from Package D as shown.
Mount these on the original X Idler front plate using the included M5x8mm button head screws.
17. X Motor Sub-Assembly
To prepare the X Motor assembly for linear rails, install (3) hex stand-offs from Package C as shown.
Mount these on the original X Motor front plate using the included M5x8mm button head screws.
18. X Axis Assembly
Mount the new Idler and Motor assemblies on the X axis extrusion using the original (2) M4x16mm screws and washers on each side.
19. Install X Motor Cover
Reinstall the X motor cover using the original M3x8mm screws, one on top and one on the bottom.
20. Install X Belt
Reattach the belt ends to the X axis carriage by sliding them into the rear notches. Tension the belt as needed by turning the knob clockwise.
21. Relocate LED and Sensor Wiring
To create space for the MGN12 linear rail on the left side, relocate the LED and filament sensor wiring to the outer v-slot extrusion channel.
22. Install Z Motors
Reinstall both Z axis stepper motors using the original (2) M4x20mm countersunk screws per side.
23. Install Linear Rails
Mount theMGN12 Linear Rails using the included hardware from Package F. Tighten the top and bottom screws to hold the linear rails in place, but leave them loose enough to adjust the position.
24. Align Linear Rails
Use the 3D printed alignment guide from our STL Library to ensure the MGN12 linear rails are both straight and parallel.
25. Install Motor Couplers
Place the original couplers back on the Z stepper motors. Tighten the lower clamping screws to secure them in place.
26. Assemble X Idler Side Bracket
Insert the X Idler lead nut into the new X Idler back plate (Package A), then slide it into the keyhole.
Re-use the original (2) M3x18mm screws and M3 nut to securely lock this in place.
27. Assemble X Motor Side Bracket
Insert the X Motor lead nut into the new X Motor back plate (Package B), then slide it into the keyhole.
Re-use the original (2) M3x18mm screws and M3 nut to securely lock this in place.
28. Install Z Brackets
Mount the new X Idler back plate (Package A) to the left side MGN12 linear rail using the included hardware.
Repeat the same step for the X Motor back plate (Package B) on the right side MGN12 linear rail.
29. Install Lead Screws
Thread the original T8 leadscrews through the brass nut on each side until they are firmly inserted into the motor couplers.
Tighten the top screw on both couplers to lock the leadscrews in place.
30. Install Bearing Holders
Reinstall both bearing holders using the original parts and hardware.
31. Align Z Brackets
Fix each pulley with set screws in the uppermost position after both Z brackets are aligned as shown below.
Rotate each lead screw manually until Z brackets on both sides have bottomed out.
32. Install X Axis
Mount the X axis to the MGN12 linear rails using the included hardware from packages C and D.
33. Install Gantry
Attach the gantry to the printer base using the original (4) M5x45mm bolts.
34. Install Sprite Extruder
Position the Sprite Extruder against the X carriage bracket, then use the original (4) M3x6mm sockethead screws to secure it in place.
35. Install Ribbon Cable
Plug the ribbon cable back into the Sprite extruder, squeezing the clamps to lock it in place.
36. Reconnect Wiring
Left side: reconnect the Z axis motor, LED light and filament sensor plugs.
Right side: reconnect the X and Z axis motors, as well as the X axis endstop.
37. Install Cable Clip
Mount the plastic cable clip (Package E) on the back of the X Motor bracket using the included (2) M3x6mm sockethead screws.