Ender 3 Linear Shaft Mod

Caution: 

• First off I am not responsible for any damage that may occur to your printer in attempting this mod. (not that this mod does any irreversible damage that can’t be fixed for under 5$)

• Secondly, this mod is for the base Ender 3. I repeat, this mod will not work on the Ender 3 V2 or the Ender 3 Pro.

• Thirdly there is one print that needs to be done before the installation of this mod a belt tensioner for the y-axis which will be linked 

Updates:

Rev.1 (3/25 /2024): Minor adjustments to threaded insert holes after some feedback.  

Overview:

The linear shaft mod seeks to fix the design oversights of the ender 3’s very finicky y-axis, more specifically the bed wobble that came with the decision to mount the bed on a thin 2040 aluminum extrusion (which were upgraded in the Ender 3 Pro and Pro v2 the 4040 aluminum extrusion)  by providing a sturdy linear shaft system to replaces the v-rollers on the narrow 2020 aluminum extrusion. This mod is extremely cost effective and can easily be had for under 50$ or even less if you have you have some of these parts lying around.

The Design Process (for those who care <3):

This mod came about as I received a base Ender 3 from a friend of mine for a very good deal. However, the base ender 3 did have some issues when I used it. The biggest problem being that the V-Rollers on the Y-axis seemed to wear out after a few prints even after adjusting the two eccentric nuts on the bottom. 

Being the frugal college student I am, I decided to see if I could remedy this problem with stuff I had lying around I spotted My linear shaft that I gutted from my sermon D1 (terrible printer btw don’t buy it) after doing a certain Y-axis mod from Proper Printing. I harvest the rail and linear bearings and got to work. 

It took a few iterations and some time in fusion 360.  By which I mean didn’t take into account the extra height from the design of the first sled and the z-axis couldn’t home. Then the heated insert didn’t fit. And of course the 3rd time around I put the wrong inserts in because of course I did. But when everything was done it was looking pretty spiffy.

(The first successful iteration)    (The One with the big boi sled that doesn’t fit)

I used this mod for about a month and tossed around the idea of posting it but one issue was the the rods I used were specifically sized at 370mm for the Sermoon D1. I spent 2 minutes in Fusion 360 and adjusted it for you guys.

Materials:

All of these can be sourced from aliexpress for very cheap and many parts you may have lying around already

• 4✕ M5 x 10mm threaded inserts
• 4✕ M5 x 10mm button head screws -----------------> For the sled
• 8✕ M5 washers
• 4✕ M2 x 6mm threaded inserts
• 4✕ M2 x 8mm screw or a grub screws if you have them
• 4✕ M2 nuts
• 2✕ 8mm x 350mm linear shafts
• 2✕ linear bearings LM8LUU

• 1✕ M4 x 20mm hex screw
• 1✕ M4 x 30mm hex screw----------------------------> For Mounting the motor

• 4✕ M2 x 6mm threaded inserts (optional)
• 4✕ M2 x 6mm screw or a grub screw if you have them (optional) ---->Securing the shafts

• 6✕ T-slot nuts
• 2✕ M4 x 10mm-------------------------> Front and back mount
• 4 ✕ M4 x 15mm

Note: if you're lucky enough to have a local hardware store the screws can be individually bought for 2$-3$

Printed parts:

• Front mount
• Rear mount
• Sled
• Belt tensioner (I used the x - axis one for the y axis as it only takes the top rail) link: https://www.printables.com/model/302473-ender-3-xy-belt-tensioner/files 

Print Settings:

• I recommend printing these parts at 3 walls and 75% not because these aren’t sturdy but because it frickin rattles with lower infills as the vibration of bearings on the rods resonates with those larger cavities.

• The parts can be printed in PLA as they are fairly far from the bed heater and I’ve tested prints of ABS and PETG in an open air environment and experienced 0 warping so far but we will see how it holds up long term (obviously print this in Petg or abs if your printer is in a heated enclosure)