"Relatively" simple mod for the Ender 3 V3 SE

Before you continue please read over the BOM and make sure you have everything, especially the printed parts! And remember I am not liable to any damage to your printer, you are doing this at your own risk! READ THE INSTRUCTIONS, if there is anything you are uncomfortable doing please do not attempt this!

I've been using this mod for the last 2 months this is the best way I've seen to do it so far so I have released it.

Best way to contact me about support is on the Ender V3 Series discord, just join in on the #se-upgrades post I made! - https://discord.gg/SHRjWrDfEW

Currently you will have to reduce build volume size back to the 220mm on X like stock, there is a fix in the works but it still hasn’t passed my QA yet.

BOM:

• 1xMGN9C 300mm Linear Rail (Make sure to click on the correct item before purchasing) - https://www.aliexpress.com/item/1005002516956172.html?
• 2xMGN9 Alignment tool - https://www.thingiverse.com/thing:3533580
• 3xM5-0.8x10mm Flat Round Head Screws - https://amzn.eu/d/g4peaSg
• 7xM3 drop in T nut - https://www.aliexpress.com/item/1005005751429865.html?
• 11xM3x12mm Screws
• 4xM3 washers

Printed Parts:

Please don't slice the STEP files, they are for reference only not for printing!

• 2x Rail Left-right (100% infill)
• 1x Rail Middle (100% infill)
• 1x Rail Mounting Block (50% Cubic infill, 5 walls, 7 top/bottom layers, printed on its side with the nuts vertical, use tree supports for the lower nut hole! This increases strength)
• 1x Rail Endstop Extension (50% Cubic infill, 5 walls, 7 top/bottom layers)

Print the shorter version of the endstop extension if you have a dual 5015 fan shroud, or you could print both and see which one triggers the endstop, please test this with the motors off and then you should be able to hear a click from the endstop.

Print all parts in PETG, ABS or ASA. PLA will not work and will cause issues! Remember slow and steady wins the race, this has lots of 45 degree overhangs and PETG doesn't like that, slower is better trust me. I printed at 120mm/s on my V3 SE and it turned out great

The rail mounting block should be aligned like this in slicer with auto tree supports, I havent had any issues printing with the auto supports, but your slicer may vary in results. This is OrcaSlicer 1.9

Instructions

Removing the stock carriage

• Remove everything from the X carriage, down to the metal plate at the back
• When everything is removed from the carriage, remove the X tightening belt so you can release the carriage. you will need to remove the belt tightening on the right side of the belt
• Remove the belt from the carriage
• Remove the nuts at the back of the V wheels, the lower one can be loosed with the eccentric nut, just give it a spin and it should loosen
• Keep two of the nuts from the V wheels, as we will be using those later

Cleaning/lubing the Rails

• Get your 300mm Linear rail out and make sure to clean it thoroughly with IPA (Isopropyl Alcohol) and then lube with lithium grease (preferably EP1 but if it is a high price, like here in the UK EP2 will work too) heres a great youtube video on explaining how to lube rails -

Mounting the Rail

• Once lubed, place the rail onto the X carriage, make sure to not let the block fall off the rail! If this happens you will need to buy a new block as it is nearly impossible to put the little ball bearings back in. You can use the stoppers that hopefully came with the rail to keep it on there for now
• Insert all of the M3x12 screws into the rail where they should be, two on the left, three in the middle and two on the right then add the stoppers on there, they might need to be screwed in slightly but thats ok. Then add the M3 T nuts on there very loose. you want them all to be aligned together in the direction of the rail.
• Place the rail onto the X aluminium extrusion and let all of the T nuts go into the extrusion.
• Gently tighten the most left screw and most right screw, not so its super tight, so you can still move the rail
• The rail should be all the way to the right, up against the plastic end section of the extrusion (like in the cover photo)
• Align the rail to the extrusion using the alignment tool, double check the distance between the frame with some callipers if you have them, this part is critical to having an accurate printer!
• Once aligned, screw in the rest of the screws tight, this is needed for the T nuts to be in the correct position, double check alignment after this, with the alignment tool and callipers
• Ensure the height of the rail is the same across the rail, use callipers to measure the distance between the rail and the aluminium extrusion, it should be around 9mm but it doesn't matter the exact value, as long as it is the same across your rail.

Attaching the carriage onto the rail block

• Get the two M50.8x10mm screws and the metal plate that would normally attach to the V wheels and put the screws in the top two holes, then place the nuts from before into the Rail Mounting Block print where there is the slots for the nuts, it should be a snug fit
• Screw the nuts in and make sure its tight! Depending on printer accuracy these holes might be slightly off but should still work
• Using 4 M3x12 screws with washers on, screw in the the mounting block to the rail block, make sure this is tight as well
• If you have the V2 Mount please refer to the next step before continuing to reassemble the printhead
• Assemble the carriage assembly like normal until your printer head is fully assembled.

How to install the belt on V2

• With the new mounting plate improving the location of the belt it is a little more tricky to install
• You will want to start by getting your belt, and flipping it 180 degrees before you put it into the printed plate. When its installed you want the belt to be nice and flat without any twists so turn the belt so it sits like that when installed. I don't know a better way to explain this in text so I hope this makes sense!
• Make sure that the belt is securely fastened as it would be with the stock metal plate, the belt should go behind the printed bracket as well

Replacing the X endstop

• Unscrew the hex screw under the X endstop (its on the left side of the gantry)
• Remove the old endstop, try and keep the bearings in place (it makes it easier to put the new one in
• replace with the new endstop, make sure to make it tight and aligned correctly