Linear rails AND a lightweight direct drive extruder via the Biqu H2 are a great upgrade for your Ender 6. I designed this solution as I wanted to convert to linear rails as well as direct drive with the minimal number of adapters (this is a 1 piece solution). Excluding printing time, this modification should take approximately 2 hours. After this upgrade you can print more accurately, handle flexibles like TPU and never worry about plastic rollers wearing out on your X axis. I also highly recommend using Klipper with input shaping tuned properly to maximize results overall on this printer.
1X 250mm MGN12 Single Carriage Linear Rail note: Clean and lube appropriately before installation to ensure a long life 4X M3x20mm SHCS (Socket Head Cap Screws + Washers) 4X M3x12mm SHCS (Socket Head Cap Screws + Washers) 4X M3 T-NUTS 2X Zip Ties (for simple cable management with the provided holes)
This is a fairly easy print, run at a speed your printer can faithfully produce accurate dimensions. Print at 100 percent infill, basic supports are needed. I printed one in NylonX, and CNC'd one from aluminum solely because this printer has a heated enclosure and I felt PLA might be inadequate at 60C+ ambient temperatures for this role. For non actively heated enclosures PLA/ABS/PETG will work great.
Remove supports and move on to assembly.
You will want to print two 2020 MGN12 Linear Rail alignment jigs to facilitate accurate installation of the linear rail.
Unplug your printer and remove all the wires/fans from the old toolhead carriage assembly. Loosen the X and Y motor tensioning fasteners. then slip off both belts from the old toolhead carriage. Now you can remove 2 of the old plastic wheels and take the entire assembly out. Place the m3 fasteners and t-nuts on the linear rail and set in place on the 2020 extrusion.
Note: BE SURE you use a mgn12 2020 alignment jig to get the linear rail straight before tightening it down.
Next you will populate the new printed linear rail biqu h2 adapter with the Biqu h2 unit, fans, x stop switch and duct of your choice. You may then tidy up your wire loom, and install the completed assembly onto the linear rail. Re-attach the belts and tighten them using the X and Y stepper tensioning screws. Test motion and that the limit switch is making proper contact before powering on. The Biqu H2 extruders (I have two) have been reliable and great performers for me. I converted them to all metal and print nylon at 120mms/5-8k acceleration with great results.