Ender 3 / Pro CR-10 Direct Drive - Simple and Robust

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This is a straightforward 2-part design that converts the standard Bowden-style extruder of an Ender 3 or Ender 3 Pro into a direct drive extruder. NO EXTRA PARTS (except for two screws) OR DRILLING REQUIRED! You simply need to have these parts: 1- An M3 30mm screw, which can be slightly longer if needed. This screw replaces the fan cover screw and connects the Direct Drive Carriage to the X carriage. 2- An M3 16mm screw, which replaces one of the four screws for the extruder assembly. It also connects the Extruder Spacer to the Direct Drive Carriage. 3- You need to print DirectDriveCarriage.stl and ExtruderSpacer.stl. The Extruder spacer does not require any supports, but the Direct Drive Carriage requires a small support due to an overhang. For other connections, I used screws for the top wheels of the X carriage, eliminating the need for any holes to be drilled. This conversion is reportedly the simplest one for Ender 3 and takes about 10-15 minutes if you know what you're doing. Assembly recommendations: 1- Completely disassemble the stock extruder. 2- Disassemble the top wheels of the X carriage. 3- Unscrew one bolt from the fan cover (top bolt). 4- Place the spacer from the right wheel of the X Carriage inside the Direct Drive Carriage. Note that it will be tight, so you might want to use a vise; avoid using a hammer and be careful not to break the part. 5- Place the Direct Drive Carriage on top of the X carriage; it should click into place. 6- Assemble the left wheel (looking from the front) of the X carriage, followed by assembling the right wheel. You may want to adjust the bottom wheel nut so that the carriage is not wobbly at this point. 7- Assemble the extruder parts on the Extruder Spacer; leave one screw empty (the right bottom screw below the extruder spring). 8- Cut the PTFE tube so that there's no space between the extruder and the tube when everything is assembled. This is mostly trial and error, but I recommend cutting it a little longer and working your way down; otherwise, if you cut it too short, you may have to replace the PTFE tube, which can be inconvenient. 9- Place the Extruder Spacer assembly on top of the Direct Drive Carriage. Adjust the PTFE tube length by cutting it with a box cutter; note that when you tighten the bolts, it will most likely push down the extruder a little, so make your adjustments accordingly. 10- Tighten the two screws on the Direct Drive Carriage evenly. 11- Enjoy your direct drive Ender 3 / Ender 3 Pro / CR-10. Don't forget to change your slicer settings and reduce retraction to 1mm or lower; for some filaments (mainly PETG), I used 1.4mm as well because of the strings. I also recommend increasing machine limits (acceleration, jerk, etc.) so that you can print faster. I use Prusa Slicer with increased limits and am able to print much faster without issues. I've converted both my Ender 3 and Ender 3 Pro using this design and have run the printers for over 100 hours combined; as far as I recall, I didn't have a single issue. I mostly printed face shields as PPE for healthcare workers using PETG; with correct settings, stringing was minimal. I also printed some flexible filament and ran into no issues whatsoever. If you want to make a remix, send me a message, and I'll upload the Fusion 360 files.