Upgrade the Ender 3 to Direct Drive and Dual Blower Fans (for Cheap)

The ender 3 is a cheap, open-source 3d printer that is ideal to tinker with and modify.

Recently I've been trying to get the best quality possible out of it, and so decided to switch to a direct drive. You can read more about it here.

I wanted to spend the least amount possible - hence, buying a direct extruder such as the titan or a bmg was out of the question.

I decided to use the original extruder. Some might argue that it adds too much weight, but I think the glass bed will be more impactful on maximum printing speed. Also, the results I've read from other people doing it have all been great.

In parallel, I also wanted to upgrade my cooling system. I already had a petsfang, which is incompatible with the direct dive mod I chose, and being obsessed with silence I figured two blowers instead of one would enable better performance with less noise.

The whole system needed to be compatible with my BLTouch.

Make sure to print all required parts before starting the build, as otherwise you will be unable to print.

You will need to print these:

Double blower fan mount or bltouch version. It does not fit perfectly, so you will need to either remove some plastic, or print my remix instead (BLTouch version).
Hotend cooling duct
Direct drive adapter for stock extruder - don't forget to print the endstop spacer !

Supplies

M3 and M2 nuts and bolts
Noctua fan (optional - for silence)
2 Blower fans
BLTouch (optional)

Step 1: Direct Drive

If you search on thingiverse there are many adapters to turn the ender 3's stock extruder into a direct drive.

I decided to go for this one because it fit my criteria:

Compatible with a dual blower fan mod
Motor as close as possible to the middle of the X extrusion
The creator argues that the motor being perpendicular to the X extrusion provides good absorption of rotational inertia - which I believe as well

Once printed, you need to insert the two printer's sleeves into the print holes. They are very tough to fit, I eventually melted them in with my soldering iron.

After installing everything, make sure the eccentric nut is tight.

Then you can assemble the extruder in, which is pretty straightforward.

Finally, don't forget to print the endstop to stop the stock motor from slamming into the frame !

Step 2: Install the Dual Blower Part

The next thing to do is install the dual blower part. I printed the BLTouch remix, but if you don't have one, you can print the part without the bltouch mount.

Warning: unfortunately this part won't fit in perfectly with the direct drive adapter installed. You will need to remove some plastic, or print my remix.

There are two screws, but don't screw them in completely just yet, as we will need to check height after installing the hotend and nozzle.

Step 3: Install Hotend and Fan Duct

First we need to take care of the bowden tube.

You need to cut a bowden tube to just the right length, so it can fit between the extruder and the hotend.

Here's the rundown:

Unscrew the hotend and both compression fittings (extruder and hotend)
Get the hotend up to printing temp (be careful not to burn yourself)
Remove the old bowden tube
Unscrew the nozzle around one full rotation - this will ensure the tube is flush against the nozzle
Screw in the hotend's compression fitting
Push in the new tube until it bottoms out against the nozzle. I used a capricorn
Install the hotend in front of its screw holes and mark where to cut the tube (so it's flush against the extruder's compression fitting)
Cut the tube vertically with a cutter or with a dedicated tool
Try fitting the tube in the extruder's compression fitting, and screwing in the fitting - you should now be able to screw in the hotend. If not, cut the tube a bit shorter
Once perfect, install the hotend cooling fan part on the hotend (see below)
Make sure both compression fittings are tight
Screw in the hotend, and then the nozzle

This is a lengthy process that should be done carefully as ensuring a fit tube will avoid clogging problems. Don't hesitate to cut the tube longer that necessary and then adjust.

For the hotend cooling fan I printed this cooling duct.
It's a snap-on, easy to install. You're supposed to be able to slid it in, but I couldn't manage to do it with the hotend already screwd in. So I snapped the hotend in the part first, then screwed the whole thing in, then added the fan.

Once the hotend is installed, check if the leveling of the fan ducts leaves enough clearance for the print - so they don't scratch against the surface. Then, screw in the assembly completely - but not too tight, or the plastic will crack.