Mega Mosquito

To spare you from wasting your time let me first explain what this is not:

• This mod is not optimized for fast printing, but for robustness, safety and first of all print quality.
• It's not designed to be quickly (dis)assembled, either.
• The fan duct needs to be printed with a temperature-resistant material like ABS or PC (ideally PC-FR), which can both be a challenge with the Mega X.
• You will find neither a cabling guide nor instructions for enabling BLTouch support and calibration here.
• I'm not sure whether the original hotend PCB will fit - I abandoned that long ago because of reliability issues.
• You might lose a few millimeters of print volume on both the X and Z axis.

What it does feature:

• high reliability (I've been using/testing/optimizing it for almost two years before deciding to finally make it public)
• extreme part cooling capabilities with two 5015s
• total protection of the BLTouch pin when it's retracted
• easy access to the adjustment screw of the BLTouch
• deflection of the hotend cooling air stream away from the print bed
• the option to add a dedicated fan to the Mosquito hotend for more direct cooling
• the nozzle is as hard to reach as possible when printing (for safety)
• enough space to accommodate other hotends like E3D V5 and V6, Phaetus Dragon and Dragonfly (I did not design any adapters for those, but that's pretty easy)

Bill of Materials

• Mosquito hotend with heating element and thermal probe
• 1x 4010 axial 12 V fan
• 2x 5015 radial 12 V fans (I recommend Sunon MF50151VX-A99)
• 1x 2510 axial 12 V fan (optional, for direct hotend cooling)
• 2x M2.5x25 screws with matching nuts (only if you use the 2510 fan)
• BLTouch sensor (optional)

For the Mosquito adapter:

• 4x M3 threaded inserts
• 4x M3x6 screws
• 2x M2.5x6 screws
• 1x PC4-M10 pneumatic fitting (your standard bowden tube fitting is actually PC4-G1/8", but most are sold as PC4-M10)

For the BLTouch adapter:

• 4x M3 threaded inserts
• 4x M3x6 screws

For enclosure and fan duct:

• 10x M3 threaded inserts
• 2x M3x6 screws (for the top)
• 2x M3x12 screws (for the back)
• 2x M3x6 countersunk screws (for the bottom)
• 4x M3x14 screws (for the enclosure fan)
• 4x M3x25 screws with matching nuts (for the 5015s)

All screws may be slightly longer than stated here.

Printing

Since the fan duct is rather close to the Mosquito heat block it has to be printed with a temperature-resistant material like ABS or (even better) PC-FR.

If you use the 2510 direct cooling fan, you'll also want to print the "Mosquito Air Deflector" part - this needs to be rather temperature-resistant as well (PETG is probably enough, though).

All other parts can be printed with PLA.

You'll probably need supports for the fan hole of the enclosure and maybe the "fins" of the fan duct. Nothing else requires supports.

Everything prints fine with 0.2 mm layer height.

Assembly

Melt in all threaded inserts.

Screw the Mosquito to the adapter (it needs to be taken apart for that). These screws need to be driven into the plastic directly, because there's simply not enough space for threaded inserts there. Next screw in the PC4-M10 fitting and screw everything to the original top plate.

Screw together the BLTouch and its adapter. The BLTouch's PCB should be on the same side as the "slot" in the adapter. Also attach it to the top plate (mind the direction, the PCB should face away from the Mosquito). Make sure it's as close to the front as possible.

If you intend to use the direct 2510 fan, attach it.

Now is a good time to wire, test and calibrate everything, the components will be hard to reach once the enclosure is installed.

Screw the 4010 fan to the enclosure and test it.

When everything works, screw the enclosure to the top plate. Then attach the fan duct to the enclosure, bottom screws first, then the backside screws.

Lastly install the 5015s and test everything.

Important Notes

• Even if you use PC-FR for the fan duct, never heat up the hotend without using a silicone sock!
• If you print materials with higher temperatures than usual for PLA, better turn on the part cooling to at least 10% before heating up the hotend.
• Only attempt this mod if you know what you're doing. I'm not responsible for any damages to your hardware or to yourself.
• You must calibrate the BLTouch! Probe-to-nozzle offset is -27 mm on the Y axis, 0 mm on the X axis. Z offset needs to be precisely tested - for me it was -2.48 mm, but every assembly is slightly different.
• You should also PID-tune the Mosquito heater with part cooling at 100%.