MakerBot Print is our newest print-prepration software, which supports native CAD files and STL assemblies,
allows you to interact with all your printers via the Cloud, and many other exciting new features.

Download Now


Prusa MK3S/MMU2S BMG Mosquito Extruder

by zcubed Jul 5, 2019
Download All Files

Thing Apps Enabled

Please Login to Comment


thanks for this design! I'm considering upgrading to a Mosquito, and this is just what I needed. I've got a couple of questions.

1) How are you liking the Mosquito Magnum? Have you done any very slow precise prints on a small nozzle with it? I'm sure it can go fast, but I'm wondering how well it works when I need precision.

2) Is this compatible with filament sensor mods, such as https://www.thingiverse.com/thing:3681220 ? It looks like the mounting holes are all wrong. The reason being, MK3 style sensors, when used indirectly, are superior to the MK3S one (can detect filament movement, not just presence). Or even better, could such an indirect sensor be directly integrated into the body? Like what martin_au did to the MK3s body: https://www.thingiverse.com/thing:3431164

3) Is it possible to use other fan ducts? I see you're using a slightly modified variant of jonathanrswift's https://www.thingiverse.com/thing:2978427 but I prefer one of its remixes, https://www.thingiverse.com/thing:3684396 . Trust me, having the left fan closer to the extruder looks sooo much better ;) and leaves more bed space for printing objects sequentially.

Thanks a lot!

Prusa I3 MK3/S Bondtech Extruder - Filament sensor adapter in a separate housing
Prusa Mk3s extruder using an indirect Mk3 filament sensor.
Dual Part Cooling Fan Mount / Shroud with Nozzle View for Prusa i3 MK3
Dual Cooling Fan/Shroud for Bondtech (Prusa MK3)
  1. Yes its great, no more jams or heat creep but I have only tried a 0.4 nozzle. Precision would be more determined by your stepper drivers and motors since they control the movement of your extruder filament and position. This is why I use 0.9 degree motors on my X, Y and E axis.

  2. No, it would only be compatible with mods that fit the Bondtech BMG holes at the top. The IR sensor is significantly more reliable than the old sensor as I went through 3 of them, one actually melted my extruder by combusting. The MMU2S mount for the IR sensor can also sense filament movement by the idler door movement (just not direction like the laser sensor).

  3. The only other fan ducts that work are any stock MK3S ducts since that is the extruder cover I use in this design. I simply remixed my existing dual fan remix to make this one. You are welcome to remix the design you like to fit this!

Hey, thanks for your reply.

Precision would be more determined by your stepper drivers and motors since they control the movement of your extruder filament and position. This is why I use 0.9 degree motors on my X, Y and E axis.

I remember reading that 0.9 steppers had worse results when used with geared extruders. Probably somewhere in this thread, or its precedessor: https://forum.prusaprinters.org/forum/original-prusa-i3-mk3s-mk3-user-mods-octoprint-enclosures-nozzles-.../fine-vertical-artifacts-trinamic-chop-tuning-any-effect/

Also, precision on E is not the motor alone. The larger melt zone of the Magnum means there's much more soft/melted material between the extruder drive and the nozzle, which makes extrusion "spongier". For slow extrusion rates, it also means the material has more time to degrade/pyrolyze due to being kept at high temperatures. Which makes me wary whether I should go Magnum or not.

The MMU2S mount for the IR sensor can also sense filament movement by the idler door movement

Oh? If I understand things correctly, the MK3s has a steel ball actuate a lever which obscures the laser sensor. The MMU2s has the extruder door itself obscure the laser sensor. In both cases, there's only two states, obscured or not obscured. How would you detect filament movement? Can you confirm that you can detect movement? (on the MK3, under Support->Extruder Info you can see the sensor track filament movement)

They change their tune in this forum discussion: https://forum.prusaprinters.org/forum/original-prusa-i3-mk3s-mk3-user-mods-octoprint-enclosures-nozzles-.../stepper-motor-upgrades-to-eliminate-vfa-s-vertical-fine-artifacts/paged/23/
Guy Kuo's firmware forks work really well with Linear Advance 1.5 and 0.9 degree stepper adjustments: https://github.com/guykuo/Prusa-Firmware/tree/LA15-and-0.9-Degree-Stepper-Support
I have not noticed any 'spongier' extrusion, maybe because retraction with BMG + LA 1.5 + Mosquito is set to 0.3mm or lower. I get what you are saying as I had to make unique cooling tube settings for the Magnum on MMU2 ramming and retractions.

The idler door lever used to trigger the IR sensor on the MMU2S makes very fine movements when loading and unloading filament. If the sensor detects several tiny triggers in a short period it flags it as a failed load and tries again. If it fails again then it asks you to manually intervene. The tiny triggers are even impacted by slightly chewed up filament during clogs/jams, I successfully recovered from a few e3d v6 clogs using the MMU2S IR sensor. If calibrated correctly you IR sensor will do nearly as well as the laser one without the high failure rates.

Thanks for the info on the 0.9° steppers, but it seems there's no conclusive information yet. I'll stick with my 1.8° Moons pancake on the extruder for now.

I suspect that Linear Advance can work around the sponginess, but it will need manual calibration. I think I'll go with the Magnum after all.

As for the filament sensor, it appears from your description that the laser sensor is not perfectly reliable either. I'm also not sure it can detect jams until the extruder gears have chewed through enough filament to "close" the door. Optical sensor 4ever! :P

Remixing on my own is quite hard. None of my CAD software can handle existing STL properly, so it's bound to become a disaster. Bondtech has released Step files, maybe I can start over from that.


Comments deleted.

First of all thanks for the Design. I had a question with the Filament Sensor. is this the normal Lever which is also used in the official Bondtech addon for the MK3s Sensor? I had the Problem that is doesn't move free because it seems that the Lever is to long

I didn't make any changes to the sensor area on the MK3S version. It is a direct copy and paste from Juan Puchol's BMG design which should be a copy of the official Bondtech addon. I would try the lever from this design https://www.thingiverse.com/thing:3469271

Bondtech BMG Upgrade MK3S FDM printable new sensor integrated

thanks for the reply. there are some small changes to the original bondtech addon. i will try it later when i'm back at home if this one works

Sorry about that, I didn't know there were changes. Let me know how it works out for you, I want to know how well the MK3S version works!

What if I want to use just a single part cooling fan!

You can use the regular mk3s cooling fan duct if you want to use a single fan.