Bondtech LGX™ For Prusa i3 MK3S With Mosquito™ Hotends
Was wondering what levels of success users are having with this upgrade. Even more important is its compatibility with MMU2S. Thanks for your feedback.
RE: Bondtech LGX™ For Prusa i3 MK3S With Mosquito™ Hotends
Response from BondTech...
We have upgrade kits for Prusa based on the BMG or the LGX.
The BMG kits are compatible with the MMU.
The LGX based kits aren't.
The reason is the way the MMU detects how the filament reaches the extruder.
On the BMG based kits, the MMU uses sensing the hinge slight movement when filament gets in between the drive gears.
On the LGX extruder, the pre-tension lever is fixed at a given position to ensure repeatability.
There is no hinge to signal the MMU filament is in the extruder already.
RE: Bondtech LGX™ For Prusa i3 MK3S With Mosquito™ Hotends
I sent a request to Bondtech regarding the LGX Lite, but the same would apply to the normal LGX; essentially, both drive gears are exposed on the LGX extruders, and both move in relation to the lever. The problem is that even though only the max expansion is needed for the extruder to work correctly, for simplicity it also restricts the max compression when no filament is present.
If a case is released which does not limit the compression (but retains the max expansion), and a very low-strength spring is added to allow the drive gears to be brought together when no filament is present, the exposed drive gears will be in a detectably different position when filament is present in the gears vs when it is not present.
Then an enclosure could be designed with levers or sensors that can detect the position of the exposed drive gears. enabling MMU2S compatibility again.
I've roughly measured the difference in length between the two outer edges of the drive gears (by opening and removing the lever restriction max compression) to be 0.4mm, which isn't much (and certainly less than the 1.75mm of typical filament width), but it should still be enough to design the sensor/lever to multiply that difference enough for the stock sensor to work as normal using the standard MMU2S Prusa firmware and design.
If I can get Bondtech to provide an alternative casing with this feature, I will try to design a forked version of the PitStop extruder to use this method since it is already using gearing in its current design and offers all the step files needed to mod it for use with a LGX Lite.