Prusa MK3 BT 1.8 (BMG) Extruder v2

grabcad

A finely tuned blend of the Prusa MK3S and Bondtech extruder, paired with a pancake stepper 1.8 Nema17 25mm motor, features a gear ratio of 3:1 and is equipped with an IR sensor from the MK3S. The hotend can be quickly and easily swapped or maintained, making it perfect for use on the original Prusa MK printer 3 series, even when paired with an MMU2s. All parts were printed using PA12 material at a nozzle temperature of 270C, a bed temperature of 110C, and layer heights ranging from 0.1 to 0.15mm. To prevent overheating, the enclosure was set to 45C without the nozzle fan. Firmware updates are available for download here: https://github.com/BondtechAB/Bondtech_Prusa_i3/tree/master/FirmwareUpdate. As of October 22, 2019, a PTFE tube measuring 4/2.5 x 20.6mm and four thread-inserts for the fan were added to the design. The parts list was updated accordingly in partslist.xlsx and BT_Extruder_MK3S_MMU2S.stp. On October 27, 2019, a new version of BT_Extruder_MK3S_MMU2S.stp was released, featuring a PTFE cutting template. Additional updates were made on November 1, 31, and December 16, 2019, to include a hotend lock, chimney sensor LED, and extruder cooler in the design. On December 29, 2019, it was recommended not to use PC for printing extruder parts due to its unsuitability for alternating loads and temperature fluctuations. Instead, polymax PC is suggested. On January 2, 2020, a new chimney construction with fine sensor adjustments was added, along with an x-carriage-back and side cutout to facilitate cable removal during servicing. The complete extruder was printed using Nylon (PA12) material. On January 31, 2020, a fan shroud for more even air distribution was introduced, printed with CarbonPEEK due to its high temperature resistance. Finally, on February 1, 2020, fan bridges were added, and the parts list was updated in partslist.xlsx. The most recent version of BT_Extruder_MK3S_MMU2S.stp includes all these changes.