Superfly Extruder - A Compact BMG Conversion

thingiverse

# Superfly Extruder ## A Compact BMG Conversion **Update (28th Sep 2021) - A user reported an interference between the tensioner and the plastic gear when used with flexible filaments. This was an error in the design, so it is now corrected. The high-tension version is also removed as the new one should cover all use cases.* The Superfly is a compact extruder designed to reuse the excellent dual drive gears of the beloved BMG extruder. As with the BMG, the Superfly is a dual-drive geared extruder with a 3:1 gear ratio. It is designed with the following characteristics in mind: - compact and lightweight - short filament path - balanced center of gravity - easy to source hardware - support both NEMA 17 and round NEMA 14 motors - easy to print Please see the project [GitHub Page](https://github.com/mustcode/superfly) for more detailed information on the Superfly including additional assembly instructions and images ### Parts You will need the following parts of your BMG: - the **drive shaft** with the large plastic gear attached - the **drive gear**, this is the gear that is on the drive shaft - the **idler gear**, its shaft, and the two needle bearings inside, these are the parts that were on the BMG's tension arm - **2 x MR85 bearings** that the drive shaft runs on - **Thumbscrew** and **spring** (the washer is optional) - The **motor gear**, if you're planning on using a motor without a gear pre-installed In addition to the BMG parts, you will also need the following hardware: - an M3 nut for securing the thumbscrew - 4 x M3 screws for mounting (6mm-12mm depending on your motor and mounting needs). If you're going to be running a reverse-bowden, you'll also need: - an embedded bowden collet (the type commonly used on a V6 heatsink) - 4mm OD PTFE tubing ### Printed Parts There are only 4 parts that you need to print: - The **main housing** holds the drive gear assembly and one of the MR85 bearings - The **back housing** holds the other MR85 bearing and keep the drive gear assembly in the main housing - The **tensioner** holds the idler gear pressed to the drive gear with the tension from the spring and thumbscrew - The **motor spacer** is an optional part designed to go between the main housing and the motor to allow you to use motors with shaft longer than 15mm. - Additionally, some variations of the drive shaft are known to be a bit long and may protrude beyond MR85 bearing at the back. If this is the case for your drive shaft, then you will need a spacer to make sure that the shaft is not pushing against the motor's body. - Finally, if you are using a NEMA 14 motor and you prefer to save weight than adding a spacer, you can grind away the protruding portion of the drive shaft, this is commonly done on other similar round NEMA 14 based extruder like the Sherpa Mini ### Printing Recommendations: All parts are printable in under 3 hours and should be an easy print for most modern printers. The following are some recommendations to help increase your chance of success: - The main housing should be printed "face down" as oriented in the STL, the model is designed to minimize supports in this orientation. - Supports are only needed for the main housing where the two motor mount holes are. Other overhangs and bridges are very printable. - Raft should be enabled for the main housing unless you're very confident in your bed-adhesion. - The tensioner should be printed with plenty of walls and infill to make sure that it doesn't break under stress. - As with most mechanical prints, your printer should be capable of producing parts with decent dimensional accuracy. If you found that your printed parts are too tight, try the "extra_clearance" version of the main housing instead