The Bondtech BMG, or Bondtech Mini Geared extruder is a lightweight, compact, and powerful dual-drive extruder that excels in direct drive or bowden 3D printers. The BMG features a 3:1 gear ratio, the perfect combination of speed for high flow applications and precision for tiny-nozzle, high-resolution parts, and accurate retraction. From rigid materials like PLA to super-flexible filaments like NinjaFlex, the constrained filament path of the BMG makes this a great choice when building from scratch or upgrading your existing 3D printer for better performance.
Note that this extruder is sold without a motor, add one on if you need it!
The Bondtech BMG leverages Dual-Drive hobbed gears for maximum contact and power
No matter what your use case is with 3D printing, absolutely everyone can benefit from enhanced extruder performance. The Dual-Drive gears of the Bondtech BMG create constant contact with both sides of the loaded filament, allowing for greater grip during both extrusion and retraction operations. Not only are there hobbed gears on both sides of the filament, but they are geared together to apply pressure evenly on both sides of the filament at all times. Idled extruders leave room for slippage as the filament can simply slide along the bearing if pressure is too high, but Dual-Drive ensures constant grip over a much larger pressure range.
Take advantage of engineering-grade materials with confidence thanks to the BMG's Hardened Extruder Gears
The most significant growth in the 3D printing world today is the constant stream of new and exciting materials being manufactured for desktop 3D printers. Entry-level materials like PLA, ABS, and PETG remain available in a wide variety of colors from many manufacturers, but stronger, reinforced composites are becoming more prominent every day. Carbon-fiber reinforced materials like NylonX or PRO Series Carbon Fiber PLA provide superior stiffness over their regular counterparts, but at the cost of having to process an abrasive material. This abrasion is a concern for 3D printer nozzles, but also for the extruder gears that have to control this material going into the machine. All Bondtech extruders are built with hardened steel drive gears with CNC-machined teeth for maximum grip. Using a Bondtech extruder means peace of mind no matter what materials you are processing, from high volumes of PLA for prototyping to kilograms upon kilograms of carbon or glass-fiber reinforced materials.
One of the Hardened Gears is visibly attached to the tension lever
A 3:1 gear ration makes the Bondtech BMG a beast of torque and speed
Every 3D printer hotend shares one thing in common, the filament must transition from a large diameter into a smaller diameter to pass through the nozzle and be added to a 3D print. This transition is made possible by heating the filament, but even at extrusion temperatures, there is pressure to overcome when extruding material. While most Nema 17 stepper motors are capable of producing enough torque to overcome this pressure, there is still a speed limitation. To overcome this, Bondtech has designed the BMG with a 3:1 gear ratio for triple the torque output, even in this compact package. This gear ratio is a great choice because not only does it provide additional torque but does so without sacrificing speed. Another benefit of this gearing is the ability to create smaller extruder movements with increased precision over direct extruders.
3:1 gear reduction applied more torque than direct connection
Nothing escapes the constrained filament path of the Bondtech BMG
Not all 3D printing filament is created equal, and while most are rigid plastic that easily flows through the extruder and to the hotend, thermoplastic elastomers like NinjaFlex and MatterHackers PRO Series Flex have the consistency of cooked spaghetti and have a tendency to travel along unwanted paths, leading to failed prints and other hardware issues. The BMG extruder body is designed by and SLS printed for Bondtech. This design constrains the filament path from the entrance, through the dual hobbed gears, and out the exit of the extruder, leaving no room for flexible materials to turn sideways and cause a misfeed.
The Bondtech BMG is ready to integrate into any 3D printer thanks to easy-adjustable tension
In the same way that every maker is unique in their use case, from the hobbyist experimenting with new materials to mass-manufacturing operations who rely on 3D printing to run their business, every 3D printer and filament are unique in their own ways. Having the ability to adjust the grip strength or tension of the extruder is a key element to adjust when setting up and fine-tuning any operation. The Bondtech BMG features a thumbscrew and spring mechanism for adjustable tension without needing special tools while maintaining the ability to handle slightly out-of-diameter materials. Filament tension is something that may need to be adjusted due to changes in material or hotend configuration, and not all extruders make it easy to adjust on-the-fly. With a Bondtech BMG, you can constantly keep your extruder tension just right with the easy-access thumbscrew.
Easy access thumbscrew tension adjustment
A master of bowden or direct drive configurations, the Bondtech BMG is a valuable upgrade for any FFF 3D printer
The extruder is a necessary component of any and all FFF 3D printers, so choosing a powerful and reliable extruder is a worth-while endeavor. Beyond that, making the extruder easy to integrate into a printer design only makes life easier, and also opens up more options for mounting positions and configuration styles. The Bondtech BMG is designed to mount directly onto the extruder stepper motor, sharing its dimensions and mounting hole pattern. The BMG itself is held together by three screws, which also affix it to the stepper motor. For bowden-drive 3D printers, it's easy to integrate the BMG and it's attached stepper motor via a sandwiched mount between them, while direct-drive configurations take advantage of the small extruder profile and integrated Groove Mount slot for easy and secure assembly. No matter what kind of filament feed system your 3D printer is based on, the Bondtech BMG makes it easy to upgrade the performance or migrate to a different configuration if desired.
BMG and E3D v6 in a direct-drive configuration
- Filament Diameter: 1.75mm
- Compatible Motor: Nema 17
- Compatible Motor Shaft Diameter: 5mm
- Gear Ratio: 3:1
- Weight: 75g
- E-Steps: 415 (Start with this value but also follow our guide on fine-tuning for best results)
- Motor Gear Material: Brass
- Output compatibility: Groove Mount
What's in the Box?
- Bondtech BMG Extruder Body
- Bondtech Motor Gear
- BMG POM Gear
- Tension Thumbscrew with spring and washer