How to Install BMG Extruder onto A FDM 3D Printer

The Bondtech BMG extruder is quite popular among 3D printer users. Today we’ll learn how to install BMG type extruder onto Anet ET4 or Anet ET5 3D printer step by step.


Why users are installing the BMG extruder?

The BMG extruder has a dual-gear system with 3:1 gear reduction and a lever for quick release which allows a much higher push force with less filament tension. Lower tension means lower filament deformation and a better grip means less grinding and slipping which causes under extrusion. Also, it allows a more efficient filament feeding at higher print speeds.

Comparing to most stock extruders, the BMG extruder works better.

Occasionally, I found this similar and much cheaper model with nearly the same features as the Bondtech extruder on AliExpress.

Here, we’ll install this extruder onto Anet ET4 3D printer as example.

Guideline of Installing the BMG extruder onto FDM 3D printer

1.Hold the stepper motor underneath and unscrew from the top to remove the stock filament feeder. Remove the stock gear on the stepper motor.

2.Install the provided gear onto the motor shaft with the set screw side up and tighten the set screw. Note: make sure the gear section is underneath and set screw is on the top when install the new gear.

bmg installation

3.Put the motor back into the mount. Place the bottom half of the extruder on to check the gear alignment and adjust it if needs to.

4.Place white gear assembly into the gear groove near the stepper motor gear and make sure the two gears align well.

5.Put the coupler on top right as below picture shows.

bmg assembly

6.Put the top part of the extruder on and then secure it tight. Perfectly align gear parts and then assemble the top parts of the extruder on.

7.Insert the bolt with a spring and a washer into the puller hole and screw it a little tight.

8.Insert the Bowden tube into the coupler as deep as possible and then clip it tight.

bmg installation

9.Plug in stepper motor wiring and other wires on the circuit board. Cut the PTFE tube into appropriate length for your 3D printer, and then insert it into the other coupler on the other end of the extruder and clip it tight.

Tips: motor direction will be reversed and we need either change it in the firmware or invert motor cable wires.

10.Load the filament into the extruder.

Insert the filament until it reaches the gears inside the extruder, turn the motor or rotate the white gear, or do automatically filament loading to push in the filament.

11.Calibrate step value for the newly installed BMG extruder.

There might be some slight Estep difference on the newly installed BMG extruder comparing to the stock extruder. So the next is to calibrate the new extruder and get it work properly.

bmg extruder assemble

Usually we can mark a 100mm filament length and then load the filament in at a constant speed. According to actual loaded filament length, we adjust step value for the new extruder.

Now, we’ve completed the installation of the new BMG extruder onto the Anet ET4 3D printer. Don’t you want to try? Get started right now!


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