Depending on the orientation of your extruder and if you use the top or bottom port as the output port to your hotend you might need to change the rotation direction of the motor. Also using a gearing ratio will reverse the rotation direction compared to an un geared extruder.
There are two ways of doing this, either by reversing two of the 4 cables to the stepper motor or by doing a change of direction in the firmware.
In order to reverse two cables you can use a sharp tool to lift the little plastic tab on the connector on the cable and gently pull the crimping contact out of the housing.
Remove two cables (for 1 of the coils of the stepper motor) and let them switch place with each other. Please take note of how the two coils are placed in the connector.
For Bondtech CR-10 Upgrade Kit (Based on BMG)
Use the following image sent by our friend Tom Quach as guide:
For Bondtech geared stepper motors
Coil 1 is A-C and Coil 2 is B-D, this is valid for our geared steppers, other stepper motors can have different positions and different connectors, please look at the datasheet for your motor.
For the 25m Pancake stepper motor
Our 25 mm pancake motor uses another configuration of the connection as shown below.
On this motor the middle wires is swapped when compared to the 40 mm Geared Nema 17 motor.
Coil 1 is between PIN1 and PIN3, Coil 2 between pin 4 and 6.
Revert direction using the firmware
You can also change the setting in the firmware, the below picture shows the file Configuration.h in the Marlin Firmware for Ultimaker, to change the rotation direction edit the appropriate line from TRUE to FALSE or the other way round.
The picture below shows the configuration file for Smoothieboard. Change the direction by adding a ! after the 0.22 on the line highlighted below.
If the material gets pulled up in the heat-break during retractions there is a risk that molten material get stuck in the heat-break. Make sure that you are not using longer retracts than necessary.
Click the button below to read an interesting guide on retractions.Click here to visit 'Musings on retractions'
The volumetric extrusion rate is a combination of layer height, extrusion width and speed. If this combination of values give too a high volume / second the hotend does not have the capacity to melt the filament at the needed rate, this means that the extruder tries to push semi-molten plastic out of the nozzle orifice and this will also lead to too high extrusion force.
When the QR extruder is used in a direct drive application (Hotend is placed into the extruder and the whole unit is placed on the printhead) it is important to use a piece of PTFE tube connecting the hotend with the extruder, if the PTFE is not used there is a free space in the extruder where the filament can buckle and create jams.
The length of the 4/2 mm PTFE tube on the 1.75 mm QR must be 31 mm.
For the 2.85/3.0 mm QR a PTFE tube 6/4 mm with the length of 2.5 mm must be used.
The PTFE tube is highlighted in blue color.
To learn how to setup a E3D V6 hotend on a BMG check this guide.
To learn how to setup a Mosquito hotend on a BMG check this guide.