Retract distance too long
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 here to read an interesting guide on retractions.
Extrusion rate set too high
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.
Extruder turning in the wrong direction
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 is 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.
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.
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.
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 below picture shows the configuration file for Smoothieboard, change the direction by adding a ! after the 0.22 on the line highlighted below.
As the slicer tells how much filament should be extruded for each move the controllerboard uses the e-step value to determine how many steps it needs to send to the motor in order to feed the correct lenght of filament. Since drive-gear diameter and gearing ratio affects the number of e-steps needed it must be adjusted in order to get the correct extrusion lenght.
The E-step values for our extruder are:
|Extruder||E-step value||E-step set G-code|
|Bondtech QR 1.75||476.5||G-code file|
|Bondtech QR 2.85/3.0||492.45||G-code file|
|Bondtech Mini||140||G-code file|
|Bondtech BMG||415||G-code file|
|DualDirect for Raise3D||415|
Direct mount applications
When the QR extruder is used in a direct 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 shall be 31 mm and for the 2.85/3.0 mm QR a PTFE tube 6/4 mm with the length of 2.5 mm shall be used. The PTFE tube in below pictures are highlighted in blue color.
|X-section of QR 1.75||X-section of QR 2.85/3.00|