Troubleshooting Bondtech extruders and Upgrade Kits setup and operation

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Troubleshooting

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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 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.

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 the button below to read an interesting guide on retractions.

Click here to visit 'Musings 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.

Direct Drive applications

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.

Cable connectors

Different controller board uses different connectors for the cables to the steppermotors. We currently have 3 different options of cables. Our standard is the PC2510 connector but we also supply cables with JST-XH4 and the Dupont connector. Outside dimensions of the connectors are presented below. Further options of different types of connectors are available as customized products, please contact us if you have a need for any special connector.

Stepper motors - Supply voltage

Stepper motors are normally driven in a constant current mode by the stepper driver and since the torque a motor provides is proportional to the current all the way up to the motor’s cornering speed the supply voltage controls at what speed the cornering speed happens. With higher supply voltage the motor can be run at higher speeds than with a lower voltage; this is the reason for why we recommend to use a 24V PSU on your printer. Below image is from a very nice write-up by GeckoDrives you can check by clicking this button.

Click to visit Gecko drive
Electric current settings

The geared Nema 17 motor that is used in our QR Extruders are rated for 1200 mA (1.2A), at this current the motor will reach about 50 degrees in continues printing, when using PLA that get soft at about this temperature we recommend to lower the current for the motor to keep it cooler. The following table shows the temperature of the motor in continuous mode at each current setting.

 Current settingMotor temperature 
 1200 mA50°C 
 1100 mA47°C 
 1000 mA45°C 
 900 mA39°C 
 800 mA37°C 
 700 mA34°C 

As your slicing parameters, nozzle diameter, temperature and polymer type all affects your extrusion pressure you will need to use a setting that works best for you. Also one option is to attach a heat sink to the back of the motor to increase the heat dissipation to lower the temperature.

Depending of your printer and your controller different methods are used to set the correct current. Stepper drivers that have an adjustable potentiometer are adjusted measuring a Reference voltage that corresponds to the current used. Check the procedure in the following video.

Stepper drivers that are using a digipot can adjust the value by sending a G-code. If your system uses a digipot you normally adjust the current for the motor sending M907 Exxxx where xxxx is the current in Milliamps. So to set the current to 1000 mA for the extruder motor send M907 E1000.

In Ultimaker you can adjust the current for the motor from the LCD-panel directly.

You can of course insert M907 Exxx to the start section of G-codes in your slicer program.

Bowden tube gets pushed out during printing

Our bowden couplings can withstand a force of 14 kg for the 4 mm push-fit connector and 22 kg for the 6mm push-fit connector under ideal conditions. If your bowden tube keeps getting pushed out it is not a problem with the extruder, the root cause of the problem originates from another source. Below we have listed the most common probable causes. It can originate from one of them or be a combination of several problems.

Important to know if the tube have been pushed out.

Very IMPORTANT!
If the bowden tubes have been pushed out, you will need to cut off approximately 10 mm in order for the steel teeth of the bowden coupler to bite into a fresh PTFE surface. As the tube get damaged after repeated pushouts, failing to refresh the bite area will invariably result in more pushouts.

Bowden tube not properly inserted

If there is a movement during retractions the teeth in the coupler will eat itself into the PTFE and this will lead to a pushout sooner or later.

We recommend that the following procedure is performed when connecting the PTFE tube:

  1. Remove the bowden clip.
  2. Grab the black collar with your nails.
  3. Pull the black collar upwards when at the same time push the PTFE tube hard into the extruder, make sure the PTFE tube is all the way into the housing.
  4. Try to jerk the PTFE tube out and in, if there is any movement repeat step 3.
  5. Place the bowden clip under the black collar.
Bowden tube diameter

For our 1.75 mm extruders the PTFE tube must not be smaller than 4.0 mm, imperial size 5/32″ is 3.96 mm nominal so it is too small in order to have an optimal grip in the push-fit.

With our extruders for 2.85/3.0 mm filament we recommend to use our PTFE tube that is 6.4 mm outside diameter and 3.18 mm inside diameter (1/4″x1/8″), this will give maximum gripping force of the tube and as an added bonus it will also reduce the hysteresis effect during retractions that will make it possible to use shorter retractions distances.

Tip! If your diameter is slightly too small you can use a lighter to heat up the end of the PTFE tube until it gets clear and then let it cool off, due to the memory effect from the extrusion process the diameter will increase some tens of a millimeter and will improve the grip. Make sure to do this in a well ventilated area since the fumes from PTFE are toxic.

Bowden tube not fully inserted

If the bowden tube is not fully inserted into the housing it can move that can lead to that the bowden gets pushed out, make sure the PTFE is seated all the way into the housing.

Bowden clip is not used

If the bowden clip is not used the bowden tube will move during retractions, this can give the bowden enough momentum to break out of the bowden connector. It is also bad for your retractions since a part of the retraction distance gets eaten up of the movement of the bowden tube. If you do not have any bowden clips you can download the STL models from this page.

Bowden clip for 4mm push-fit
Bowden Adapters

Our bowden adapters will let you connect a bowden tube to the bottom of the extruder, this way you can use the bottom port as the output port. When using it as an output port it is important to make sure that the PTFE tube extends through the bowden adapter as it otherwise will be a free space where the filament can buckle and create jams.

The PTFE tubes are highlighted in blue color in the images below.

Heat-creep

Heat-creep is one of the most common causes for extrusion related problems.

In order to reduce the risk for this check the following:

  • Make sure the cooling fan for the heat-sink is mounted in the correct orientation (blowing towards the heat-sink).
  • Make sure the fan blows with full power and is not obstructed.
  • Adding thermal paste to the heat-break where it screws into the heat-sink will improve thermal conductivity and can make a big difference.
  • PLA is sensitive for heat-creep, do not print PLA in a sealed chamber.
  • Has the surrounding temp increased? This is a common problem during hot summers.
Nozzle Temperature

Different materials uses different temperature settings, lower extrusion temperature equals higher extrusion force and if the temperature is too low you risk pushing the bowden tube out of the coupling.

Nozzle clogged due to dirt particles

If dirt particles enters the hot-end there is a risk of getting the nozzle clogged if the particle size is in the range of nozzle diameter, smaller nozzles equals higher risk since smaller particles will block the nozzle. A good solution for this is to use a filament filter (a small sponge that the filament goes through and that cleans the filament before the hot-end. Here is a good design from Creative Tools:

Nozzle too close to build surface

If the nozzle is too close to the build surface the extrusion pressure also goes up creating high extrusion forces. Bondtech Extruders can supply about twice the extrusion force when compared to other extruders but at some point it will of course reach the maximum holding force of the bowden connector.

Hot-end cooling fan

If the cooling fan for the hot-end is not cooling the cold section of the hot-end correctly it will lead to heat creep, this will make the filament soft where it shall be hard and stiff and this will lead to problems with too high extrusion force. Make sure that there is nothing that is obstructing the flow of the fan, make also sure it is running at correct speed and also make sure it blows in the correct direction towards the heat sink, not from the heat sink.

Thermistor/Thermocouple

It is essential that the thermistor has a good contact with the heating block of the hotend. If not it will not report the correct temperature. This in turn might cause an over temperature that leads to heat-creap (heat travels up to the cold section and makes the filament soft and this results in a clog of the nozzle that creates very high extrusion pressure.

Filament grinding

If one section of the filament has a bigger diameter than the normal it can happen that the filament gets jammed in the filament path inside the extruder.

Our extruder for 1.75 mm filament has a filament channel of Ø2.0 mm. The extruder for 2.85/3.0 mm filament has a filament channel of Ø3.5 mm.

If the filament is thicker than the filament channel, it will get jammed and the gears will grind it since the filament is wider than the channel.

This problem was more common in the past but because filament manufacturers have better tolerances and higher quality now, it is no longer a very common problem.