While doing dual extruder prints one head is too high/low and causes either filament to squash into the layers of another (too low) or the second filament does not align/connect with the other (too high) and probably does not stick to the bed when printing from this extruder. You may see "drag through" where the lower nozzle draws patterns in the printing of the other (even when only single extruding from the other (higher) nozzle.


In a twin head machine you need both nozzles to be perfectly aligned in the Z axis (in height). They can get out via:

  • Manufacturing not perfectly aligned
  • Changing a nozzle with one that is very slightly different in height
  • Time - heating and cooling over time can put them out slightly

Process to fix it

  1. Unload any filament present in the machine.

    Flashforge Print head

  2. Preheat the nozzles of your machine.

  3. Once at temperature clean the nozzles thoroughly using paper towel dipped in acetone, or a brass brush.

  4. Level the bed thoroughly to the lowest nozzle so you are sure it is very flat (you may wish to run the bed leveling several times).

  5. You may wish to place a sheet of paper on the bed after it is levelled for future use.

  6. Using the jog mode (Tools -> Manual) to move the head to the centre of the build area and move the bed to its highest position.

  7. Turn the machine off and unplug the printer from the mains power.

  8. Disassemble the print head until all you are left with is the aluminium mounting block and the hot ends. (Dissembly article coming soon)

  9. There is a screw on the back of the mounting block that holds the hotend in place. Identify (using the paper we put on the bed earlier) which nozzle is on the bed and which one is above.

  10. Loosen the screw on the back of the mounting bar that corresponds to the nozzle which is lower (touching the bed). You do not need to remove the mounting bar from the carriage however some people may find it helps access to the back of the bar.

  11. Using the bed raise the nozzle to be the same height as the other nozzle. You may find that measuring the resistance of the nozzles using the paper can help.

  12. Tighten the screw on the back of mounting bar to lock the hot end back into place. Make sure that the hotend is square with the other and not rotated.

  13. Re-assemble the print head.

  14. You may wish to do a test print to make sure that the heights are correct.

Happy printing

Bilby 3D