A 3D printer that stops feeding plastic or suffers from poor extrusion can be very frustrating. This is a common problem and therefore it is important to understand why it occurs and what to do to solve it and minimize the chance of it happening again.


Looking at the 3D Printer itself

Hotend: This is where the plastic is heated up to a temperature where the plastic enters a molten state.

Drive Block: The drive contains mechanincs that feeds the plastic to the hotend.

Drive Gear: A hobbed gear mounted on a stepper motor, grabbing and pushing plastic.

Direct Drive: The "drive block" is directly connected to Hotend, currently this design applies to all Flashforge 3D printers.

When no plastic is ejected from the nozzle, there is something that prevents flow. There are 3 areas to look at where a problem has occurred:

  1. The filament spool does not move freely
  2. There is something blocking the filament on it´s way between the roll and "hot end" (the part where the plastic is melted) Usually there´s filament residue blocking the entrance to the hotend.
  3. There is something that blocks the flow in the nozzle

1. When the spool with filament can not move freely, it may be something blocks the spool itself, make sure it can spin freely and easily.

It may also be that the filament is tangled on the spool and simply stuck. When swapping filament in the machine always make sure to secure the end of the filament to the spool. There are clips that can be printed or just use tape or secure it in the holes in the spools if there are any.

2. If the spool spins freely then it´s time to look at the filament path where the filament travels from the spool down to the "hot end" of the extruder. Follow the filament from the spool, if the thread goes in a plastic filament tube, make sure that the filament runs freely in the tube. Also check the connection between the filament tube and drive block so there aren´t any filament residue blocking the entrance.

Direct drive. By "direct drive" is meant a extruder design where the filament feed is directly connected to the "hot end". The filament is then pulled from the spool into the filament tube and onwards to the drive block where the drive gear is pushing the plastic thru the hotend. A common problem is when the drive gear may dig into the filament due to excessive pressure on the drive gear. From the filament tube, the filament then goes down into the so-called extruder. Remove any components that are in the way of inspection of the drive gear. Then check if there are plastic residues on the drive gear and or around it. Also check that the entrance hole to the hotend is free from plastic residue. Clean the drive gear with an old toothbrush or similar. Clean the drive gear and surrounding components, adjust the pressure on the drive gear and try to extrude plastic again via the "load filament" function of your printer . If this doesn´t help,  proceed to step 3

In the case of direct drive, it may also be a "heat creep", which means that if not preoperly insulated heat travels up to the drive block, thus heating the drive gear and the plastic, causing the drive gear to start digging into the filament. It ay also be that the fan that is supposed to cool the cooling flange that cools the drive block is in the wrong direction and thus the components become too hot. Look at the fan, the label on the fan should be twards the drive block. Looking at the front of the machine, Turn it on.

3. If none of the above helps, it is probably something in the "Thermal Tube" or the nozzle that sits below that blocks the flow of plastic. There are several ways to clean / clean the nozzle from debris. One with a narrow object is a straw from a steel brush, acupuncture needle or the like. Then try gently inserting the needle into the nozzle and thus reset the flow. The procedure is described in more detail in this video. It can of course be difficult to get out of this way that blocks the flow, but it can still be enough for it to work normally again. Another way is to make a so-called "Cold Pull". This means that heat is heated than manually pushes a piece of filament down until it stops or comes out of the nozzle if the flow is only partially prevented. Then, the temperature is reduced to about half and manually pulls the filament bit. This causes you to get dust or other particles in the nozzle and block the flow. Repeat the procedure a few times