When starting the print, no filament comes out of the extruder

It may happen that no filament comes out of the extruder when starting the print. This can have four different causes, but fortunately it is easy to solve. Below you will find all four causes and the corresponding solution.

The extruder is not primed to start the print

Most extruders leak filament when they are not operating at high temperatures. This often happens at the start of the print when the extruder is heating up, or at the end of a print when the extruder is cooling down. The hot filament then seeps out of the nozzle, creating an empty space where the filament has run out. Because of this empty space, it often takes a few seconds before the filament comes out of the nozzle again when you start a new print.

Therefore, make sure that you prepare the extruder just before starting the print, so that the nozzle is full of filament and ready to start. The most common way to do this is to add a "skirt" to the print in the printer software. This skirt draws a circle around your print and during this process the nozzle is filled with filament.

The nozzle starts too close to the print surface

If the nozzle starts printing too close to the surface, the filament will not have room to exit the extruder. In this case, the filament does not come out of the nozzle during the first layers, but only really starts printing with the third or fourth layer of the object. You can easily solve this problem by lowering the bed manually or by using G-Code offsets in your 3D printer software. These offsets allow you to fine-tune the Z-axis without having to change the hardware.

The filament is stripped by the drive gear

Most 3D printers have a gear that pushes the filament back and forth, the so-called drive gear. Its teeth "bite" into the filament in order to accurately determine the position of the filament. Do you see a lot of scraped pieces of filament? Then it may be that too much filament has been removed and the drive gear no longer has anything to bite on. You can fix this in a few different ways:

1. Check the extruder retraction rates.
If the retraction speed is too high or if you try to retract too much filament, it may overload the extruder. To test this, you can reduce the retraction speed by 50% to see if the problem goes away. Is this the case? Then the retraction speed is (part of) the problem.

2. Increase the temperature of the extruder.
If lowering the retraction speed does not help, increase the extruder temperature by 5-10 degrees. The filament flows more easily at a higher temperature and this may be the solution to the stripped filament problem.

3. Reduce the print speed.
The next step after increasing the temperature is to decrease the print speed. Because the motor of the extruder does not have to rotate as hard, the filament is stripped less quickly by the drive gear.

4. Check whether the nozzle is clogged.
If the above steps did not help, the nozzle may be clogged. The solution for this can be found on the page about clogged nozzles.

The extruder is clogged

Did none of the solutions cause the filament to start running again? Then the extruder is probably clogged. If this is the case, please contact us. It is possible that the extruder needs to be disassembled, we are happy to help you.