M2 Extruder

The extruder is the entire assembly responsible for drawing in and extruding filament. It consists of the extruder motor (a stepper motor with attached 5.18:1 planetary gearbox), filament drive, hotend, and other support components (extruder motor mount, fans, etc.).

Filament Drive

Filament Drive Components
Highlighted Section Notes Part Render
Hotend barrel/heater/nozzle, and Extruder Motor shaft, not included in view; orange rod is filament filament_drive_complete.png
Filament Drive Github link filament_drive.png
Filament drive split down middle for demonstration purposes general_split_filament.png
Top Filament Path Filament enters top section of Filament Drive and moves through the Top Filament Path top_filament_path.png
Extruder Drive Gear Filament is compressed between Extruder Drive Gear (extruder motor shaft not shown) and Idler Bearing drive_gear.png
Idler Bearing Filament is compressed between Extruder Drive Gear (extruder motor shaft not shown) and Idler Bearing idler_bearing.png
Bottom Filament Path Filament then enters Bottom Filament Path bottom_filament_path.png
Idler Tension Adjustment Bolt Used to adjust the amount of force applied to the filament; for PLA, can generally be left quite loose; for ABS, generally needs to be quite tight idler_tension_bolt.png
V3 PEEK Insulator Press fits into Filament Drive; brass barrel of hotend screws into V3 (not shown) insulator.png
Filament "window" Filament can be seen through this "window"; if attempting to remove hotend from filament drive, one can use a sharp blade to cut the filament at this location window_zoom_circled.png


The M2 has had two major hotend revisions ship as stock, the V3A and V3B, and two minor revisions of the V3B.



The V3A is the original hotend that shipped with the M2, from ~April 2012 to ~November 2013. The V3A uses a hand-wrapped Nichrome heater coated in ceramic adhesive, with a glass bead thermistor taped to the side of the nozzle with Polyimide tape. General temperature starting points for the V3A are 195°C for PLA, and 220°C for ABS.



The V3B was standard hardware as of 5/19/2014, and was replaced by the V4 in July 2015. The changes from V3A to V3B are the heater and thermistor style and location; the V3B uses a milled aluminum heater block, with a cartridge heater as the heat source, instead of the Nichrome/ceramic heater of the V3A. The thermistor has changed slightly as well - it now has a metal sheath, and is inserted directly into the aluminum heater block.

The different location of the thermistor in the V3B causes it to read a higher temperature than the V3A, for a given barrel/nozzle temperature. This requires a general increase of ~20°C over the V3A. Thus, the recommended starting temperatures for the V3B are 215°C for PLA, and 245°C for ABS.

The V3B has two minor revisions, having to do with the power rating of the cartridge heater. R1 configurations have a 12V/40W cartridge heater, while R2 configurations have a 24V/40W cartridge heater. This is the only difference, and is easily accounted for in firmware.


Like the V3B the v4 uses a milled aluminum heater block with replaceable heater cartridge and thermistor. The v4 is much shorter, made primarily of stainless steel with a brass nozzle similar to the V3 series. The V4 is shorter and used with a new mounting plate rather than plastic. This gives the V4 a much higher operating temperature limited by the operating range ot the thermistor at 300ºC.
NOTE: The V4 hotend must be removed from the metal mounting plate before removing the nozzle. The very thin heat-break could be easily damaged by the torque required to remove the nozzle.

Maintenance and Standard Procedures

Inserting Filament

When inserting filament for the first time, one can follow the video here. The basic process is to cut a fresh tip on the end of the filament, then feed the filament up through the X endstop wire cover/filament guide, through the filament guide tube, and into the top of the filament drive. Then, with the hotend at your starting temperature, Extrude several hundred mm of filament. You may need to apply a small amount of force down on the filament, to make sure that the extruder drive gear "bites" into it. If the filament misses the bottom filament path, Retract 100mm, cut a new tip, and try again. You may need to change the angle of your cut, and rotate the filament so that tip does not miss the bottom filament path.
The image here shows a 60° cut, with the cut oriented so that, once pushed around by the extruder drive gear, it will guide the filament into the bottom filament path. More information on adjusting/fixing a misfeed is available here.

Once the filament is extruding out of the nozzle, Extrude 100+mm more to make sure it's flowing well, and then you can begin printing.

Switching Filament

When switching from one filament to another, the process is mostly the same as inserting filament, except that you will Retract the old filament out first, and then run several hundred mm of the new filament through. While retracting, you may need to apply upward force on the filament, so that once it clears the extruder drive gear, you can pull it out of the filament drive. You will run the new filament at whichever temperature (between the old and new) is higher - if both are PLA, then you would run them both at your PLA temperature; switching from ABS to PLA, or PLA to ABS, would be run at your ABS temperature. Once you've extruded several hundred mm of filament, and the extruded filament is coming out without streaks of the old color, you can change to your intended temperature and begin printing.

Simple Unclog/Unjam

There are two primary ways for a hotend to stop extruding: a jam or a clog.

A jam is simply when the filament binds up for some reason - either on the spool, in the filament guide, in the filament drive (by missing the bottom filament path, or wrapping around the drive gear), or in the hotend. The general cause is increased force required to move the filament - either from the spool, or into the hotend.

A clog is when debris or some form of contamination blocks the actual nozzle orifice, or far less likely, the barrel.

The vast majority of extrusion failures are jams.

Unjamming a hotend is generally as simple as removing the jammed filament, cleaning any filament debris from the filament drive, and starting again. If you experience multiple jams, presenting in the same way, you may have a specific issue causing the jams. If the below (currently incomplete) table does not offer a good solution, please contact support.

Jam styles
Description/symptoms Checks to perform Resolution
Extrudes fine for 5-30 minutes, then stops extruding;
Filament, especially ABS, found wrapped around the extruder drive gear;
Check that 40mm extruder fan is running constantly, and not being turned off by g-code Replace 40mm extruder fan if necessary