3D40/FLX Extruder

  • Unclogging Extruder
  • Replace Extruder Cover & Runout Sensor
  • Nozzle Gap Calibration

Unclogging the Extruder

This video will walk you through the steps to properly clear out a clogged extruder on your 3D40 or 3D40-FLX Printer.

Replacing Extruder Top Cover & Runout Sensor

Caution: Use proper anti-static precautions when performing this replacement. Discharge static electricity before beginning. Work on a static-free surface.

This service document will outline the steps to replace the top cover of the extruder on the Dremel 3D40 3D printer. The top cover consists of the extruder cover and a runout switch assembly. The runout switch assembly senses the absence of the filament while printing and pauses, so that the user can load a new filament to continue printing. The user will need to replace the top cover if the printer shows a filament runout error but the filament is still going through the cap into the extruder or the printer does not have filament, but continues printing in the air.




Step 1: Remove excess filament from the extruder (if filament is running through the cover into the extruder)

a. Turn on the printer.

b. Cut the filament near the top of the extruder.

c. Navigate to the preheat screen.

d. Begin the preheat command and allow the extruder to heat up.

e. Begin the purge command.

f. Once filament is no longer leaving the extruder, press “stop purge” and exit the preheat screen.

Step 2: Bring printer to safe state for service

a. If Step 1 was performed, allow the nozzle to cool until the thermometer icon reads cool (blue).

b. Turn off and unplug the printer. 

Step 3: Remove top cover of extruder

a. Unscrew the two screws on the top of the filament guide bracket.

b. Remove the top cover.

c. If the filament runout switch terminal (encircled) was already disconnected, reconnect it to the circuit board, replace the top cover and skip to step 6. This disconnection may have been the source of the issue.

Step 4: Install new top cover of extruder

a. Attach the filament runout switch terminal of the new cover to the extruder circuit board.

b. Place the new top cover over the extruder.

c. Replace the two 2mm screws onto the cover.

Step 5: Load a filament

a. Plug in and turn on the printer.

b. Load a filament onto the spool.

c. Load the filament onto the extruder by pressing the filament button on the screen.

Step 6: Test the replacement

a. Plug in and turn on the 3D40.

b. Build the “Test Print” file on the machine to ensure the 3D40 printer is working properly.

c. After 5 minutes of print time, pause the print and cut the filament as shown in Step 1. Press play to continue. The printer should automatically pause within a few minutes and show a “Filament Runout” Error. This confirms that the runout switch is working as intended.

d. User can use the Filament Change option to load the filament again and build the rest of the print.

Nozzle Gap Calibration

If you are having first layer issues, calibrating your nozzle gap (or z-gap) could be the solution to your printing issues. If the nozzle gap is too small, you may be hearing a clicking at the beginning of your print, or you may have a first layer that appears "smashed" or too flat. If your nozzle gap is too large, your first layer may print in air, or just have poor bed adhesion. If you have 1st layer issues multiple prints in a row, try following these directions to calibrate your nozzle gap.


Step 1: Test the machine

a.Level the printer before moving forward – Navigate to the leveling screen by pressing level on the home screen, and following the instructions on screen.

b. Navigate to “Filament” and follow the on screen instructions to load filament.

c. Build the “Test Print” file on the machine to ensure the 3D40 printer is working correctly.

d. If prints are not adhering to the build plate, the z-axis offset may need to be adjusted. If so, continue to step 2.

Step 2: Adjusting the z-axis offset

a. Navigate to the z-axis offset screen, following: Tools→ Settings→ Z-Axis Offset.

b. Follow the on-screen instructions to either increase or decrease the offset.

c. Always adjust the z axis offset once (0.1mm increments/ decrements) and test by repeating Step 1 above, before making any further z axis offset adjustments.