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I have a Prusa i3 (from FLSun). I have assembled the printer, calibrated it (fairly decently), and have successfully demonstrated extrusion manually. However, when I try to run a print job (the G-code clearly contains E commands), the extruder motor never rotates. Is this a common problem? Any suggestsions for how to resolve/troubleshoot?

I can confirm that the extruder was pre-heated for PLA (up to a generous 220 C).

I load an STL file into Repetier v.1.0.2, use the built-in slicer (Slic3r) to generate the G-code. I include a sample of that below:

; generated by Slic3r 1.2.9 on 2017-11-08 at 10:54:07 ; external perimeters extrusion width = 0.50mm ; perimeters extrusion width = 0.72mm ; infill extrusion width = 0.72mm ; solid infill extrusion width = 0.72mm ; top infill extrusion width = 0.72mm M107 M104 S200 ; set temperature G28 ; home all axes G1 Z5 F5000 ; lift nozzle M109 S200 ; wait for temperature to be reached G21 ; set units to millimeters G90 ; use absolute coordinates M82 ; use absolute distances for extrusion G92 E0 G1 Z0.350 F7800.000 G1 E-2.00000 F2400.00000 G92 E0 G1 X76.952 Y76.952 F7800.000 G1 E2.00000 F2400.00000 G1 X78.055 Y75.850 E2.04824 F1800.000 G1 X78.650 Y75.324 E2.07282 G1 X81.121 Y73.387 E2.16997 G1 X81.780 Y72.933 E2.19472 G1 X84.467 Y71.309 E2.29186 G1 X85.167 Y70.940 E2.31635 G1 X88.143 Y69.602 E2.41730 

As an update, I can no longer reliably get the extruder motor to run (even when I pre-heat) from the LCD. Sometimes, it works fine, but other times it doesn't seem to. Will confirm whether switching the motor connector to the z-axis to test the motor works when I get home this evening.

I can confirm 1) that there is no tension pulling on the cable connections during the run, 2) the mainboard and motor connector aren't burned, cracked, and the mosfets have heatsinks on them, and 3) the extruder gear is fixed and rotates freely on the motor axis (I tested this by switching it over to the z-axis connection temporarily and confirming rotation).

Here's a photo of my motherboard:

A photo of my motherboard

1 Answer 1

This should have been a comment: when you say "manual extrusion", do you mean moving filament by hand or using extruder position commands from printer menu? Is extruder motor working at all? You can for example plug it instead of a Z-motor to check.

Suggested points to check:

  • Motor wire connections, both on extruder and mainboard. Are plugs experiencing tension (being tilted, pulled out) from improperly fixed cables?
  • Hardware on mainboard next to motor connector. Does it look burned, cracked, lacks heatsinks on mosfets?
  • Is extruder gear not fixed and rotating freely on extruder motor axis? You will hear sound of working motor, but it will look like it's not pulling the filament.