Extruder not gripping Well (Kossel Mini)

Hello All!

I have a Kossel Mini (think3dprint3d) running:

Firmware Name: RepRapFirmware for Duet
Firmware Version: 1.21.2beta1 (2018-06-23b1)
Web Interface Version: HTML: 1.11, JS: 1.11

I am having issues with the extruder inconsistently gripping and pulling filament (Hatchbox 1.75mm PLA) into the bowden tube and thus it starves the hot end during printing causing failures. Is there any way to adjust the tension or increase the force of the gripper gears? Any other solutions to remedy this? It is the release 3 variant with the spindle on top.

If the motor is skipping steps, increase extruder motor current (M906 in config,g) or increase extrusion temperature. If the hobbed insert is losing its grip on the filament, AFAIR the extruder drive has a screw to adjust the clamping force. Also check that the bearing that presses the filament against the hobbed insert rotates freely.

HTH David

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Is there a recommended step increase for M906? I'll give that a try. I think I may have identified the screw that adjusts clamp force. Thanks for the help.

Thinking back a bit more, AFAIR the extruder on that machine has 5:1 gearing and a 48mm long motor, assuming that they didn't change it between version 1 of that kit and later versions. So you are unlikely to need more motor current.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

I got rid of varying layers on my printer by changing spool holders, went from a solid plastic one to one with bearings embedded into it. Turns out there was enough friction to interfere with smooth extruder movements.