Problems with Geeetech prusa i3 pro b extrusion.

So a few months back ive got myself a budget 3d printer. I knew the basics of how to use them as we had them back at my old college. we used maker bot printers. ive learnt a hell of a lot over the past months and overcome many problems myself but im stuck with one problem that i cant seem to fix.

i had a lot of success with a lot of prints but all of a sudden my printer started under extruding. ive been using PLA and ABS, both in a controlled environment, (IKEA lack enclosure). I found that the plastic tensioner on the MK8 extruder had cracked. so i ordered an aluminium one. this fixed some of the problems i was having with extruding. but there was still some problems when the prints got 20+ layers high at 0.2 layer height. it was still under extruding. so i changed some settings in slicer for extrusion widths. ive changed heat settings for PLA between 90 and 230. ive cleaned the extruder nozzle and feed holes. ive adjusted spring tension and ive changed the potentiometer on the driver for the extruder stepper motor. everything seems to be working smoother now but the only problem i have is with white PLA ive tried 2 different brands. Geetechs own and some unbranded one. the issue im having with the white PLA is that when using it the stepper motor is jumping back and forth. even on high heat it seams not to be pushing it through but when i feed it by hand it runs through fine. anyone come across a problem like this or am i just missing something so simple? any suggestions would be greatly appreciated.

did you measure the diameter of the filament.. could be way under sized..

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Originally Posted by airscapes

did you measure the diameter of the filament.. could be way under sized..

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good shout, ill double check ordered it as 1.75, all the others are that anyway. how would that affect under extrusion? just not heating it up quick enough to push it through the nozel?

The diameter of the filament is part of the calculation of how much is extruded so 1.68 i a lot less plastic than 1.75. Also if too thin the drive can slip .. you must measure multiple places over a few meter to get the average thickness and enter that into the appropriate location of the slier you are using..
Good luck

hi again mate checked the diameter of the filament all seems good, ive taken the heat sink and fan off the mk8 extruder, it doesn't seem to be slipping now it just seems to be not wanting to budge at all no matter what i change the patentiometer too. although if i hand feed it through whilst extruding it through the slicer at 210C it moves the stepper motor but it still seems to struggle even when hand feeding like its resisting the force of me feeding it. could this be a knackered chip/driver for that stepper?

ok so update, more fiddling, removed filament completely swapped the x/y axis plug onto the extruder motor and controlled it via slicer, found that it works perfectly fine. re plugged back in the extruder motor plug and found that it had the problem again, but when doing so i wiggled the wires on the plug a little and it suddenly worked perfect for about 10 seconds, at this point i kept wiggling the wires and found that in random positions the stepper motor would run free, does this suggest its the wires from the driver to the stepper or could it possibly still be the driver even tho ive not changed anything at that side apart from the potentiometer?

figured it out there was no continuity on the blue wire for that cable to the stepper motor so guessing its either burnt out or somethings nipped, ordered a new cable which will be here tomorrow hopefully it works.