Prusa I3 Extrusion issues
October 16, 2017 09:45PM
Long story short I printed an 11 hour print, best print I ever did with my machine, everything calibrated perfectly. Now I go to print something and I'm having bed adhesion issues (which I never have), under extrusion on base layers (outter shells not touching, infill not touching), under extrusion throughout prints leaving air pockets and weak areas. Some of the layers were also stringing and not bonding with each other.

-Tried cleaning extruder since it was partially clogged, didn't do anything
-Replaced extruder with new one, still underextruding.
-Lubed whole machine and releveled, still underextruding.
-Tried using white filament instead of beige, thinking the filament was bad, still underextruding.
-Adjusted extrusion multiplier from 1.06 to 1.1, did nothing.

Does it sounds like the motor controlling the extruder has gone up or maybe the chip that controls that stepper motor?

See attached images
open | download - 20171016_213040a.jpg (152.6 KB)
open | download - 20171016_212845.jpg (187.3 KB)
Re: Prusa I3 Extrusion issues
October 25, 2017 07:57PM
I had this happen once. The set screw on the stepper gear had backed out and not all of the rotation translated into filament movement.
Nothing sounded bad, nothing overheated or errors out, I just got under extrusion.

Re: Prusa I3 Extrusion issues
November 01, 2017 11:56PM
What changed between the good prints and bad prints? Filament brand or anything?
Have you tried giving your bed surface a good clean? It might have reached the point where enough dirt or oils built up to start causing adhesion issues.
Also, how's the hotend temperature? If you've tinkered around there you might want to check for broken wires (they're quite fragile, my thermistor wires broke after a few disassembles) so the heater or thermistor could have a sketchy contact which is causing temperature to fluctuate. This could cause underextrusion (too cold), stringing (too hot), and fires (especially if safety features are disabled in firmware, ala most Chinese printers if that's what you have).

When you say your extruder was partially clogged, do you mean your hotend? And when you say you replaced the extruder, are you meaning the hotend or extruder? You're getting some blobbing and over extrusion in some places as well I think (hard to tell with white filament in photos) so to me this points to something tugging on the filament every now and then when extruding (i.e in an i3 type design, the extruder moving in the x direction causes the filament to tug on the extruder which can cause extrusion issues like you're seeing).

I don't think it's a driver failure, those usually fail completely, meaning they won't do anything at all rather than give glitchy performance. That and they release their magic smoke.
Re: Prusa I3 Extrusion issues
November 02, 2017 12:15PM
Also, printing directly on your heater plate will not be a path to success. Get a borosilicate glass top and some wide kapton tape. I found that this combo with a very light dusting of the hairspray will stick just about anything down.

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