Repeated failures in last few layers
Hi there,
My Prusa i3 MK3 has developed a rather annoying eccentricity lately where the last upper section of a print seems to fail, even though the rest printed absolutely perfectly. It's always the very tip, at the end of a print, and it doesn't seem to matter how high the models are (i.e don't think my printer is struggle past a set height. Extrusion flow stops, but printer carries on, and I'm left with a messy bit.
Photos attached. The red one (failed on telescope at tip) was an 18hr print which executed flawlessly except the very last 1% where under-extrusion seems to begin. Same for the one in grey, which is an excellent print, except the nose and mouth. Does this problem look familiar to anyone?
print details:
Filament: Prusament grey / red 1.75mm
Temperature: 210 deg c
Layer height: 1.5mm
Outer walls: 2
Infill: 10%
Slicer: Simplify 3D
Re: Repeated failures in last few layers
too much shacking on the top layer? maybe?
I have a Prusa,therefore I research.
Re: Repeated failures in last few layers
Justin:
How about a photo of your filament spool and holder and how the filament feeds into the extruder.
ps: The only thing that comes to mind from past reading is intermittent power to the hot end caused by a broken wire. But you should be able to see temperature drops on the Info screen if that were happening.
Re: Repeated failures in last few layers
maybe a retraction issue? just throwing out ideas... I almost posted my spool holder.... 😀 so far so good.
I have a Prusa,therefore I research.
Re: Repeated failures in last few layers
If You are printing higher in the Z than you normally Do and so the printhead is flexing its wires differently which might be causing a intermittent interruption in one of the wires to the extruder and or hot end. Or the spiral wrapped cable bundle could be pulling on the extruder hot end carriage enough when the z axis is working that high to cause the contact... pure speculation on my part bu I look at that stiff as a bar cable bundle exiting the extruder /hotend as the it whips back and forth at max extension and it makes me a touch apprehensive when prints near the top of the build space
Re: Repeated failures in last few layers
Thanks for the advice all. Attached is a photo of my spool holders @tim.30. from what I can tell they seem fine but I've only been doing this a short while comparatively .
Sharking may very well be an issue as the printer table isn't that stable. Will sort that out and see if the problem persists!
Re: Repeated failures in last few layers
Nothing wrong with the spool to feed horn... more or less rules out that issue.
My printer sits on a wood kitchen table, 3" legs, it shakes when the printer is busy. I also thought that might cause problems, and it does, but generally when the part has a high mass at the end of a skinny part. Think Atlas holding the globe in one hand. But your observatory would not see those forces. Shaky table or not.
The only other thing that comes to mind is the cable flex causing a power out as the table rises up ... aka a broken wire.
You said the prints fail based on % complete, towards the end of the file. Might be a sleep/hibernate issue on the computer, if you are printing from one. I only print from an SD card - never from a computer. Can you try printing something from the Prusa sample gcodes on the included SD card?
The dragon Alinda is pretty fast and only uses about 60g of material.