MK3S Crash Detected, Extruder seems to occasionally leave blobs on the object.
I'm somewhat new to 3D printing and trying to learn about this. Purchased the MK3S used (only a few hours on it). I've printed a fair number of items successfully, but recently it started showing me "Crash Detected" and stops the print. I've been trying to dig into the problem, but I'm not finding too much relevant.
What's happening is that there will be a glob of the PLA plastic that is left somewhere, and eventually, the extruder tip (stock) will hit the glob and break the object away from the base, and thus "Crash Detected". I've tried a brand new (sealed) filament.
The Fail Stats show last failure as Crash "X1 Y2". (Power/Fil.runouts =0). Total are "Crash X27 Y40" (Power=0, runouts=1 - not for me though). Some of these will be from when I first bought the printer and the slide bars were dusty/gritty which I had to clean and grease to get it to work the first time...
I went through the Calibration Wizard successfully today, and reset the Live Z back to about where it was before, around -1.90.
I'm trying to print out a box, about 75x90mm. The first complete print went fine (didn't meet my needs) but after that, I haven't been able to successfully print the box. When I print out the base layer (fan is not supposed to be on for the first layer, I learned) but this layer is not really smooth. It has little projections coming up (pretty small though). These recent failures have occurred with in the first hour or so.
I've been babysitting my current print and cut out a couple small globs and stray strings, but obviously I can't do that all the time.
I copied this basic box design from Thingiverse and modified it to my needs using TinkerCad (increased the width, added holes). I did find that some of the printer settings didn't match those from some previous successful prints, which I changed to match, but so far, it doesn't seem to help. Still getting occasional globs.
As a side note, this is an MK3S. The printer came with the "+" modification kit which I haven't put in yet (I did print out the required parts though). I've read that there isn't much difference between the MK3S and the MK3S+, so I haven't installed it yet.
Is there some troubleshooting chart somewhere that might help me? I've found a LOT of hits when searching for "Crash Detected) and they're all over the board. How do I search for the problem where my filament globs (better word???) up.
Mike
RE: MK3S Crash Detected, Extruder seems to occasionally leave blobs on the object.
Pictures might help!
One cause for blobs of filament causing crashes, is incorrectly installed nozzles.
typically this is caused by the heatbreak and the nozzle, not touching intimately inside the heated block of the extruder after a nozzle change.
this allows hot filament to ooze out between the heatbreak and the nozzle, and dribble down the outside of the heater block, before dripping onto the model, (Look at the top of the heat block, there should not be any filament there!)
Often these dribbles are discoloured.
https://help.prusa3d.com/article/changing-or-replacing-the-nozzle-mk2-5-s-mk3-s-mk3-5-s_2069 
another possibility, particularly common with PETG, is slight over extrusion
this can cause the model height to grow, slightly quicker than expected by Prusa slicer (Particularly common on perimeters and solid infill)
as the model grows, the Nozzle, has to plough through the previous layer, causing tiny bits of filament to stick to the outside of the tip of the nozzle
these bits build up to a blob, which typically falls off at the most inconsiderate moment, and stick to the model, then the nozzle catches on the blob on a later layer!
Another cause of collisions is warping where typically a corner of a print lifts off the build plate and catches on the nozzle, looking at the bottom of a print can often show where the model has lifted off the build plate,
this can be a result of build plate contamination, (often finger prints)
this doesnt typically cause blobs
many filaments print better in an enclosure! (ABS, ASA, PC for example!~)
Prusa Knowledge Base is a good place to look!
Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility.Location Halifax UK
RE: MK3S Crash Detected, Extruder seems to occasionally leave blobs on the object.
I'm not sure about the gap in the nozzle theory. The printer has been working fine, unless it has loosened over time. But I do understand what you are talking about. I'll check it soon...
In this case, I'm not using PETG, I'm using PLA. I am sticking to the default temperatures for the extruder and platten.
"Another cause of collisions is warping where typically a corner of a print lifts off the build plate and catches on the nozzle, looking at the bottom of a print can often show where the model has lifted off the build plate, this can be a result of build plate contamination, (often finger prints)"
If you'll check the picture I uploaded, the "Lifting" is prevalent also. Is that due to a problem with the bed temperature?
I've got the print running now, and it seems OK, but this is after I "babysat" it through the start, the first few layers that seem to glob up.
Sir Michael
RE: MK3S Crash Detected, Extruder seems to occasionally leave blobs on the object.
Good Evening Sir Michael,
Looking at your picture I would say that your first layer calibration, is a touch too low (too big a negative Live Z number
when you lay down the first layer, Prusa Slicer estimates the correct amount of filament to fit between the Build plate surface, and the nozzle lower surface.
First layer calibration attempts to ensure that the nozzle is the ideal distance from the build plate, in order to allow space for most of the filament, with the filament bead being compressed into an oval shape, to make it squish into adjacent filament traces, to create a continuous film smoothly across the build plate surface.
What you seem to be getting, is a first layer with ripples in it.
this is caused by the nozzle being too close to the build plate, and squishing the filament wider than expected, this then causes pressure against previously laid strings of filament, pushing them sideways. however when pushed sideways, there is an obstruction from other previously laid strings of filament, causing them to buckle and lift off the build plate, this in turn, reduces adhesion, and creates opportunities for the nozzle to catch on previously laid ripples in lower layers
the Actual Ideal LiveZ value is Unique to every printer and does not necessarily equate to a Live Z number ending in a 0 or a 5
there are many first layer calibration STL's on the various repositories.
the one I remember easiest is 'Life Adjust 'Z' My Way' by Jeff Jordan (largely because it is Mis-Spelled.
https://forum.prusa3d.com/forum/original-prusa-i3-mk3s-mk3-assembly-and-first-prints-troubleshooting/life-adjust-z-my-way/
there are test profiles for a 0.4mm nozzle, at the bottom of the first post.
Regards Lady Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility.Location Halifax UK
RE:
Many Thanks Lady Joan,
I'll give it a try in the next few days. I have some (other) projects to attend to for a few days, so playing with the 3D printer may have to wait. I'll read the post (again) and see what transpires. I had found that earlier when I was first got the printer, trying to keep the project stuck on the platen. I do understand about the Live Z adjustment. I may have it too close...
I WILL let you know how it comes out.
Sir Michael
RE: MK3S Crash Detected, Extruder seems to occasionally leave blobs on the object.
Thank You Sir Michael,
I hope the information helps wort your issues.
regards, Lady Joan...
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility.Location Halifax UK