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Longer prints failing, pls advise  

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Mishti3D
(@mishti3d)
New Member
Longer prints failing, pls advise

Hi, I've had the Prusa MK4 for about 2 wks now and it was printing mostly perfectly fine until about two days ago, when 2 longer prints failed (models from reliable sources, one I have successfully printed before on the exact same machine).

Saddest of all, both prints failed after about 6 hrs of running very smoothly and printing beautifully. I returned to find a giant filament mess on top of the well-printed parts. One was printed with Prusament filament, so filament was not likely the issue.

Any idea what could be going wrong? It's super disheartening to have a print fail after 6 hrs... and makes the machine super unreliable. Now I will feel worried about wasted time/filament with every long print.. 🙁

Posted : 27/02/2024 5:13 pm
Mike B
(@mike-b-3)
Eminent Member
RE: Longer prints failing, pls advise

Was the "good" part of the print still attached to the bed?  Obviously if it detached then that's the issue.

Do you have an enclosure?  I had what I think was a clogged nozzle from the enclosure temperature rising too high, which reduced the effectiveness of the hot end fan which caused the filament to melt too high up in the nozzle.  At least that's my guess - with PETG I now open the door  a bit to control the temps.

I've read some other posts where the print head runs into an obstacle at a certain z value (or the cables get tangled once they tighten up from the rising print head, or it interferes with something around the printer).

I had an otherwise good print fail from tangled filament - it looped under itself (well obviously I did it while doing a filament change somehow) and the extruder could pull it out.  Maybe you had a temporary tangle?  Not sure about 2 in a row though.

Can you tell where the filament last appeared to be put down correctly?  Is there a clue in the position of it, or the thickness, or something that might indicate a layer shift?  Tighten your belt wheel screws on the motors just to be sure.

I'm relatively new to 3D printing but those are my guesses.

Prusa MK4 since Jan 2024, Printables: @MikeB_1505898

Posted : 27/02/2024 8:57 pm
Diem
 Diem
(@diem)
Illustrious Member

A new machine is always going to have shake-down issues and new-user familiarity problems ... pushing boundaries and tackling new problems is half the fun.  A picture of the failed print would be useful, on the print sheet for preference but if it's too late for that at least show us the underside as well as sides and top.

Cheerio,

Posted : 27/02/2024 11:45 pm
pink_clown
(@pink_clown)
Estimable Member
RE:

@flavy

it is nice you put here your emotions, but we would more appreciate detailed facts. Please consider to use these guidelines

This post was modified 2 months ago by pink_clown
Posted : 28/02/2024 3:17 pm
Mishti3D
(@mishti3d)
New Member
Topic starter answered:
RE: Longer prints failing, pls advise

Sorry guys, I am adding pictures now. I am also relatively new to 3D printing; and I will try to follow the guidelines for posting better.

The two longer prints were not consecutive. There were a few good short prints inbetween. Nothing was changed or upgraded. The vase in the pictures below was about half-way done when it messed up.

Bed adhesion was never a problem for my machine, and this print too was firmly adhered to the bed when I found it.

I have since Factory Reset the machine and it seems to be running fine again for smaller prints.

 

Posted : 29/02/2024 3:46 am
Mishti3D
(@mishti3d)
New Member
Topic starter answered:
RE:

Hi, the print was firmly attached both times. No enclosure.

The two failed prints did in fact fail around the same Z value, now that I think about it (guestimating on my part), so you may be onto something there. 

One extra detail for the second failed print - the filament was not extruding when I found it, and the extruder box was making that clicking noise when it's trying to pull the filament inside and can't for whatever reason (I had this happen with a clog before). Not sure if this was the cause or the result of the failed printing..

Thanks so much to everyone who is taking the time to respond!! Much appreciated 🙂

This post was modified 2 months ago by Mishti3D
Posted : 29/02/2024 3:53 am
Mike B
(@mike-b-3)
Eminent Member
RE: Longer prints failing, pls advise

 

Posted by: @flavy

Hi, the print was firmly attached both times. No enclosure.

The two failed prints did in fact fail around the same Z value, now that I think about it (guestimating on my part), so you may be onto something there. 

One extra detail for the second failed print - the filament was not extruding when I found it, and the extruder box was making that clicking noise when it's trying to pull the filament inside and can't for whatever reason (I had this happen with a clog before). Not sure if this was the cause or the result of the failed printing..

Thanks so much to everyone who is taking the time to respond!! Much appreciated 🙂

Something else that could be related to both z value and filament under-extrusion - could the filament be catching on something higher up that prevents the extruder from pulling it in?

Your second failure sounds like a clog - even with the failure it shouldn't be doing that.  It could be the result of too low a temperature...

I'll let more experienced users weigh in.

Prusa MK4 since Jan 2024, Printables: @MikeB_1505898

Posted : 29/02/2024 10:25 pm
Diem
 Diem
(@diem)
Illustrious Member
RE: Longer prints failing, pls advise

Bed adhesion was never a problem for my machine, and this print too was firmly adhered to the bed when I found it.

The bottom picture shows you did in fact have adhesion issues and the upper left quarter as pictured was warping up off the bed and of course overhangs always tend to warp upwards.   The print was not knocked free so there is a good chance that a crash caused the printer to lose position and generate spaghetti ... what do your crash statistics say?

I agree, the second fail sounds more like a clog or a mistensioned extruder idler.

Cheerio,

Posted : 01/03/2024 12:02 am
Mike B
(@mike-b-3)
Eminent Member
RE: Longer prints failing, pls advise

 

Posted by: @diem

Bed adhesion was never a problem for my machine, and this print too was firmly adhered to the bed when I found it.

The bottom picture shows you did in fact have adhesion issues and the upper left quarter as pictured was warping up off the bed and of course overhangs always tend to warp upwards.   The print was not knocked free so there is a good chance that a crash caused the printer to lose position and generate spaghetti ... what do your crash statistics say?

I agree, the second fail sounds more like a clog or a mistensioned extruder idler.

Cheerio,

I'm curious (and new at this) - the evidence of the bed adhesion issue is that the triangles around the outside perimeter of the bottom show signs of "lifting"?  And the theory is that the lifting of the base lifts the top of the print during the print, and that collides with the nozzle which causes the position to be lost, ultimately causing the mess of filament in some of the other pictures?

Prusa MK4 since Jan 2024, Printables: @MikeB_1505898

Posted : 01/03/2024 5:48 am
Thejiral
(@thejiral)
Noble Member
RE: Longer prints failing, pls advise

Yes, the signs of lifting of the outer triangles is a clear sign of adhesion failure. Nothing should lift anywhere during the print. 

If you have such adhesion failure it can indeed increase the upcreeping of overhangs. If your cooling is not enough that can also happen even with perfect adhesion. But on the images I do not see signs of insufficient cooling. 

My bet is on a partial nozzle clogg and/or too low hotend temperatures. 

Rainbow filaments are a bit tricky as the different colours can behave a bit differently and you have no control when you print which. 

Mk3s MMU2s, Voron 0.1, Voron 2.4

Posted : 01/03/2024 7:49 am
Diem
 Diem
(@diem)
Illustrious Member

You have the essence.  Your choice of fill may have contributed to distorting force - does it align with the lifting area?  Cubic or possibly gyroid might have been a better choice.

The usual advice about getting the print sheet scrupulously clean applies and a brim should help prevent lifting.

Newcomers to fdm are often surprised to find that issues late in the print may be caused by a poor first layer but think of it like the foundation of a tower; the stresses are small until it get's high enough to topple.

Your machine is very new, every user builds their printer slightly differently and pre-built models are shaken up in transit so during the first few weeks of use the printer will run-in and settle its parts together; then you will have to go over the basic maintenance checks, lubricate and recalibrate. Even if you got everything dialled in perfectly at the start, it would all need re-doing.

In your case it might be worth bringing forward your first service, you can take extra care knowing the new settings on your now stable printer are likely to last for several months.  Many here are used to two or three day prints without issues but few of us would have attempted them in the first month of a new printer.

https://help.prusa3d.com/article/regular-printer-maintenance-mk4_419000

Cheerio,

 

Posted : 01/03/2024 9:00 am
JoanTabb liked
pink_clown
(@pink_clown)
Estimable Member
RE:

In another thread and I can confirm I verified that they are right, users are complaining about the bad adhesion due to the significant defference between the bed temperature shown on the displej (e.g for PETG  85°C on display and 71°C measured on the bed surface)

So adhesion issue could happen and especially on the longer prints can impact the result.

Another issue I have in mind are the overhangs already mentined by the others. To verifie could be to cut the model in slicer a few milimeters below the failed layer slice it and try to print this critical part.

This post was modified 2 months ago by pink_clown
Posted : 02/03/2024 1:45 pm
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