Prints stopping midway  

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matt.p3
(@matt-p3)
New Member

--I have read other forum posts on this topic but still have more questions--

Hello I have a mk2s that I built recently (was sitting in the box for a while) and it made some fantastic prints after I got everything calibrated. However a couple weeks ago a print came off the bed midway and created a big melted mess around the extruder. I followed forum advice and gently removed what I could from the heated extruder and didn't touch the wires and got it mostly cleaned it out. And its been working fine, until today.

I'm now noticing prints will stop 10% into the job, and the screen reports its 100% finished. Reading the forums it could be either an SD card failure or a thermistor issue. I removed and reformatted the card, reloaded the stock Prusa .zode files, switched to PLA and tried to print the Marvin file. However that's also stopping midway which tells me its not related to material or bad slicing settings.

I'll get another SD card and will try that (just in case the card's bad) but I have a sneaking suspicion that my thermistor was compromised when it had resin melted around it around it may have caused problems that didn't manifest immediately. Should I just order a replacement? If so, being in the US, where can I get a new one fast so I can get up and running again?

Thanks for any other advice or ideas.

...
Posted : 12/03/2019 10:34 pm
Tim
(@tim-m30)
Illustrious Member

You could spend some time cleaning the hot end; that'd probably help. But I doubt the thermistor died just because plastic got near it.

The 100% shown on the display is the print speed.

What does the error history report? It looks like a movement failure, a crash of sorts. But noting like a common failure I've seen. If I were you, I'd connect with Prusa tech support (log in, select chat on the sales page). They might have more experience with real hardware failures.

It is always wise to get more than one opinion......
Posted : 13/03/2019 2:13 am
matt.p3
(@matt-p3)
New Member

Tim, I've been doing some testing to try and narrow things down.

I carefully cleaned the hotend with a wire brush (did not touch thermistor wires) and replaced the nozzle with a brand new one, just to rule that out, and material is feeding clean and consistent. I am able to print small items successfully (around 40x40x40mm) in various places on the bed. But printing large items, it stalls 3-4mm into the job (below image). I got a one time Bed Thermal Runaway error which has mysteriously disappeared. I read up on the issue https://help.prusa3d.com/article/aicptwdn3b-thermal-runaway and confirmed I have no issues with ambient drafts, the thermistor tape looks good and I'm keeping PETG items away from the center of the bed. So not sure if I'm dealing with multiple elusive issues.

I also seem to be hearing a knocking sound, which I'm not sure if its normal, or related.
[youtube] [/youtube]

I have not been able to get a new SD card yet but I have to test this. But the fact that I can print small items successfully tells me that (hopefully) I don't have issue with the main board.

I'm not able to find the chat feature on Prusa's site anymore. Not sure if they disabled this. Thanks for any additional insight.

...
Posted : 22/03/2019 5:37 pm
Tim
(@tim-m30)
Illustrious Member

To get CHAT - you need to first log into their Store as if you are going to buy something.

The "knock" almost sounds normal, just the table mass stopping and restarting the other direction. Might be a slightly loose X or Y belt; and a check for any loose screws just in case. The print doesn't show any major "looseness"... I doubt the knock is part of the problem. Nor do I think it's an SD card problem.

Since you are rafting, the part that sits on the raft may come free of the support with little or no effort. I have had this happen many times. Printing PET, I'd keep the print fan off to get better layer to layer adhesion in this crucial region.

And I'd also look at the failure with an eye for any hint of material curling or warping. If a section of the part curls, you will hear the nozzle striking it during moves (a clicking noise), and if not dealt with, the nozzle will knock the part free. When that happens, the spaghetti starts.

It is always wise to get more than one opinion......
Posted : 22/03/2019 10:52 pm
tyson.g
(@tyson-g)
Active Member

Iit looks like one of the reasons the MK3 design starts clicking/under-extruding and sometimes jams is that the “custom” PRUSA e3D heatbreak changes bore size from 2.2 to 2 close to the heat zone. Proto-Pasta did a bunch of testing that showed that this was probably the major cause of the click (stepper slips) and under-extrusion sometimes leading to jams. If this is your problem, the solution is to by the non PRUSA custom e3D heatbreak https://shop.prusa3d.com/en/mk2-spare-parts/121-e3d-heatbreak.html

Posted : 29/03/2019 6:22 am
Tim
(@tim-m30)
Illustrious Member


Iit looks like one of the reasons the MK3 design starts clicking/under-extruding and sometimes jams is that the “custom” PRUSA e3D heatbreak changes bore size from 2.2 to 2 close to the heat zone. Proto-Pasta did a bunch of testing that showed that this was probably the major cause of the click (stepper slips) and under-extrusion sometimes leading to jams. If this is your problem, the solution is to by the non PRUSA custom e3D heatbreak https://shop.prusa3d.com/en/mk2-spare-parts/121-e3d-heatbreak.html

While this a place to look when all else fails, it is provable and disprovable as a cause. Whenever I've done cold pulls to fix printing issues, I have never seen a "double hump" in my filament that would support this theory being given by Proto-Plasta. In all cases, I see my filament from a cone to 2.0mm, and then 1.75mm. The 2mm section being what is inside the nozzle and early section of heat-break; and never have I seen any 2.2mm section that would support the "bad" heat-break theory of jamming.

Anyone having jamming issues caused by the heat-break design would easily see the 2.0mm to 2.2mm section on their cold pulls.

It is always wise to get more than one opinion......
Posted : 29/03/2019 4:14 pm
PJR
 pjr
(@pjr)
Antient Member Moderator


While this a place to look when all else fails, it is provable and disprovable as a cause. Whenever I've done cold pulls to fix printing issues, I have never seen a "double hump" in my filament that would support this theory being given by Proto-Plasta. In all cases, I see my filament from a cone to 2.0mm, and then 1.75mm. The 2mm section being what is inside the nozzle and early section of heat-break; and never have I seen any 2.2mm section that would support the "bad" heat-break theory of jamming.

Anyone having jamming issues caused by the heat-break design would easily see the 2.0mm to 2.2mm section on their cold pulls.

Totally agree with this.

I did find a couple of flaws in the PP guy's suggestions and I think the addition of the sock (which I have used since it was available) contributes more to the solution.

In any event, this issue is posted in the Mk2/S forum, so it's not even known which heat break is in use here.

Peter

Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…...
Posted : 29/03/2019 4:22 pm
tyson.g
(@tyson-g)
Active Member

I replaced my PRUSA custom heatbreak with the e3d v6x heatbreak used in the MK2x and my issues went away.

Posted : 08/04/2019 5:31 am
Tim
(@tim-m30)
Illustrious Member

@Tyson - great, but this thread and posts are about a person using a MK2/s ... so I doubt your MK3 heat break experience will help. Besides, not every MK3 and MK3s has the special heat break. And beyond that, you may have cleared a PTFE jam when you replaced the heatbreak, or reset the PTFE position or collet lock, or any number of things that aren't at all heat break related.

Until you show me a piece of filament removed from the suspected "bad" heat break jam that clearly shows three diameters, I don't buy the argument.

@Matt - any progress?

It is always wise to get more than one opinion......
Posted : 09/04/2019 2:10 am
PJR
 pjr
(@pjr)
Antient Member Moderator


...but this thread and posts are about a person using a MK2/s ... so I doubt your MK3 heat break experience will help. Besides, not every MK3 and MK3s has the special heat break.

Tim, sorry to correct you but...

The standard E3D heat break was shipped with the Mk2, until just after the MMU1 was released. Later Mk2 printers shipped with the same modified heat break as the Mk3 and to the best of my knowledge, all Mk3 printers have this modified heat break.

The Mk2S was available as an upgrade for the Mk2, although all Mk2S printers shipped from PR have the modified heat break, there are user upgrades with the standard one. The modified heat break was also included in the MMU1 upgrade kit.

Until you show me a piece of filament removed from the suspected "bad" heat break jam that clearly shows three diameters, I don't buy the argument.

Again, with you 100% on this.

Peter

Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…...
Posted : 09/04/2019 11:32 am
tyson.g
(@tyson-g)
Active Member


Iit looks like one of the reasons the MK3 design starts clicking/under-extruding and sometimes jams is that the “custom” PRUSA e3D heatbreak changes bore size from 2.2 to 2 close to the heat zone. Proto-Pasta did a bunch of testing that showed that this was probably the major cause of the click (stepper slips) and under-extrusion sometimes leading to jams. If this is your problem, the solution is to by the non PRUSA custom e3D heatbreak https://shop.prusa3d.com/en/mk2-spare-parts/121-e3d-heatbreak.html

This did work for me in eliminating the under-extrusion and clicking caused by the slipping extruder motor due to the 2.2mm to 2mm change in the heatbreak. After many successful prints I started to get jams again. After talkign with support It turns out there is a second problem if you don't use Slic3r PE. Other slicers aren't putting out gcode that is entirely compatible with the MK3S for some reason. I switched to Slic3r and the last of my problems with clicking, under-extrusion and jamming are gone. I have literally printed for hundreds of hours now without any issue at all.

Posted : 21/04/2019 8:15 am
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