Factory Build MK3S Consistent Hotend Problems (heat creep?)
 
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sgath92
(@sgath92)
Active Member
Factory Build MK3S Consistent Hotend Problems (heat creep?)

I have a factory built MK3S+ and have been dogged, almost since day one, with hot end problems. Burnt looking pieces of plastic would end up in the print & around it on the build plate, lots of spaghetti messes on the build plate, lot of print failures. I was chasing bed adhesion & calibration assuming one or the other was the cause only for at around six months in, the hot end failed and started leaking into the heat-break and killing the thermistor (the whole hot end assembly was then replaced under warranty).

The new hot end cured the problem,  but only for a couple months and then I was back to the same symptoms: print fails very early on, with burnt looking crud all over the place.

I only print with PLA, of various brands, and I suspect whats going on is heat creep when A- working with a low melt point material, and B- printing at a low speed since most of what I print are physically small objects that need high res settings/details.

I use the OEM prusa slicer settings with the following different perimeters: Supports Everywhere, Organic Supports, Hexagonal infill, with both skirt & brim enabled at 5mm distance from the object.

When the printer actually works, the quality is amazing. But I have had really rotten luck with getting consistent success.

I suspect that a higher temperature material would go a long way to helping,  but it seems like most of the selection (of colors, especially metallic looking filament) is in PLA.

I have read some people elsewhere online speculating that the MK3S+ is especially prong to heat creep failures/clogs due to the design of the hot end assembly, as its 45degree taper et al was needed for the MMU (which I don't have). Is there any truth to this? Is there a hot end assembly that will do better with low-speed prints using low melting point filaments?

You can see the burnt "crud" in this picture (attached). My printer is acting like there is a partial clog.

 

I have tried: Cleaning the crap out of the build sheet & then wiping it down with acetone, and then using bed glue to make certain that the prints are super strongly attached to the build plate. I have calibrated and recalibrated the machine multiple times. And then today, at tech support's suggestion, I have done no less than three cold pulls.

None of this has helped and my printer is not currently usable.

I have had the printer since ~april and have only managed to run 2969m through it (83 days of print time), it would be running continuously if it were functional/able to do so as I have enough I would like to print with it. It has had more down time than up time.

I am not sure if the X axis is side-to-side or if that's the Y axis, but regardless, it is now making a loud grinding noise when moving the extruder left/right but I don't know if that's related to my problems.

Every 20 hours I have lubricated the solid shafts involved in all three axis with the included prusa lubricant.

 

Are my problems typical? Am I doing something wrong?

Opublikowany : 11/11/2023 11:22 pm
Diem
 Diem
(@diem)
Illustrious Member

 print fails very early on, with burnt looking crud all over the place.

Most often a first layer issue, either adhesion or a poor 'Z' calibration.

I have read some people elsewhere online speculating that the MK3S+ is especially prong to heat creep failures/clogs due to the design of the hot end assembly, as its 45degree taper et al was needed for the MMU (which I don't have). Is there any truth to this?

No.  There can be heat issues with PLA if printed in an enclosure but that's different.

glue to make certain that the prints are super strongly attached to the build plate

Glue is used to *reduce* adhesion to prevent print-sheet damage.

it is now making a loud grinding noise when moving the extruder left/right but I don't know if that's related to my problems.

Probably not but it should be addressed.  An audio/video recording would be useful.

OK, Clean the crap out of the build sheet again but this time use dishwashing detergent (Dawn/Fairy) and plenty of HOT water, dry with a fresh paper towel and handle by the edges only.  NO ACETONE.  Then run another first layer 'Z' calibration but don't change anything, let it run then show us the result *on the print sheet*.

And let us examine that troublesome print; Save it as a project:

Files > Save Project as

Zip the .3mf and post it here. It will contain both your part and your settings for us to diagnose.

Cheerio,

Opublikowany : 12/11/2023 12:30 am
sgath92
(@sgath92)
Active Member
Topic starter answered:
RE: Factory Build MK3S Consistent Hotend Problems (heat creep?)

> Most often a first layer issue, either adhesion or a poor 'Z' calibration.

There is no adhesion problem (at the moment), I have to fight to get the prints off the build sheet. The acetone was to "refresh" the build sheet; when simply using dawn dish soap with a sponge and the hottest water that can come out of my sink's faucet, the prints were not adhering to the build sheet and I had major adhesion problems. The glue actually improved, but did not fix that problem (and the vendor suggested that it helped, not reduced, adhesion to the build plate). From there I discovered that acetone can refresh the build sheet, and that fixed the adhesion problems for me (I have only used the acetone once, after the most recent time I have washed the sheet).

If the Z calibration is the problem then the machine is not taking a z calibration. I have recalibrate it over and over again and it has not changed any results.

Tech support from Prusa leads me to believe the problem is related to either the hot bed getting coated with unwanted material; or retractions; or heat creep/clogs. I am not sure which of those it is (or a combination of them).

Opublikowany : 12/11/2023 12:40 am
Diem
 Diem
(@diem)
Illustrious Member

either the hot bed getting coated with unwanted material;

It needs to be clean.

or heat creep/clogs.

Heat creep is unlikely unless you are printing very slowly or using an enclosure with PLA

Clogs should have been cleared by the cold-pulls.  If you have been using a variety of filaments then a cold pull with the highest printing temperature filament is sometimes necessary.

I have recalibrate it over and over again and it has not changed any results.

Then run another first layer 'Z' calibration but don't change anything, let it run then show us the result *on the print sheet*.

And let us examine that troublesome print; Save it as a project:

Files > Save Project as

Zip the .3mf and post it here. It will contain both your part and your settings for us to diagnose.

Cheerio,

Opublikowany : 12/11/2023 4:09 pm
sgath92
(@sgath92)
Active Member
Topic starter answered:
RE: Factory Build MK3S Consistent Hotend Problems (heat creep?)

So here's an update with what I've discovered...

The problem is the tree supports.

I am using factory/OEM settings in the Prusa Slicer (always the latest version I can get including betas). I don't/haven't felt I know enough to manually alter any of the slicer settings for things like retraction, flow rate, temperatures or supports beyond choosing which type of support I use and how much skirt/brim to use on the first layer.

So using the default support settings, the tree supports are malfunctioning because the default refraction settings are not working for this printer.  Somehow, either A- the refraction is insufficient and its making physical contact with the print knocking supports over & creating a mess, or B- the act of refracting the filament is causing heat creep, leading to the burnt filament gobs that then fall onto the bed/print and later get contacted by the nozzle causing stuff to rip apart or fall over.

It's either A or B and I am not sure which.

Prusa's tech support (via chat online) confirms this with me. They had me switch out of tree supports in order to verify it (apparently rectinlier or hexogonal supports do not use refraction like tree supports do).

I have been using tree supports this whole time (outside of my first 2-3 prints when I got the machine) because they seemed superior in almost every way; easier to remove from the part, left less maring, used less material. When they work, they're amazing.

So now the question is, why are tree supports no longer working?

Opublikowany : 12/11/2023 5:46 pm
sgath92
(@sgath92)
Active Member
Topic starter answered:
RE: Factory Build MK3S Consistent Hotend Problems (heat creep?)

Here's one of two identical Prusa slicer project files (the forum is only letting me attach one file at a time not counting images), the only difference between them is that one is using hexagonal supports and the other is using tree supports. The tree support one fails very early on (picture included); the hexagonal support one prints successfully, though one of the six parts does have some debris attached to it as if the printer is still having issues just not as badly (?).

Opublikowany : 12/11/2023 6:34 pm
sgath92
(@sgath92)
Active Member
Topic starter answered:
RE: Factory Build MK3S Consistent Hotend Problems (heat creep?)

And here is the other file.

Opublikowany : 12/11/2023 6:35 pm
sgath92
(@sgath92)
Active Member
Topic starter answered:
RE: Factory Build MK3S Consistent Hotend Problems (heat creep?)

Okay apparently the forum's "attach file" feature is not working for me so I cannot share the project files.

Opublikowany : 12/11/2023 6:36 pm
Diem
 Diem
(@diem)
Illustrious Member

its making physical contact with the print knocking supports over & creating a mess,

heat creep, leading to the burnt filament gobs that then fall onto the bed/print and later get contacted by the nozzle

Both of these have several possible causes.

It's either A or B and I am not sure which.

I doubt it's either of them, let us examine that troublesome print; Save it as a project:

Files > Save Project as

Zip the .3mf and post it here. It will contain both your part and your settings for us to diagnose.

I have been using tree supports this whole time (outside of my first 2-3 prints when I got the machine) because they seemed superior in almost every way; easier to remove from the part, left less maring, used less material. When they work, they're amazing.

They are intended for 'organic' prints, figurines and the like.  For functional prints snug supports are the go-to.  Other support types have limited applications but are ocasionally useful.

So now the question is, why are tree supports no longer working?

I'm sure they still work when used appropriately.

Okay apparently the forum's "attach file" feature is not working

Sigh,  *ZIP* the file.

Cheerio,

Opublikowany : 13/11/2023 2:27 am
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