Dramatic loss of print quality [probably cool issue]  

RE:

This exact same thing has been happening to me recently too.. I just made an account to make a (albeit much more hastily worded,) post about this. It's really upsetting me

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

Make certain your filament is thoroughly dry, protect the printer from drafts and try again.

If problems persist come back and ask again.

Cheerio,

RE:

Thank you for your reply.

I did full maintenance of extruder, checked tightening belts, checked all wires, made a cold pull, and checked all bolts.

Additional working together with tech sup:

• Remove printer from the enclosure
• Measure of resistance and voltage of electricity (thermistors and heaters), all passed well.
• Checked first layer test
• Hard reset with write FW (5.1.3)

The problem reproduces with the new spool of PETG, with other spools of PETG, with PLA.

Tech sup thinks that this is hotend thermistor(despite normal resistance) and sent me another one. I'm waiting for this now.

RE: Dramatic loss of print quality [probably cool issue]

Printing PLA with closed doors is a bit like asking for troubles. It can work but you are living on the edge of a nozzle clogg. 

I assume you printed all Benchies in the exact same orientation?

In general these images look very much like a weakening of part cooling for whatever reason. This can be either because the enclosure is now warmer than a few months ago, or that the fan might be a big clogged by dust or weaker for whatever other reason. There are special radial fan combs on printable with which you can pull out the dust from the radial fan. That can help a lot, if a lot of dust has accumulated. 

In general, whatever the cause, what you can do to improve overhangs is:

Increase part cooling fan power (if not already at max)
Slow down at ovrehangs or in general.
Orient the steepest overhang towards the partcooling fan shroud. 

RE:

Thank you for your reply.

So, failed 3mf: https://www.printables.com/model/794594-just-to-share-on-forum

Printing PLA with closed doors is a bit like asking for troubles. It can work but you are living on the edge of a nozzle clogg. 

I print with PETG in general, thank you for the warning. I tried printing with opened doors and outside of the enclosure. 

I assume you printed all Benchies in the exact same orientation?

Yes, the same model printed well with the same orientation a month ago. I checked fans for sure)

The problem corner is towards exactly the partcooling fan shroud. 

Additionally, I ordered a new cooling fan.

I think 3d benchy should print well on default settings in Prusa Slicer at any orientation, no?

RE: Dramatic loss of print quality [probably cool issue]

At a second thought, it can be of course that the hotend is for some reason hotter than before. If you did not mess around with the hotend/thermistor or damage any cables I would think it is more likely something related to cooling though. 

RE: Dramatic loss of print quality [probably cool issue]

Posted by: @faunris

Additionally, I ordered a new cooling fan.

I think 3d benchy should print well on default settings in Prusa Slicer at any orientation, no?

Actually, this is not the optimal orientation for overhang cooling. For the Mk4 the optimal cooling orientation is a bit less clear than for the Mk3. I would think the front of the Benchy should look diagonally towards the left front corner, maybe straight to the front. 

I would assume that the default settings are optimized for printing without enclosure. You have to be aware that in enclosure ambient temperatures will be higher and therefore cooling more demanding. For every filament other than PLA higher temperatures are actually something you want but they do have some downsides and cooling is one of them.

Thats why we have test prints. To calibrate settings for the very own setup. Of course, that doesn't explain the deteoration in overhang printability in your case. 

PS: You don't have to throw away your part cooling fan, usually it is totally sufficient to simply clean it from dirt with one of those fan combs from time to time. It is amazing how much filth can get caught in the impeller. 

RE: Dramatic loss of print quality [probably cool issue]

PS: You don't have to throw away your part cooling fan, usually it is totally sufficient to simply clean it from dirt with one of those fan combs from time to time. It is amazing how much filth can get caught in the impeller. 

Thank you)
I checked the print fan, it's clean like brand new.

For now, I try to print only with open doors, PETG\PLA. The problem is still here: 56b3d2e3-img_5685-scaled.jpeg

I found the problem when trying to print this detail (PETG):

Many tries with different angles. Quality is not well(

I hope it wires from a fan or a thermistor.

RE: Dramatic loss of print quality [probably cool issue]

Posted by: @faunris

PS: You don't have to throw away your part cooling fan, usually it is totally sufficient to simply clean it from dirt with one of those fan combs from time to time. It is amazing how much filth can get caught in the impeller. 

Thank you)
I checked the print fan, it's clean like brand new.

For now, I try to print only with open doors, PETG\PLA. The problem is still here: 56b3d2e3-img_5685-scaled.jpeg

I found the problem when trying to print this detail (PETG):

Is that one of the corner pieces for the (Un)original Drybox?  The one I printed yesterday in Prusament PETG Jet Black looks almost identical!  Especially those indentations at the same level as the screw hole.

RE: Dramatic loss of print quality [probably cool issue]

Posted by: @mike-b-3

 Is that one of the corner pieces for the (Un)original Drybox?  The one I printed yesterday in Prusament PETG Jet Black looks almost identical!  Especially those indentations at the same level as the screw hole.

Exactly 🙂
The sides printed perfectly, but problems started with the corners.

You can try to direct the flat part(where the fastening strip) to the backside, that can help.

After a few tries, I've seen usually problems with left-back corners. After research, I reproduced that problem with 3d benchy.
Made a comparison with old prints and saw a difference in quality.

RE: Dramatic loss of print quality [probably cool issue]

Did you optimize the hotend temperature yourself? In any case, doing a temperature tower with max part cooling would be helpful. Check if you are printing at the optimal temperature in regards to layer adhesion and overhang quality. 

RE:

So, the next part 🙂
I changed:

• hotend thermistor 
• print fan
• nozzle to obxidian (have the plan to use carbon fiber later)

The problem is here.
I tried to print temp tower (with closed doors), but to be honest, I don't see the big difference:

RE: Dramatic loss of print quality [probably cool issue]

I found source of problems here (Input Shaper): 

Flow rate doesn't correspond to extruder speed.

If we decrease overhang speed for 75% from 80% to 30mm/s then the surface will be much smoother