Print quality suddenly gets worse

[Lez0]

Help!
I have tried printing this part a few times and I always have the same problem. It's a thin walled cover, 2.2mm thick 100% fill.
The print starts off perfect then you start to here the stepper filament motor clicking and the print quality suddenly gets worse.
This particular print I could snap the top part off as if the layers weren't sticking.
It's as if the nozzle get a bit blocked, it's fairly new.
I did a test print of about 12mm and it was perfect, so I put a brand new roll on that arrived the same day, A Sunlu silky white.
After a few hours I checked the print and it was like this, well 10mm taller as I snapped the top off easily, the bottom part is very strong, so I don't think it's the filament.
Settings in Cura have not changed.
Any ideas.

Thanks

[Roberts_Clif]

Lez0 Post the G-Code

This is crazy, it could be caused by Z-Height tension, or better yet this could be caused by corrupted configuration.
I would try to reinitialize 3D Printers firmware or examine the sliced G-Code produced for some sort of corruption.
Could be also caused by a defective or corrupted SD Card format.

[Lez0]

The firmware were updated a few months back. I have done many prints, although smaller, without any problems, apart from this one.

gcode file.

JA5A5S_Tooth-Brush-Casing-R1-14-Dec-2022.zip

(17.28 MiB) Downloaded 432 times

Thanks

Lez0

[Lez0]

I'm doing a test print of the previous file to see what happens.

[Lez0]

Well I did a second print without changing anything, using the same SD card and gcode that was in the machine.
Well I just a slightly better print, the good part is higher than the first print and it's not as fragile.
But after the good part there are slight gaps in the layers as above.
One thing I did notice was the Filament motor clicking now and again as if it was struggling to feed the filament.
It's as if the nozzle gets slightly blocked after a period of time.
Generally the print looks good apart from the layers not sticking.
Can anyone point to anything I should look at because this is baffling me.
Thanks
Lez0

[Roberts_Clif]

I too am at a loss!

Though if as you said the stepper is clicking, what is the temp, did hot-end cooling fan increase in speed.
Is build plate area enclosed too keep breeze from blowing across part.
Is the hot-end stepper motor getting overheated.

[Lez0]

I have the printer in an enclosure bed temp 50° for the PLA they recommend 220° Fan 80%.
Don't know about the stepper for the filament, filament goes through bowden sleeve.
I've done some big prints, 72 hours for one and had no problem, but that was a couple of years ago.
Lez0

[LePaul]

Hi, sorry I haven't been on...COVID landed here. Finally feeling better

Usually clicking means a blockage somewhere, something is constricting that flow of material.

Also, 220C for PLA seems really high to me. Have you done a temperature tower to see the best setting on your machine?

I stick to 60C for bed temps.

A few things I would check would be the nozzle and bowden tube. I have many instances where a Creality PTFE tube got cooked over time and made it difficult for filament to flow smoothly into the hot end. The symptom was very similar to yours - print start good that deteriorates as the print goes.

I do the cold pull to clean my nozzles often, since different materials over time can leave residue.

Another thing to check is your part cooling fan, is it blowing on the nozzle or below? I ask since I had one machine that had the duct blowing on the nozzle and it caused all sorts of extrusion issues.

I keep a large supply of extra Capricorn bowden tube on hand since I have several machines that have the issue you describe. The stock PTFE that comes with some of these review machines is very poor quality (cheap!)

[Lez0]

Thanks Paul
Hope you recover quickly from Covid I hope you just had a mild dose, I found it took about a month to fully recover, but then you're much younger than me.
I lot of good advice. I too think it is a hardware problem, it's just strange it happens after the print has been working for a few hours, and isn't consistent. Sunlu recommend 205-230°C for there PLA filament, it seems to work OK at that temperature. I was using a higher temp for the bed, but the prints really stick to the bed and I have a big problem getting them off, so I dropped it to 50° to see if it would help, that was months ago.
I'll strip out the bowden tube and hot end to see if there is anything there to worry about, the tube is covered in a corrugated tube to stop it kinking so I can't see what it's like without a strip-down.
The fan has a cowling to direct the air, I'll check it's working OK.
Thanks for all your advice Paul.
I'll let you know how I get on.
Lez

[LePaul]

Hi,

Any findings?

Still have the covid cough thing but over the worst of it!

[Lez0]

I've been super busy with work so I haven't had time to look at it.
Also there is this thing called Christmas that seems to interfere in everything
I hope to get it stripped down over the next few days. I'm keen to get to the bottom of this as I need to print the part.
I have to take it out of the enclosure and do this in the patio as there's no room in the garage, I keep adding toys, sorry, other essential machines.
As a side note I'm waiting for a Saturn 2 to arrive.
Lez

[Lez0]

Not having much luck.
I set the large print away this morning and it started then stopped after about 2 seconds, the machine had re-booted.
I'll have to think about this one.
Lez

[Lez0]

I am at a loss.
I did another part similar size but not as high, 12 hour print and it cam out OK.
So I tried printing the part again, after about 9 hours I noticed gaps in the print, splitting, no sound from the feed motor.
You can see on the print where it starts to deteriorate.
The temperate for the filament was 200°C, Sunlu recommends 200-230 for this PLA.
I can get short prints OK, but not tall ones. I can't see anything wrong with the printer.
I may go back to the old firmware and try that as I installed the latest a few months ago.
Lez

[Lez0]

I've printed a temp tower, 235-195.
I think about 215 seems to be the best, but there isn't much to choose from any of them.

Lez

[LePaul]

Wow the bridging is really bad. Is the part cooling fan working?

The edges are very blobby. Is the esteps right? Tension good?

What about a different PLA?