Having this with just one of my printers, midway through a print it just starts massively under extruding leaving the print like dust. Replaced, hot end, cooling fan, nozzle, extruder motor, ptfe tube, ran it through the ams and also separately to the ams.
Done cold pulls on the nozzle.
It’s doing it at different points of the model aswell. Sometimes it will complete a print and then cock up the next one, some it will go wrong right near the end and some mid print.
Now I’m lost
All the files are ones i have printing on other machines and the filament can be swapped between the machines and it works perfect so it’s not software or filament issue imo
P1S
Only thing I have just spotted which I haven’t changed is the sd card, do you think it could be that?? I’m desperate now!
Not the best pic but you can see what’s happening!!
Try what a good inventor does : Once enough mistakes were made something has to work eventually
The print seems to start just fine, fails at random points and seemingly always with the sort of failure = should be possible to repeat the conditions that cause it.
As you already tried so much, let me add some things you might not have tried:
What about retractions ?
E.g.: Does a simple test cube or such print fine while models with lots of retraction keep failing?
The reason could be heat creep, especially with effect/filled PLA filaments.
The extruder pushed but the filament is too soft and widens rather than entering the hotend.
As a result you never get enough filament flow unless the flow gets better and the retractions less.
Sometimes you can see this when you check the end of the filament - it looks deformed.
A workaround is to lower the retraction and de-retraction speed while also making sure only as little as required is retracted.
Do hear the extruder clicking or such noises while the print struggles so badly?
Would indicate that there is a transport problem.
Overcooking can also be a factor with certain filaments.
Very low flow rates, lots of retractions and there is always some filament stuck on the walls of the melting chamber.
Sometimes these leftovers get too hot from being stuck for so long, they get brittle or discolour.
If they break free the can cause a partial nozzle block, or even a full one.
Try with some light coloured filament to see if there is dark or discoloured bits being extruded before these prints fail.
Last but not least: The extruder itself.
If not enough filament makes it out then it has to get stuck somewhere.
Check if the print works when feeding directly into the extruder with just a short teflon tube in it and the filament running free from an external spool.
In case all works just fine I would tend to say things get stuck on the way to the extruder.
If it fails the same way you should be able to see whether or not the filament is transported while the extruder works.
Observe the noise !
Check the filament for wear marks caused the extruder - a bit is normal, cracks and deformation is not good.
Quite often is helps to turn out the screw for idler pulley a bit to reduce the pressure on the filament going through those wheels.
There is not much wiggle room though unless you are prepared to make a hole into the head cover.
Works really well for TPU…
Have had this on my A1 awhile back, can’t 100% remember the fix but things I did was:
Used some cleaning filament, this comes with Ziro brand filament, run it through.
Looks like silk filament, check you have adjusted the profile as stock ones for me are way too fast, there is a page on the wiki with recommended speeds, I think I have everything 100 or lower, about 60 on outer walls.
I know I have also since replaced the sd card with sandisk ones.
Try using non silk filament and see if it still happens.
Hey, thanks for the reply, I’ll have a bash at some of these, with regards to the extruder idler, how tight is it supposed to be, there doesn’t seem to be any kind of gauge on the screw, and it isn’t really adjustable others than making it more loose? Or have I done it too much with all the way in?
So I’ve done 3 cold pulls to clean everything from the nozzle then used Bambu filament to print the vspooler handle and it’s come out perfect. I’ll try a plain filament on the previous failed print and see how that comes out!
This happens when I print this model face down I’m using bamboo labs branded basic PLA filament it does the same both my P1S and my A1 mini any suggestions on how to get rid of these strings thanks in advance
Some new sd cards landing today! Bambu suspect if the sd card doesn’t fix then it’s the th board. Just going to end up having replaced the full unit in warranty parts the way it’s going!
It doesn’t matter whether it’s through the ams or direct to the extruder the same result happens
Update, swapped out the sd card and it seems to of fixed it! That isn’t even something bambu recommended but I’ve done more than 5 prints with the new card and it’s been perfect again!
Thanks for the suggestions but I think I can call this case closed!
