Filament stuck onto nozzle

My P1S was fine when I first got it, but then things went downhill fast. After the purging the wiper should cut off the filament. However during the purging process some filament can curl upward and stick to the nozzle. The wiper is ineffective because it can’t reach the filament stuck there. The purge line might take some of the poop off but most of the time the stuck poop gets dragged all the way to the start of the print where it gets deposited at the first layer, creating an ugly lump.

This has happened to all of my FDM printers. However I don’t see a lot of people having the same problem. Just want to know if there’s a solution.

Yes, others also have these problems. One culprit is a dirty nozzle. Clean the nozzle from time to time, from the outside with a brush when the nozzle is warm. With a damp cloth when the nozzle is warm. Warm so that the filament is soft and you can get it down. There are also cleaning filaments that you can send through once for rinsing. There are also cleaning filaments with solvent that should be left to work for a few hours (also just filament sticks). Another cause could be damp filament, moisture causes uneven extrusion. Once the nozzle goes over the wiper, it can then stick your filament to the nozzle. The filament must emerge from the nozzle as an even strand, it must not curl.

If you do not get this completely under control, it can happen that the filament residue from the nozzle settles on the print object during printing and causes faults due to the lumps there. In this case, place a small object (1 mm high and 1 to 2 cm in diameter) next to it, as near as possible from the rear wall of the printer (if you still have space) and print “by object” instead of “by layer”. This small sacrificial object / cleaning object helps with the deposition of filament residues. Just make sure that it is printed first, i.e. above the main object in the hierarchy of objects.

Best regards!

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Thanks. I was just thinking if I could find a better wiper and a better Gcode. What the wiper really does is to move the filament up and let it stick. Also it only wipes from the sides so there are filament at the back and front untouched. Probably a brush like the voron ones should do better?

It is impossible to say whether it works better. I even tried my own modification a long time ago by using a ballpoint pen feather. I partially achieved what I wanted by getting the filament to stick in the nib. But metal nozzle on metal wiper is not so good, the nozzle should remain as undamaged as possible. That’s why I dismantled it again. Also because there was no advantage.

I’ve just had the same phenomenon again with PETG. The pressure does not adhere and the nozzle is not wiped clean. I dried the PETG for 30 minutes at 65 to 70°C in the oven with circulating air. Now it works again, even the first stripping was absolutely flawless.

somę people use A1 mini wiper. maybe it is better? I also was thinking about this mod.

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Und? Wie funktioniert er?

problem might be solved with this… but I’m unsure if it will do too well.

I have a solution that works well in my head, but I have to build it first.

Anyone? Problem still exists.

As other mentioned, you could replace the wiper with something more robust. I find keeping my nozzle clean with a brass wire brush helps a lot with preventing filament from sticking and causing imperfections in my print.

Your filament shouldn’t be curling upwards towards the nozzle. If it’s extruding evenly it’ll come out perfectly straight and not curl like what you are experiencing. The most probable cause is that your nozzle is dirty and is experiencing a partial clog. Having gunk in the nozzle can lead to uneven extrusion and curling like you are seeing and in the worst case you can start experiencing complete nozzle clogs.

Like many things, Bambu Labs has some great guides on their wiki that cover many of the common issues users can experience. I suggest reading over their nozzle clog wiki page. Specifically at the bottom it has a video which covers doing a cold pull. If it was me, that’s where I would start since its a great way to pull out any built up gunk and gets the nozzle clean again.

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Once the nozzle starts having filament stick to it, it can get problematic. It’s like a nonstick pan that starts losing its non-stick properties and bits of filament can kind of cake on.

I bring the head to the front of the printer every so often and use some Kleenex to wipe down the nozzle while it’s hot. Not ideal and I still get small blemishes when the nozzle drags on a high spot, but manageable. If the filament is kind of hanging up on a nozzle while purging between colors, I sometimes use some tweezers to pull the plastic off the nozzle.

A non-stick coating on those nozzles might help? Maybe even a little wax applied to a clean one before use?

Thanks for that link to the nozzle clog page. I haven’t had a clog yet but there is some really good information there - especially the cold pull.

I printed an outdoor part in ASA for a friend and learned my lesson - high temperature plastics get their own hot end. I had fine strings of ASA coming out of the print head for a while after that but wonder if a cold pull might be in order. The higher temps with high temp plastics are probably more likely to leave those charred bits in the print head too and some blemishes might be bits of char coming out?

I’m not to sure, since I don’t typically have that kind of problem. Usually when I switch between filament types, I will do some long extrudes to clean out any of the old filament and clean the nozzle tip with a wire brush. If I’m going from a high temp to a low temp, like going from ASA to PLA, I will set the nozzle temp to the low end of the ASA filament and do a long extrude with PLA to help clean out the nozzle. Basically I try to reduce the amount of any left over residue form other filament types. I use the same nozzle for all the filaments I print (PLA, PETG, TPU, ASA, PC).

I’ve found that I’ve not needed to do any cold pulls on my X1C since I’ve owned it, but I also chalk that up to having to replace my hot ends multiple times due to me not paying attention and starting a new print before I check that the build plate is clear and bending the nozzle. :smiling_face_with_tear:

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Ouch! I think your strategies sound good, though. The long purge after using high temp filaments probably helps a lot.

the filament doesn’t curl, but because the wiper didn’t do its job the filament got stuck to some other filament on the nozzle and curled.