I have a P1S, less than 3 months old, with a new AMS. I have printed a lot of prints, both PETG and PLA without issues until now. Suddenly I have a very consistent problem where a blob of plastic is forming on the nozzle after filament load, and before the print starts. This blob then falls off, usually on the first layer but sometimes later, leaving a hard nugget of plastic on the print. Collisions with the turd ensue as layers are deposited, and things generally go downhill from there. This seems to be happening now with every print, and I need to watch carefully and try to pick it off at the beginning of the print, or the print is doomed. Once I clear it, things proceed fine, and there don’t seem to be any other problems with blobs. This happens with both PETG and PLA, Bambu and generic filament. I have recalibrated, but as this is upon start before the file prints, could this be a firmware issue? Could the AMS be pushing filament into the printer creating the blob? and AMS firmware issue?
I have replaced the nozzle. I lubed and cleaned the rods. The wiper looks ok, but I will change it anyways (I don’t expect it will help).
Watching the process closely, the blob forms on filament load, there is a wipe, but filament seems to keep oozing after the wipe. Then the head moves to the special wiping area at the back of the plate, and the printer drops the nozzle and shoves the oozed filament up onto the metal part of the nozzle, and smears it around a bit during this “special wipe”. Then the head moves to the front of the plate and the purge line is printed. Generally, this doesn’t remove the blob, which is now shoved far up onto the nozzle (sometimes it will catch the blob just at the end of the purge line, and produce a big string which is drug across the first layer). Usually, the blob comes off during printing of the first layer, as the head heats up, softens the blob a little and it sags down and catches on the print. It then pulls off the head and sticks to the first layer like a little rock-hard turd. It’s fairly large, and when the head collides with it there is an audible CLUNK from the printer, and the print is usually ruined.
What could this be? It’s definitely a new problem for me. Related to the new AMS? AMS firmware? Help!
Maybe your reverse bowden tube(s) have worn out? Technically speaking, they are consumables. I’m not sure what the symptoms of a worn out reverse bowden tube are for certain, but maybe it’s worth looking into.
I have on occasion experienced a similar thing when printing PETG, but I’m told that kind of random behavior is fairly typical for PETG.
I replaced the wiper, and no change. So per your suggestion, I replaced the PTFE tube in the printer. I also added the custom part that holds the radius coming out of the head which helps with feeding and keeps it from rubbing on the glass (this one .. It was starting to make a really annoying screeeeek screeeek sound anyways. The first test after changing the tube failed with little bits and crumbs of plastic all over the bed. These might have been left over from an earlier print, so I cleaned around the nozzle real good and am attempting another test.
Be sure to use teflon tubes with a 2.5mm inside diameter. Regular tubes, like Capricorn, have to small an ID and cause too much friction, and BBL says that using teflon tubes with an even larger than 2.5mm diameter also comes with a different set of problems. 2.5mm is the sweet spot.
I used Bambu 2.5mm tube. Still fails and leaves crumbs all over the print. This almost seems like it’s colliding with the support and knocking it over. Happens a lot more when there is any kind of support structure.
I doubt it’s a firmware issue, or else it would be affecting everyone. Right?
If you haven’t already done so, it would be smart to install orca slicer and run the built-in calibrations and adjust your profiles accordingly. It’s easy to do, and it will either solve the problem or else you can at least cross those items off your suspect list.
Another thing to consider is whether your filaments have absorbed too much humidity, as that’s another known cause of undesirable oozing.
The printer has been making a “screeeeek noise” when printing. I thought it was the ptfe tube rubbing on the glass. But I eliminated the rubbing and it still makes the noise. Could it be a bearing or something? It makes the noise when the head is moving toward the back left.
Have you done a preventative maintenance yet? There are cleanings, lubrications, and rust preventions you need to do on a regular basis. There exist some youtube videos that can walk you through it.
I cleaned and lubed the screws, cleaned the carbon rods, and adjusted belt tension. I also changed out the nozzle and replaced the wiper and the PTFE tube to the nozzle. Cleaned the plate, and tried multiple plates. Still does it. I reset by filament calibrations to the default suggested by Bambu and then slowed them down a bit, as this is generally necessary for PETG for me. I think I’ll try disconnecting the AMS and printing directly from my heated filament drier. That’s what I used to do before I got this AMS.
You didn’t just now say you lubricated the idlers, but that’s on the list. Also, you didn’t mention the steel rods either, and those are the ones that need the rust prevention.
I presume BBL has reasons to recommend doing prevention on those things. If you have a squeek, like in your video, then lubrication is worth looking into. If it still squeeks after that, then consider what else, but at least knock out the easy suspects first.
Things have improved somewhat with the following settings.
Line infill. No more bumping and crossing the infill picking up little bits of molten plastic on the nozzle. I think this helps a lot.
Reduce infill retraction UNCHECKED(off). Same reason.
Check and clean the nozzle of any accumulated plastic after each print. Even with the above settings, some bits of plastic accumulate on the nozzle.
I switched back to eSun Translucent orange, as it seems to behave the best for me.
This has allowed me to get a couple successful prints again. I put the troublesome Bambu blue PETG back in the dryer, and I’m trying that filament agin with these settings.
If the Bambu prints well, I will probably just start printing ALL PETG from the heated dryer (like I used to do), and I will no longer store it in the AMS, even though the AMS has plenty of extra desiccant in it.
Printing the Bambu PETG from the drier helped a little. There were fewer blobs and artifacts after re-drying, and I got the last of the spool to print. So I switched to a white Overture PETG that has really been a nightmare to print with. It produced several failed prints in a row. Specifically, it does not stick to itself when printing infill, and it especially fails to stick when printing the transition layers of support structures. This leads to a lot of strings, loose blobs and lumps in the print. Usually this cascades into a failure. The surface of the part actually looks a bit chalky and dull, even though I am printing near the high end of the recommended range. I tried adjusting support and infill settings, but after the forth failure I gave up and switched to a roll of eSUN’s new high speed PETG that I wanted to test…
I loaded it, set the generic PETG profile, bumped the max flow up a bit to 15, and set the temps to what was recommended on the spool. I also did a manual flow calibration, then I printed a part with lots of infill and support that was giving me all the problems and…
it produced the most beautiful and perfect PETG print I have ever seen! The quality rivals anything my printer has produced with PLA. Not a spec, smudge, blob, or string to be seen anywhere. Not only that, but this is printing faster than any other PETG I have used, and I haven’t found the limit.
Welcome to the club. There definitely are meaningful differences between filaments. Other than trying everything, it’s really hard to figure out which one will work the best.
What’s even more frustrating: the next spool you buy, same model and everything, from the same manufacture may well perform differently.