I’ve been using the H2C’s right nozzles with a dedicated material each. It works great for everything, except TPU. The assigned TPU hotend will constantly clog and stall when loading the roll. I can print with the bypass and external spool just fine, it’s an issue limited only to loading and purging old material (so TPU on TPU).
As much as I know that flexibles are not easy to purge, I didn’t imagine that it would prove this annoying. I would probably put the blame on the section left in after cutting, which is way above the melt zone and not easy to push down. I never had issues with my other non-Bambu printers.
Cold pulls works great, mostly because PLA has the rigidity to push everything out.
Anyone with a similar experience?
Would really love to try a cold pull automatic gcode that loads and unloads from AMS. Probably not feasible, there will be plenty of guards against low temp filament moves and no-cut AMS retractions. and you’ll be left with a pretty long thinned PLA string on a spool, and no way of inspecting the results.
I experienced the same problem. Whenever I try to print with TPU for AMS filament, the filament from the previous print doesn’t eject and the nozzle clogs. I’m even experiencing clogging with filaments like PLA or ABS, which I’m currently using for color prints. Recently, I tried to print with PLA, but the filament wouldn’t go into the AMS’s filament feed slot. Upon inspecting the filament, I noticed the end of the rewound filament was swollen (see picture).
I have tpu clogs on the right nozzle often. I have noticed it happens if I stop a print, while printing tpu, nearly every time. If the print stops naturally, its usually fine. It clogs all the way to the cold section. I actually have 3 .4mm nozzles that need unclogged right now.
I use a nozzle unclogging tool(Allen wrench works too) and shove it down the nozzle throat while heatingvthe tip with a torch.
The crappy one is when it happens after its been cut. New filament has nothing to grab and can’t push the old tpu out because(in my case) its stuck above the melt zone
Just to be clear, I can’t get the needle to work either. I have to push it out from behind. With the nozzle not installed on the machine.
I had the same problem with overture 95A TPU. It’ will clog every.4mm vortex nozzle I tried even brand new one right before the actual print start, with or without feed assist module. I discover it’s more of a default start up script problem and lead directly to the heat creep clog. After purge it was doing nozzle wipe 3 times in a row for way too long while it’s still hot. I replaced stock start code
{if filament_type[…] == “TPU”}
G150.2
G150.1
G150.2
G150.1
G150.2
G150.1 {else}
with this
{if filament_type[…] == “TPU”}
M109 S140 A
G150.2
G150.1 {else}
So it drop the temp down to 140c immediately after purge and let it does only one wipe seems stopped the clogging. Still need to print some more to see if it’s reliable enough.
I’ve printed Creality CR TPU (95A) and Bambu Lab TPU 90A on my H2C with .4 Vortek nozzles without a problem. I do a cold pull first to make sure the prior filament is cleared before I load the TPU, which is what Bambu recommends. I also remove the top cover. I’m using a TPU Feed Assist Module and feeding the TPU into the feed assist from a dryer.
Holy sh*t that sounds like it might actually be the solution.
The machine behaviour you described is EXACTLY what I am observing too.
I have to pause the machine right the moment it does the little purge/priming line, do cold pull and then it works (if it doesn’t overload the extruder motor after lol)
Will try out your GCODE, thank you for sharing that!!!
I’m wondering what we’re doing differently, or if there’s some equipment difference… I’ve not had a single clog on my H2C since last December, printing Overture 95A HS (several colors), BL 90A, ST 85A, ST PEBA Air (or anything else for that matter). 0.4 & .6 induction nozzles. No assist module. Before I dedicated a couple nozzles I didn’t do any cold pulls either. One time the printer actually switched nozzles on me (due to some mixup between slicer and printer) after I’d loaded TPU into the nozzle I wanted to use… and it still worked fine (I forget what was in the nozzle it ended up using… PETG HF maybe). Also this is my first printer so not like I have/had lots of prior experience… just (mostly) following BL-recommended practices.
I hardly print any PLA, if that makes any difference (though folks reporting this with new nozzles also).
I print from my own roller dryboxes built into Rubbermaid 21c bins, via dedicated PTFE tube running directly to the print head (through bypass port on back). Smoothest/straightest path possible, no splitters or other interference in between. Never did the top mount thing, all glass closed up.
There must be some difference… right? I’m happy to compare notes if that’s helpful to anyone. Not sure where to start though.
When y’all initially load the TPU, are you extruding some to make sure it’s flowing OK?
Since yours is overture highspeed and other brands. I still suspect it’s the regular overture 95A TPU doesn’t work well with vortex nozzle. Especially with that redundant triple wipe action. Although delete that section seems work for me but I still don’t like it spend so many minutes between filament change purge and first prime line without any flow doing those nozzle tip cleaning wipes and offset calibration etc. at higher than room temperature. I know it’s not drying, not cold pull, feeding or feed assist issue. The left nozzle works fine, and on right nozzle as long as it can survive past the single prime line step it will print fine afterwards. The symptom I experienced (and probably most of others as well) was it will purge fine at initial feeding but clogged when doing the purge line right before the print.
I came here experiencing the same issue with Bambu 90A with Vortex 0.4 standard nozzle. I never had this issue, I did not have issue with Bambu 85A with 0.6 nozzle but 90A… wow one successful print. Then started the next same print, it no longer print but clogged. Why?
I have TPU Assist Module installed as well and it runs with it.
I am testing out your change of codes. See if this fix it.
Side note, I think Bambu has been quietly updating those gcodes for H2 because of all the new accessories and hotends for TPU but all these changes caused a side effect for original nozzle or setup.
Gcode “TPU” is very much all egg in the same basket regardless if you have nozzle designed for TPU or standard nozzle. I think this default code will works well with the new TPU nozzles.
Having the exact same issue. My theory was clamping force too high deforming it. So the longer it sits in the extruder the more like it fails. Mine ends up sliding out sideways as well, but as other have said, loads and extrudes completely fine initially. If I get a print going it prints fine, problem is between load and start print.
I will try the gcode change. Using siraya TPU air which is quite squishy.
Guess what, the change of the GCode Machine Start code fixed the problem. I have been printing new model with TPU 90A after one and another. No clog so far.
I really want to try this. I’ve JUST tried printing with a packaged roll of TPU I had in storage for 8 years (I was always too afraid to print TPU). Dried it overnight, and the first print was amazing. But trying it again it would give an extrusion motor overload error. Long story short, I got some cleaning filament clogged when trying to clear out the TPU and had to disassemble the thing and clear out the broken bits stuck in there.
Where do you change this start GCODE? I assume it’s in Bambu Studio > Prepare tab > Edit the TPU Filament from the list > Advanced > Filament Start G-code? Please let me know, thank you!!
This may be helpful to some. What i have found(early h series adopter) is that if I cancel a print midpoint the tpu clogs all the way up into the cold section. If I pause the print correctly and then cancel it, no clog. I havnt paid enough attention to know why but I imagine that when I cancel it, the cooling stops before the nozzle is cool. So the heat bleeds off into what should be the cold section.
