I clicked that escalate your case button in the email, then also replied to it explaining I had some all the things in the wiki, pointing to my original ticket and that I had done all that, and linked to this thread as proof it’s a defective product issue not user issue.
Been running hardened gears/extruder for the last 2000 hours and do both firm (98A) and softer (85A) TPU on occasion. The 98A I pretty much run like a normal filament through the external port, I don’t even have a MMU, the 85A I run 0.6mm nozzle and run the filament straight from my dryer, then disconnect the PTFE tube from the top of the extruder and feed the filament straight into the extruder.
While I can’t say that I have never had a problem as I do remember some heat creep issues initially, even with the 98A stuff, I resolved it by lowering temps a smidge and using the larger nozzle in the case of the softer TPU.
Some people suggest loosening the extruder idler tension just a bit for TPU (I think normally this should be “tight”), but then you have to take it apart to get to it.
What exactly is the mod for the extruder?
Drilling/cutting a hole on the side of the head enclosure plastic so you can easily access the tension screw.
I think they prefer to be called “Speed Holes”
I thought they were called Burr Hole or Trepanning? 
Oh! I did not even notice it!
Just dropped this, this might be the fix. TPU Feed Assist Module | Bambu Lab US Store
I can’t see that helping, even if it’s driven, I was pushing the TPU straight down into your extruder and it wouldn’t extrude.
In a way of love to be wrong, in another I’m in disbelief that they’d try to sell something extra to use rather than fix the issue with the HS gears.
I might test it out once I get more gift cards.
Drop an update if you do please.
Interesting. I wonder how they solve the dragging/friction problem that cause the filament stretch thin at the extruder gear.
I do not know, but I hope to get one soon. I will let you know if I get it.
A couple weeks ago I went through a saga… or I could say a nightmare. A whole weekend, starting from friday night going through the weekend, ending at monday night, with a partial solution, almost 90% complete solution. And this solution is this same mod. I don’t remember being so angry as that “TPU weekend”… I couldn’t sleep, eat, think… TPU was destroying me. My P1S simply wouldn’t print TPU. A dozen minutes printing, and it started a severe under extrusion. If I didn’t stop the printer, it would clog the nozzle.
I tried everything throughout those 72 hours… stock nozzle, hardened steel nozzle and gears, tried every possible combination of speed, flow, temperature… nothing… filament was drying for 48h straight on my Creality Pi… tried printing directly from it… with PTFE, without PTFE… fed from the back spool holder with PTFE, and without PTFE… finally I printed a top spool mount, to feed TPU DIRECTLY from above, without ANY interference.
I had more than 12 clogs that weekend, I stopped counting after that… after each failure I did 3 cold pulls sequences, and used a needle to unclog the hotend… I diassembled my extruder 9 times… cleaned everything, everytime I opened it… checked my fans everytime… I made sure that I wasn’t having heat creep issues… door opened, top lid removed, controled room temperature…
NOTHING WORKED!!!
Than… after some last resort research… I decided to mess with idle tensioner spring… did exactly that mod, a hole to be able to access that bolt… Manually fed the TPU with a 250ºC nozzle and started extruding, while unscrewing the bolt at the same time, and observing the thickness of the extruded material, until it turned a fatter line. And finally I managed to print flawlessly…
Loose the screw, just do it! How many turns? Three, four… seven… don’t know. Just loose the bolt while extruding at 250ºC and look for a fat extruded molten material.
So… the problem is inside the EXTRUDER… too much tension, squeezing the soft filament, making it unable to be extruded correctly. And, when I said 90% solution, it’s because sometimes I still have under extrusion issues. Sometimes I need to cancel the print, and sometimes the extruder “corrects itself”. Perhaps I still couldn’t find the REAL sweetspot on that spring.
- Are you using a 0.6 mm nozzle?
- Are you feeding it directly to the tool head?
- Make sure you are not using PTEF tubes
- I would double check that your nozzle is clean, and that your gears are clean.
- Make sure you have a sharp filament cutter
Hope this helps!
That 90% was because the spool rotational spin drags back the filament –> stretch thin the filament thin at the extruder. It causes problem with low tension then slip when the filament stretch thin.
Doesn’t matter how much you reduce this dragging force (friction of PTFE tube and the spool spinning), it’s still there even you put the spool right on top of the printer and feed directly to the print head, it’s just a bit less than filament spool at the side of the printer.
It’s some math there. Your filament spool is about 1kg (when full), yeah? So that every time you pull the filament and spin the spool, you pull an object with mass about 500g (or half of the spool weight) or maybe less depend on how mass distribute on the sppol.
Eventhough the extruder can do an amazing force of 20-30kg, it still slips in our case because we adjust the squeezing when almost there is nothing pulling back. Say, about a few gram of filament. So that when it comes to spin the spool, 500g of force is enough to stretch thin and slip at the extruder.
That is why I am interested in this
This setup basically replaces the filement buffer (detect when extruder needs assist) + AMS (with assisting motor)
But not really sure if this can be used with P1S.
Anyhow, I am staying outside of walled garden: Orca + old firmware P1S so I don’t think I will go and buy this TPU feed assist module + AMS HT.
Meanwhile, I’ll take my time to do this as a hobby
I know this setup works flawlessly with TPU 85A because I already did it, but don’t have time to perfect it into open source project.
Do you think the TPU assist would really help?