We are only printing high temp on the left as its recommended by Bambu due to brittle filament and the left has a bigger tube bend radius. Our prints are functional so there generally only one color. The right nozzle is not used but still has low temp filament in it(not loaded but left over). This is what we think is causing the issue.
I just did a high temp print with the left nozzle and switched both nozzles. Right nozzle was empty and i did a cold pull on it. After the.print both nozzles removed easy.
Fundamentally, I agree with @StreetSports : if there was better surface contact between the mating surfaces, then this would be a non-issue. Seems as though some of the nozzles in the photographs have little to no issue, whereas some appear to have had a lot more.
In the event @StreetSports is correct about some of the mating surfaces being a bit too loosey goosey, I notice that there is a replacement right-hand hotend heating assembly:
A different version is also sold for the left hotend.
From what I can tell looking at my nozzle. The rectangle sensor in the back sticks out a little past the rest of the heating assembly. Not much but just enough to have a very small gap everywhere else. I think this is by design to make sure the sensor has a full mating surface. Like everyone else, I think its due to using a lot of PETG HF in the other nozzle. PETG HF vaporizes more than other filaments. Iāve done about 10 prints so far where I swap the right nozzle out for another nozzle Iāve deemed to be HF (the stock 0.4mm standard nozzles that only get high temp filaments in it) and the problem went away.
So Iām fairly certain its due to printing high temp in the left nozzle with a low temp (for me almost always PETG HF) filament in the right that just sits there the entire time. So I would recommend to others having the same issue to try and remove the right nozzle or swap it out for another nozzle you use for high temp when doing high temp prints.
Any particular brand or model you recommend? Looking on amazon, thereās a hundred different ones, and no obvious way to separate the good from the bad other than reviews (no longer trustworthy on amazon).
Also, the leather gloves donāt mention any particular dwell time rating. Obviously, a high temperature resistance and infinite dwell time would be best, but none that Iāve seen declare a dwell time.
I would agree with you, but I do see crud on the rectangular piece (is that the temperature sensor?). The only place I donāt see it is in those two little divots. Therefore, I hypothesize that those two divots are where the actual contact is made, and everywhere else is standing off to one degree or another. Does that make sense? On the other hand, the rectangular crud is a different color (a brownish orange), which is different from the black crud. Is it a different color because it didnāt get as hot? Another piece of the puzzle perhaps.
What are those two divots anyway? Are they just for alignment with the the nozzle, or are they like pogo-pin type connectors for passing current or signals? I need an anatomy lesson as to what it is that Iām looking at.
Reporting back: Nothing loaded into the right nozzle, but I notice that while print PPS-CF from the left nozzle, the right nozzle drifts up in temperature to 86C. Not sure how well either PLA or PETG would withstand that without consequences if it were loaded into the right nozzle:
Consequently, out of abundance of caution, Iām using a 0.4mm nozzle that has NEVER had any filament loaded into it on the right nozzle, so that thereās no residual below the cutline. I means I have to dedicate a nozzle to just that purpose when printing the high temperature filaments in the left nozzle.
Yes thatās what Iāve been doing. I just change both nozzles out. The one I have in the right I did a cold pull on so thereās nothing it it. Iāve done probably 10+ prints and it comes out easy every time.
For basically a dedicated NOP hotend nozzle, maybe this is a case where one of those cheap aliexpress H2D nozzles would be good enough? I bet thereās no quality control, so no PLA stuck in the nozzle when you get it.
All I want is to:
Adequately cover the right hotend so that filament spray from the left nozzle doesnāt deposit difficult filament particles onto it; and,
Spoof the firmware into thinking thereās a real nozzle there, so that nothing gets derailed from a total absence.
Iām not sure whether #2 is even necessary, but lowest chance of unexpected outcomes is just to play the game as it was designed.
I tried to remove my right nozzle the other day and it was stuck because of messy residue around the tip that got behind the nozzle. This is the first time ever with this type of removable nozzle ( I have 2 miniās and an A1) that this has happened.
In brief, the left nozzle moves up and down, whereas the right nozzle stays fixed. If I had paid closer attention to my H2D, I would have (should have?) known that. Well, maybe Iām not the only one, which is why I point it out for the benefit of anyone else. That means any residual filament below the cutline wonāt get in the way with the left hotend, whereas you may have to finese the right hotend a little.
But honestly, I got tired of swapping nozzles.
So Iāve dedicated my left to 0.6mm and my right to 0.4mm and I just swap AMS from left to right (as well as the PTFE tube on the back, working on a PTFE tube manual switch as well!)
In his video, the needitmakeit guy said he did the same thing, but then he ran into problems with that configuration in regards to purging filament. Not sure what he meant by that, but his advice was to use the same type of nozzle and nozzle diameter in both left and right:
But perhaps you know more than he does. Just pointing it out. I think we would all like to at least have the option of having different nozzle diameters mounted at the same time, even more so if they could ever both cooperate on printing the same print.
Well, maybe Iām not the only one, which is why I point it out for the benefit of anyone else. That means any residual filament below the cutline wonāt get in the way with the left hotend, whereas you may have to finese the right hotend a little.
