RE: MK4S: What Nozzle to choose ?
I continue to struggle with petg and hf nozzles. I am continuously getting filament stuck faults after the first layer.
You most likely need to increase your nozzle temperature to accommodate the higher speeds.
RE: MK4S: What Nozzle to choose ?
I'm also going back to my old nozzles, in my case Obxidian. In my hands, I didn't see any meaningful speed improvements while preserving the same level of quality, so I'd rather go with the "no need to worry about it anything" Obxidians.
In retrospect I should have skipped the upgrades as I'm really not getting anything out of it. I design most models myself and take care avoiding overhangs so the improved performance of the new fan doesn't help me. And compare to the old fan, which was elegant and functional, the new design is an abomination. To see what's going on, you have to kneel in front of your printer.
I am like you and design all my own stuff.
Where I've seen the cooling improvement is in thin sections that were on the opposite side of the cooling duct. In some cases I would get little dimples where the nozzle changed direction on outer perimeters, especially if it was an overhang, even a very shallow one. I would often have to do design iterations to make those sections thicker or change the shape. That same geometry that printed facing the duct or to the left or right of it would print fine. Since the 4S upgrade, the addition of the 360 cooling duct has so far eliminated this issue for me.
Now they need to design something for the XL because it has the same problem. It's a much tougher task on that printer though because the tool changer is in the way and you have all the tool heads bunched together.
RE: MK4S: What Nozzle to choose ?
A prusa tech has been very good about working with me to troubleshoot the stuck filament error i am getting on my MK4s machines. I had to revert back to standard flow nozzles on two printers to keep them in production. Two others have HF nozzles and are not a problem. We think it may have something to do with the load cell sensitivity. Prusas latest suggestion is to check on the tightness of screws on the heatsink. I am running parts with a .30 layer height but each iteration causes production downtime. I have ten more days of printing then i can experiment and will report back here.
RE: MK4S: What Nozzle to choose ?
I thought that too, but Prusa told me that if the temp is too high inside the hf nozzle it could cause problems with the load cell. The suggested backing off 10 degrees. It didn’t fix it by the way. They also recommended against a .15 first layer. I changed it to .20 and that didn’t work either.
RE: MK4S: What Nozzle to choose ?
I don't get the purpose of the HF nozzle. I was playing around in PrusaSlicer and putting some boxes, cylinders, and sphere's on the bed. For 2 hour prints I'm only seeing a time savings of a few minutes between the standard and HF nozzle. Generally ~ 4% improvement.
From the way I see it the HF nozzle has more opportunities for failure, with very little benefit. What am I missing?
Mini+MK3S+XL 5 Tool
RE: MK4S: What Nozzle to choose ?
Nothing.
RE: MK4S: What Nozzle to choose ?
😂
Mini+MK3S+XL 5 Tool
RE:
I don't get the purpose of the HF nozzle. I was playing around in PrusaSlicer and putting some boxes, cylinders, and sphere's on the bed. For 2 hour prints I'm only seeing a time savings of a few minutes between the standard and HF nozzle. Generally ~ 4% improvement.
From the way I see it the HF nozzle has more opportunities for failure, with very little benefit. What am I missing?
Are you increasing the layer height? Here's a comparison I just did with a roughly 2hr part:
0.4 nozzle, "0.2 Structural" - 150 minutes (baseline)
0.4HF nozzle, "0.2 Structural" - 150 minutes (same as baselilne)
0.4HF nozzle, "0.25 Structural" - 119 minutes (saves 31 minutes)
I calculate that as about 21% time saved, which obviously becomes even more significant with very large parts. The "0.28 Draft" is even faster, at 82 minutes, but it would be fairer to compare that to a "speed" profile rather than the structural one. The savings will vary by part, but I have found it significant.
So, the HF will complete parts faster -- IF you use larger layer height. That said, I print mostly PETG and had problems with the HF nozzle (see my earlier posts in this thread). The time savings is irrelevant if the print is ruined. 🙁
RE: MK4S: What Nozzle to choose ?
Apoligies for resurrecting such an old thread. I have been having some of the same issues and this thread seems to have a lot of information already that is helpful.
I appreciate there are various issues with quality, which I have not experienced yet but I suspect I will do soon as I print more with CHT and HF nozzles
I have been having "blocked filament" issues. I saw the suggestions by Prusa help channels mentioned in the thread about the loadcell sensitivity. I am fairly sure that's not the issue because in my tests the extruder is definitely skipping at the same time. At least Prusa are catching that correctly with the blocked filament message even though it's not really blocked filament. I do also agree with what was said before, that if I disable the check I get birds nest due to underextrusion
Has anyone actually managed to resolve their issues without sacrificing volumetric flow rate (i.e. without going for lower layer heights that cap you on speed/acceleration before reaching the same volumetric speed, etc)?
My case with Prusa support is ongoing but I am not optimistic.
I have realized that it's crucial to use the high flow profiles (obvious) with their higher temps and also I think quite useful to use the sock.
I am still getting other issues too though, especially for larger nozzle sizes (High Flow 0.8) that are I think unable to get to the volumetric speeds of the prusa profile without sacrificing stuff or modifications.
I believe the HF 0.8 nozzle, being longer, is hit by the part cooling fan which is pointed at just below a normal nozzle but finds a part of the HF there instead. Also the HF nozzle is bigger and more exposed to the fan air and I can see the temperature not being able to stabilize. They get about 6C below the target. For this case instead of a "blocked filament" mesaage the printer resets because it thinks the temp reading is wrong. I am using a sock. Indeed for this case, I can get quite high volumetric flow speeds if I disable the fan and then the temperature stabilizes. Around 46mm3/s the heater or heater block stops being able to keep up. Has anyone managed to overcome a challenge like this? Using a different heatblock or heater perhaps? Or any special sock that can cover the exposed part of the HF nozzle too? I don't think that I can print in those flow rates with the prusa profile which has rhe fan on (and disablinng the fan causes other issues)
Any help or similar experiences and solutions would be appreciated