Help With 0.2 MM Nozzle

[Adventurehill1 0]

I've switched to a 0.2 MM nozzle on my Anycubic Kobra Max, and I'm using Overture PETG. I've only done a few prints so far, here are some examples of what the tests look like.

 

As you can see, not exactly ideal. I'm just wondering the best way to troubleshoot/improve this. Thanks!

.2 CalibrationCubehelp.3mf

Edited May 15 by Adventurehill1

[Slashee_the_Cow 429]

Generally whenever you're going to test something (like using a tiny nozzle for the first time) it's better to do it with PLA since it's more forgiving and doesn't have problems other filaments do (like how PETG is stringy).

 

Also worth noting that as you get down to this small, the resolution (steps/mm of the motors) of your printer can come into play, especially on cheaper printers. I'm not saying your printer is cheap. I've never looked up its price 😄

 

Now if I may do a Big Bulleted List™:

• Your layer height is so low it's asking a lot of the printer to be able to both move the head and feed the correct amount of filament accurately. Most "standard" profiles for a 0.4mm nozzle use a 0.2mm layer height, so try upping your 0.2mm nozzle to 0.1mm, at least until you can get things a bit more dialled in.
• Not a problem, but having your line width at 0.22mm sort of defeats half the purpose of a small nozzle (a 0.4mm nozzle can generally do 0.24mm accurately). The guideline for line width is 60-150% of nozzle diameter, but the starting point is usually the same as your nozzle diameter (so 0.2mm) but then you can set the thin will width lower (0.12mm).
• *scrolls down to "Minimum Wall Line Width"* Okay, yeah, having that at 0.28mm is going to cause you problems given you set your line width to less than that. I'd set it to 0.14mm myself, but you can try going down to 0.12mm.
• Consider increasing Infill Line Width to 0.3mm. Nobody's going to see it and it's going to be stronger.
• That printing temperature looks a bit low. I usually do PETG at 240°. Often you have to increase the temperature if you're using a big nozzle so it can heat it up the whole way through at a high flow rate, but it doesn't work like that the other way around: even a little bit of filament needs to be the same temperature to go down successfully as what  you'd get out of a 0.4mm nozzle.
• Your flow settings are all set to 90% - that makes it look like you need to calibrate your printer's E-steps because you're compensating for underextrusion. I don't know if that's what's happening here, but if it is, you're much better off calibrating the printer. Your flow rate is low enough to begin with; you don't need to make it any harder for the printer.
  • Unlikely but plausible explanation for lower flow rate: you want to be able to break it easily. Don't worry, using a 0.2mm nozzle will make that easy enough to begin with.
• 50mm/s is about as fast as I'd print PETG with a 0.4mm nozzle. With the higher precision required of a 0.2mm nozzle I'd knock that down at least 10mm/s.
  • Yes, I know I've said a couple of times now that reducing the flow rate is bad. This is justified bad, so it's alright.
• Those acceleration settings... holy %(#@ing #!#$^($ with a %^=#$%^&. Lower them. Now. Like, maybe 300mm/s, tops. Especially with PETG. PETG is stringy and wants to stay with the nozzle on one big string so at a higher acceleration rate it's just going to be dragged behind the nozzle than dry enough to stay where it is.
• Retraction speed: I'm not sure I often see extruders capable of retracting that quickly... even if you can, you probably don't want to do it that fast because it'll probably just make the stringy bit currently in the hot end want to stay hot and stringy instead of coming backwards with its friends. 40mm/s would be my suggestion. And probably don't need quite 8mm (I see the profile you're using is called "TPU") - PETG requires more retraction than PLA but less than TPU - been a while since I had to tune retraction for a Bowden extruder, but... 6mm?
• Turn that fan on to 100% (well, maybe take it up to 100% over the first five layers or so). We want PETG to dry as quickly as possible as opposed to string.
• *Looks through printer settings*
  
  I'm pretty sure your printer can't print at 849,270 times the speed of sound (yes, ran the numbers, jokes have to be based in truth). You might want to have a look at that profile. And despite the pissing contest for "fastest acceleration" between printer manufacturers, I'm pretty sure yours can't go that fast. And it shouldn't. Not even the default acceleration, except maybe if you're running specialty high speed PLA.
  • Also 10,000mm/s² acceleration for the extruder? The only thing I've seen feed that quickly is me at a buffet, and even then only when I'm desperate to finish before my free parking runs out.

Hope that helps you with your print and/or breaking some world speed records.

[Adventurehill1 0]

5 hours ago, Slashee_the_Cow said:

Also worth noting that as you get down to this small, the resolution (steps/mm of the motors) of your printer can come into play, especially on cheaper printers. I'm not saying your printer is cheap. I've never looked up its price 😄

It is a fairly low end printer. It's not exactly cheap, but that's mostly because of its size.

 

Thanks for the line size guidance, it seems like in the 3d printing world you can ask 5 people and get 7 different opinions on the right way to do something. 

 

As for my flow rate, the profile I am using is based on the stock TPU settings for this printer. All the stock profiles have flow set to 90%, which seems like a strange way to do things, but it works on 0.4 nozzles for me. I have calibrate E-steps, but it has been a minute. I may need to do it again.

 

Acceleration is also part of the stock profile, but I was questioning that myself.

 

For the printer settings, where did you find those? I don't think I've ever seen those, and I definitely didn't set them to that. Thanks!

[Slashee_the_Cow 429]

32 minutes ago, Adventurehill1 said:

For the printer settings, where did you find those? I don't think I've ever seen those, and I definitely didn't set them to that. Thanks!

I use @ahoeben's Printer Settings plugin which makes them show up in the sidebar:

(As the description says, only change things with it if you know what you're doing - you're much better off just setting the speed and acceleration in the speed section of the print settings rather than accidentally stuffing this up. Or maybe you do know what you're doing 😉. Still, be careful.)

 

The settings themselves come from the printer definition file - or more specifically in this case, they don't come from the printer definition file because the definition file doesn't set them, so it just inherits from the basic printer template (fdmprinter.def.json and no, don't ask me why the numbers in that are so ridiculous) and uses the values from that.

(Good artists copy. Great artists steal. Lazy artists just leave a blank canvas, apparently.)

 

50 minutes ago, Adventurehill1 said:

Thanks for the line size guidance, it seems like in the 3d printing world you can ask 5 people and get 7 different opinions on the right way to do something. 

I won't even try and say I'm the most knowledgeable person when it comes to stuff like this. But I'm 100% sure I'm more knowledgeable than some people. Like whoever spent five seconds on the definition file for your printer just putting in the right size values and calling it a day. Or whoever wrote the definition file for my printer (Ender-3 V3 SE) which is one of the reasons why I use my own custom definition file. Which is a pain whenever I try and share a project with someone because I have to get them to add it to their config folder.

(This is exactly the sort of thing that Universal Cura Projects were designed for. Too bad it's bugged and you still need the definition file from the person who made the project)

 

59 minutes ago, Adventurehill1 said:

Acceleration is also part of the stock profile, but I was questioning that myself.

Creality's website made (there's an even faster one out now) a big deal about how my printer could accelerate at 5000mm/s². Main problem with that is it can't. Manual says it can accelerate at 2500mm/s². But getting the settings from the printer itself reports it can do 4000mm/s² 🤔. Only took me two prints to manually lower the max acceleration to 1000mm/s² (for PLA). The first was an extremely simple test print. The second was a slightly more complex (in that it wasn't  just a primitive solid) print and in a couple of places after it finished printing a bit and zoomed off towards the next one at 4000mm/s² it actually pulled parts of the print with it because they hadn't dried yet so they ended up warped. The contest between (mostly Chinese) printer manufacturers for the fastest printer could learn from Dr. Ian Malcolm: "your scientists were so preoccupied with whether or not they could that they didn't stop to think if they should".

(If you’re sure you’ve heard that but can’t quite place it, you probably haven’t watched Jurassic Park recently enough)

 

1 hour ago, Adventurehill1 said:

the profile I am using is based on the stock TPU settings for this printer

On a scale of 1-10 where 1 is PLA and 10 is TPU, I'd put PETG at about 7 overall. But the really important differences are temperature and speed:

    Temperature: I run TPU at 220°, but PETG at 240°. I'm not a material scientist so I have no idea why these completely different kinds of plastic print best at different temperatures, but they do.

   Speed: TPU goes best driving like your grandma down the highway: at about a third of the speed limit, max. I usually run it at 20mm/s. 15mm/s if there's some finer details. PETG can handle itself a lot better: for basic stuff I run it at 50mm/s. If there's details... I'm usually not using PETG but if I am, I just knock it down to 40mm/s.

(n.b. trying to print fine details in TPU is usually a fool’s errand)

Retraction: I mean, you set it ultra high for TPU because it's so soft you know there's next to no chance you can fully retract it anyway (string city on travel moves). PETG isn't soft like that but it just gets really stringy and wants to stay connected at both ends, so you just try and keep a bit of control over it rather than letting it roam free in the pastures. On my printer (with a direct drive extruder so numbers aren't an apples-to-apples comparison) I retract PLA 0.8mm, PETG 1.5mm and TPU 2mm. It's not going to be as stringy as TPU, but there's still cleanup required. When manually purging (have the hot end hot enough to print, hold the lever on the extruder and force it in yourself) PETG because I just switched to it, a couple of centimetres sticking out of the nozzle I can sometimes pull to about a metre long before it actually detaches from the nozzle (although it's this stringiness which gives it its flexibility).

 

One important thing to remember about printing PETG (or TPU, FWIW) compared to PLA is you need your filament dry. And I don't mean don't spill your coffee on it. Well actually you shouldn't do that either, but they're hygroscopic - absorb moisture from the atmosphere, and if they're too moist when you try and print they'll tend to go into a mushy mess. Some people store their filament in bags with desiccant and just recharge the desiccant when it's absorbed all it can. Too much hassle for me. I bought a filament dryer (not very expensive) and run it with my filament in there for a few hours before I print. If it's going to be a long print (anything of a decent size in TPU is because of how slow it prints) I actually leave it in there (there's a hole for filament to come out) on a lower temperature while it prints. Probably not necessary, but I'm that kind of crazy/paranoid/prudent (depends on your point of view). The cheater's way is to warm your printer's bed up to 50°, put your filament on there, cover it with it a towel and let it sit for a few hours.

(Unlike my filament dryer, you probably shouldn't print while your filament is drying with this method)