Burned filament flakes?
I have been printing dozens and dozens of hexagon Lego minifig displays. As I was approaching 100 hours of prints and about to start my 4th spool, I started noticing little black/brown flecks in the print. A few at first, then a lot more. Example A shows some of the worst prints.
The nozzle exterior gets brushed after each print so I did a cold pull to see if it was something inside the nozzle. Sure enough, it was covered in brown flaky material (Example B). Thinking that surely pulled out whatever gunk was in there, I moved on to another print I need to get finished.
Same thing happened to the print (Example C) and maybe even worse. I did another cold pull and it still had some, but perhaps less, of the brown flaky stuff.
This MK4 just hit 80 days of print time and I feel like this has only started happening over the last 48 hours of print time. What the heck is going on here and how can I troubleshoot/solve it?
If it makes a difference, I have been running a 3DMaker Engineering tungsten carbide nozzle since day 1.
RE: Burned filament flakes?
What temp are you printing at? It could also be the filament.
Keep cold pulling until it comes out clean. You may also look into some nozzle cleaning filament.
Ultimately you'll want to find the root cause or it'll just do it again. I guessing maybe your printing too hot, or it's bad/dirty filament.
Check your filament: A long time ago my Mk3 started making discoloured prints and it turned out a certain small person had spilled a drink, milk I think, on a spool.
Cheerio,
RE: Burned filament flakes?
Some users report a certain tendency of tungsten carbide nozzles to leak. I also observe that on two MK3S+ we have in our company although I torqued them hot throughly with 3Nm.
Drying the filament might also help to reduce stringing and, as a consequence, gunk building up at the nozzle that might char and fall down after a while.
RE: Burned filament flakes?
What temp are you printing at
This is PLA at 220. And I actually do have some cleaning filament and use it regularly. Every time I change filaments I feed maybe 5cm in before the next filament. I used to do cold pulls between every filament change on my MK3. Maybe I need to try doing that again.
had spilled a drink ... on a spool.
While I can 100% guarantee nothing was spilled on it, I can't rule out something wasn't wrong somewhere in the middle of a spool. For this particular project I flew through three spools and never once paid attention to the condition of the spool--just loaded them up and started printing.
tendency of tungsten carbide nozzles to leak
I keep hearing this and it made me hesitant to use one but I installed this on my MK4 day 1, and I now have nearly 2000 hours on this nozzle and not even a hint of leaking.
Drying the filament
Every spool I have gets 24 hours in the drying before printing with it and the nozzle gets brushed after each print. The gunk is coming from inside the nozzle. I just need to figure out how/where.
My leading thought at the moment is that in the middle of this huge, 100-hour print marathon, I ran a short print with some Galaxy Black PETG Prusament. I am wondering if when I went back to the PLA, if perhaps some of that PETG wasn't hot enough to melt and be pushed out and basically just sat there and burned inside the nozzle over the next 30 hours of printing PLA.
For now, just doing a bunch of cold pulls until the gunk some coming out.
RE: Burned filament flakes?
It would seem that I actually developed a small leak around the tungsten carbide nozzle. Printed fine for the first almost 2000 hours. But, alas, that seems to be where all of these burned flakes are coming from. After a dozen cold pulls I realized it must be something that isn't fully in the filament path.