Having some wierd issues printing with Bambu PA6-GF. I’ve tried many variants:
Nozzle 0.4mm and 0.6mm (worse results)
Temp- from 265 - 290c
Speed from 30 - 100mm/s
Fan OFF - 40%
inner-outer and outer-inner sequence
Dried the filament using Ams HT for 24h.
The darker lines are slightly narrower(last picture is very noticeable), which led me to believe there may be some thermal-related factors involved… but so far, nothing has really solved the issue.
Printed the same file in PLA, no issues. Any tips? starting to consider some hardware problems, perhaps a inconsistent fan. But so far, no warnings or errors.
First what temperature did you dry it at? If it was less than 85° then it’s not good enough. PA6 is aggressively hygroscopic and needs high temperature drying as well as drying while printing. Without this it can pull enough moisture within a couple of hours to cause issues.
If you do think it’s dry enough and you printed immediately after the drying cycle then after you slice it, look at the Layer Time preview. Do the bands correlate with the speed changes? If so try increasing the minimum layer time and retest. In the “No Cooling” example, was part cooling turned completely off?
Also, did you calibrate the max flow rate? I’m sure you are using the BL setting for this material but it might need tweaking.
I don’t go near PA6 for any reason anymore because it’s too difficult to work with. What is this part for? Is it subject to high temperatures? Is it going to be exposed to harsh chemicals or solvents?
Open the file in Studio and cycle through the preview options and see if any one option looks to have a similar pattern.
For example, I created a shape and sliced it with PA6-GF and found the layer time preview revealed odd lines that could show in the print. And I’m thinking when you do the same it may be similar or identical to your lines.
I dried it at 85 °C for 24 hours, Printed with part cooling completely disabled. I also reduced the max flow rate to 8 mm³/s. One thing I noticed is that the layer time fluctuates quite a bit, so my next step will be reducing the minimum layer time.
The choice of PA6 isn’t driven by any specific requirement. I just need some thermal resistance, around 60 °C, so PETG or ABS would probably work fine as well. At this point, I’m mainly trying to get consistent, reliable prints with it.
If that is the result for your layer time change, you might have moved the wrong minimum. The one that should make a difference will be the Maximum Fan Speed Threshold. This is what my layer time preview looks like when I change it.
However, in all honesty, I was expecting your preview to look just like your print with these lines all the way up and down the model. Your problem is likely something else. However, I would still try to get a more consistent layer time for consistency.
What color is this filament actually supposed to be – gray, brown, or black?
My observations:
Bambu Lab recommends a drying temperature of 80 °C for their own filament. In my experience, this temperature is completely sufficient.
If the filament were actually affected by moisture, the prints would show a very different type of defect.
The geometry of your parts is relatively simple and should print without any issues using this filament.
In one of the photos, you are holding what appears to be some kind of elbow fitting. It is noticeable that the spacing between the prominent lines seems to increase proportionally as the part tapers. This could indicate that there is an issue with the filament itself. One possible explanation would be a manufacturing defect, such as an inconsistent material composition or other material variations.
The dark color pigments didn’t spread well enough, causing the filament to print like this.
Another potential reason is moisture. If the filament was not dried evenly, some part of it would print slightly over extruded (raw material would expand more after extrusion, causing the raw color to show more), and some part of it would look just fine (dried, so no expansion, color pigments would look even and uniform).
I am squinting at these pixels real hard, and if those are visible light gaps freckled in to that print, maybe its a filament feed problem [somethign catching over and over] or the material itself is wildly swinging in diameter
The Filament is Dark Grey, I read some posts saying that Nylon needs more than 85c to properly dry. I opened this filament almost one year ago so I will dried it again for 24h and try.
Be careful not to over dry it, Nylon needs some moisture or it will become too brittle to print. 8-12hrs should be enough. Also, PA6 needs to be printed from a drybox or be actively drying while it printing. This is why I don’t go near PA6 anymore. It’s just too niche and difficult to work with. There are better materials.
filament always get brittle when it absorbs water.
There’s no “over dry”. What could actually happen is crystallization or annealing (due to temperature being too high). You don’t need any water, neither crystalized filament, in the nozzle.
This isn’t true either with respect to PA filaments (in particular) and I encourage you to check out CNC Kitchen’s video on nylon filaments as well as My Tech Fun if you would like a second opinion.
@hyiger, is there a reliable, maintained list of what is available and what the characteristics are? I don’t have access to Google through the firewall here, but IT can whitelist individual websites if they are legit. Thanks.
Point me to the exact video that claims dry filament is more brittle. Or any claim that any filament need some water to be not brittle.
Igor from MyTechFun mentioned multiple times that wet filament would be more brittle. I’ve been a Patreon supporter of Igor since very early days, and I don’t think I’ve ever heard Igor said anything about Nylon need some water to be not brittle. It’s always the exact opposite.
Thanks, @hotellonely, but my question is in a general sense–i.e. beyond PLA, PETG, ASA, TPU etc. what more advanced materials are available? As I mentioned, Google (and its equivalents) is a closed book to me…
There’re no well-known lists available for free. Although, Igor maintains a tested chart which is available once you become his Patreon supporter.
Here’s the link to Igor’s Patreon.
I have to remind you that even this list is not perfect. Some test methods have been changed and some results are not updated afterwards. Also it’s not covering all the filaments, just the ones that Igor was able to test.
