Help troubleshooting PA6-CF issue

I’m new to Bambu printers, and have printed some things now with good luck using PETG-CF and PLA. All my attempts at printing PA6-CF however are failing.

My first print with PA6-CF had a rough tar look, like when they put hot-mix paving on a pothole. Rough edges. It was a fresh roll, straight from the package when I tried it. I thought perhaps moisture was the issue, so I bought a Sunlu S2 filament dryer, and ran the roll through that for many hours, and then put the roll into airtight storage with desiccant for a few days. The desiccant is still the original color, and humidity is very low. I pulled it out and put it in the sunlu and tried to print again but I’m having the same results. This is using a .6 hardened steel nozzle in my X1C, and using default printing options when selecting that filament in bambu studio. I will throw the file on here too. Just trying to figure out what the heck I’m doing wrong so that I can start making PA6-CF look good.
Oh, and I’m using the textured PEI plate. I see in a different thread someone says the engineering plate is recommended, but when I follow the link it now shows the smooth and textured but not the engineering. Also, I don’t know if the engineering one is available…I tried to buy every plate I could and didn’t see it.



I guess it won’t let me upload the .3mf file.

I have to say it’s not dry. I would guess that in an S2 that is cracked open you might need a day or two (barely crack the S2 or it will trap moisture), depending on your environments humidity. I think that worked for me before I bought an S4, but I was using PA6-GF in Arizona (low RH).

Keep in mind that keeping it in the dryer is going to remove moisture at a much higher rate than an airtight enclosure with desiccant.

Based on the looks I would say you should hear the popping of the boiling water.

Edit: everything I said was for 0.4mm nozzle. Going to 0.6 I think you might have to really dial in the filament settings, afaik we don’t have perfect default profiles for all filaments and nozzle combos. Still doesn’t excuse the 40 grit outer wall, I think that is certainly moisture.

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I absolutely appreciate the feedback. I’m still trying to wrap my head around it being THAT subject to moisture. Mainly because: Like I mentioned, it was a fresh roll from Bambulabs in their vacuum packed bag, on the first run, and was only in free air for 10 mins. Then, I did run it though the dryer for maybe 12 hours on the highest setting (70c) (I know, Bambulabs recommends 80C but I don’t see many dryers can do that temp). And, when it came out, it went right into airtight storage filled with about 1" of media that hadn’t changed any colors, and it spent at least 5 or 7 days there with humidity that had to be below 15%. So I’m just blown away if it’s moisture because I can’t imagine that everyone who prints with this stuff gets it much more dried out.

I’m not sure what I’d tweak with filament settings. I may just swap back to a .4 nozzle and see how that goes, because that would be an easy quick change.

I have to laugh at your “40 grit outer wall” comment because you’re right, that’s exactly what it looks and feels like. It’s just so ridiculous.

I’ve got a lot to learn. I have the filament in for a 24 hour dry cycle and I’ll try it after that and if it’s the same thing, I’ll try the other nozzle…

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Well, I made the mistake of using S1 specs for your S2 so I thought it was 55. 70C is much better and should do the job but takes a bit more time than it would at 80C, that’s all.

I also made the mistake of assuming 0.4mm would be just as ‘recommended’ as 0.6 nozzle but that is wrong according to the web site, so I have to expect you have their recommended settings and simply have a waterlogged roll.

They don’t dry filament at the factory so the best you can do is dry at first and weigh at intervals to see how much weight is being lost, keep drying until its only losing fractions of a gram.

I didn’t see you mention if you are running out of an airtight chamber, I assume you are since the S2 would work for that. By the way do you have the newer model with the fan, iirc the older one didn’t have one and people disliked it very much. (Since you can afford PA6-CF I would say get an S4 and send the S2 back if you can, I like mine but I can only speak from the perspective of a person in Arizona where humidity is not an issue)

Bottom line is that this is not normal filament, it requires drying before printing and then, even if perfectly dry, it will suck up moisture from the air fast, so if you have high RH you probably need to make sure its mitigated while you print.

So just to be sure, are those pictures pre drying or after? If its after then I have to say something seems off. Perhaps it is the stories Ive heard about the S2, it traps moisture inside and you have to keep it open a bit to vent it (unless youre going to manually do so every hour or whatever). This would be greatly affected by the RH in your home due to the filament type, it wants to suck up moisture unlike most filaments and it does so fast.

Find small test prints or use the calibration tab in bambu studio to dial that filament in without wasting much more of it, I’m a tight wad so hate to see it go to waste. And hopefully I’m providing the best guidance but there are others on here with far more experience than I so don’t put too much weight into my singular opinion.

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I think your guidance is on the right track, actually.

So when I first dried the filament, I dried it maybe 6 hours or 8 hours and then stuck it in a desiccant filled cereal container with a sealed lid. I had mistakenly assumed it was dried from the factory, and that the container would continue to dry it fine. Even though it was there for many days, apparently at room temp that’s just not going to cut it with PA6-CF.

So this a.m. I started drying it in the S2, and now that it’s been 12 hours, I decided to try a print again to see how it looked. The first maybe 2-4 layers or more ended up looking pretty good, but then it started to look like “40 grit” again. So, my assumption based on reading a ton of forum threads tonight, is that I must have dried out the outer layer on the spool but not dry enough overall, and now that it started to feed in “wet” it started looking bad.

The S2 is something I got on Amazon only just over a week ago. What I’m tempted to do is keep the S2 for printing when I can’t use the AMS (most of my filaments can use the AMS), and maybe get another larger dryer for doing the initial drying. I did print a bunch of desiccant holders for the AMS, so I’m thinking that once I get filaments dry, if they’re ams compatible I should be able to get by using them in the AMS. I will always store them in sealed cereal containers, after also putting them in those vacuum bags made for spools. I also bought a bunch of slice engineering desiccant canisters that go inside the center of the spool, so those will stay with the spools too…and I’ll dry them with the spools as well.

What I’m considering doing is getting either the big/ugly PrintDry Pro 3 that can dry a couple rolls simultaneously at 85C, or pick up a 10-12 tray food dehydrator that can do 90C. Would love your input on which you think would be best. Then I’d dry everything in that, canisterize and vacuum bag it, and when I print touchy filaments I’ll just throw it in the S2 while I print.

I printed a bunch of parts using PETG-CF and was very happy with how those worked right out of the package. My intention with buying the Bambu was to be able to print Nylon, mainly because most of the stuff I want to print is either for outdoor use or I want it to be strong. First project were some large clamp brackets that hold a 20’ tall flag pole for a starlink mini. The PETG-CF seems plenty strong for that. I was just hoping that by using PA6-CF and PAHT-CF I could get some really tough stuff printed when I need to.

So does that all sound pretty reasonable? Food Dehydrator or PrintDry Pro 3, plus S2 at print time. I don’t really want to have all my space used up because I don’t have a lot of in-the-house climate controlled storage for things like the print dry pro 3 or the dehydrator. Those things would have to live outside in a shed that may get to -20F or -30F at some point, and I’d have to bring them in the house to fire them up. So the S2 just seems like a good way to go for small.

A secondary option is, just buy one or two more S2’s because they fit nicely on tables and are small, and run them for 2 days for each new roll I buy. If that works just as well, I could save money and space by going that route. Or do the S4 thing like you suggested, but then I’m losing more storage/table space.

BTW: My S2 is the newer model with a fan. So that at least is a positive. Overall my only complaint with the unit that I see is that I wish it went to at least 80C.

I could dry the filament in my standard household oven too, but that seems like a big energy waste and probably not great temp control, unless maybe since it’s a convection oven the air circulation would be better and more even. I do have temp probes I can throw in there to validate that the filament area is being heated to 85 or 90C.

Very thankful for your advice. I think once I get the drying done it’ll likely look better, based on my first few layers on this test print.

I watched a few more reviews and decided to just scrap the plain dehydrator idea and the printdry pro 3. A plain dehydrator would be ok, but you can’t print out of it easily if you ever want to. The print dry pro 3 is really kind of a primitive looking thing.
The Sunlu S4 I saw a video where the measured air temp coming out of the vents was in the 80’s, so even if the machine heat sinks that heat away, at least some seriously warm air is coming into the chamber. The biggest negatives I see are 1) size, and 2) LOUD. But, if I run this mostly for just pre-drying rolls, and I print using the S2, I think that will suffice.
So when it shows up Monday I’ll just start throwing spools in for 24-36 hours at a time. I kind of went all out when I got the X1C and have about 32 rolls of filament of various types and colors to try out.

@RVTim
The bad printing quality is 100% a result of too much moisture in the filament.
Some rules and ideas:

  1. The Sunlu S2 is perfect for drying PA6-CF (or is it PAHT-CF?). Set the temperature to the maximum available value (70degC). Be sure that the cap of the Sunlu S2 has a perfect closing fit (no remaining gap is allowed). Leave the filament in the Sunlu S2 as long as required to reach 20% humidity or below. To be sure, set the duration to 99hours so that the Sunlu doesn’t switch off too early.
  2. PA6-CF attracts moisture very fast, so start printing immediately after drying. Storing the filament for even as little as two days, attracts already too much moisture.
  3. Personally, I print PA6-CF and PAHT-CF while the filament is still in the actively heating Sunlu S2.
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I had the exact same problem with the PA6-CF. It looked exactly like that and drying more was not really helping much.
I had to calibrate the filament properly and now it looks much better. So this is really important here.
I still have problems with wrapping, where I can´t find a solution for until now, but the look is good now.

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Regarding your warping, with PAHT-CF and normal PA I find running the bed temp at 80c helps, along with copious amount of gluestick :slight_smile:

thanks for the suggestions.
I tried various settings of temperature already.
My last try was to rise the bed temperature to 95 for the first layer and to 100c for the rest.
In the beginning it looks good, but the end result is always similar. One side bends up and the hole with the thread is oval and the screw doesn´t fit.
I´ll make now one more try with drying two days before and taking more glue :crossed_fingers:

this were my settings:

and that´s the result:
image
image

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You should try to print without the redbull can, that should help :rofl: I kid.

@user_3946463143 Since you said the S2 is perfect for you would you report your homes RH, that way @RVTim can compare. The problem can be in very high RH it gets hard to dry unless you’re drying the incoming air.

And yes calibrate first with manual calibration (or auto but I prefer manual to inspect myself). Hopefully that way the least filament is wasted.

As far as your warping @that1 I did not see you report that you are printing fully enclosed, but I assume you are. In this case you could try this: Heat the bed to 100C then start the print to let the chamber soak up a bit of heat.

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good point, as Red Bull gives you wings, maybe this was the reason for wrapping :stuck_out_tongue_winking_eye:
Just kidding, I put it on for the photo, to show the wrapping.

I´m printing with a x1c, so with housing.

Good point. Next time, I try it with the pre-heated housing and on a textured pei plate. :smiley: :crossed_fingers:

I’m following along with interest. It’s nice to hear everyone’s story with this.
Regarding my environment, I’m in WI, so this time of year it’s pretty dry. Right now my sensors are showing about 44% humidity in the house.

I’m trying to use Bambu’s PA6-CF, but haven’t tried PAHT-CF yet.

I haven’t done a manual flow calibration before. It almost seems like when you go to the calibration page in bambu studio that they discourage manual over automatic. That said, my flow test lines that the printer lays down before printing seem pretty good, but I haven’t looked at them super closely. I’ll do that next time.

One setting I just tweaked on the filament is the “layers without cooling” setting. It was set to 3 by default and so I set it to 5. Just because last night’s print looked good for the first few layers and then deteriorated. Should I be disabling the part fan when I print?

Here are some settings:


I can’t wait for the S4 to show up. The one encouraging thing is that it supposedly heats up much faster than the S2. It will be nice to start out with everything dried well, and if I can do it quicker in the S4 I will.

BTW, with the humidity of my filament and room right now, I don’t get condensation in my S2. I do have a bag of desiccant in there with the roll, along with the Slice Engineering canister, so maybe that’s helping soak it up.

I may give a test print another try now that the filament has gone a full 24 hours or so.

I think you are on the right track with the S4, since you have all that filament and apparently a decent budget, I would also pick up a good scale. You should be able to find a thread around here with some links to scales with good resolution so you can measure fractions of a gram. Then you can take the guesswork out and know your filament is dry.

Then it only leaves calibration and based on what you said about picking up all that filament I would start calibrating by type everything but PLA (as you use it of course). I just don’t trust the auto calibration, it may be perfect and better than my manual, but with manual I inspect and choose and it is quite easy, only a bit time consuming. Keep in mind there are calibrations for flow dynamics and rate so do both.

Is your S2 bottoming out the RH by now? I mean what is it reading?

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I am living in Eindhoven, the Netherlands. In general, we have a lot of rain but mild temperatures.
The inside-the-room humidity always stays within the 40%RH and 70%RH range, throughout the year.
I just measured temperature and humidity both inside the room and outside.
See pictures 1 to 3 below.
I must emphasize the importance of closing the gap of the Sunlu S2. Without closing the gap, you will not reach the low humidity values. (picture 4 and 5)





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LOL on the budget! I went into the X1C because my anycubic resin printer screen died, and I wanted to get some brackets made. I could have farmed it out for way less money but in the long run I wanted to get into more printing capabilities and had been looking for a reason to get the Bambu because I wanted to print nylon. So I went into it just not wanting to take shortcuts that would leave me with regrets. Then, when I ordered it, I got a pile of various filaments…PETG-CF, PLA, PA6-CF, PAHT-CF, ASA, ASA-CF… all because I didn’t know which one would be strong enough and good enough for my starlink brackets. Turns out I could have just done PETG-CF and called it good. But, i wanted to learn. So I bought at least 2 rolls of each, in at least 2 or 3 colors of each (other than nylons which I only got black). And then I ordered spare build plates, belts, and other stuff, and the bill just kept getting higher. I still have a mako print head on order for diamondback nozzles too. I wanted to go all in so that I wasn’t limited. My B motor failed after my FIRST print, so I bought a spare motor and got the one warrantied. So at this point, it’s like “Well, I’ll just keep throwing some cash at it until I have everything I’ll need to guarantee successful prints.” I would love for my budget to completely end at this point…and it should soon. I have enough filaments for a long long time.

I’ll try out manual calibration and see how that goes. I’ll have to learn how the process works, but that will be a good experience. I think I have a scale that should work already. I’ve got a couple for postal stuff.

The S2 humidity was pretty much bottomed out yesterday. It was 13 last night. Now it’s 12 though, so maybe there’s a little ways left to go.

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About warping and calibration:
I have an X1E, which has a temperature-controlled chamber, up to 60degC.
For PA6-CF, the profile advises to use a chamber temperature of 60degC. See the screenshot below.
This means, that in an enclosed but not actively heated chamber (chamber passive end temperature is about 40…45degC), there is an increased risk of warping.
One way of decreasing the risk of warping (without needing to change your 3D model) is, to reduce the number of bottom layers.

About calibration: it doesn’t make sense to calibrate Flow Dynamics and Flow Rate before the filament has reached its final humidity after drying.

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Good point about calibrating AFTER drying. The auto flow calibration is done very slowly, then you speed things up for the model and the moisture really starts to mess things up, more material passing, more boiling and splatter. That’s my thought at least.

Thanks for all the info, based on that I think @RVTim should be able to get good results with the equipment he already has. Warping may become a concern but cross that bridge when you come to it I suppose.

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12%RH is perfect, you should be able to print without artifacts. Just keep the spool inside the active SUNLU S2 while printing (don’t use the AMS).
Now, fully calibrate the Flow Rate and Flow Dynamics with the fresh 12%RH filament.
PA6-CF just isn’t an “easy” material, it requires full attention and commitment…

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