Frustration, but it’s manageable. First. I tried the Flow Dynamics calibration and that worked. It gave me something like .035 for the K-factor.
Then twice I did the Flow Rate with the same issue. It printed a nice thin coupon of plastic with lines on it. Cool stuff, actually. But, it failed both times to complete because the filament cutter got stuck pushed in. So I decided to just press on and do a test print. All of the calibration stuff was looking good. One difference this time around was that I told it not to do any part cooling for 5 layers. I think I use 5 bottom layers as well, and 5mm to define the bottom layer. I don’t know if that’s an issue or not, but I did that on my other parts that I made because I wanted them to be solid thick layers that would not let bolts pull through an outer shell.
Anyway, this time after about 18 layers, i’d say that a little under 1/2 of the print looked real good. So it made it farther without the rough edges. I don’t know that I can see well enough to count the exact layers, but it could be the 5 bottom layers, or it could be 8 or 9.
But then I noticed the bumps so I looked at the printer settings and sure enough the parts fan was on 40%. so I quick switched that off and let it do a couple more layers just to see if it would go back to being smooth. But, it did not.
I’m not 100% sure what I learned from this. It’s either A) I need to make sure the parts fan never comes on and keep that chamber warm (it was around 40C), or B) That filamet spool is going to take at least a WEEK to dry out all the way in the S2.
I think I’ll give up on it and keep it running all weekend in the S2 until the S4 shows up, and then put it in there for a couple days.
It is encouraging that the bottom maybe almost 1/8" looked good.
You should be fine with the default cooling settings, its not the solution to the sand paper problem. I did some more reading and you should be on the right track:
DRY, DRY, then DRY some more.
Manual Calibration: PA6-CF surface texture might not work so well with lidar and what do we know about matte black? It doesn’t reflect light well. I’m concerned that the cutter was involved in calibration? Was this at the very end or did you calibrate multiple filaments at once? Don’t do that if so.
Filament path: I saw some posts about winding PTFE etc, make sure the path to the external spool is short and clean with no binding.
I think the cutter switch was just getting sticky. Bambu has a write-up about what causes it to stick. On a real print, the cutter worked without sticking, so I think I just got unlucky. When I pushed it by hand, if I can sometimes get it to stick too. So I may need to look at that. It was at the very end of the calibration and I only had that one filament in. it was at the point where it cuts the filament off, which is almost 100% done.
Good point about the winding. The tubing is a little long and not straight, to the S2 right now. I’ll probably buy some more tubing so I can cut some that is a good length. I didn’t want to cut the one that came with the S2 too short and limit myself in the future, but I really just need to.
Circling back on this now that I have something to share. My last PA6-CF print was back I think on 10/11. Since then, I’ve had my PA6-CF in my Sunlu S2 and then starting on 10/14 I got my Sunlu S4 and put it in there with some other spools. So it’s been constantly drying, non-stop.
I did make ONE machine change, in that over the last couple days I wanted to print some other things so I swapped my .6 nozzle for the .4 nozzle. Otherwise, everything is the same except the filament should absolutely be dry.
Today I started a print of the same part, and it’s been a few hours and it’s coming out absolutely beautiful. So you’re all right that it just took a lot longer to dry than I had thought. With my S4, I’ve started keeping it filled with 4 spools all the time, so I can dry out everything I bought, an then vacuum bag it all.
I really appreciate all the comments and help. I’m new to this printer and filament printing, and you’re all making that experience good.
Oh, side note: I printed with some of the new PETG-HF from Bambu and that stuff prints darn fast and stuff came out awesome. That’s what got me to switch back to the .4.
Home the head. Lower the plate. Load filament at intended print temperature. Move the head to the front, Tap the extrude button multiple times. Support the extruded filament so it comes out straight and so it doesn’t stretch from its own weight.
If the filament is really wet you will hear it popping and possibly see puffs of steam coming out the nozzle.
Run the extruded filament between your fingers. It should be perfectly smooth. If it is damp you will feel rough bits and pock marks and that is how it will print.
