I’m printing YXPolyer PC-CF on H2S and H2D printers, and I’ve noticed that when the last roll of filament runs out and I add another to the corresponding slot in the AMS, my printer seems to lose or reset the Flow Ratio (see attached photos).
At first I thought it was just shrinkage but then I noticed the awfully rough top surface as well. Is this a bug that needs to be reported? Has anyone else had this issue? It has happened to both H2S and and now the H2D printer, as well.
My current flow ratio is set to 0.90, but it looks more like 1.00 after the filament change. This filament generally has a low shrinkage factor. Also this brand of PC-CF seems to be consistent in quality, as of 150+ prints.
Moisture expands during heating, causing the increase in flow rate. .
You could also check the diameter of the filament from the old (if you still have some) and the new spool. Most filaments are 1.75 ± 0.05mm. The better ones are within 0.03mm. But the amount of difference for your over extrusion seems to be far beyond that. Therefore moisture (also given the image of the ribs), is highly probably the cause.
Flow ratio can also differ from batch to batch; there is no guarantee that the values will be the same. I have had several ASA Aero batches where the calibrated values differed quite significantly between batches.
Here is a pic of the finished print top surface. If this isn’t over-extrusion, then what else would it be? I don’t feel like it’s just moisture doing that, but I could be wrong
Also I’ve tested that specific spool of filament against one of the others (they all have the same batch number), and there was virtually no line when it switched spools on a test block print.
I have included a pic of a completed piece, so you can see what the surface usually looks like.
Probably true. I normally never bother changing a calibrated flow rate for standard filaments, but with foaming filaments I do need to recalibrate when they come from different batches.
I’m guessing it probably is mostly moisture as I’ve seen this on my CC2 now, as well…
But the amount of expansion is truly pretty drastic. - Moisture along with a maybe very slight deviation in filament diameter?
But here is another to consider - I have original Centauri Carbons that are running full spools wet when they start(I insert them into the dryer and start them right away on the printer) and I don’t see a difference in quality from the bottom to the top of the print.
Would the filament be drying fast enough as it gets pulled from the dryer that layers following say, the first layer - end up looking decent? (Dry enough?)
Pressure advance is what happens around corners, seams, and sharp turns for rapid acceleration - more that sort of thing. This is happening along the complete extrusion path. But I do agree that it seems to be the moisture.
You can see that you have more over extrusion at the accl and descl part but less over extrusion during the high speed part (middle). That’s a clear sign of PA issue, usually caused by moisture.
