Can't Hit Ideal PA Values w/o Extruder Skipping Steps

Bambu Lab X Series Bambu Lab X1C
1

Has anyone else been able to demonstrate their X1C extruder is capable of running ideal PA values with some headroom before skipping steps?

Even with basic filaments like Bambu PLA Basic and PETG HF, I find the extruder limit is either way too close to the ideal PA value, or below it. I have noticed this since my X1C was completely stock, and even after some recent modifications that should help, if nothing else, like the E3D Obxidian, it persists.

I troubleshot this with Bambu quite a while ago and they ended up sending me a new extruder motor and extruder unit. I didn’t get around to installing until today. Spoiler alert, these made no difference at all.

I like using the Line PA test in Orca Slicer for this. Here is is running on PETG HF at 0.2mm layer, 235*C nozzle, and going between 20mm/s and 160 mm/s:

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Then, the same gcode with the new extruder drive, motor and TH board:

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Skipping steps on both the accel and decel phases at PA=0.038. The fact that it skips steps on the decel phase as well tells me that even trying to bandaid it with higher nozzle temp won’t do anything.

Even if I just settle for it falling a little short of an ideal PA value, how much below 0.038 do I need to be, to avoid skipping steps when everything is really hot and running for hours? Or, when it is doing even faster transitions, like infill or inner walls?

2

Here it is with white PLA Basic. Same behavior:

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3

Hi,

Can you clarify what is the question?
Your test results clearly show that PA = 0.038 causes skipping during both acceleration and deceleration, even after replacing the extruder and motor.
I agree that it relates to extruder mechanical limits (not only), but I don’t see this as a defect. I tend to see PA as a tuning parameter, not a maximising goal, but I may misunderstand the intention.

1 Like
4

The question is: are other people’s X1C’s giving the same result in the same type of test?

IMO the extruder system should be capable of running a test like this, to a PA value above ideal, where you can see a bulge during accel and a neck during decel. Only once you have data above and below the ideal value, can you find the real ideal value.