Someone thought about “magic number”?
https://3dprinterly.com/3d-printer-magic-numbers-getting-the-best-quality-prints/
It can make sens, but we need to know what stepper is for Z axis
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Sounds interesting, if we can get the info, i will give this a try
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Well, I doubt magic numbers will work. X1C and P1P both use a heightmap of the printbed and will adjust the z-axis in order to negate height differences there. So you would need to disable to ABL feature and need a perfectly flat and perfectly leveled bed.
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Exactly! that’s should be interesting to disable it and try.
All these speed related fixes/tests seem to be addressing the symptom. Shouldn’t we/Bambu work on fixing the cause?
Has anyone considered drawing and printing new carriage ends with the “correct” idlers?
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My X1C has noticeable VFAs since I received it 3 week ago. So I did some LFA tests couple weeks ago:
It was visible on all soft fever LFA test model’s fins, so I’ve mostly printed single fin where it was most pronounced (30deg) to save time.
- As Bambu CEO stated in his AMA, it is speed dependent, disappearing on 200+ speeds.
- Position on the built plate has NO effect.
- Printer placement stability has NO effect. No difference when printer was placed on the concrete floor or cardboard box.
- It is NOT the extrusion. I have printed it in semi transparent material to check it.
- It is NOT the motors. 1A vs 1.2A motor current was indistinguishable.
Then I have retensioned the belts, recalibrated and self tested the printer.
LFA completely disappeared and 40 printing hours later still no trace of it.
Here is the worst case (black color and harsh light) before/after :
Ignore the moiré on both as it is just a photo artefact.
I have checked the belts resonant frequency with printhead Y all the way back and X centered.
It was around 146Hz before, and 162Hz after retensioning. It is probably a second harmonic, but it was most consistent in spectroid app.
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So just retention the belts does the trick ?
Yes, at least for me.
You are in the minority. Glad it worked for you!
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How you did it ? Did you follow the official method from the bambu wiki?
I’m wondering the same. I tried retensioning the belts and it made no difference. Wondering if I didn’t do it properly.
Thanks for sharing your experience
I wonder, if the springs used in belt tensioners are having different stiffnes in different batches resulting in the actual belt tensions being all over the place on these machines.
Having some resonanse numbers is a good datum point
UPD - just checked my belts - the peak is at 223 HZ. And I have quite noticeable VFAs on any speed below 180mm/sec
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How did you check the belt frequency?
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Spectroid app on the Android phone.
Move the toolhead to Ymax and X128. Turn the power off, so you don’t pick up any fan noize. Gently pinch the belt as it was a guitar string. Let the app pick up the sound. 
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I believe yours is a third harmonic or it will be way over belt spec tension, which is not possible with properly working auto tensioning mechanism.
223/3*2=148.6Hz for the second harmonic.
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Just because i could!
My frequency was 140.16Hz. I used app Phyphox for Android.
Also i have not reset the tension in three weeks. My printer is a X1CC delivered 10-2022.
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I haved cleaned my maschine and saw many play in the Toolhead. I think 0,05mm-0,1mm. It is the camp not the plastic from toolhead
I opened a ticket.
Is it comming from the carbon rod bearings ?
Look at this post I think you are describing the same thing. There’s a solution posted.
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