Fine vertical ripples on walls: VFA causes and fixes

This guide is for prints whose walls look clean from a distance but show a fine, even pattern of vertical lines when you tilt them in the light. It explains what Prusa, OrcaSlicer and Bambu Lab call these lines, what they attribute them to, the speed ranges they name, and the slicer and firmware features that target them. Features are kept to the slicer versions and printer models each maker names. Make sure you're in the right place:

What makers call them

Prusa: "VFA are microscopic imperfections in the extrusion that repeat at the same point in each layer, creating vertical lines on the model." Prusa says the lines are "visible from 10um," with the worst it had seen "around 40um from peak to valley." It says "you can't even feel them by hand," but "you can see them due to the way a shiny filament reflects light. In other words, it is an optical imperfection." Prusa's tip for spotting them is to rotate a glossy print, such as one in black PETG, "so it catches the light reflection under a specific angle."

OrcaSlicer: "Vertical Fine Artifacts (VFA) are small surface imperfections that appear on vertical walls, especially near sharp corners or sudden directional changes." Orca names one subtype, MRR (Motor Resonance Rippling), "caused by stepper motors vibrating at resonant frequencies, leading to periodic ripples on the surface."

Bambu Lab: we didn't find a Bambu Lab wiki page on VFAs. Bambu Studio 2.08.02.61 uses the term in a setting tooltip, about "speeds which cause VFAs (fine artifacts) on the external walls."

VFA, ghosting or Z banding?

The makers' own terms overlap, so go by the pattern:

• Ghosting and ringing echo a sharp feature and fade along the wall. Prusa's ghosting article describes "several waves that follow after a sharp edge of a model." Orca's Resonance Avoidance setting, below, is aimed at VFA-causing speeds but its tooltip describes the result as "ringing," so expect the words to be mixed. Our ghosting and ringing guide covers input shaping and acceleration.
• VFAs are fine, evenly spaced vertical lines that Prusa says repeat "at the same point in each layer."
• Z banding runs horizontally. Bambu Studio and OrcaSlicer both say a change in outer wall speed "may create slight wall artifacts that appear like Z banding." Our Z banding guide covers the Z axis and layer-line causes.

What causes VFAs?

Prusa's own pages differ on motors. Its blog says that for the VFAs it studied on the CORE One, "we ruled out the motors as the cause," because they "don't match the specific pitch that would be caused by our motors." Its Phase Stepping articles say that feature addresses "visible fine artifacts (VFAs) and noise caused by the natural variance in stepper motor manufacturing." Both can be true on different printers, but don't assume motors are the cause before you've checked belts and speeds.

Step 1: Tune the belts

Prusa's first recommendation is belt tension. For the CORE One, it says "I strongly recommend tuning your printer right now," using its reworked belt-tuning procedure and the tuner in the Prusa App. Its tips:

• Park the extruder in the front right position.
• "ALWAYS adjust both screws (left and right) by the same amount." Prusa says turning only one screw "will actually result in a skewed gantry."
• If your phone struggles to read the belt frequency, try a different mobile browser or a different phone.

Prusa says properly tuned belts also mean "less 'banging' during the homing procedure." For other printers, follow your printer maker's own belt procedure. Our ghosting and ringing guide links the procedures for Prusa, Bambu Lab and Creality models.

Step 2: Find and avoid the speeds that cause them

The makers don't give one speed range for every printer. Prusa identified the problem speeds for the CORE One itself, and OrcaSlicer has you find yours with a test print.

OrcaSlicer: the VFA test

OrcaSlicer's VFA Speed Test "prints a vertical tower with walls at various angles while progressively increasing the print speed." Orca says:

1. Set the speed range. It "has to cover the full range of Outer Wall Speeds used in your prints (e.g., 20 mm/s to 200 mm/s)."
2. Set the step between sections, for example 10 mm/s.
3. Print it and look "for speeds where the surface becomes visibly smoother or rougher."
4. Enter the bad range in Resonance Avoidance in the printer profile.

The wiki marks a nozzle-aware version of the tower, with automatic volumetric speed handling, as available in nightly builds or "Releases greater than 2.4.2." It warns that without those options, the filament's Max Volumetric Speed may cap the tower before it reaches the end speed.

OrcaSlicer: Resonance Avoidance

Resonance Avoidance is in the printer's Motion ability settings, in Advanced mode. Orca says that "by reducing the speed of the outer wall to avoid the resonance zone of the printer, ringing on the surface of the model are avoided." In OrcaSlicer 2.4.2 it's off by default, with a Min of 70 mm/s and Max of 120 mm/s. Its tooltip adds: "Please turn this option off when testing ringing." Orca's VFA page says to set the range from your own test result.

We didn't find Resonance Avoidance in Bambu Studio 2.08.02.61's settings source.

Prusa CORE One profiles

Prusa says it adjusted the CORE One print profiles "to avoid the print artifacts, while keeping very similar print times." It made only minor changes to the STRUCTURAL profiles to protect strength, and says these "will still produce prints, where VFA can show up, especially with PETG." It added BALANCED profiles for the CORE One, which it describes as "fast, great surface quality, good durability." Prusa's blog doesn't publish the speeds it changed.

Step 3: Stop cooling slowdowns from changing outer wall speed

When a layer prints too fast to cool, slicers slow it down. Prusa says that in slicers derived from Slic3r, this slows every part of the layer, and that the slowdown can push outer walls into a speed "that causes vibrations or resonance." Each slicer has a way to keep outer walls at speed:

Notes on each:

• PrusaSlicer. Prusa's blog introduced Consistent Surface in the PrusaSlicer 2.9.3 beta and said it's "robust enough that we can turn in on by default," and that you can switch back under Filament settings > Cooling > Cooling slowdown logic. The 2.9.6 source's base default is Uniform cooling, so check what your filament profile is set to. Prusa says the gain is "dramatic" with black PETG and more subtle with matte filament.
• OrcaSlicer. The setting is in the filament's cooling settings. Its tooltip also lists avoiding "changes in shine when printing glossy filaments" and wall artifacts "that appear like Z banding."
• Bambu Studio. The 2.08.02.61 source also contains a "Cooling slowdown logic" setting with Uniform cooling and Consistent surface options, whose tooltip says Consistent surface "helps reduce VFA (Vertical Fine Artifacts)." The source marks it as a developer-mode setting, so it may not show in the normal settings view.

Step 4: Soften short travel moves

Prusa's second PrusaSlicer change uses "a gentler, lower acceleration only for these very short travel moves on external perimeters, while normal travels remain fast." Prusa describes it as reducing ringing near sharp corners "without impacting overall print time."

• PrusaSlicer 2.9.6: "Travel short distance acceleration," an Expert-mode setting. Its tooltip says short travel distance "is determined by the retract_before_travel setting." The base default is 0.
• Bambu Studio 2.08.02.61: "Short travel," with a tooltip that says "Lower values (e.g., 250-500 mm/s²) reduce ringing artifacts on sharp corners without significantly impacting print time," and that 0 disables it. The source default is 250 mm/s², and it's also marked as a developer-mode setting.

Prusa says it started with the CORE One, that it has seen these changes "also improve print quality on the XL and MK4/S," and that other printers it tested "also benefit."

Step 5: Printer calibrations that target motors

Prusa XL and CORE One family: Phase Stepping

Prusa says Phase Stepping "customizes the drive signal for each motor" to address VFAs and noise from motor variance. The calibration is part of the starting wizard. To run it on its own:

Prusa's notes:

• Don't run it on several printers side by side at once, because "the neighboring printer performing similar motions may affect the measurement."
• If it shows "Calibration failed," check belt tension.
• XL only: once Phase Stepping is enabled, "the crash detection is automatically disabled." Prusa says you can't currently use both. To switch back, disable it under Settings > Hardware > Phase stepping, then turn on Crash Detection.

Bambu Lab: motor noise cancellation

Bambu lists motor noise cancellation as a calibration item on the P1 series, alongside vibration compensation and auto bed leveling, and in the A1 mini setup. On the A1 mini page, Bambu says it works by "measuring the undesirable characteristics within the motor" and applying compensation that generates "reverse vibrations within the motor to counteract the vibrations caused by the motor's imperfections." Bambu describes its aim as reducing "the overall printing noise." The Bambu pages we read don't say it affects VFAs, so treat it as a noise feature. Bambu's calibration guide does say to recalibrate after moving the printer, tensioning belts or updating firmware.

Can you hide VFAs you can't remove?

Prusa says "there are several ways to hide them, from using matte filament to lowering print temperatures." It adds that once you learn to spot VFAs, "you will find them on pretty much any 3D print in the world," and warns that a test object designed to trigger VFAs will always find some.

A sensible order

1. Confirm the pattern: fine vertical lines at the same spot on every layer, not echoes after corners or horizontal bands.
2. Tune the belts using your printer maker's procedure.
3. On a Prusa XL or CORE One family printer, run Phase Stepping calibration.
4. Keep outer walls at a steady speed with Consistent surface or Don't slow down outer walls.
5. In OrcaSlicer, print the VFA test and set Resonance Avoidance to skip the bad range.
6. Check short-travel acceleration in PrusaSlicer or Bambu Studio.
7. If faint lines remain, try a matte filament or a lower print temperature.

Checklist

• Lines are vertical, fine and evenly spaced, and repeat on every layer.
• Belts tensioned to the printer maker's procedure, both sides adjusted equally on the CORE One.
• Phase Stepping calibrated (Prusa XL and CORE One family), and not run beside another printer.
• Outer wall speed not changed by cooling slowdowns.
• Outer wall speed outside the range your VFA test showed as rough.
• Resonance Avoidance turned off while testing ringing, as OrcaSlicer says.
• Short travel acceleration checked.
• Matte filament or a lower temperature tried if faint lines remain.

How this guide was checked

This is a research-based guide. We haven't printed the VFA test for it. Every definition, cause, setting name, menu path and default comes from the Prusa Research, OrcaSlicer and Bambu Lab pages and source files listed above, retrieved on 2026-10-13. Defaults are from PrusaSlicer 2.9.6, OrcaSlicer 2.4.2 and Bambu Studio 2.08.02.61 source files. Firmware features are kept to the printer models each maker names. Read more in our editorial standards.

Print problems: what to check before you buy ↗