Ghosting and ringing: fixing ripples beside edges on 3D prints
are explained briefly when you hover over or tap them.
Ghosting, also called ringing, shows up as fine ripples on a wall directly beside an edge, a hole or an embossed detail. It looks as if the detail repeats a few millimetres further on, like an echo. You see it most clearly in raking light on smooth outer walls.
How do you recognise ghosting?
- Ripples directly after a corner that fade after a few millimetres.
- Shadows of letters or holes beside them on the wall.
- The ripples are evenly spaced from one another.
- They occur in the direction of travel, so often only on walls along the X or Y axis.
Do not confuse it with a shifted layer: with a layer shift the whole part is offset from a certain height. Ghosting, by contrast, is a surface pattern, and the dimensions are correct.
Why do the ripples appear?
The print head, and on many printers the bed as well, are masses that are constantly accelerated and braked. At a corner the head changes direction abruptly. The frame, belts and mounts flex briefly and oscillate. This oscillation is printed into the wall as a ripple.
The faster and more jerky the changes of direction, the heavier the moving mass and the softer the mechanics, the stronger the ghosting. Bed slingers are somewhat more susceptible because the whole bed with the print moves back and forth. More on this in Bed slinger or CoreXY.
What helps, sorted by effect
1. Use input shaping
Input shaping measures at which frequencies the printer vibrates and adjusts the movements so that these vibrations cancel each other out. Many current printers have an accelerometer built in for this and calibrate it automatically, sometimes under the name vibration compensation or resonance compensation. With firmware such as Klipper and with current Prusa firmware, it can also be set up or recalibrated.
Important: After changes to the mechanics, such as retensioned belts, a different hotend or a new location, run the calibration again. The vibration frequencies change as a result.
2. Tension the belts correctly
Loose belts act like a spring. The head keeps swinging before it comes to rest. Belts that are too tight, on the other hand, put strain on bearings and motors.
Solution: Check the tension against the manufacturer’s instructions. Many manufacturers specify a method, for example with a frequency app or a tensioning tool. On CoreXY printers both belts should be tensioned equally.
3. Reduce acceleration
Acceleration has more influence on ghosting than speed alone. High values cause hard changes of direction.
Solution: In the slicer, deliberately reduce the acceleration for outer walls. Many profiles use lower values for outer walls than for infill anyway. Lower the value step by step, for example by a quarter, and compare. A somewhat lower speed for outer walls helps too. More on this in Print speed.
4. A stable base
If the printer stands on a wobbly table, the table oscillates with it. This noticeably amplifies the ripples.
Solution: Place the printer on a solid, heavy surface. A solid slab, for example of stone or concrete, under the printer adds damping. A piece of furniture that visibly wobbles while printing is unsuitable. Important: after moving the printer, recalibrate input shaping.
5. Find loose parts
Loose screws on the frame, a wobbling print head or a rattling fan housing can create vibrations of their own.
Solution: Carefully feel over the printer while it is at rest. Does the head wobble on its guide, is the bed secure, are the frame screws tight? On bed slingers, check the eccentric nuts on the wheels: the wheels should run without play but still be able to turn. Heavy add-ons on the print head increase the moving mass and with it the ghosting.
What hardly helps
- Higher temperature or more cooling: Ghosting is a mechanical problem, not a thermal one.
- A different wall count: The outer wall stays the outer wall, and the ripples stay visible.
- A different filament: At most it helps visually. Matt or dark filaments make ripples less noticeable, while glossy and light ones show them more clearly.
Test: where does it come from?
Print a small cube with embossing on two sides, once with the normal profile and once with the acceleration for outer walls halved. If it gets clearly better, it is down to the dynamics. If it stays the same, look instead for loose parts or a wobbly surface.
Quick checklist
- Input shaping or vibration compensation calibrated, including after the last modification?
- Belts tensioned according to the manufacturer’s instructions?
- Acceleration for outer walls reduced?
- Printer standing on a solid, non-wobbling surface?
- Frame screws, print head, wheels and bed free of play?
- Change only one thing at a time and compare with the same test part.
Continue with: Calibration for the other tests that make sense after modifications.