Symptom: just past every sharp edge, hole or piece of lettering on a wall you can see a repeated, steadily fading echo of the same shape. The surface looks rippled, and the pattern always runs in the direction the head was moving. The dimensions are correct and the layers bond well — only the appearance suffers.
Ghosting (also called ringing, or simply vibration echo) is not a problem with the material or the slicer in the usual sense. It is the natural vibration of the structure. When the head changes direction sharply, the whole machine takes an impulse and starts vibrating at a frequency set by its stiffness and mass. The nozzle carries on laying plastic down, just no longer exactly where the G-code tells it to. The vibration dies away after a few or a dozen millimetres, which is why the echo is strongest immediately after an edge and then fades. The practical conclusion is simple: either you reduce the impulse, or you stiffen the machine, or you have the firmware compensate for the vibration.
The most common causes and their fixes
1. Acceleration and jerk are set too high
The strength of the impulse rises directly with acceleration, and jerk (in Klipper square corner velocity) decides how abruptly the machine enters a corner. Factory profiles are often set up for print time rather than surface quality.
How to check: print a tower in which the acceleration changes every few layers. The height at which the echo disappears indicates the working value for your machine.
What to do: lower the acceleration by about a third and judge the result, and only then start on the jerk. Reduce the acceleration for the outer perimeters separately as well — the inside of the model can carry on going fast, because you cannot see it anyway. This is the cheapest way to improve the look without a significant loss of time.
2. The belts are slack or a pulley is turning on its shaft
A slack belt behaves like a spring. The head reaches its position late and overshoots it, which produces exactly the same picture as too high an acceleration.
How to check: pluck the belt with a finger at its midpoint. It should answer with a clear, short note rather than a soft slap. Check as well that the pulley's grub screw sits on the flat of the shaft and not on its round part, because in the latter case the pulley will turn on the shaft at every change of direction.
What to do: tension the belts on both axes equally, tighten the pulley screws onto the flat and check that the idler pulleys have no play. After any intervention in the mechanics, the acceleration calibration has to be repeated.
3. The printer stands on an unstable surface
A worktop that flexes stores vibration energy and gives it back late. A shelf made of furniture board, a folding table or a desk with drawers are the worst possible bases for a machine that changes direction dozens of times a second.
How to check: put your hand on the worktop next to the printer while it is printing. If you can feel vibration, the worktop is part of the problem.
What to do: stand the printer on a heavy, rigid base, ideally a stone slab or a thick concrete paver with a damping mat. Level the feet so that the machine does not rock on three points. Enclosing the printer, which is required in any case for ABS, ASA and PA from the engineering filaments group, adds stiffness to the frame while it is at it.
4. A heavy bed being accelerated along the Y axis
On designs where the bed moves back and forth, vibration is unavoidable: you are accelerating kilograms of glass, aluminium and print. The taller and heavier the model, the worse it gets, because the centre of gravity travels upwards.
How to check: compare the echo on walls parallel to the X axis and to the Y axis. One side being clearly worse is the signature of a moving-bed design.
What to do: set a separate, lower acceleration for the Y axis than for X. Position the model so that the longest, most visible walls lie along the axis that vibrates less. Take everything you do not need off the bed, including heavy clips.
5. Input shaping is not calibrated
Vibration compensation (input shaping, resonance compensation) modifies the movement so that a second impulse cancels the first. It works well, but only at the frequencies actually measured on that particular machine. Values copied off the internet or left at their defaults can make the picture worse.
What to do: take a measurement with an accelerometer if your firmware supports it, or print a test pattern and read the frequency off the scale. Repeat the measurement after every change in the mass of the head, for example after replacing a hotend or a fan, or adding a camera.
6. The head is too heavy or has play in it
The mass of the head translates directly into inertial force. An added fan, a thick cable, a second heatsink or an extruder moved onto the carriage all change the vibration characteristics of the whole machine.
What to do: check the play in the wheels or linear carriages by moving the head by hand with the motors off. Tidy up the cable loom so that it does not pull the head sideways. If you have added cooling, expect to have to recalibrate the vibration compensation — fan requirements vary a great deal from material to material in any case.
| Porima material | Nozzle range | Part cooling | Enclosure |
|---|---|---|---|
| PLA | 200–230 °C | 100% | open |
| Tough PLA (PLA+) | 210–240 °C | 100% (required) | open |
| Hyper PLA+ | 220–250 °C | 100% | open |
| Silk PLA | 230–260 °C | 80–100% | open |
| PLA/CF | 220–250 °C | 60–100% | open |
| PETG | 240–260 °C | 100% | open |
| HT PETG | 270–300 °C | 0–10% | open or enclosed, glue recommended |
| ABS | 250–280 °C | 0–40% | enclosed, 50 °C |
| ASA | 250–280 °C | 0–30% | enclosed, 50 °C |
| PA (nylon) | 260–290 °C | 30–100% (first 5 layers without) | enclosed, heated |
| TPU Flex 98A | 230–260 °C | 40–70% | open |
Source: the official FDM technical data table from the manufacturer, Porima. The full set: print temperature table.
Quick checklist
- Check the belt tension and that the pulley screws sit on the flat of the shaft.
- Stand the printer on a rigid, levelled base.
- Lower the acceleration by a third and judge the effect.
- Set a separate, lower acceleration for the outer perimeters.
- Reduce the jerk if the echo only shows at corners.
- Calibrate the vibration compensation by measurement, not with values from a forum.
- Rotate the model so that decorative walls lie along the stiffer axis.
The overriding rule: change one parameter at a time. Sort out the mechanics before the settings, never the other way round.
When it is not ghosting
Not every ripple on a wall comes from vibration. A regular pattern repeating at an identical spacing over the whole height of the model, regardless of where the edges lie, points to the Z axis: a bent screw, a coupling or stress in the motor mount. Ghosting, by contrast, is always tied to a specific feature of the geometry and fades as you move away from it. If the echo appears only where the perimeter starts and ends on the same layer, the source is nozzle pressure rather than mechanics, and then you need to deal with blobs and zits. Note too that once you lower the speed and accelerations, the material spends longer in the hot nozzle. If stringing or discolouration appears after tuning out ghosting, come down 5 °C towards the bottom of the range for that material.
Related problems
Once the mechanics are set up, it pays to print with a material that brings no surprises of its own. Porima filaments are produced to a ±0.03 mm diameter tolerance, and we publish the manufacturer's full official print data — you don't have to guess it. Our warehouse is near Poznań, in Swarzędz.
See Porima filaments · Print temperature table · All 3D printing problems