How to Tune Input Shaping to Remove Ringing and Ghosting

Those faint repeating echoes that trail behind every sharp edge on a 3D print have a name, and input shaping is how you make them disappear. Ringing, also called ghosting, happens when the toolhead changes direction fast enough to set the frame vibrating at its natural resonance, and that wobble gets stamped into the plastic. The fix is not slower printing forever. It is measuring exactly which frequencies your machine rings at, then telling the firmware to cancel them.

Quick Answer

Measure your printer's resonance frequencies, usually somewhere between 30 and 80 Hz on each axis, then apply a shaper filter that cancels them. With Klipper and an ADXL345 accelerometer you can auto-measure with one command. No accelerometer? A ringing test tower gets you close by eye.

What ringing actually is

When a printer makes a rapid move and then stops or reverses, the mechanical structure does not stop instantly. The belts stretch, the gantry flexes, and the toolhead oscillates around its target for a few milliseconds. Those oscillations decay, which is why the artefact looks like a fading echo of a corner or a hole. Each axis usually rings at a different frequency because the X carriage and the Y bed carry different masses and ride on different rails. The X axis might settle around 45 Hz while the Y sits closer to 38 Hz.

Input shaping is an open-loop technique. It does not add a sensor that constantly corrects the head. Instead it splits each commanded move into a short sequence of sub-moves, timed so the vibration from one cancels the vibration from the next. Done right, the surface comes out clean even at higher accelerations.

Measure resonance with an ADXL345

The accurate route is an accelerometer. The ADXL345 is the sensor almost everyone uses with Klipper because it is sensitive, cheap and well supported. Wire it to the SPI pins on your control board or a Raspberry Pi, add the config block, then run the measurement so Klipper sweeps each axis and records the vibration.

The critical part is the mount. If you cable-tie or tape the ADXL345 loosely, it rattles against its own mount at its own frequency, and the test records that rattle instead of the printer. Bolt it solidly to the toolhead. Once it is rigid, Klipper runs a Fast Fourier Transform on the captured data, finds the dominant peaks, and recommends a shaper for each axis. You can browse compatible boards and printers in the 3D printer range at Evetech when you are speccing a Klipper-ready build.

Reading the recommendation

Klipper does not just give you a frequency. It suggests a shaper type per axis, for example MZV, EI or 2HUMP_EI, along with the residual vibration it expects each one to leave behind. Lower residual vibration is better, but a shaper that smooths too aggressively also rounds off fine detail. The tool prints a recommended choice that balances vibration reduction against detail loss, and that is usually the one to start with.

No accelerometer? The ringing tower

You can still tune by eye. Print a test tower that changes printing speed or acceleration at known heights, look at the spacing of the ghost lines on a sharp corner, and work backwards to a frequency using the move speed and the gap between echoes. It is less precise than the ADXL345 and it takes a few prints, but it costs nothing and gets you a usable shaper frequency. Treat it as a starting point, then refine.

Apply, then verify

Add the recommended shaper and frequency to your config, save and restart, then print the same test object again. The corners and holes that showed echoes before should now be crisp. If a faint ghost remains on one axis only, re-measure that axis. The most common reasons a tuned printer still rings are loose belts, a wobbly accelerometer mount during the test, or a frame that flexes because it is not bolted down firmly. Adjusting belt tension before you measure gives the cleanest result, and you can pick up belts, nozzles and other spares from the printer parts and accessories best sellers.

Frequently Asked Questions

What is the difference between ringing and ghosting?

They are two names for the same defect. Ringing describes the mechanical cause, the toolhead oscillating after a fast move, while ghosting describes how it looks, faint repeated echoes of an edge. Both are fixed the same way.

Do I need a Raspberry Pi to run input shaping?

You need a host that runs Klipper, which is commonly a Raspberry Pi, but many modern control boards can run Klipper directly. The ADXL345 connects over SPI to whichever device is acting as the host or MCU for the measurement.

Will input shaping let me print faster?

Yes, that is the main practical benefit. Once resonance is compensated, you can raise acceleration well beyond stock values without ringing reappearing, which cuts print times noticeably on parts with lots of direction changes.

Why does my printer still ring after tuning?

The usual culprits are slack belts, a loosely mounted accelerometer that gave bad data, or a frame that is not rigid. Re-tension the belts, mount the sensor solidly, and re-measure that specific axis.

How often should I re-measure resonance?

Re-measure whenever you change the toolhead mass, swap to a different hotend, retension belts, or rework the frame. Day to day the values stay stable, so there is no need to run it before every print.