Guide · Measurement tools
Input shaping and accelerometers: Klipper, Marlin and Prusa
What input shaping fixes and what it does not, when you need an accelerometer, Klipper's ADXL345 warnings, Marlin's test-print method and Prusa's pre-tuned printers.
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Short answer
Input shaping reduces ringing from fast direction changes. It does not make prints faster by itself; only a higher acceleration setting does. You need an accelerometer only on Klipper if you want measured tuning, or on a modified Prusa. Marlin tunes by test prints, and stock Prusa printers come pre-tuned.
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What input shaping does, and does not do
Klipper's documentation says input shaping is meant to reduce ringing (ghosting) caused by vibration from quick direction changes.[1] It does not by itself change print time; only the max_accel setting does.[1] Shaping makes a higher acceleration usable with less ringing. You still choose that acceleration.
Shaping has a cost. Klipper notes that it adds smoothing to printed parts, and that some shaper types and very high accelerations can round off fine detail.[1] MZV is Klipper's default.
Fix mechanical causes first, where possible
Klipper says ringing usually has mechanical origins, such as a weak frame or loose belts, and that these should be checked and fixed first where possible.[1] Prusa likewise recommends checking belts, the nozzle and smooth rods first.[2]
Do you need an accelerometer?
| Firmware | How shaping is tuned | Accelerometer |
|---|---|---|
| Klipper | Measured resonances, or test prints | Optional; supported chips listed below |
| Marlin | Test prints (M593 sets frequency and damping) | Not used: no accelerometer-based tuning |
| Prusa (MK4/S, MK3.9/S, CORE One and others) | Factory pre-tuned | Prusa's set is for modified printers |
| Prusa MINI/MINI+ | Input shaper in firmware 5.1.0 | Prusa's set is listed as not compatible |
Marlin. Marlin's input shaping is tuned by printing test patterns, and its documentation says it does not provide accelerometer-based tuning.[3]
Prusa. Prusa says its optional Accelerometer Set is not needed on stock printers, because factory input-shaper values are pre-tuned. It positions the set for recalibration after modifications, and calls the gain from recalibrating a stock printer "rather insignificant".[4] Prusa added input shaper to the MK4 with firmware 5.0.0 and to the MINI/MINI+ and XL with 5.1.0, and requires a matching PrusaSlicer profile.[2] Its product page lists the MINI and MINI+ as not compatible with the set.[4]
Klipper. Klipper lists built-in support for ADXL345, MPU-9250, LIS2DW and LIS3DH-compatible accelerometers.[5] Support changes between versions, so check the current page.
Klipper's warnings about ADXL345 boards
We give no wiring steps here; follow Klipper's documentation and your board's pinout. These are the points Klipper itself warns about:[5]
- Some ADXL345 boards are hard-wired for I2C, which is too slow for resonance measurement. The board must support SPI.
- With a 5 V printer MCU, the board needs a voltage regulator and level shifters.
- Double-check wiring before powering up.
Picks that fit1 product
Klipper printers only: BIGTREETECH says this board supports Klipper firmware only. Choose the 'ADXL345 V2.0' style, the USB version (1030000156), not the S2DW or a bundle.
More on choosing
It names no printer model, so plan a rigid mount for your toolhead and bed. Not for Marlin or stock Prusa printers. On Amazon, check that 'Ships from / Sold by' shows Amazon.com, BIQU or BIGTREETECH.
BIGTREETECH ADXL345 V2.0 accelerometer board (USB)
Mounting and axes
Klipper says the accelerometer must be rigidly mounted on the moving part, and electrically isolated from the frame. On a bed-slinger, X is measured on the toolhead and Y on the bed, or with two accelerometers.[5] A loose mount distorts the data.
The suggested max acceleration is theoretical
Klipper describes the maximum acceleration its shaper calibration suggests as a theoretical maximum, not a recommendation, and does not apply it to max_accel automatically.[5] Keep max_accel below it with a conservative margin, and check with test prints.
Klipper's ringing test disables pressure advance, and it says to re-tune pressure advance after shaper tuning if needed.[1] See pressure advance and Linear Advance.
Next
Questions
Do I need an accelerometer for input shaping?
Not always. Marlin tunes input shaping by printing test patterns and does not provide accelerometer-based tuning. Prusa pre-tunes its stock printers. Klipper can use one to measure resonances directly.[3][4][5]
Will input shaping make my prints faster?
Not by itself. Klipper's documentation says input shaping does not change print time; only the max_accel setting does. Shaping lets you raise acceleration with less ringing, within the limits of smoothing.[1]
Which ADXL345 board works with Klipper?
One that supports SPI. Klipper warns that some ADXL345 boards are hard-wired for I2C, which is too slow for its resonance measurement. With a 5 V printer MCU, Klipper says the board needs a voltage regulator and level shifters.[5]
Can I use Prusa's Accelerometer Set on a MINI+?
No. Prusa's product page lists the MINI and MINI+ as not compatible with its official Accelerometer Set. The MINI/MINI+ did get input shaper in firmware 5.1.0.[4][2]
Should I use the maximum acceleration Klipper suggests?
No. Klipper describes it as a theoretical maximum, not a recommendation, and advises keeping max_accel below it with a conservative margin and test prints.[5]