Accelerometer

(CORE One, MK4/S, MK3.9/S)

Relevant for

CORE One family
MK4 family
MK3.5 family
MK3.9 family
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The Input Shaper functionality on the Prusa CORE One/+, and on the Original Prusa MK4/S, MK3.9/S, and MK3.5/S can be calibrated using an optional accelerometer. 

The accelerometer assembly consists of a small PCB enclosed in a printed cover, which connects to the printer. Please note that using the accelerometer requires partial disassembly of the printer. 

The input shaper is pre-calibrated from the factory, so this calibration is usually unnecessary on a stock printer. However, if you've made any modifications to the printer hardware, it may be beneficial to recalibrate the settings using the accelerometer. 

Contents of the accelerometer set.

 
Assembling accelerometer for CORE One/+, MK4/S, MK3.9/S. Assembled accelerometer for CORE One/+, MK4/S, MK3.9/S. 


Assembling accelerometer for MK3.5/SAssembled accelerometer for MK3.5/S

Prusa CORE One/+

Temporarily remove the Wi-Fi board cover, by loosening its M3x12 screw.

Connect the jumper cable between the xBuddy connector and the Wi-Fi module connector. 

Remove the circular cover on the back. Then, route the accelerometer cable in the hole. 

Connect the accelerometer cable to the connector at the back of the printer. 

Original Prusa MK4/S, MK3.9/S

On MK4S and MK3.9S, connect the accelerometer to the dedicated port on the xBuddy board. 
Alternatively, you can install a short jumper cable between the xBuddy and the Wi-Fi module on the back of the printer. Then, you can connect the accelerometer to the connector on the back of the printer. 

On MK4 and MK3.9, connect the cable to the accelerometer's PCB and attach the printed covers. The accelerometer connects directly to the dedicated port on the xBuddy board. 

Without the jumper cable, the connector on the rear of the printer provides no functionality.

Accelerometer connection on MK4S and MK3.9S

Original Prusa MK3.5/S

For MK3.5 or MK3.5S, please visit the dedicated guide.

Calibration

The accelerometer is used to calibrate the input shaper parameters. You can launch the calibration from the LCD Menu -> Settings -> Input Shaper -> Calibration. 

X-axis

Before proceeding with the next steps, ensure the printer is fully cooled down. 

On MK3.9 or MK4, open the fan-door completely before the procedure. Remove the silicone sock, if installed. Identify the part of the accelerometer that is in the shape of the heater block. 

Fit the accelerometer to the heater block, by pushing it from the bottom of the hotend. If there is any resistance, do not attempt to push the accelerometer harder, as excessive force might bend the heatbreak. 

Y-axis (MK4/S, MK3.9/S, MK3.5/S)

Identify the part of the accelerometer that protrudes from the rest. On the front side of the Y-axis, place the protrusion between the steel sheet and the heatbed. 

Results

The results shown on the printer's display at the end of the calibration indicate the optimal input shaping type and frequency found with the calibration. 

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48 comments

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HoryAycardo
•
I have 2 MK4S. I tried the accelerator on one of them. I must say that after calibration and did a test print, the printing was smoother and more quiet than the other printer. For almost $20, I think this is a good mod to make sure input shaper is dialed in to your printer. My MK4S have no mods. I think it's a must have if you want to fine tune the input shaper rather than taking the default provided.
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zzing
•
For the core one this leaves it at a bare wire assembly going into the main area. What do I do after?
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xorath
•
run the calibration, then remove the cable until next time.
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Pyrolit
•
The prints from my kit-built core one plus have very pronounced seams, in my search for a solution I saw some mention of calibrating the input shaper to help reduce the seam.
I was under the impression that the accelerometer kit was not necessary even for the kit-built printer but do wonder if it could improve the situation...
I'd obviously rather not buy the accelerometer unless I actually need it, in which case I would have gladly added it to my original order.
Would I need this anyway whenever I get and install my INDX conversion?
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mrFenyx
•
For Core One + (mine ordered in April 2026), the jumper cable is already connected between the xBuddy Board and the WiFi module. This means you only use the long cable, the jumper cable is left over. To check, you can still remove the cover of the WiFi board and if there is already a black & white cable connected to it, you should be good. Or maybe just try doing the calibration and see if the system detects the accelerometer.
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Coule
•
What's the use of the included SN label?
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greymouser
•
You stick it to the back of your machine, next to the other labels. (I think I'm up to 4 now.) That's pretty much it.
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pauliesnug
•
You'll also need it if you have some sort of warranty issue if you want them to repair it or send you free parts. Although, considering the accelerometer kit is only 3 parts and most people only use it a few times, I think it's mostly a formality.
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