Adjusting belt tension (CORE One)

On the Prusa CORE One, adjusting the belt to the optimal tension is crucial to achieving good quality on the prints. A loose belt can cause Layer shifting, Ghosting, or other print abnormalities, like getting an irregular shape instead of a perfect circle. An over-tightened belt can cause an irregular movement in the X and Y axes. 

Belt tuner

We have our own belt tuner, incorporated in our Prusa App.

The application uses your device's microphone and determines the belt tension by measuring the frequency of the vibration generated by strumming it. 

Using a mobile device, open the Prusa App, and navigate to Menu >Belt Tuner. Select CORE One, then select XY-belt, and follow the in-app instructions. When ready to measure the belt frequency, tap on Start listening to use your device's microphone. 

Adjusting the belt

1. Ensure the stepper motors are disabled. This can be done by switching the printer off, or through the LCD Menu -> Control -> Disable Motors. 
2. By hand, move the Nextruder to the rearmost Y-axis position, and to the center of the X-axis. 
3. Strum the left and the right belts in the middle. Place your device next to the belts during this step, to have a frequency measuring, in Hz, of the belt sound. 
4. The strumming sound frequency is typically between 80-90 Hz, with the ideal value at 85 Hz. 
5. Adjust the belts by tightening or loosening the indicated bolts in the below picture. A tighter bolt causes a higher frequency, and vice versa. 
6. It is fundamental for belts to have ideally the same frequency, or at most a very small difference, up to 3 Hz.