Comment by jdietrich | Hacker News Reader

Comment by jdietrich | Hacker News Reader

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>Well we don’t really know that an accelerometer is needed for input shaping for a nozzle that is only accelerating across a single plane.

Input shaping requires an accelerometer for calibration. On a bedslinger like the Mk4, you need two sets of measurements - one for the toolhead and one for the bed, because both are moving and both can experience different resonances. The Prusa solution is to pre-calibrate input shaping from the factory; this is less than ideal, because printer resonances can be substantially affected by the surface that the printer is sitting on. The user could re-calibrate input shaping, but that would require them to connect their own accelerometer module to the motherboard and find some means of jury-rigging it in place.

https://blog.prusa3d.com/announcing-original-prusa-mk4_76585...

I’m not sure what you are trying to say. It sounds like you are saying that because they are factory calibrating it, it’s not needed… so then it’s not needed? What does it matter if it’s less than ideal if it produces satisfactory results? Results are the only thing that matter and Prusa is consistent with producing them so I’m not sure why this is different?

>What does it matter if it’s less than ideal if it produces satisfactory results?

Input shaper calibration is affected by the surface that the printer is standing on. If your workbench happens to be more or less rigid than the surface the printer was calibrated on at the factory, the calibration won't be accurate. The input shaper could fail to correct for some resonances, or correct for resonances that don't exist. This will cause visible artefacts in the print.

Other printers at a similar price point offer one-touch calibration of input shaping, or automatically calibrate before each print as part of the homing and warmup routine. On the Mk4, you need to buy an accelerometer module, figure out some way of attaching it to the printhead and the bed, then run the calibration routine twice.

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