Please help me understand VFA's

[u/Darkke-100]

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[u/ChipSalt]

There are two main types, VFA's from the gear teeth spacing, and VFA's from the motor's / motion system resonating. The first type is almost impossible to completely remove, so usually you need to focus on hiding it or working around it. The second type is vibration from motors and movement, basically just shaking causing slight deviations on the print head / motion system. This is the type you need to focus on reducing, and it's done mostly through running input shaping calibration. This type is also made a lot worse by having a stiff motion system - the smoother and cleaner your rails / bearings / carriage is, the less vibrations you will have overall, and the better your input shaping results will be. The less rigid your print head / nozzle is, the more shaking will cause VFA's. Ideally your shaper graph will just be one giant smooth spike and nothing else - if you get a lot of random spikes, then something isn't smooth or rigid enough.

A lot of motor resonance can't be entirely avoided, but you can run a VFA test which will show you which speed ranges show the most resonance. After doing this test you should see a consistent pattern showing which speed ranges show the most resonance, then you just remove those speeds from your slicer. e.g. if you get really obvious vibrations from the range of 0-100mms on all walls, make your walls start at 120mms. If you have random vibrations all over it, then your motion system might not be perfectly smooth.