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I'm having trouble tuning a custom 3-inch build on Betaflight. I can't get general vibrations to go away. I'm using RC in Power 1506 4100KV motors on 4S. These are very notchy motors. I've been told notchy motors are difficult to tune. Are there any pointers out there for such a build with notchy motors?

I've tried several versions of Betaflight 3.5.7 through 4.1. I've turned down the filtering and the motors stay cool. I've tweaked the PIDs a lot and it hasn't helped much. I've even changed to a completely different Frame to get rid of any possible resonance. I've tried soft mounting the FC, and hard mount. TIA

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What frame are you running? Which propellers? What craft AUW?

I have very similar setups built as racers, that perform brilliantly on both BF3.5.7 and BF4.1.1. Even super-notchy 1408 motors on aggressive 3052F props can fly quite cleanly.

In terms of tunes and filters, both are nearly stock tunes and fly well, at most some filter adjustments to compensate for the higher RPM that naturally comes with 3" craft.

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  • $\begingroup$ The first was an Amax Racer 3, now the same gear is in a Amax Dragonfly 3. I've tried several props the most recent being GF3052. I've even tried setting up rpm filters. Nothing seems to work. $\endgroup$
    – Jim
    Commented Apr 15, 2020 at 21:12
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I have a 3 inch copter with iflight Xing 1408 4100kv motors. They have very strong magnets and are super notchy.

In older betaflight versions, I tried everything to get a clean tune. I softmounted the motors with some 3d printed TPU pads. This helped a lot!

But with betaflight 4.1 a new feature was implemented: RPM Filters! This changed everything for me!

Here is a bardwell video that may help to setup the filters: https://youtu.be/6a69juWsqyU

I recommend you try it! It could get rid of the motor noise completely in your tune.

RPM filters use a new bidirectional DShot-Protocol. When this is enabled, the ESC will tell BetaFlight the rpm for each motor. BetaFlight can than set a filter to exactly this frequency.

This can remove the noise completely on the software side. This is super crazy! I flew with props where one blade was gone! Of course, this is only software. Vibrations in your video feed may not be fixed, and softmounting the motors can help with that...

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  • $\begingroup$ Hi! It would be best if you could edit this answer to include more detail. While I can kinda decipher how it answers the question, it would be much better to explain why RPM filters will disable the noise, and why you put "disable" in quotations... Thanks! $\endgroup$
    – anonymous2 ♦
    Commented Apr 24, 2020 at 11:33
  • $\begingroup$ Jup, you are right! $\endgroup$
    – heavykick
    Commented Apr 26, 2020 at 0:20

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