Just a note to other builders. I bought several black cubes in total more than 10 and had only one with serious vibration and clipping issue on IMU3 on every airframe where it was installed. I changed the cube on airframe and vibrations was gone.
The problem was very simple. I found loose all 4 cube attach bolts right out of factory. I never suspected that as the problem but actually it was I found it out only bcs Im switching to core carrier boards and Im short of cubes and used this for testing (I keeped it for more than a year in quarantine as faulty) but this peice was ok only loosen screws.
If the screws are loose and the cube is attached only on connector to carrier board it can slightly move and amplify the vibrations and cause high vibration values and clipping.
If the cube all 4 screws are tightened it works perfectly and the vibration drops significantly with no clipping in hover.
The only tricky part I see that cube is attached to carrier board on very long screws sp visualy is impossible to tell its loose. But I removed other cube + carrier board from my other airframes all of them was OK and this made me a fault confirmation togheter with improved vib data.
I think can be recreated but I dont want to test on my equipement bcs I realised the cube can be easyli detached from connector on carrier board. Luckyli I didnt used it much in this dangerous condition bcs everybody gave me advices that its 1000% airframe problem but after swaping the whole cube assy for another one the airframe was always within limits.
Note: I dont want to say anything negative about this product bcs its great thats why I use only them in my copters also on commercially made copters nd at some point its my failure that I didnt determined this during troubleshooting. I mean this only as a help guideline to anybody who will have the same problem
@philip Its fine it may happen. Outcoming QC is never perfect in any production line Lesson learned also for me - deeper incoming ispection needed we are responsible what we install on our copters
Important is thus can be used for future as troubleshooting step.
I found it out only bcs Im switching to core carrier boards and Im short of cubes and used this for testing (I keeped it for more than a year in quarantine as faulty) but this peice was ok only loosen screws.