Alt hold issues. Tried everything... Please Help

I am having major issues with alt hold on my 450 quad copter using the APM 2.6. I have read about vibration issues and have attempted to correct this issue. Here is the list of things I have done…

Tested motor vibration. I see a nice straight line with props off.

Mounted the APM in all 4 corners with a 3/8 square… 2 sided foam tape (one layer and 3 layers / stacked, zeal gel, zeal gel with light strap (zip tie in fuel tubing), added weight to the apm via a large washer and soft foam pads.

Balanced all 4 props on a dubro balancer.

My motors/ ecs / props are the t-motor air gear 350 set. My frame is a aphid 450 (dji flame wheel arms). I have the APM mounted in the center of the upper and lower frames. I checked and the is foam over the barometer.

Copter flys in stabilize mode. Motors pulse in alt hold and in changed altitude violently.

Maybe someone can help me with this? One thing I cant wrap my head around is what is a direct cause of Z axis vibration. motors spin on X/Y. The only thing I can come up with is standing wave or prop thrust buffeting?

Here is my log

[attachment=0]2015-02-23 17-42-02.log[/attachment]

those vibes are very bad :open_mouth: . hehe sorry

I think the arm shading can cause some issues but not like you are seeing.

Its got to be something mechanically vibrating, resonating, rattling and hitting the autopilot.

I know. Something is defiantly wrong. Only thing touching the APM is the wires that are connected to it. Can you explain what causes Z axis vibrations? I 3D printed a vibration mount so I will put the APM on top and see if it helps.

lots of things can cause z accel…the x/y vibes of props can bend the arms translating xy vibes to z for example.

that mount should help hopefully

Hopefully your Board does the trick.

Below I attached a photo of my DIY vibration board using 32DB ear plugs. The frame it’s on is known for high vibrations. I was getting the IMU mismatch in the 200-350 range. I too had some thoughts about the wires. However, When I switched to this board the IMU readings went down to .25 to .35