Could use some help diagnosing head "wobble" on N7 ...

[Kevin Feil]

One thing I want to add that I have seen happen more often than not. Is pay close attention to how tight you have your Blades tightened down, Too tight especially lower headspeeds will cause a lead/lag issue with the blades and create one hell of a wobble. Have seen this more on Nitro's since they ideally run lower head speeds than electric.

It's hard to say Torque the Blade Bolts to "X" . I generally use the two finger method, cup the blade last 1.5 inches of the tip and pull back with light but some resistance, you want to get it as even as possible between the two blades. This is I formation you may already be aware of, but want to take the time and opportunity to mention it in the event it helps others that may not know.

Best Regards,

Kevin

[Chief58D]

Good tip, Kevin -
Thanks!

[Chief58D]

Decided to take up the main shaft slack with the upper collar adjustment (please advise if that is not a good idea!).

New feathering shaft with the .75mm shims, loosened up the blade bolts a bit, leaned the motor a couple of clicks (running Byron RotorRage 22.5), and reset the low RPM governor to 1750.

2 flights today - seems to be flying smoothly at all 3 flight mode settings w/ very minor track differences in the blades (I'll tackle that tomorrow, weather-permitting), and a LOT less fuel-tank foaming than I had seen previously!

I think I'm getting there! 

Thanks again for all the tips and feedback!

[Kevin Dalrymple]

Glad to hear you are getting it dialed in.

[Mark Dean]

Decided to take up the main shaft slack with the upper collar adjustment (please advise if that is not a good idea!).

Great to hear everything is working out. It is perfectly acceptable to take the slack out with the collar. I recommend tightening both of your bolts on the autohub and gear prior. Then take up the slack with the collar. If it really bothers you, you could always shim.

EDIT: After some conversation with the rest of the Synergy family I will add this:
While you can run with the slack being mitigated with the collar, hard 3d maneuvers could cause the collar to slip. Shimming the transmission should be done to prevent the collar from being the only mechanism to stop the movement.


Mark

[Chief58D]

Decided to take up the main shaft slack with the upper collar adjustment (please advise if that is not a good idea!).

Great to hear everything is working out. It is perfectly acceptable to take the slack out with the collar. I recommend tightening both of your bolts on the autohub and gear prior. Then take up the slack with the collar. If it really bothers you, you could always shim.

EDIT: After some conversation with the rest of the Synergy family I will add this:
While you can run with the slack being mitigated with the collar, hard 3d maneuvers could cause the collar to slip. Shimming the transmission should be done to prevent the collar from being the only mechanism to stop the movement.


Mark

Appreciate the update, Mark.

Concerning the shim(s) -

It looks like it would probably take 2 or 3 shims to take up most of the slack.
Any problem stacking shims for this purpose?

[Mark Dean]

There is no issue stacking the shims. The only reservation I have is you shouldn't need so many. I can see the use of two at the most. Please do a check on all the parts and ensure all of your components are straight and assembled correctly.

Mark


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[Rob Cherry]

Excessive vertical play is usually attributed to the bottom (3rd) block being bent. A direct inverted crash or something similar that pushes downward on the head can deform that 3rd block into a slight U-shape. Check to make sure it isn't bowed downward by laying it on a flat surface. It's quick to remove.  Rob!

[Chief58D]

Thanks for the additional info -

I plan to put the N7 back on the work bench over the weekend and take another shot at cleaning up the slack in the main shaft.  I'll post back with the results.

[Chief58D]

Turns out my problems with the vertical slack with the main shaft was an indication of a VERY serious problem developing from an easily-made mistake! 

It appears that during the build, the middle main shaft bearing block was installed with the bearing facing the wrong direction.  As a result, instead of riding against the bearing surface, the top of the auto hub sleeve was actually gradually burrowing into the wrong side of the main shaft bearing block.  As this wore, it was also allowing the mounting hardware for the main gear and lower jesus bolt collar to move, creating noticeable wear in the auto hub sleeve, jesus bolt collar, and mounting holes in the main shaft!  Needless to say, this could have gotten VERY ugly in probably a very short time!!

So, off to the Synergy store for a new main shaft, bearing block & bearing, auto hub sleeve, and the associated hardware for the main shaft.  All things considered, this could have turned out to be MUCH more expensive than relatively small amount I'm spending now...

[Mark Dean]

Glad  to hear that you found the problem and can get it corrected before any serious issue.

Mark


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[Chris Sexton]

Wow good catch. Sorry to hear you had trouble but glad others probed for more details and you found the error.


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[Chief58D]

Wow good catch. Sorry to hear you had trouble but glad others probed for more details and you found the error...

Yeah, me too ~
This could have become REALLY expensive in a hurry!!!