Main shaft play

[Greg Jackson]

Yesterday after a couple of flights I noticed that when I picked up the heli by the head, there was a small clicking sound.  I checked to make sure there wasn't any play in the main gear and there was by about 1-2 mm.  Came home and adjusted things.  Did 2 flights today for number 370 and the play is back.  What gives?  Is it the crazy hot weather?  Most importantly, what can I do so this doesn't occur again for a long time?  I adjusted the collar and both bolts that go into the main gear and main shaft.  Very tight. 

[Brandon Bartolomucci]

I'm guessing since you mentioned you picked up the heli by the head you mean you're getting vertical play and not horizontal play. Are you sure you haven't accidentally stripped the bolts by a few threads in the main shaft collars?

Also are the raised boss sides of the collars facing the right direction?

Finally is the one way hub fully secured to the main gear to ensure it's not allowing the one way to move vertically?


Regards,
Brandon Bartolomucci
Sent from my iPhone

[Greg Jackson]

Nevermind, there wasn't any play.  I think that might have been my ears freaking out because I finally had a little play after so many flights.  Checked everything, pulled pretty hard and no movement.  I still checked how tight things were though so I'm good with that.  Thanks for the tips!

[Brandon Bartolomucci]

Glad it's sorted. Always better to have your mind playing tricks than a real problem...mechanically speaking that is. Haha. =)


Regards,
Brandon Bartolomucci
Sent from my iPhone

[Greg Jackson]

Lol, I guess it's good to be over cautious sometimes.  Some people try new tricks instantly but I like to practice the new moves for at least a week on the sim (clean execution) before I try it on the real thing.  Then it's easier with the real Heli.

[Greg Jackson]

Three more flights without anymore "play" issues, guess its good to go now, but I'll keep an eye out for that and other things.

[Greg Jackson]

Here we go again.  After the second flight I picked the Heli up to move and heard the sound of play again.  Checked and saw the top collar on the main shaft move up and down by a mm or less.  Decided to do another quick circuit because I know rain is coming and kept the flight lighter this time.  Checked for play and there was nothing.  What is going on with this?  Headed home after doing some errands to look over everything again.

[Greg Jackson]

For it adjusted, 3 flights and its fine.  But still hear something kind of loose.  When I did the landing gear on the build, I missed one of the screw things inside the skid, every now and then I hear it.  At least that is what I'm assuming it is at lower rpms (take off and landing).

[Matt Botos]

Inner3,

You can use 109-110 10mm Main Shaft Shim(optional) to remove up/down play in the main shaft.
Usually this is only needed with the E7, see page 25 of the E7SE manual for placement of the shim.

http://synergyrchelicopters.com/E7SE_Manual_v1.0.pdf

Thanks,

Matt

[Greg Jackson]

Thanks for the info, if the play returns I will try that out. 
Greg

[Clay333]

I have had a similar issue with my main shaft collar. I would have to adjust it after every flight. I swapped over to red loctite and used more torque on the screw than I really like, but i still have to tighten it every 5 flights or so. I have considered either using some rough sandpaper inside the collar to try to give it more grip or drilling and tapping a 3mm hole and installing a set screw that grabs the main shaft. Or possibly both. I am pretty certain that the threads in the collar are good because I can't feel anything odd while tightening the screw. I will probably end up grabbing a new collar at IRCHA if anyone has them available just to try before I do any modifications. I figure if I screw one of them up i would have an extra then so i wouldn't have any downtime.

[flyalan]

I have had a similar issue with my main shaft collar. I would have to adjust it after every flight. I swapped over to red loctite and used more torque on the screw than I really like, but i still have to tighten it every 5 flights or so. I have considered either using some rough sandpaper inside the collar to try to give it more grip or drilling and tapping a 3mm hole and installing a set screw that grabs the main shaft. Or possibly both. I am pretty certain that the threads in the collar are good because I can't feel anything odd while tightening the screw. I will probably end up grabbing a new collar at IRCHA if anyone has them available just to try before I do any modifications. I figure if I screw one of them up i would have an extra then so i wouldn't have any downtime.

ExperienceRC will have their mobile hobby shop at IRCHA and they typically have just about anything you might need (or don't need)  Synergy or otherwise. 


Cheers
Alan

[RichH]

No need for red Loctite. The shaft collar is not intended to control vertical play in the shaft. It's there to keep the top bearing from falling out of the bearing block.  You can't expect that collar to take all the high G loads during negative pitch maneuvers.

Vertical play is controlled by the tolerances of the components between the lower two bearings and tolerances in the main shaft holes. What Matt is suggesting is adding a shim between the spur gear and the OWB. This will lower the bottom of the main gear assembly and take up the slop above the lower bearing.

First though, be real sure the lower two bearing blocks are in the right direction to take the vertical loads on the main shaft, lower bearing facing up and middle bearing facing down. I can imagine play being present if the blocks are in the wrong orientation.


Rich

[Darren Lee]

No need for red Loctite. The shaft collar is not intended to control vertical play in the shaft. It's there to keep the top bearing from falling out of the bearing block.  You can't expect that collar to take all the high G loads during negative pitch maneuvers.

Not only is red Loctite unnecessary, no Loctite should be used at all on "pinch" bolts.  The pinching force provides preload that keeps the fastener from backing out.

It's true that on the E5 the upper collar shouldn't carry any flight loads with the lower components asssembled correctly.  However, the N5c uses the same collar and it actually does carry flight loads.  When torqued properly this collar is quite capable of holding tight.