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Main Rotor Gear Wobbly - 9/25/2007 3:24:10 AM   
StevesRCHeli


 

Posts: 7
Joined: 9/21/2007
From: Virginia Beach, VA, USA
Status: offline 		I had a mild crash (tips of blades hit soft couch-2 inches off ground), and then there was excess vibration. Did the "tracking check" on the main rotor gear and saw that it was moving up and down on the motor gear instead of just dead straight. The flybar was just as wild, so I replaced both the main shaft and main rotor gear and it still does the exact same thing!! Don't get it. When you fix something, shouldn't it be, well, fixed? I put nothing else back on when I checked it. Its just the main shaft, main rotor gear and main shaft collar. I replaced the parts because it seemed logical to me even though the "crash" was very mild (carpet, too). I was gonna take it to Debbie's RC World tonight, but got caught up talking the co chaplain... Gotta have priorities I guess...! (Was a hard choice though!)lol Just doesn't make sense to me... What are ya'll thoughts?

Thanks
Steve
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RE: Main Rotor Gear Wobbly - 9/25/2007 3:09:18 PM   
Heliko



Posts: 591
Joined: 1/16/2007
From: Long Island, NY, USA
Status: offline 		There is a bit of play between the mainshaft and bearings. If the blades are not tracking correctly the rotorhead will wobble and cause the shaft to wobble making the gear look warped. If you've tried to track the blades and they just don't seem to cooperate you still could have a bent feathering spindle or maybe a plastic part in the head was tweaked in your blade strike.

Try taking off the the rotor head at the points in the pic and spin it up. See if the gear flattens out or still wobbles. This will tell you if the wobble is actually coming from the gear and mainshaft or an untracked or unbalanced rotorhead.

Good Luck!

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RE: Main Rotor Gear Wobbly - 9/25/2007 3:17:41 PM   
123Splat


 

Posts: 413
Joined: 4/27/2007
From: Austin, TX, USA
Status: offline 		You DID check the new Main shaft for run-out before installing it, didn't you?

I wacked my AXE CP into the wall once. had to replace the main shaft (amoung lots of other stuff). Ordered the replacement from Tower. When recieved, it was out of run-out (BENT!). I ended up straitening out the original and using it, holding the new one for reserve.

For your case, failing the above, I guess your next option is to replace the Main Gear. But first, while main shafe and head are out of frame, run up the main motor a little (NOT FULL THROTTLE, if you run it up too high without a load, excessive rpm can cause the armeture windings to seperate) and watch for wobble in the motor shaft and pinion.

Good luck,
Splat

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It's not the takeoff or the flying, it's the landing and repairing, so I can takeoff and fly again...

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RE: Main Rotor Gear Wobbly - 9/25/2007 11:57:38 PM   
dtacmed


 

Posts: 65
Joined: 8/5/2007
From: Kannapolis, NC, USA
Status: offline 		I would as said earlier check the feathering spindle. I bent 3 in 1 afternoon on the mx pro. Does not take a hard crash to bend them. And when you do the Heli will shake like it's having a seizure.

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RE: Main Rotor Gear Wobbly - 9/26/2007 1:00:40 AM   
StevesRCHeli


 

Posts: 7
Joined: 9/21/2007
From: Virginia Beach, VA, USA
Status: offline 		I haven't put anything back together. It is just the main shaft, main rotor gear and shaft collar. I replaced the shaft and gear and spin it by hand and it wobbles exactly like the ones I replaced. So I was thinking maybe that was just normal and maybe it straightens up when it powers up? Just never noticed it before. I haven't checked to see if it isout of round yet-no time. I will take it to the hobby shop tomorrow after work (or, again, attempt to). They are closed on Tuesdays which is weird, but open 9-6 on the weekends! thanks for the responses...

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RE: Main Rotor Gear Wobbly - 9/26/2007 2:05:40 AM   
StevesRCHeli


 

Posts: 7
Joined: 9/21/2007
From: Virginia Beach, VA, USA
Status: offline 		Heliko, thanks a lot for the detailed picture. That was a lot of trouble to go to so I just wanted to make sure you knew it was appreciated...

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RE: Main Rotor Gear Wobbly - 9/26/2007 2:16:27 AM   
MMatheny


 

Posts: 805
Joined: 1/23/2003
From: Dickinson, TX, USA
Status: offline 		StevesRCHeli
Are you saying your main gear wobbles as the main shaft turns?? Is it tight on the shaft - no play? Are the bearings tight in the frame? I just can't get precisely what is wobbling on what!

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"Never use your shins as a blade tracking device" - Mike

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RE: Main Rotor Gear Wobbly - 9/26/2007 3:10:34 AM   
Heliko



Posts: 591
Joined: 1/16/2007
From: Long Island, NY, USA
Status: offline 		Steve glad to help.

MMatheny I think he means as the main gear rotates it's liked a warped record.

< Message edited by Heliko -- 9/26/2007 3:11:23 AM >

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RE: Main Rotor Gear Wobbly - 9/26/2007 12:21:07 PM   
StevesRCHeli


 

Posts: 7
Joined: 9/21/2007
From: Virginia Beach, VA, USA
Status: offline 		That is the best analogy heliko! Just like a warped record! someone mentioned that there is a bit of play in the top bearing-I was gonna ask if that was normal...
yes the gear is tight on the shaft and it is disengaged from the motor gear. motor gear runs true-no bend or anything. only thng I cn thnk of is I got a new shaft tht is also bent or the wobblys are normal...your guys' rotor gear runs flat. right? no warp at all?

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RE: Main Rotor Gear Wobbly - 9/26/2007 2:42:46 PM   
MMatheny


 

Posts: 805
Joined: 1/23/2003
From: Dickinson, TX, USA
Status: offline 		I have never looked real close at my main gear when running - how much wobble are we talking about? 1/32 inch or less?

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Mike
"Never use your shins as a blade tracking device" - Mike

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RE: Main Rotor Gear Wobbly - 9/26/2007 2:57:21 PM   
123Splat


 

Posts: 413
Joined: 4/27/2007
From: Austin, TX, USA
Status: offline 		My Axe has been bashed in just about every angle possible and the main gear runs flat as a pancake.

Feathering shaft and 'o' rings is a good place to check for button wobble, but NOT main gear...

Again, sadly, if the main shaft is good, and the main gear is on tight and true, looks like it might be time to replace the gear.

While you got it all apart, check the frame for cracks (particularly the bottom bearing races).

Splat

_____________________________

It's not the takeoff or the flying, it's the landing and repairing, so I can takeoff and fly again...

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RE: Main Rotor Gear Wobbly - 9/26/2007 3:53:41 PM   
Heliko



Posts: 591
Joined: 1/16/2007
From: Long Island, NY, USA
Status: offline 		Steve my stock maingear wobbled a bit too. I really think it was from the small amount of play between the shaft and bearings, but it's also true that sometimes the new shafts can come pre-bent. I've had one or two like that. The other thing is sometimes they're under cut which can contribute to even more play.

I now have an MX400 maingear on the Axe and since it's not rigidly connected due to the one-way bearing it wobbles a bit too, but straightens out when the RPM's get close to take-off speed.

I wouldn't worry about the wobble too much as long as gear mesh is smooth and the blades can be tracked. Usually if something is bent the blades are difficult or impossible to track so you may want give that a shot and see what happens.

Good Luck!

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RE: Main Rotor Gear Wobbly - 9/27/2007 1:58:57 PM   
StevesRCHeli


 

Posts: 7
Joined: 9/21/2007
From: Virginia Beach, VA, USA
Status: offline 		Well I took my Axe to the hobby shop last nite. The guy had me put everything back together to see if the wobbly gear would affect flight. It flew just fine! Better than fine really-he had that thing hovering on a dime-amazing! I can't keep it within a 5 ft diam!
Anyway, apparently the wobbly gear doesn't affect it too much. I guess as you get the higher end models the quality will get better... So all is good! thanks for everyone's input. I have learned so much from these forums!
Steve

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RE: Main Rotor Gear Wobbly - 9/27/2007 6:35:44 PM   
123Splat


 

Posts: 413
Joined: 4/27/2007
From: Austin, TX, USA
Status: offline 		Glad you're back in the air and flying happy!

5ft diam? WOW how do you manage that? (I usually resort to flying in a 10'x10' room to keep my hover down to less than 20', 'little hard on the walls though, BUT, my JCS plastic blades are holding up just fine!

Good news, congrats,
Splat

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It's not the takeoff or the flying, it's the landing and repairing, so I can takeoff and fly again...

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RE: Main Rotor Gear Wobbly - 9/27/2007 6:47:54 PM   
MMatheny


 

Posts: 805
Joined: 1/23/2003
From: Dickinson, TX, USA
Status: offline 		Maybe he meant a 5' radius!

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Mike
"Never use your shins as a blade tracking device" - Mike

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RE: Main Rotor Gear Wobbly - 9/27/2007 8:59:14 PM   
StevesRCHeli


 

Posts: 7
Joined: 9/21/2007
From: Virginia Beach, VA, USA
Status: offline 		I definitely meant radius! Wish I could claim that diameter though!
Steve

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