Canopy/Main Frame Vibe

[Filby]

Ive had a few engine issues in my sport 600N over the past few weekends so haven't noticed any problems until today after I got the new engine sorted. The heli has quite an intense vibration at anywhere between 1600 and 2000rpm. The canopy vibrates a lot and this is also throwing the gyro off a bit.
Anyway I got it home today and pulled down the head to see if I could find the problem. I checked the main shaft and it was straight. Pulled out the spindle and low and behold I had two IN thrust washers on one side and two OUT washers on the other side. Not exactly sure how this happened as I was pretty meticulous about this when putting the kit together... oh well.
So I haven't had a chance to test it out and wont until next weekend. Does anyone know if this would have been causing the vibe, or should I continue looking?

Cheers

Fil

[Filby]

Well this didnt fix the problem. Anyone got any advice on where to look?

Cheers

Fil

[matrix1171]

what about run out on the fan hub and clutch assembly ?

[mjws]

If it is a large vibration it's usually in the head (slow speed). Bad set of blades? Swap them out, double check the balancing. Fan and clutch should give a very high vibration and shake fuel. I'd also put in a fresh mainshaft, flybar and spindle just to rule them out as they are the primary culprits on large vibrations. Besides having the spares is good.

If you've swapped blades, lubed dampeners, checked shaft, spindle, fan, clutch, pinion, maingear mesh, flybar out of balance (not centered) paddles out of alignment. Even poor tuning can get ya. Then it's on to the more involved last resort processes.

If you are a rookie, get help as I can't protect you from yourself. You can make a mess of yourself and your heli if you aren't paranoid and safe. You can disconnect the tail and spool GENTLY to rule out that assembly. Probably isn't it, but at least you'll have it out of the loop.

Take the main blades off and spool GENTLY. The flybar and head will give you some load, but STAY OUT OF THE THROTTLE. Flybar paddles will be invisible so look out. Bent shafts, out of balance flybar are still going to shake, screwy maingear mesh, fan, clutch will still shake. If all of a sudden you are dead smooth. It's your blades which you already swapped out right? You can go as far as mainshaft only, and add back components to rule them out. Just don't get the revs up as the load is small.

You'll notice all the emphasis on GENTLE, LAST RESORT, GET HELP. There are lots of people who would never spool up a nitro bird with no blades. I wouldn't either until dynamic balance was all that is left. Your throttle still works, idle is still idle, and the clutch won't engage until you ask it too. You can spin at 10 rpm or 2000, but if you go nuts you'll over rev and damage your motor. It's much more common on electrics where an unloaded motor isn't likely to hurt itself.

Chasing an elusive vibration is difficult. Be careful, and safe. Get local experienced help if you're new. I've put as much FAIR WARNING in as I can. But unfortunately sometimes the simple stuff doesn't work.

Good luck. Be Safe. (Seriously if you're not comfortable and experienced just skip everything after paragraph 2. Swap parts and balance till you get it.)

Mike

[skaterx]

I have exactly the same problem. I've changed:

Main Blades (proven by a local pro)
Main Shaft
Spindle Shaft
Torque Tube and bearing location
Tail rotor assembly (I have 2 kits, swapped this out with the other one)
Tal blades (proven by a local pro)
Metal Flybar Seesaw holder
Blade Grips to Metal
2 Different oneway assembly (both locked up which sucks!!!)
New engine
New servos (from 6965hb to Futaba 9252)
Gyro location (from front to back)
Balanced the fan unit with magnets installed
Tuned up engine perfectly
Paddles are the same weight to .x of a gram
Flybar is exactly the same on both sides

Not much left to try, other than different paddles, different head and replace main shaft bearings.

Landing gear are vibing about 1/2 an inch back and fourth and the body is moving about 1/4 an inch back and fourth... Tail seems to be vibing about the same as the body.

[mjws]

Pretty thorough list skaterx.

You're lucky to have two full kits available. Swapping out the head for a fresh one should show you a lot. 1/2 an inch back and forth is a HUGE lowspeed vibration. Gyro, fan, bearings, servos, are pretty unlikely culprits. It's probably not something at 17K its something at <2000.

You pretty much have the ultimate troubleshooting tool I'm sure you'll nail it quickly.

Mike

[Fabian85]

Hello!

I have the same problems with my 600N Pro! The whole Heli vibrates, the more rpm on head, the more vibrations!

I don´t know whats the reason for those vibes! They come up with the 4th flight!

Sorry for my bad english, i´m from germany!

[skaterx]

I'm starting to lean towards the front drive gear being slightly warped or bent, although I cant see the shaft moving, the gear does move up and down about 1mm... next would be head bearings... When I spool this thing with no blades it'ss smooooth.


Pretty thorough list skaterx.

You're lucky to have two full kits available. Swapping out the head for a fresh one should show you a lot. 1/2 an inch back and forth is a HUGE lowspeed vibration. Gyro, fan, bearings, servos, are pretty unlikely culprits. It's probably not something at 17K its something at <2000.

You pretty much have the ultimate troubleshooting tool I'm sure you'll nail it quickly.

Mike

[Ticidytoc]

Check your dampeners. Lube them and then try it again.

[Filby]

Thanks for the help. Much better than some other forums....

Alright. I took the fan completely out of the equation and removed it. Still got vibration.

The following are things that I have checked:

Changed tail blades
Checked main shaft
Balanced head
Balanced main blades
Balanced fan/clutch assembly
Changed Dampers for softer ones
Changed fan over
Checked clutch bell
Adjusted needle settings on hyper
Rebuilt tail
Rebuilt head
Changed to a TT muffler
Took off fan completely
Changed glow plug
Played with mixture again

I can spool up at full headspeed on the ground and see the vibration occur. If I switch off the motor while the vibration is happening (easily seen in the fuel tank) the vibration continues to occur?????

If I take off the blades and spool up to full headspeed the heli is smooth as silk. Put the blades back on, vibrations occur..????

Also, it was noticed this afternoon that there is a very small amount of play in the main shaft. If you rock it backwards and forwards it moves slgihtly. Its obvioulsy play in the bearings that hold the shaft. Not sure if this is normal?

[Ticidytoc]

Also, it was noticed this afternoon that there is a very small amount of play in the main shaft. If you rock it backwards and forwards it moves slgihtly. Its obvioulsy play in the bearings that hold the shaft. Not sure if this is normal?Mine is solid. There is 0 play in the bearings in either direction, sideways or up and down.

[Filby]

No even a tiny click backwards and forwards?

[Ticidytoc]

no sir. its in there solid.

[Filby]

'Are you really the head of the quicky-mart?' :)

These are brand new parts. Surely the bearings and blocks havent worn. I also didnt put any bearing retainer in those blocks as it was stated in the manual.

Do the electric metal bearing blocks work for the Nitro version?


Cheers

Fil

[Ticidytoc]

'Are you really the head of the quicky-mart?' :)

These are brand new parts. Surely the bearings and blocks havent worn. I also didnt put any bearing retainer in those blocks as it was stated in the manual.

Do the electric metal bearing blocks work for the Nitro version?


Cheers

Fil

Nope, the frames are wider on the nitro. You could put a small dab of med/thick ca inside the block to hold the bearing. I seriously doubt that is whats causing your problem, but its worth a look.

Also, are you using the grey dampeners and metal or plastic grips ? Are the dampeners new ?

One other thing, when you pushed the TT into the boom did the bearing jump out of the rubber retainer ? Oh never mind you said its silky smooth without the blades.... hmmm, If you balanced everything on the head then the only thing that could be causing it would be the dampeners. Otherwise its from something else.

[Filby]

Ive swapped out the black dampeners for grey ones but they are all brand new as the kit is only a couple of weeks old..

Im using plastic blade grips. Im not using a TT as I have the Sport version.

[Ticidytoc]

Normally I would advise against this but in your case give this a try. Put the black dampeners back in and lube them. You could try this with the grey as well.

Is it possible the main shaft got bent or is bent ? Do you have any ball links that are excessively tight ? Tight ball links will induce a vibe or wobble. What HS are you running this at ? NM you said 1600-2000, does it vibe without the canopy ?

[Filby]

Ive checked the spindle and main shaft for bends and both are perfect since they havent been through a crash yet and are relatively brand new. The dampeners were well lubed when I first put them in but I will try it again.

I run 1600, 1800, 2000 hs. At 1600 I dont believe there is a vibe but I havent checked as have not been running with the gov on for the last few test flights.

[Filby]

Also mine vibes with or without the canopy. All the ball links are smooth and beautiful.

[Ticidytoc]

Check through the links. Lube the dampeners with grease not oil. I'm sure you have all of the bearings and washers on the head in the right places ?

Wish I could see a video of it hovering to understand how bad the vibe is also. This would help.
How much fuel through the engine ? Whats your needle setting and at what altitude do you fly ?

[Filby]

Fly at effectively sea level. Run 15% nitro and 20% Coolpower LV.
Engine has had about a gallon through it. Ive tried needle settings all the way from 1 turn out through to 2 1/2 turns out. Doesnt seem to make any difference.
I wish I had a video camera to take some video of it.

[Filby]

What about the whole 'unloaded engine' idea? The fact that the heli is light and the hyper is powerful and therefore in hover at 2000rpm there isnt enough pitch on the rotors to make the engine stable?

[Ticidytoc]

Fly at effectively sea level. Run 15% nitro and 20% Coolpower LV.
Engine has had about a gallon through it. Ive tried needle settings all the way from 1 turn out through to 2 1/2 turns out. Doesnt seem to make any difference.
I wish I had a video camera to take some video of it.

At 2 1/2 turns out mine is drowning in fuel. I run 30% with my needle at a turn out at 800ft above sea level. Its dry here also.

If your at a gallon then the engine is well past break-in.

One of the guys here tried the TT pipe and it was horrible at the higher RPM. It's tough to trouble shoot over the net, esp when I can't see and hear it.

I'm running out of ideas, I can't imagine the lower nitro fuel causing this, maybe try some 30%CP and run the needle at a 1 turn to 1 1/4 and see how it runs.

[Ticidytoc]

You said you balanced the blades, have you tried to swap blades from another heli that doesnt have any issues ? Tail blades also just for grins.

[Filby]

Though not exactly sure what has fixed it but the vibe is gone!

I spent the morning fully pulling it apart. I did the following things:

- Pulled out the tail and boom, removed the landing gear and bottom frame, took out the fuel tank and took the head off. This was so I could check the alignment of the frames on a piece of glass. No matter how I twisted things the rear left bottom of the frame would pull up when I tightened the screws that hold the main shaft bearing blocks. I got it as close to level as I could and then tightened everything back up again.
- Tightened the tail belt. I don't think this has done anything but was on the list of things still to check.
- Tightened the clutch hub down onto the engine. I noticed that there was about a 0.5mm end play that wasnt being tightened up when I put the nut on. I made sure that this was taken up before putting the engine back in.

After doing this I noticed that there was no slop in the main shaft anymore. This, and the re-alignment of the frames are what I believe fixed the vibration problem. The heli now goes all the way to 2100rpm without any vibration and sits in the hover beautifully!
Thanks go out to everyone who has given me suggestions over the past week!

Cheers,

Fil