vibration and rough gritty sound after a days flight

[deepak]

Folks,
I flew six six flights today 2 in the morning and 4 in the afternoon.
This morning there was some vibration on the vertical and horizontal stabilizer and on the left skid.
Someone checked by belt tension and said that they found it to be to tight. I moved the tail assembly back a mil or two and it really did help but not all is gone.
I flew again in the afternoon and the vibrations were "basically" gone. I came home and while cleaning her up I spun the main gear and heard this awful gritty sound almost as grinding dirt.
Any Ideas what could cause a orbit 30/12 he to do this?
77 flights thus far. Grass flying field . Every now and then the nuts and bolts have to be tightened up but apart from that everything seems alright.
What do you think is causing the gritty sound?
Let me have some thoughts please.
Thanks
Deepak

[stvjeep]

I'm a complete newb but sounds like bearing damage. Any rolling element should move smoothly and freely. A grinding type of sound or feel is not good. Perhaps your belt being too tight caused too much of a radial load to the bearings and wore them out? You also mentioned that you live in a hot environment, so heat does not help the situation. Any temperature over 100 C (motor temp), dust, or shaft/bearing deflection would cause damage. Again though I'm a newb with helis but have a good understanding of bearings..

[deepak]

I'm a complete newb but sounds like bearing damage. Any rolling element should move smoothly and freely. A grinding type of sound or feel is not good. Perhaps your belt being too tight caused too much of a radial load to the bearings and wore them out? You also mentioned that you live in a hot environment, so heat does not help the situation. Again though I'm a newb with helis but have a good understanding of bearings..
The bearings the tail rotor drive belt go through are fine. They run smooth. It has something to do with the engine.
Thanks
D

[Big Fil]

Is it coming from the motor?

Also do you add a drop or two of light machine oil to your main shaft and tail shaft every few flights? Depending on how much you fly it's also good to clean the shafts with alchohol then re-oil once in a while. The oil on the shafts can pick up dust and debrit which you don't want wearing out parts that make contact with the shafts.

Other thing to check is all your bearings as well as the one way.

Take a look at your pinion too.

Not sure if any of these are the culprit but that's what i'd look at as a start.

[stvjeep]

I meant the bearings in the motor itself. If you turn the motor pinion by hand it should be freely turning and smooth. If its grinding its the motor bearing. Most likely the lower bearing that the shaft/pinion is attached to. If it's nice and smooth, then its another bearing, perhaps the one way as Big Fil mentioned. Just my thought anyways.

[deepak]

I meant the bearings in the motor itself. If you turn the motor pinion by hand it should be freely turning and smooth. If its grinding its the motor bearing. Most likely the lower bearing that the shaft/pinion is attached to. If it's nice and smooth, then its another bearing, perhaps the one way as Big Fil mentioned. Just my thought anyways.
The culprit is the main gear itself.
Its rubbing on the frame. Thanks for the input
D

[stvjeep]

That must be a relief. I was thinking if its your motor lower bearing then you would be one unhappy guy. Glad to hear it was a minor problem. Just so you know I'm just graduating a Mechanical Engineering Technician course I've been doing now for few years and thought it sounded just like a bead bearing. Enjoy the Logo. I'm picking-up a 500 3D flybar next month. Looking forward to the build and finally getting into this hobby seriously!

[LITHIUMSTATIC]

The culprit is the main gear itself.
Its rubbing on the frame. Thanks for the input
D

Mine did this too..... a little work with a dremel fixed it.

[deepak]

Mine did this too..... a little work with a dremel fixed it.
Hey Guy,
Did you figure out why it did it?
I dont understand why it would move upward to touch the frame.
D

[OICU812]

Hey Guy,
Did you figure out why it did it?
I dont understand why it would move upward to touch the frame.
D


Again repeating from another site, when many people build this heli they do not push the bottom bearing up enough and never properly seat it in its holder before tightning it, then all of a sudden they have a suprise.

[LITHIUMSTATIC]

Again repeating from another site, when many people build this heli they do not push the bottom bearing up enough and never properly seat it in its holder before tightning it, then all of a sudden they have a suprise.

If the bottom bearing isn't seated then the main gear would be lower.... away from the frame. My first set of frames had notches cut in them for the main gear to clear, my second set didn't.

[Wbird]

Mine had the notches and I still had to trim a small amount of plastic for proper clearance. It was rubbing when I first assembled, I thought I had something wrong and went over the manual and parts 3 times, finally did some shaving and it has been working fine since. My one way was a little snug at first also, I left it that way and after a couple of flights it is spinning free.

[Flybar-less]

I have seen several instances where the main gear rubbing the frame caused ESD. I applied Graphit 33 to the top edge of the gear to stop the ESD. Re-shimmed later.

[deepak]

I have seen several instances where the main gear rubbing the frame caused ESD. I applied Graphit 33 to the top edge of the gear to stop the ESD. Re-shimmed later.
Excuse me, but what does esd mean.
I did pull the main haft upon installation and did hear a click.
I checked for slack in as well and there isn't any.
I put the shim in and all is well now. I think I might file away a mil or two later in the week.
Thanks for the advice.
Does any one lube there motors? Plettenburg says there motors are virtually maintenance free. Change bearings when they make noise kinda thing. Wondering if its a science and should be changed every so many hours or flights or something other than noise? let me have your thoughts please
Thanks
D

[Flybar-less]

Plastic rubbing against plastic creating eletrostatic discharge. Or kinda like the fat woman at work that would kill computers when she touched the keyboard after walking back from the soda machine in polester slacks. You probably don't see much of this on a humid Island, it's a dry climate thing.

[OICU812]

If the bottom bearing isn't seated then the main gear would be lower.... away from the frame. My first set of frames had notches cut in them for the main gear to clear, my second set didn't.


If the bottom bearing was not fully seated "upwards" this allows the gear to move upwards, thus allowing the gear to rub the frame. Correcto mundo? :lol: :hug:

[Wbird]

ESD - Electro Static Discharge Static electricity - normally builds up from tail belt rubbing inside of tail boom.



As for lubing bearings I had 2 T-rex 600's and lots of flights with Helical Gears. Worst combination possible with known bearing problems. I lubed the bearings with Trinity bearing lube or Tri-Flo every 2-3 flights and never had an issue with either.

[wiltonh3]

I am a bit confussed about the bearing question. Yes, if the bearing were not seated fully originally then later seated itself, then then gear would be able to move upward, possibly hitting the frame when it did not originally. But an improperly seated bearing would only explain why the design flaw did not show up right after the build, but would have no "bearing" (forgive the pun) on why the gear was hitting. After seating itself would not the gear on it's uppermost travel only be as high as it would have been had everything been seated correctly?

I am new this hobby so forgive if this is ignorant, but it seems a problem with the frame cutouts. The mis-seated bearing only delays one discovering the problem.

Wilton

[OICU812]

If the bottom bearing isn't seated then the main gear would be lower.... away from the frame. My first set of frames had notches cut in them for the main gear to clear, my second set didn't.


Ahh your up is my down and reverse in thinking, lol. Been agreeing all the time, lol.

[LITHIUMSTATIC]

LMAO!!! We are thinking the same thing but wording it different. LOL!