Vibration or shakes? CHECK THIS!

[BPINE]

The disk wobbles after you add some (not much) collective, it has never been crashed. I only have about 4 flights on it now and it seems like it is head speed related. Funny thing is when I go from normal to idle up there is not any change in head speed with the stock settings on a Dx6i. I lowered the throttle curve in normal a bunch just to see if I could hear it change going into idle up and it does but not as much as I would think. The head speed seems lower than by buddies running a DX7.

I checked the main gear and nuts on the servo and all is good. Seems to be getting better with time.

Originally Posted by mejmea

There are a few threads going in the mCPX forum with suggestions including these:

https://www.helifreak.com/showthread.php?t=288652

https://www.helifreak.com/showthread.php?t=287334

Some basic things to check are that the main gear is oriented properly (i.e. not spun on the shaft, the flat spots should line up), the main gear is pushed all of the way up on the main shaft (NO vertical play in the main shaft), and that te retaining nuts on the servos are not backed off.

I had a relatively light crash into grass from 6-10 inches that spun the main gear on the shaft and before I figured that out I had intermittent shakes as I was hovering. Once I fixed that it went away.

I would search the mCPX forum for additional vibration related threads and you'll likely find a lot of information. It would also be helpful to have a more detailed description of the symptoms you are seeing and when they occur.

[ChrisH]

Definitely sounds like headspeed Blair.

Mine freed up and felt like it had more power after 10-15 flights. These little 200mAh cells need a bit of time to break in, and the motor brushes need to wear in to the shape of the commutator (then they can pass more current and in turn, more HS).

[Sundown798]

Another problem I am having with these servos is slop on the servo horn that slides up and down on the threaded rod inside the servo. The threaded rod does not move at all and its pretty stationary. The actual plastic block that rides inside the servos moves a little up and down. Seems like they maybe getting worn from a ocasional crash. This causes slop in the swashplate witch leads to wobble. Does anyone else have servo play? Move your pushrod up and down a little to see if loose. All my servos do that and elevator is the worst. I checked my friends new one and they are pretty solid for now anyways. If they wear out this fast im not impressed with these servos.

[ChrisH]

Originally Posted by Sundown798

Another problem I am having with these servos is slop on the servo horn that slides up and down on the threaded rod inside the servo. The threaded rod does not move at all and its pretty stationary. The actual plastic block that rides inside the servos moves a little up and down. Seems like they maybe getting worn from a ocasional crash. This causes slop in the swashplate witch leads to wobble. Does anyone else have servo play? Move your pushrod up and down a little to see if loose. All my servos do that and elevator is the worst. I checked my friends new one and they are pretty solid for now anyways. If they wear out this fast im not impressed with these servos.

It's a plastic submicro heli. If you are worrying about excessive slop there are better ways to spend your time

[Sundown798]

Originally Posted by ChrisH

It's a plastic submicro heli. If you are worrying about excessive slop there are better ways to spend your time

Yeah chris I probably spend that time cleaning the servo board as you mentioned. But I am picky when it comes to these details. Ill probably order the new servo mechanics that are $11.99 for now I guess. Thanks bro

[Jskrapper]

Thank you ChrisH.

Add me on the list of failure/success



I was just out doing my normal flying and she developed a shake just as you described. You could hear the disc slamming the air around. This thread was my first thought. Cleaned as described, issue went away.

[ChrisH]

Nice work!

Now get those tiny little screws off the slidy table before they disappear

[tracknoob]

Originally Posted by Jskrapper

I was just out doing my normal flying and she developed a shake just as you described. You could hear the disc slamming the air around. This thread was my first thought. Cleaned as described, issue went away.

Some people go for bling, and hotter motors, and colorful canopies.... nothing wrong with that.

Now me, I can do without all that other stuff, but I would pay dearly for a servo that could really stand up to the constant motion this little FBL system is apparently asking these cheesy resistive strips to deal with.

Glad to hear you have yours back in operation, but something tells me that with the blade grip issue eventually solved, that this one is then likely to be the real remaining issue with this heli as time goes on and the usual early production issues are sorted out.

[More helis]

HI,What part of the servo do we clean,It looks like there are two strips do we clean the strip that looks white or do we clean the strip that looks real black?Thanks, Opps the pics on the first page didnt load up the first time i checked,i know to clean the silver track now.

[ChrisH]

Originally Posted by More helis

HI,What part of the servo do we clean,It looks like there are two strips do we clean the strip that looks white or do we clean the strip that looks real black?Thanks, Opps the pics on the first page didnt load up the first time i checked,i know to clean the silver track now.

Yep just the silver one ... black one is carbon ink and is needed for resistance !

[General38]

Well my experience is slightly different. I was experiencing severe shakes sometimes when I throttled to 80-50% pitch. It seemed that the occurrence of wobble was greater when using a freshly charged battery. I also found that by spraying lube directly into the lower and upper shaft bearing, main cog and a tiny bit on the swash seemed to reduce the shakes dramatically. I am not keen on pulling apart my servos yet. I am going to try electrical contact cleaner next time it starts to shake.

[Jskrapper]

Originally Posted by ChrisH

Nice work!

Now get those tiny little screws off the slidy table before they disappear

I have a high strength neodymium magnet taped to the bottom of the table. Those screws will not, and did not, go anywhere!

Thanks again for the tip, but I feel these servos are hurting already and will need to be replaced very soon.

[ChrisH]

Originally Posted by Jskrapper

I have a high strength neodymium magnet taped to the bottom of the table. Those screws will not, and did not, go anywhere!

Thanks again for the tip, but I feel these servos are hurting already and will need to be replaced very soon.

Nice!!

Good thing servos are available now that people need them ... But they're pretty expensive.

[matt blaisdell]

i get a bad vibration after 2min of flight ebery time

[ChrisH]

Originally Posted by matt blaisdell

i get a bad vibration after 2min of flight ebery time

Low headspeed.

Try bumping up your headspeed, or fly it some more to wear-in the brushes and break in the batteries.

[VaderSS]

Well, about 2 hours of flight time after cleaning my servos, and the jitter is back. This time, no wobble, but the starboard servo is glitching and causing the heli to jump up and down. I just ordered a replacement servo but will try cleaning it again in the mean time. That was the same servo that was probably 3 times as dirty as the other 2.

[ChrisH]

Originally Posted by VaderSS

Well, about 2 hours of flight time after cleaning my servos, and the jitter is back. This time, no wobble, but the starboard servo is glitching and causing the heli to jump up and down. I just ordered a replacement servo but will try cleaning it again in the mean time. That was the same servo that was probably 3 times as dirty as the other 2.

Let us know how it looks when you take it apart again!

[VaderSS]

Originally Posted by ChrisH

Let us know how it looks when you take it apart again!

Will do. I'll snap a picture this time.

[mejmea]

Originally Posted by VaderSS

Well, about 2 hours of flight time after cleaning my servos, and the jitter is back. This time, no wobble, but the starboard servo is glitching and causing the heli to jump up and down. I just ordered a replacement servo but will try cleaning it again in the mean time. That was the same servo that was probably 3 times as dirty as the other 2.

Is it feasible to use subtrim to shift the zero point of the servo and then mechanically adjust the ball link to get the swash back to level? These servos seem to have plenty of travel so it seems like you could subtrim quite a bit without binding them. This would force the servo wipers to operate (at least partially) in a different section of the resistor. You'd have to have enough thread on the ball link rod and it might take a bit of work to re-level the swash but.....just a thought to try and get as much time/use out of the servos as possible.

Edit/addition. I suppose the easiest way to do it would be to adjust all three ball links at the same time and by the same amount, then reset your mid-stick pitch to zero using the pitch subtrim. This way you wouldn't have to guess at how many turns you need just on one link/servo.

[VaderSS]

Originally Posted by mejmea

Is it feasible to use subtrim to shift the zero point of the servo and then mechanically adjust the ball link to get the swash back to level? These servos seem to have plenty of travel so it seems like you could subtrim quite a bit without binding them. This would force the servo wipers to operate (at least partially) in a different section of the resistor. You'd have to have enough thread on the ball link rod and it might take a bit of work to re-level the swash but.....just a thought to try and get as much time/use out of the servos as possible.

Edit/addition. I suppose the easiest way to do it would be to adjust all three ball links at the same time and by the same amount, then reset your mid-stick pitch to zero using the pitch subtrim. This way you wouldn't have to guess at how many turns you need just on one link/servo.

Actually, that is a great idea for extending the life of the servos and decreasing the cleaing interval. That won't help me with my current problem, because It is causing the heli to jump whenever I am in that section of servo travel, but I think I'll try making that a preventative maintenance item from now on.