Vibration or shakes? CHECK THIS!

[renefigueroa]

Hello ChrisH: My heli started an intermittent shake after 85flights. It check the main gear, tail rotor and basic stuff. I finally broke down and did your procedure. It went well except I cannot figure out how to remove the rear servo without possibly bending the servo rod. I tried removing it but that is proving difficult without bending it. Any suggestions?
Thanks
Rene

[renefigueroa]

And I should add that the two servoes I cleaned did not appear very dirty at all after 90 flights.

[renefigueroa]

One more post and I will stop promise. I changed the rotor blade, no change. I swapped the bullet blades that are new, only 5-10- flights on them, and installed the blade orange ones I had a set laying around. It flies perfect now. I flew two packs to make sure, and it flies like new. Any ideas??? I would still like to hear your technique to remove the tail servo. Again than you
Rene

[mejmea]

Originally Posted by renefigueroa

One more post and I will stop promise. I changed the rotor blade, no change. I swapped the bullet blades that are new, only 5-10- flights on them, and installed the blade orange ones I had a set laying around. It flies perfect now. I flew two packs to make sure, and it flies like new. Any ideas??? I would still like to hear your technique to remove the tail servo. Again than you
Rene

Tail servo - It's been a while since I've done it but I believe I just snapped the control rod off of the swash ball, unscrewed the servo, and then was able to get it out. It certainly isn't as easy as the other two servos but I never bent the control rod.

Blades - did you perhaps lose one of the small weights in the bullet blades?. Also, you probably checked it, but a bent feathering shaft can cause problems that come and go also. The easiest way to check that is to remove one main blade, have the other one sticking straight out, and then use a screwdriver to turn the feathering shaft. If it's bent then the tip of the blade still installed will move up and down.

[renefigueroa]

Sir you are a genius!!! I just looked at the bullet blades and indeed one has lost a small piece in the tip of the bullet. I never noticed it!!!! It is hard to see unless you really look at it. Heck it is new, just a couple of drops in grass. What a difference that makes. I have another set I will put on, thank you. I do hate to unscrew the servo rod, thinking I may have to level the swash again, but I guess I could measure it beforehand and that would take care of that. But as I said the other two servoes didn't look anything like the ones on the postings here on Helifreak. barely a little black smudge, the Q tip and alcohol removed very little of nothing. I also just purchased the expensive DeoxIT at Radio Shack. 18 bucks and change.
Cheers

[mejmea]

Originally Posted by renefigueroa

Sir you are a genius!!! I just looked at the bullet blades and indeed one has lost a small piece in the tip of the bullet. I never noticed it!!!! It is hard to see unless you really look at it. Heck it is new, just a couple of drops in grass. What a difference that makes. I have another set I will put on, thank you. I do hate to unscrew the servo rod, thinking I may have to level the swash again, but I guess I could measure it beforehand and that would take care of that. But as I said the other two servoes didn't look anything like the ones on the postings here on Helifreak. barely a little black smudge, the Q tip and alcohol removed very little of nothing. I also just purchased the expensive DeoxIT at Radio Shack. 18 bucks and change.
Cheers

You are too kind, "even a blind squirrel finds nuts every now and then". At 3000+ rpm a little bit of imbalance goes a long way.

You should not have to un screw the servo rod. What I meant was to unsnap the ball link from the swash and then unscrew the entire servo board from the frame. You can then remove the entire assembly, unhook the rod from the servo, and dissassemble the servo for cleaning. When you are done, reassemble the servo, rehook the rod onto the servo, slip the entire assembly back into place, and then snap the ball link back onto the swash.

[renefigueroa]

Thanl you sir, i will try that

[renefigueroa]

I did as you suggested and it worked great, servo now clean. It is actually the only one that had an appreciable amount of black soot on it. Good to go, thanks again for your suggestion

[ChrisH]

Odd that your elevator had more carbon buildup on it ... from experience, typically it is the two aileron servos that have more on them.

[renefigueroa]

The other two had barely any buildup after 85 flights, and the elevator servo had a bit more, but not a lot, and certainly nothing like some of the pictures posted. Well at least I learned to take them apart and clean them so it was a good exercise. I had checked the servo operation on all three before cleaning, and there were no glitches, binding or any abnormal behavior that I could tell. I had read of some folks having erratic servo operation, but not here,YET!!!! I am up to 110 flights and it keeps on ticking like the energizer bunny. Of course just basic flying, no hot dogging or 3D. I am nowhere near that skill level.

[Chappyy]

Of all the fixes for the "shakes" this one made this biggest difference. just some before and after of my 10 month old mCPx. Most amazing, thanks for the tip

[ChrisH]

Originally Posted by Chappyy

Of all the fixes for the "shakes" this one made this biggest difference. just some before and after of my 10 month old mCPx. Most amazing, thanks for the tip

Nice! Super dirty for sure!

[dirtbike_421]

i took mine apart..its a hiskyfbl100 but it had two black strips is this not right or is one of the strips completely coated?

[Tailbender]

I’ve notice after flying the mCPx for about 20-30 hours, the linear servo will wear or pick up dust that sometime make the heli shudder in flight. I used to pull the servos apart and clean or just replace the jumping servo with a new one, but happened to try some M.G Chemical Zero Residue Contact Cleaner and was amazed… This 30 second repair save the time of pulling a servo to clean it - spray, dry, fly... Details at: http://helifreak.com/showthread.php?...57#post4329057

[RTR104]

OK, So I crashed, had the shakes so bad it looked like the Bird was danc'in.....Well, I know the usual culprits, Worn links= Replace/Grommet MOD
Bent Spindle=Replace
Cracked Shaft= ( I said shaft) Replace
Main Gear loose=Seat correctly, Blah Blah Blah Blah.
So whats a guy to do. If he/she is smart they log in to HF right? Well I went through the whole bird and every possible fix on this forum.......went as far as thinking I should rebuild from top to bottom with new parts, just so I could find the exact issue, which I didn't, thank goodness. Nothing, long story short, by luck I just happened to notice that the bullet on the Main Rotor blades had a tiiiiiiiniest chip, the freakin weight was missing, threw a new blade on aaaaaaand BLAMO no more Jimmy leg. Now before anyone starts Hootin and Hallarin and saying I should have looked and made sure the blades where good, I did, this chip was made by God, it was in the most perfect spot and just the right size to allow that weight to fall out and created for me to think it was a flaw in the mold, like a little burr, I mean it was pure luck. Bad luck it hit in the right spot and good luck I noticed it. So kids take a look at them weights and make sure they are still home. Also, I threw the blade out, even though I should have waited for it to happen again and made a lighter weight set, I never wanted to see that specific blade again.

edit: P.S. After knowing my issue and posting this semi Rant I did a quick search and yea it happens, tons of posts about it, but if ya don't know...??????? G.I. Joe had it nailed. "Knowing is half the Battle"

[Atchuuu]

So easy a caveman can do it. (with reading glasses and a strong light). Great tip Chris. I was having the same issue. Cleaned up well and went back together well. Problem seems to be fixed.

[mejmea]

Not so sure it's related to the shakes, but I have had slop issues with the inner swash on the mCPx. Specifically, on some there is a lot of vertical play between the inner and outer swash I pull up and down. Some of this is simply slop in the swash bearing and there is nothing to be done about it. On some swashes I've seen, however, there is also slop in the molded plastic part that snaps through the inner bearing race (the inner swash arms/balls are on top and there is a lip on the bottom that, after being pushed through the bearing, is supposed to be up against the bottom of the inner race. I've seen some that are relatively tight/slop free and others that seem to have maybe 0.5mm or so vertical play.

On the ones that have this slop I have found that I can take some dental floss and tie it tightly just above the top of the inner race. When you pull it tight, it sucks into the gap and gets rid of the slop which makes the swash much more "connected".

Hopefully the images below will make it clear what I mean. The 1st image is a sketch to illustrate the technique. The 2nd is a photo of the floss in place and shows the knot (looks bad but doesn't cause any problems. The 3rd is a photo that shows the opposite side where the floss is nicely sucked into the gap. I have used just one wrap with a tightly tied double knot and then trim the loose ends to about 1/16-1/8".

I find that mint floss works the best, hence the green color........

[Pfloyd]

Originally Posted by mejmea

Not so sure it's related to the shakes, but I have had slop issues with the inner swash on the mCPx. Specifically, on some there is a lot of vertical play between the inner and outer swash I pull up and down. Some of this is simply slop in the swash bearing and there is nothing to be done about it. On some swashes I've seen, however, there is also slop in the molded plastic part that snaps through the inner bearing race (the inner swash arms/balls are on top and there is a lip on the bottom that, after being pushed through the bearing, is supposed to be up against the bottom of the inner race. I've seen some that are relatively tight/slop free and others that seem to have maybe 0.5mm or so vertical play.

On the ones that have this slop I have found that I can take some dental floss and tie it tightly just above the top of the inner race. When you pull it tight, it sucks into the gap and gets rid of the slop which makes the swash much more "connected".

Hopefully the images below will make it clear what I mean. The 1st image is a sketch to illustrate the technique. The 2nd is a photo of the floss in place and shows the knot (looks bad but doesn't cause any problems. The 3rd is a photo that shows the opposite side where the floss is nicely sucked into the gap. I have used just one wrap with a tightly tied double knot and then trip the loose ends to about 1/16-1/8".

I find that mint floss works the best, hence the green color........

Have you tried pushing up on the whte bottom gear to get rid of the slop?

[mejmea]

Originally Posted by Pfloyd

Have you tried pushing up on the whte bottom gear to get rid of the slop?

I'm not sure I'm following your logic. I do take care to keep the main gear pushed up all the way. My experience is that if it slides down you start to lose positive pitch since the main shaft/head can then "float" up and down relative to the swash. The gear sliding down has no effect on the slop in the swash however since the main shaft isn't attached to the swash but rather just slides inside of it.