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 THE DEATH VIBRATION HAS RETURNED!!

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chiefqm

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PostSubject: THE DEATH VIBRATION HAS RETURNED!!   Tue Apr 28, 2009 11:47 am

OK guys start chewing on this. I had a bad vibration on my HBFP right out of the box. After all the great advice I received from many of you I replaced, balanced, and tweeked everything above the swash plate. It made a tremendous difference. It only vibrated occasionally, and at the current level of my expertice, no problem just a few bumpy landings. Now the vibration is back with a vengance!
I disassembled the whole main shaft. Shaft is straight, main gear has slight wobble,(not the shear pin slack) no cracks, bends, or distorted parts that I can see. With fly bar centered and paddles aligned, head runs true until swash plate is moved. When tipped forward it also tips slight left (side servo does not move) and head starts vibrating. Back to center and vibration stops. When plate is tipped backwards it also tips right (again no side servo movement) and vibration returns, return to center and vibration stops. this is without the main blades on the helo.
HELP orange75 Thanks --Bruce navy1
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Nuttcaze
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PostSubject: Re: THE DEATH VIBRATION HAS RETURNED!!   Tue Apr 28, 2009 1:05 pm

Is your Swashplate binding up, like if you take it off the heli does it move freely?
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Donnie D

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PostSubject: Re: THE DEATH VIBRATION HAS RETURNED!!   Tue Apr 28, 2009 1:19 pm

Disconnect servo linkage from swashplate and see if servo arm moves. This will let you know if servo is bad.

Donnie D smiley-happy088
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chiefqm

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PostSubject: Re: THE DEATH VIBRATION HAS RETURNED!!   Tue Apr 28, 2009 3:55 pm

both servos work fine, when I give her side stick the head moves side to side the head also moves slightly front and back. again this is without the main blades installed and under power. Is the aileron servo supposed to move some when the elevator servo moves or visa-versa? Looking closer the swash mechanisim is jiggling quite a bit when full stick is applied in any direction, the vibration/jiggling starts at half stick and gets worse as it is increased. navy1
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Prel

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PostSubject: Re: THE DEATH VIBRATION HAS RETURNED!!   Tue Apr 28, 2009 5:34 pm

IMHO if all 3 shafts are straight. Blades and flybar is balanced. There can only be a few things left that will cause the problem.
1/ Check that the pin holding the center hub to the main shaft is not sloppy. This will cause the hub to move about and will transmit as vibration in the head. The pin esky uses is soft and can bend in the shaft on impact making everything loose as it twists about in there.
2/ check the swashplate as Nuttcaze suggested. If it is binding then as it pivots it will bend the head and cause vibration.
3/ Donnie D is onto the other problem. Check all servos are working correctly and that they are not twisting. Check all the mounting screws to make sure they are tight and not bent. If the servo is twisted or loose then the servo arm will not track correctly. It will look and work as it should but with a Z link that the HBFP uses it can twist the link and bind the head as it moves and cause vibration in the head.
4/ Check all your ball links to make sure they are all moving smoothly and not to tight or binding. They are plastic and can be damaged fairly easy. If 1 of them is binding it can cause vibration.

We forget that even though some of these hilis are at the lower end and not worth $500+ and all CNC they are still a piece of percision engineering. It take very little to upset them and you will find that the cheaper the heli, the more maintance and care it will need. Just work through it. troubleshooting these things is really basis when you get down to it. All you need to do is start at the botton and work your way up. If you get everything spot on you will find your troubles gone.

Maybe we need to create a sticky of cause and effect. A referance to what will cause different problems to arrise. I still have so much to learn about this stuff and it would be a great help to us all.
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Donnie D

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PostSubject: Re: THE DEATH VIBRATION HAS RETURNED!!   Tue Apr 28, 2009 5:53 pm

The reason you need to remove the servo link from the swash to check if servos are working, is that if you don't the movement of one servo will make even a nonworking servo apear as if it is working. I had a bad servo on my Belt CP, and could only tell it was bad after I disconnected the link.

Donnie D smiley-happy088

Good idea Prel about the cause and effect sticky.
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chiefqm

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PostSubject: Re: THE DEATH VIBRATION HAS RETURNED!!   Tue Apr 28, 2009 8:46 pm

I have disconnected the servo arms and they both work to their approprate limits. the swash seems to work smoothly (I just ordered a new one to see if that makes a diff.) This is so frustrating, I get her up and she's doing fine then all of a sudden she starts shaking her guts out! orange75 navy1
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Prel

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PostSubject: Re: THE DEATH VIBRATION HAS RETURNED!!   Tue Apr 28, 2009 9:07 pm

Hey Chief, you need to set aside some time with no other distractions, turn on your favorite tunes and relax with your heli and your tools. Try to make repairs and maintenance just as much fun and just as relaxing as flying them. Only way you will survive in this hobby lol. I sometimes think I subconsciously crash mine so I can spent some time relaxing doing the repairs (either that or I just sux at flying them lol).
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chiefqm

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PostSubject: Re: THE DEATH VIBRATION HAS RETURNED!!   Tue Apr 28, 2009 10:24 pm

I understand what you are saying. Today I took the entire main shaft apart and checked each piece for damage. (none found) Then as I put it back together I tested each section under power before I moved on to the next. I spent over 3 hours putzing around with it. Folks like you and others on the 2 sites have given me great practical info and much appreciated. Another problem is that the vibration is intermittent. That makes it even harder to find it. I thought I was maybe over correcting it, so I started paying close attention to that. What I observed was that she would be hovering with minimal input and then suddenly go nuts. So now what. navy1


Last edited by chiefqm on Wed Apr 29, 2009 8:04 am; edited 1 time in total
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Donnie D

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PostSubject: Re: THE DEATH VIBRATION HAS RETURNED!!   Tue Apr 28, 2009 10:34 pm

Chief, I can't remember what you said you have checked or replaced so far, but there is one thing you may want to check. This my have possably been a problem all along. The flybar fit thru the center hub MUST be a VERY loose fit. See the sticky Tips and Tricks under RC Info.
To see what I mean, take a new center hub, and a new flybar, and insert the fly bar into the hole in the center hub(center hub only, without the extra parts of it attached)
You should then be able to hold the flybar in one hand and spin the center hub loosly and freely on the flybar. That is how loose the fit should be. If it is not that loose you will need to ream out the hole in the center hub with a rat tail file or small drill bit until it is. Don't install the center hub until the fit is that loose. If it is a snug or tight fit, it will cause the head to bind and will cause all types of flight problems. In fact you may want to check yours even if it is the one that came on it when you bought it.

Just a thought, may not be your problem, but even if it isn't, let not your heart be troubled, we will figure it out and get you fixed up. That's what this forum is all about.

Donnie D smiley-happy088
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chiefqm

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PostSubject: Re: THE DEATH VIBRATION HAS RETURNED!!   Wed Apr 29, 2009 7:59 am

I've looked at that and it's not quite that loose. I will take it off and make sure that it is that free. Thanks, I will let you know the results. navy1
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Donnie D

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PostSubject: Re: THE DEATH VIBRATION HAS RETURNED!!   Wed Apr 29, 2009 8:39 am

Just to be sure you're not beating a dead horse, my HBFP will get a bit of vibration during flight for a few seconds and then smooth out. Then sometimes the vibration will stay, and that is usually something like a flybar paddle slightly off adjustment. You are proably never going to get it to be 100% vibration free. For instance, if you still have the stock skids, even a loose skid could cause a vibration. When I was using training gear, I noticed a lot of vibration. I don't think the gear caused vibration, but it definately magnified it tremendously. Just a few things to think about.

Donnie D smiley-happy088
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P3tras

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PostSubject: Re: THE DEATH VIBRATION HAS RETURNED!!   Wed Apr 29, 2009 8:43 am

Can you post a photo of your hb? orange45
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Donnie D

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PostSubject: Re: THE DEATH VIBRATION HAS RETURNED!!   Wed Apr 29, 2009 10:57 am

I'm what is known as a computer idiot, but as soon as I learn to post pics, I will.

Donnie D smiley-happy088
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chiefqm

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PostSubject: Re: THE DEATH VIBRATION HAS RETURNED!!   Wed Apr 29, 2009 1:03 pm

I will try to post a pic. I may have to send it to someones e-mail from my phone and then maybe they can post it for me. For I too am a computer idiot, BIG TIME!!! I realize that things that spin fast and are forced away from their axis don't like it much, (a gyroscope for example), and will fight to stay as they were, therefore some vibration is going to appear. The question is how much is survivable? I don't want to go into a hover at 10 to 15 feet off the ground and have the helo go into convultions and smack the ground! I know crashes are inevitable but I hate breaking stuff. I once built the coolest little naval landing craft, it was about 7 inches long and ran perfect. I was at a model boat contest and was running the course when the wind came up. Unfortunatly she went down with all hands. Ironicly at the prize drawing I won a submarine, which everyone thought was funny as hell. Later that day I traded it off for a small metal lathe. that was cool. navy1
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Donnie D

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PostSubject: Re: THE DEATH VIBRATION HAS RETURNED!!   Wed Apr 29, 2009 1:47 pm

Wow; I thought you wanted me to post a pic of my heli. DUH slaphead dunce
I was wondering why you would want a pic of mine. laughing013

Donnie D smiley-happy088

By the way chief, are you useing training gear?
If so, with the balls attached or not?
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chiefqm

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PostSubject: Re: THE DEATH VIBRATION HAS RETURNED!!   Wed Apr 29, 2009 3:18 pm

I have tried to post a pic. As you can see I was unsuccessful. Ok, yes I do have male training wheels on. lolol I am ready to take a break, I think I will go get a root canal. orange69 navy1
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Donnie D

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PostSubject: Re: THE DEATH VIBRATION HAS RETURNED!!   Wed Apr 29, 2009 4:12 pm

Chief,
Probably would be a good idea to get your mind on something else for awhile, but when you're ready to mess with it again, try this.

If you can get to a place that has a reasonably smooth surface to fly over, remove the balls from your training gear. You only need them when flying over rough areas or grass,etc to keep the training gear from snagging on something. Like I said before, the training gear will greatly magnify any vibration you may have, but removing the balls will reduce this.

Imagine holding a fishing rod in your hand and rocking your wrist up and down slightly. Very little movement at your wrist, a lot of movement at the tip of the rod, and you will feel that tip movement back at your wrist.

Now attach some weight to the tip of the rod and do the same thing and there will be even more movement at the tip of the rod that translates back to your wrist.

Same principle with the training gear. I was lucky enough to have access to a large indoor area with a smooth floor to train on. I started out useing the gear with the balls on but the vibration was sometimes so bad that I removed them, and just used the gear without them.

Good luck,
Donnie D smiley-happy088
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chiefqm

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PostSubject: Re: THE DEATH VIBRATION HAS RETURNED!!   Wed Apr 29, 2009 7:56 pm

Well glad I don't have to get one of those every day. It wasen't to bad though. Sounds like a plan on removing the balls. Would the asphault parking lot surface be smooth enough? I downloaded my camera card to my computer but i couldn't get them to the message screen. I did not try the photobucket yet though. navy1
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Nuttcaze
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PostSubject: Re: THE DEATH VIBRATION HAS RETURNED!!   Wed Apr 29, 2009 8:01 pm

oh, you have the training gear on? Blazemob had an HBFP that would vibrate VERY badly any time he put the training gear on it, with out it the heli was fine.
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Donnie D

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PostSubject: Re: THE DEATH VIBRATION HAS RETURNED!!   Wed Apr 29, 2009 9:49 pm

Chief,
I think you should be fine in an asphalt parking lot. The balls are just to keep the rod ends of the training gear from snagging weeds, grass or carpet, stuff like that. I'm thinking that is your problem. You probably have a very minor vibration in the heli (most of them do) and that vibration is resonating thru the training gear and back into the heli. Mine would vibrate like crazy most of the time until I removed the balls. The gear without the balls will still magnify any vibration, but not nearly as much.

Donnie D smiley-happy088
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chiefqm

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PostSubject: Re: THE DEATH VIBRATION HAS RETURNED!!   Wed Apr 29, 2009 10:43 pm

Ok weather permitting I will try without the balls tomorrow. It's usually pretty calm around 0530. I have gotten to the point where I'm lifting off pretty good without skating around much. I also have the long version of the training gear which makes it even worse. navy1
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Donnie D

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PostSubject: Re: THE DEATH VIBRATION HAS RETURNED!!   Wed Apr 29, 2009 11:03 pm

Chief,
Good luck orange74 flyaway

Donnie D smiley-happy088
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