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08-04-2007 05:53 PM  13 years ago
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daz

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uk

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trex nitro sport
has anyone had trouble with vibration on trex sport if so how did you cure it
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08-04-2007 06:10 PM  13 years ago
ArtK

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Temecula, Ca

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Vibration
Going through that right now.

I have purchased a 3dx fan to see if that fixes it. There is a post just downstream from this all about vibration. Check it out. Are they high freq vibes above 2000 rpm? Those are the vibes I am getting. If it is alow freq vibe causing the tail to go up and down that is the rotor head. If it is RPM dependent most likely it is the motor and drive train. I am hoping the fan will fix it.

Good luck? I'll keep you posted.
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08-04-2007 07:39 PM  13 years ago
inkspot1967

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Cranston Ri

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if motor is new and running wet rich you will get vibes also. not sure what kind of vibe you are getting.
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08-05-2007 02:29 AM  13 years ago
ArtK

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Temecula, Ca

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Still Vibrating
I am only one turn out. Still lots of smoke though. Maybe I can lean it more. Not sure. Kind of scared to go inside of one turn. I have the governor up to 2100. I set it to 2050 for now just to keep it melow until I figure this thing out. It doesn't vibrate at 1750 only after I break 2000.
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08-05-2007 08:08 AM  13 years ago
PHILR

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Sheffield -UK

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Got exacly the same problem.
New heli but engine from my raptor which was dialled in.
If you saw it you would say "bent mainshaft" or "blades out of balance" but it is neither of those, but it is that sort of vibe/shake.
I dont think it engine generated it doesnt look like a 18000 r/m engine induced vibration and it is too severe at times.
I have also noted that sometimes on the start of a flight the vibe are mild and I think OK I will give this a go. A few flips and a few tic tocs later the vibes are worse and I have to cut.
Its as if something is moving in and out of position. Which raise the question are the thin sport sideframes flexing and allowing something to "shuffle" out of line.
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08-05-2007 08:25 AM  13 years ago
Filby

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Adelaide, South Australia

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See my thread here with the problem explained and solved!

http://runryder.com/t362955p1/
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08-05-2007 08:42 AM  13 years ago
PHILR

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Just been to your post again and you have added "I pulled out the main shaft bearings, made sure that the A's and B's were facing the right way up"
Were they the wrong way round?

Iam pulling mine down now to check.
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08-05-2007 08:46 AM  13 years ago
Filby

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One of my B's was the wrong way up. I actually think this makes no difference, I think its more to do with the alignment of the bearings in the frame. If you go to one of the pages in the manual just after you put the frame together it says about aligning the frame on a piece of glass and using the main shaft to align the bearings. I believe this is what has solved the vibration issue in both of the Trex600N's that I have seen with the vibe.

Fil
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08-05-2007 09:09 AM  13 years ago
PHILR

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Have just looked at the manual and B is the bottom smaller one.
Will realign side frames as amatter of course.
In what sequence do you tighten up the side frame screws?
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08-05-2007 09:15 AM  13 years ago
Filby

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I started at the bottom and went diagonally..So Bottom Left Rear, Bottom Right Front, Bottom Left Front, Bottom Right Rear..then moved up to the next block and then the top block. I found that it took quite a few shots at getting the frames aligned as they naturally want to sit 'correctly' on the blocks but that didn't necessarily mean the frames were aligned.
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08-05-2007 04:05 PM  13 years ago
ArtK

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Temecula, Ca

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Vibration
I think it is engine drive train related. Not the engine itself just how it interacts with the bell. Not sure yet. Will keep working it.
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08-05-2007 06:03 PM  13 years ago
PHILR

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Sheffield -UK

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After conferring with FILBY and discussing frame/bearing alignment on his post I suspect that bearing alignment is crucial.

Consider this:

Three bearings in alignment with no flex in the a shaft is always an engineering problem which can only be solved by very careful alignment of the three bearings . Couple to this that the third bearing is on a different diameter . This diameter has to be generated separately to the first diameter and can result in some eccentricity between the two shaft diameters.

OK with me so far

Align the two top bearings.
No problem shaft slides easily in the two bearings.
Introduce third bearing.
Shaft is now tight to push through into the third bearing. This third bearing is now introducing a side force onto the shaft. We can see this by the clearance it generates around the top bearing (as FILBY and I saw)
NOW introduce any eccentricity and this will be transmitted into the shaft and each time the shaft revolves and will give the effect of a(slightly) bent mainshaft exaggerated by the clearance the side force has created.
Now align the bearings very carefully (aligning sideframes exactly etc) until the mainshaft slides easily into all three bearings and now any slight eccentricity can be taken out by the bearing, and shaft fit into the bearing tolerance.
Effect is now no eccentric or bent mainshaft.

What do you think?
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08-06-2007 01:37 AM  13 years ago
Filby

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Adelaide, South Australia

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Yep thats pretty much how I see it as well. Unfortunately the tolerances required by the main shaft are pretty high, but using mass produced plastic bearing blocks and g10 frames theres simply too much slop to allow someone to simply bolt the frames together without spending a fair amount of effort aligning the frames. Sure you can fluke it and get it right first off but its also likely that you could get mis-aligned bearings. This is why Align has highlighted this step in the manual.
Either way its a cost free fix and will solve the problem.

Cheers

Fil
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08-06-2007 02:47 AM  13 years ago
rcmike

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Dickson, TN

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I had some vibration in mine and it turned out that the tail belt was too tight. I broke a couple of boom support screws before I figured it out. I loosened it and it is much smoother.
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