Vib analysis

[alyon187]

Welp nm

[LoveToFly1]

setup numbers will not cause or stop a vibration.

i know you say everything is new, but that means nothing. check it all again. ensure thrust bearings are installed properly, there is an inside and outside to each one.

the tail was bent? it has been crashed then.....check main shaft bearings, head radial bearings, you must check every part on the heli individually. you would be surprised how small the issue may be, may be a main shaft bearing being notchy. i would also ensure the OWB hub is not sloppy. pitch arms on the blade grips are not bent, the head block is not bent.

a good set of blades really does not need to be balanced these days. maybe order a set of Rails, no need to balance them, just install them. blade balancing is not needed with todays standards. but is useful when looking for an issue....

[alyon187]

The tt itself had a slight bend in it. And I put a new one in it. I guess I'm just gonna tare it all down and go piece by piece and bearing by bearing to get it sorted out. Ive tried so many things and no matter what I still get a wobble. Higher/lower hs, new head block, fs, ms, new grips, checked and recheck thrust bearing placement, pinon to main gear mesh helped a lil, the only thing I have no changed yet is the main shaft bearings as they did not feel notchy the ms was pretty bent though so I guess its possible a bearing in the block is distorted a small amount.

How should I go about changing these out? Do I need to put lock tite on the outside to reinstall them? What's the best way to get them out without causing damage?

[LoveToFly1]

if i even tweak a mainshaft, i replace every bearing from the main shaft bearings to the radial bearings in the head. anything that could have been touched. they are not "distorted" so to say, they are damaged internally from the forces of the inner race being pushed on the balls in the bearings, the outer race also.... yes, the TT can also cause vibs, but are a higher frequency than the head. when you do your vib analysis it will tell you the RPM of the vibration, that is how you figure out what part of the heli to look at. put your finger on the screen at the top of the green peak and it will tell you the RPM and the frequency.

usually no locktight is needed. on my synergys i have to heat the blocks up to get the old ones out, then while they are still hot i install a new one and let it cool and "grab" it again.

[alyon187]

My vibs not look bad until I put the main blades on. No matter what I do I cannot get the blades to track on the same plane. I can zero the pitch and check them folded back parallel to the boom and I use a swash leveler to level the swash but when I swing the blades around to measure the at a common spot, they are not on the same plane, about 2 or 3 cm in difference.

Just to eliminate any other maybe, I took out the main block and installed new bearings, not sure if that'll have much of an impact on the tracking of the blades but well see once I get the head set up again and ran through the vibes... again.

With out changing anything mechanical, I could change parameters and I would have either good health messages w a few raised vibs, then change them some more and they would be filed w vibes. I have a feeling that this is most likely due to the tracking issue I'm seeing and why they wont line up. As of now, every bearing in the heli has been changed as well as gears, whole head, and tail hub.

[mverhorst]

You did mention some slob in the swash, didn't you?

[alyon187]

Yes, the inner and outter swashes a lil loose from eachother

[mverhorst]

Any way to get that sorted, loose swash could cause pitch changes...

[alyon187]

Yah ive got a tarot dfc swash ill put on there. I just went through the whole heli yesterday and replaced the main bearings since that was the last part that I didnt change out from the crash. Ive got everything rewired and installed. Just need to plug it up to the computer to 90 my horns then I can see about getting the head set up to see if anything helped.

[newbheliusr]

Fingers crossed dude.

[alyon187]

Yah, hope it comes together

[alyon187]

Results are in... looks promising

[alyon187]

That was a short hover out front.

[mverhorst]

Originally Posted by alyon187

That was a short hover out front.

With the new swash?

[alyon187]

Yah but think it had more to do s the main bearings causing the shaft to be misaligned

[LoveToFly1]

set 0 pitch using the mainshaft for reference, not a pitch gauge, that is the most accurate way to do it. once you set 0 relative the mainshaft, then you can teach your pitch gauge the true 0.

so.....on my helis this is what i do.....remove the blades, and put my vbar on the trim page so the servos are locked at center. then i put a carbon rod through the blade grip hole, one just big enough to fit in it so it is tight. M4-M5 depending on the heli (600-700). i then stand back and look at the rod vs the main shaft. i will adjust my pitch links until that carbon rod is right in the center of the mainshaft from top to bottom. you can use your jesus bolts as reference points, they help me a lot. do that for both grips in the same place on the heli (90 degrees to the right is where i set it at).

i do that for both blade grips. that will get you to the closes 0 pitch at mid stick relevant the main shaft possible. the main shaft is always at 90 to the head axle....

then i calibrate my pitch gauge to that 0 we just found before, so i know it is perfectly 0, even if my heli isnt sitting perfect, the gauge is 0. then i set my pitch positive and negative. if you have a slight difference it them (and your servo horns are indeed at 90), then use the endpoints in your radio to adjust one or the other to get them the same. due to the mounting of servos, they will never all be in the exact same place, it just happens like that.

then i put a sharpie mark on either one blade grip, or one blade.

then go hover the heli. if the blades are not tracking (and all you parts are true (head axle, pitch arm on grip, bearings, main shaft.....and so on....) then find the marked blade grip or blade, and lengthen that pitch link one turn and pop it back on. hover again, if it is worse, then land and shorten the link two turns, if it is better, then continue on adjusting like that. you should only need one or two turns absolute max or something else is wrong (provided you did your 0 pitch like i explained above). and you should only need to adjust one blade also.

hope that helps.....

[alyon187]

That's exactly how I set it up, seemed that the bearings were the issue and not allowing the main shaft to sit right. Think I got it figured out. The log file was w the new bearings installed. It was only about a 45 sec hover but felt good and tracking seemed ok. Before I changed them I could here thr thropping of the blades in a hover because they were off by so much but i has set it up thr same way as described so the only conclusion is that the bearings were to blame because everything else is the same part as before the bearing switch.

Thank you much for the input. If it becomes an issue when I get more tests in I will let ya know. Thanks!

[alyon187]

Ive never tracked blades before so a lil confused on how adjusting the swash to grip wo Ulf raise or lower the whole blade and not the angle of attack. If the fs is 90 to main shaft and the rest of the head is as its suppose to be then both blades should be on the same plane of rotation. Can you help explain this to me?

[alyon187]

Doesnt get much better than this. Got a flight on this am, the wind waa alnost dead still.





Even w a bit of wind I might get between 2 & 4 raised vibes through a whole 4 min flight!

[mverhorst]