vibration after blade strike repair? What do I check now?

[crashburnrepeat]

Hey everyone, this is my first post on HeliFreak after finding it via Sokal's and Helimix's youtube videos.


I just got a Blade 400 and am learning to fly it. Last week after I landed and was spinning down I got a big gust of wind and it tipped it over. The blades didn't break but had a gouge, but it was vibrating pretty bad.

I pulled the mainshaft (THANKS HELIMIX) and it was tweaked. Reassembled and put new blades on and it still had a pretty noticeable vibration.

replaced the feathering shaft and it was also bent and reassembled tonight.

now it's got a vibration that's pretty noticeable at about 1/4 throttle. it seems to "Smooth" out above that but I think it's just spinning to fast and not skipping the copter around but just vibrating at a very high frequency.

What do I need to check next? I put these blades on straight from the LHS, I didn't balance them. Would an out of balance blade cause a vibration like that?

what else should I check? I'm new so I'm not sure where to start on repairing stuff or more accurately, I'm not sure what to check.

This is a great site, I have spent hours and hours just lurking around and reading up.

[Trucknut]

I would check to make sure the blades are tracking the same. It is probally best if you start from scracth and make sure everything is setup correct. look at sokal's videos on head part one and two. it should be fine after that. but i would say your blades are not tracking the same if you have allready changed your main shaft and feathering shaft.

[WizardKing]

(Providing you have replaced, not straightened out, the main and feathering shafts :confused:;)

Firstly, I suggest, take the blades off and ensure they're as balanced as possible.
Then follow the steps above, fromTrucknut.

Try to ensure that both 'Jesus bolts' hold the blades with an equal amount of pressure.

[Redfire SVT]

Balance and track your blades.

[HeliMix]

All the above & depending upon where the vibration is, you may check your tail shaft too. I had a little vibration when I had a bent tail shaft (did not know it was bent at first) and could not identify it. As it was, the bent shaft also caused my ESC to heat up. So, not knowing what else it could be, I replaced the tail shaft and both issues cleared up.

[crashburnrepeat]

my blades appear to be tracking perfectly. I spun it up from low throttle to full throttle while holding it clamped to the table and I only see one blade patch from the side.

it's scary looking at those blades from the side when they are really cranking. I just kept thinking if one cut loose and hit me, it'd probably split my wig pretty bad.


I will check sokal's head set up video. I was hoping to not have to tear it all down or anything. It was smooth prior to the blade strike and it was so minor.


I did replace the main shaft and didn't straighten it out, so the main and feather shafts were both replaced. I also had to replace the bolt/nut that goes through the main head block and the main shaft. It was all bent up.

that sucked: 4 bucks for a head block when all I needed was that little bolt. :arggg:

[eugenefelisco]

my blades appear to be tracking perfectly. I spun it up from low throttle to full throttle while holding it clamped to the table and I only see one blade patch from the side.

it's scary looking at those blades from the side when they are really cranking. I just kept thinking if one cut loose and hit me, it'd probably split my wig pretty bad.


I will check sokal's head set up video. I was hoping to not have to tear it all down or anything. It was smooth prior to the blade strike and it was so minor.


I did replace the main shaft and didn't straighten it out, so the main and feather shafts were both replaced. I also had to replace the bolt/nut that goes through the main head block and the main shaft. It was all bent up.

that sucked: 4 bucks for a head block when all I needed was that little bolt. :arggg:

Just for your safety wear eye protection we don't want you to be hurt. What your doing is very dangerous? And remember throttle hold is your friend use it wisely.

[Redfire SVT]

If you are in a hurry and can't wait on parts you can make a blade balancer. Buy a package of 1" (or longer if you can find them) #4 machine srews with nuts, cost about a buck at a hardware store. Cut the head off the srcew and remove the burs with a file. Now install the blades on the headless screw and one nut for each side to tighten them together. Let the blades teeter toter on something like a pair of matching drinking glasses. Add tape to the light side until the blades are balanced. I didn't have any tape so I used electrical tape- works good in a pinch.

[Roehl]

Your blades may be too tight. Try to isolate the problem.

Try to run it without the blades. Then without the flybar (remember you need to balance the flybar too). If it has vibration, then you need to balance the main rotor head. May be you put too much shim on one side.. or forgot to put the shim on the others.

[crashburnrepeat]

crap. i just took the blades off and it's still got the vibration in it.

I don't have enough experience to know if it's "normal" vibration from all the moving parts or if there is still something wrong.


I haven't checked the tail boom yet but I would be very surprised if it was out of true. When I tipped it over it was actually pretty gentle.

I will have to make a blade balancer. I did just hover it and it's hovering well but i just don't want the vibration to cause any issues.


I will try and get a youtube video or something to see if you guys can tell if the vibration is just normal or excessive.

[LockMD]

crap. i just took the blades off and it's still got the vibration in it.

I don't have enough experience to know if it's "normal" vibration from all the moving parts or if there is still something wrong.


I haven't checked the tail boom yet but I would be very surprised if it was out of true. When I tipped it over it was actually pretty gentle.

I will have to make a blade balancer. I did just hover it and it's hovering well but i just don't want the vibration to cause any issues.


I will try and get a youtube video or something to see if you guys can tell if the vibration is just normal or excessive.


If you spun it up with no blades and have vibrations its prob the main shaft.

or feather shaft - feather shaft is really easy to test. With blades off put an allen screw on one side and twist it if you see wobble in the grips, thats the problem.

main shaft - spin it up with no blades (on the ground) stand over it the top of the shaft should not wobble.

[widower]

If you still have the blades off, spool it slowly, and look down at the top of the main shaft. You should see no wobble. I see you changed the shaft, but worth a check again.

[xspare]

my blades appear to be tracking perfectly. I spun it up from low throttle to full throttle while holding it clamped to the table and I only see one blade patch from the side.

it's scary looking at those blades from the side when they are really cranking. I just kept thinking if one cut loose and hit me, it'd probably split my wig pretty bad.
:



Have you considered using a little mirror or camcorder to get your head out of the way?

[crashburnrepeat]

XSpare,

I am definitely going to track the blades from a distance in the future, or wear a full face shield mask.

I was reading a thread on heli safety today on here and one guy lost his eye! :(



Rookie mistake I won't make again. I have put the blades back on but it does sort of act like the main is bent.

I wonder if after I put the main in, and left the bent feathering shaft in there, if the bent feathering shaft could have tweaked the main a little?


I couldn't stand it this afternoon, the wind died and I took it out to the school across the street and flew it and got my first inverted flight! Nothing exciting, just some flips and a little upside down hover. Scary but waaay fun.

I am probably going to need some more spare parts. :)