[Nemesis]

having trouble balancing my 600mm fiberglass main blades.
i have a helimax blade balancer http://www3.towerhobbies.com/cgi-bin...&I=LXKHJ7&P=ML

and following instructions and both weight in at 141 grams each.

just cant balance, when i think their balanced , they make my heli wobble.


with the blades off, there no wobble or vibration.



can anyone help??

Thanx in advance.

[cassat]

What kind of heli is it? What brand of blades?

[Credence]

Originally Posted by Nemesis

having trouble balancing my 600mm fiberglass main blades.
i have a helimax blade balancer http://www3.towerhobbies.com/cgi-bin...&I=LXKHJ7&P=ML

and following instructions and both weight in at 141 grams each.

just cant balance, when i think their balanced , they make my heli wobble.


with the blades off, there no wobble or vibration.



can anyone help??

Thanx in advance.

Have you checked blade tracking?
How tight are you setting the blades?
They should be tight enough that you can hold the helicopter on its side without the blades moving, but a quick jerk of the model should cause the blades to fold.

Are you spooling up to a high enough speed to allow centrifugal force to act? Most models will wobble at low RPM until the head picks up enough speed for the blades to find their spot.

[cassat]

Yeah, had that happen once when blades were too tight. You can always spool up, then shut down and tighten a bit more.

[Nemesis]

Originally Posted by cassat

What kind of heli is it? What brand of blades?

It's my Hirobo Sceadu 50 Evolution with the fiber glass TZ blades

Originally Posted by Credence

Have you checked blade tracking?
How tight are you setting the blades?
They should be tight enough that you can hold the helicopter on its side without the blades moving, but a quick jerk of the model should cause the blades to fold.

Are you spooling up to a high enough speed to allow centrifugal force to act? Most models will wobble at low RPM until the head picks up enough speed for the blades to find their spot.

blade tracking is good
blades arnt real tight, u can move the head assebly just by moving the blade, but hit lightly and the blade moves.

and the head speed is around 1100 RPM.

[CHEVPRO]

Be sure the CG matches for both blades. 1100 rpm seems kinda low for head speed.

[vinver]

What about balancing the head? The whole head unit should be balanced too, if you have a knife edge balancer and a spare mainshaft check the head with flybar attached and assembled, minus main blades.
Vince

[Nemesis]

Originally Posted by CHEVPRO

Be sure the CG matches for both blades. 1100 rpm seems kinda low for head speed.

the centre of gravity is balanced before i balnce both together.

Originally Posted by vinver

What about balancing the head? The whole head unit should be balanced too, if you have a knife edge balancer and a spare mainshaft check the head with flybar attached and assembled, minus main blades.
Vince

I never heard about balancing the head, is there any instructions?
Thanx D

[DAVE62278]

Nemesis,
When you say "can't balance". I'm assuming that after you have balanced them on the bench, everything seems good but when you install them, your heli wobbles apparently from un-balanced blades. If this the case I believe your low headspeed is likely the cause. For my Evo 30, if I hover with headspeed lower than 1550,my Evo develops a bad oscillation that just gets worse the longer your in the air.If I bump the headspeed over 1550, no problems, in fact 1650 is the lowest I hover at now.

When I have balanced the head of mine, I removed the bolt holding main gear to the main shaft, loosen the two set screws in the collar, and took the necessary ball links off the swash plate, so that I could remove the head and shaft as one. Then to check for paddle balance I would remove blades and put on my Dubro Balancer with paddles horizontal. When you check blades while bolted in the grips make sure they are in a straight line with each other(no lead or lag allowed).
Because this has to be done with the blades hanging over the edge of a table, I also clamp the balancer to the table.
Sorry for the long winded version, hopefully someone can post a picture for this.

Hope this helps,if not, keep the questions coming,

Dave

[Credence]

You need at least 1500 rpm for basic flight performance, and even higher for aerobatics. I agree that likely the 1100 is the cause for your wobble, not enough centrifugal force is acting on the blades.