trex 450se v2 head wobble

[Almostreadytocrash]

Hi all.I just finished my new heli build and spent ages getting it all spot on.Looks a real beauty.Anyway,come the test flight moment and spooled her up.I have a violent wobble,so bad that I couldn't even bring headspeed up enough to hover for fear of it wobbling itself to death.I balanced the flybar/paddles on the head first and then put the blades on and balanced the head as a complete unit while off the heli.There's no wobble with just the flybar/paddles on.There's a small amount of play in the main shaft bearings,but not excessively so,blades aren't overtightened.I've tried a new main shaft,new feathering shaft,new dampers and even a different set of blades,but the wobble remains.I'm about to throw it through the window,I've been messing about for days and to no avail.The only thing I haven't done is renew the main shaft bearings,but this is a new heli so I would have thought they would have been OK.I might add that I have other helis so it's not as if I'm a total newbie,but I'm getting desperate.Any ideas please guys?

[nameci]

When you say violent wobbles, is the head wobbling or tail wagging very fast causing whole heli to shake?

When you are spooling up w/o blades, do you see any wobbles on head button/head case?

Have you properly set up the head with even pitch on main blades for 0* on mid stick and +- 11*(or 12* which every you have decided) range for high and low stick?

Any play/slop you see on the flybar cage/blade grips/swash?

[Almostreadytocrash]

Hi nameci.No,it's a head wobble.It runs perfectly smoothly without the blades.With the blades fitted,the whole chassis flexes and the heli dances wildly on it's skids.Today I thought I'd go for bust and lifted it up into a hover,and to be fair,it seemed to reduce wobbling somewhat.It was fairly stable and I only stopped flying because it started pouring with rain.Tached the head speed at hover around 2800 with an optical tacho, I think this is OK for one of these little helis( I'm used to 30/50 size nitro )I'm going to order bearings today and see if replacing those cures it.

[nameci]

What kind of main blades are you using?
Have you tried different main blades? I have had mixed experience with cheap glass fiber blades. Some pairs balance perfectly using the scale but caused vibration and tracking issue.

Are the rest of the head parts new? No noticeable bend/damages on blade grips, flybar cage, swash follow, etc?

[Almostreadytocrash]

Both sets of blades I've tried were Align 325F carbon blades,and I checked both pairs for CG and balance,but I'll recheck them just in case.Heli is all brand new Align.I'll try the bearings and see,although I can't quite see how they could cause it to wobble.

[Almostreadytocrash]

Solved it ! Bought a cheapo pair of HK carbon blades, bolted them on and not a wobble to be seen.Put expensive Align blades back on,wobbling all over the place again.As I said,I checked the Align blades for CG and balance and they were spot on.To be fair,the HK carbons were perfectly matched out of the packet.Maybe the Align blades had a twist or warp or something?I dont know.But they're going in the bin.lol.Thanks.

[Send Money]

I've used a lot of those Aligh 325 Carbon Fibre blades and found them all to work great right out of the box without doing anything to balnce them. Did you balance yours on a dedicated blade balancer? Did you add any weight to bring them into "balance"? If so, try taking the balance tape off and run them again.

[nameci]

325f blades are different than 325d

[Almostreadytocrash]

Yea, the CG's were a couple of mm out and they were about 1/2g different but I matched them up using usual techniques with blade balancer till they were OK,then I put them on the head which was off the heli just to check the whole unit was balanced.It's not as if it was a bit of a wobble,it was virtually unflyable.I just dont get it.