600N Blade pitch setup problem - struggling to set up

[Pabs]

Hey folks,

I've got an RCLogger digital pitch gauge, and I've been trying to set up my 600N correctly.

I've measured all links and confirmed that they are the same length for each blade, but when I check the pitch on each, it is between 1.5 - 2 degrees out, and I cannot understand why.Weirdly enough - I used the same pitch gauge on my raptor 50 (which has been set up and flies perfectly with blades all in track) and the gauge seems to indicate the same sort of inaccuracies.

I have calibrated the gauge several times - which has made no difference.
I have a flybarred head - and am using a spirit level to ensure that it is level before taking readings.
The swashplate is level (admittedly by eye, but have also measured)
All servo's are centered with all links at 90 degrees (where applicable) mid-stick.
The gauge seems pretty accurate when I put it on a known flat surface (both horizontal and vertical), so don't think the gauge is at fault.

I am measuring the blade pitch when in front of the helicopter on both blades - ie take the pitch measurement, rotate the head 180 degrees and do the same for the other blade. One blade give -10 to +13, the other -12 to +12.
But surely if the links are exactly the same length, and the servos/swash is level, they shouldn't be this different? I could understand perhaps if it was a bit closer, but 2 degrees seems a lot..

Is there a novice error I am making anywhere in the above?
Thanks in advance - not really had this problem until I got a digital pitch gauge - my standard gauge/by-eye always gave me good results in the past..

[jimbojetset]

During your initial mechanical setup... did you check that the swash was still perfectly level at max & min pitch since not all servos are created equal. Measuring 'by eye' is not always sufficient to spot any differences... and for under a tenner a swash leveling tool is invaluable.

[Pabs]

That is a valid point - thanks. I will check.
I must admit, the swashmix setup screen on my dx7 has always been a bit of an known - currently I think the settings are +/- 65% and it's set to 120 degree servo swash setup which I'm sure is right.

I think i will get a swash tool as well, but haven't needed one until now (have built and set up several other heli's all ok)

[KevDavies]

what head do you have Pabs?? Sounds like the mixings arms arent symmetrical if its a flybarred head

[davec_7]

Hi,
Is the feathering shaft straight? are the blades true? have you checked that the length of the short links are the same length as well as the links which connect to the swash plate?

I usually just set the blade with the red tracking tape to the correct pitch and then hover the heli and adjust the other so they are both in track.

Hope this helps

Dave

[Pabs]

600N Blade pitch setup problem - struggling to set up

what head do you have Pabs?? Sounds like the mixings arms arent symmetrical if its a flybarred head

The standard black all metal align flybarred head.

[Pabs]

600N Blade pitch setup problem - struggling to set up

Hi,
Is the feathering shaft straight? are the blades true? have you checked that the length of the short links are the same length as well as the links which connect to the swash plate?

I usually just set the blade with the red tracking tape to the correct pitch and then hover the heli and adjust the other so they are both in track.

Hope this helps

Dave

Yep, checked both sets of links.
I think I am going to end up getting the motor running and will check on the ground and then maybe a hover if it looks ok. It really doesn't look out to my eyes, but the gauge seems to indicate different.
Just weird how my other heli seems to measure the same - but flies ok. Made me think I must be doing something wrong in the measuring rather than wrong setup.
Or I'm just having a bad week - not sure! Lol

[KevDavies]

Somewhere you have unequal link lengths on the head mate. I would start again with the head setup starting from the very bottom, making sure all the mixing arms are perfectly level

[Pabs]

600N Blade pitch setup problem - struggling to set up

Somewhere you have unequal link lengths on the head mate. I would start again with the head setup starting from the very bottom, making sure all the mixing arms are perfectly level

Well I've checked and checked, and not found anything yet. Set up to the manual spec lengths initially too. But I'll check again tonight.

But my method of measuring is correct isn't it? About 1/3rd of the way down the blade, flybar level, and in front of the helicopter?

[KevDavies]

I always check collective at the side, but thats just me.

Link lengths as I found with my R90 bear no similarity to what they need in the real world.

I adjust them like this, with collective centred and radio on so swash is level, Make sure flybar is at 90* to the main shaft and lock in position. Then adust the links off the swash driver mixing arms so the centre of each ball link is perfectly level (these go to the flybar cage on the trex IIRC). Then set the upper mixing arms so they are perfectly level. You can draw a line at 90* across the pivot point and both ball links will be perfectly centred. and then you set the small links from the upper links so the blade holders are at 0*.

Its very rare that I have to track blades using this method.

[dieselcarb]

how about this are all ya links new if not are they all tight? Secondly forget that you've set all link equal now that ou know they are close. at mid stick go through your set up again but check every thing is level even go 1 turn over and under to make sure it is perfect (it may look right but it could be 1 turn out some where) your plastic links are moulded and may not be EXACTLY the same length or dimentions to the next 1

the length of a link is actually from where the centre of each ball is going to be located within the link. also as said before swash tool and leave it on until you have end points sorted or use a nice thick zip tie

hope this helps

cheers terry

oh yea use ya known level surface to set heli on

[dieselcarb]

good thinking batman I have no idea why the last 2 posts didn't show until I posted......... I must be getting old as I refuse to belive it was the updates slowing stuff down :P



no I belive it is. this was quoted to kevs message

[Pabs]

Right, after all this faffing around, I've found my problem!!!!

It's my blades - they look "warped".
Now they've been used before, and are fibre blades - and in pretty good condition really. But it seems along the length of the blade they are twisted...

Does this mean the blades are no longer any good, or is it just because they've been used before (potentially for a heli that's been flung around a bit, maybe 3D) - or can I still use them?

I've stuck a set of 550mm brand new fibre blades on, and checked with the gauge and everything is almost spot on. Obviously can't use these blades as I need 600mm on the 600.

Has anyone heard of warped blades before??

[pgkevet]

I've seen shorter warped blades...as it happens they were fibre too.
Ditch them and buy a new set

[Pabs]

bum, figured that'd be the answer
Annoying as hell, as blades aren't cheap! Was hoping to maiden it this weekend, but looking much less likely now.