Servo alignment/position?

[ElectricSheep]

Hi all, when the cyclic servos are mounted, should the balls (on the servo) be directly under the swashplate balls when the servo arm is @ 90 degrees?

Mine aren't lining up; here's what I have: Futaba BLS451 mounted straight onto the servo mounts with no rubber bushings or metal grommets. I mounted the CF servo arms exactly as they're shown on page 14A of the manual, using the Futaba plastic servo wheels. I have the metal plate between the servo screws and the servo mounting tabs. The elevator servo is directly below the rear swashplate ball, so I assume that's good to go. (?)

But for the two side/aileron servos, the servo balls are behind the swashplate balls. I have some 2.5mm plastic spacers from another kit that I can place between the back of the servo mounting tabs and the frame, but the servo balls are still behind swash balls by about 1.5mm. I can put some rubber bushings on the servo tabs to get the balls to be aligned, but even if I use the back of the rubber bushing (cutting off the front of it), then the servo mounting screws are too short -- there aren't enough threads to go into the frame.

So, should I:
A- Leave everything as-is with no spacers - servo balls about 3.5mm behind the swashplate balls?
B- Use the 2.5mm plastic spacers and be OK with the servo balls being slightly behind the swashplate balls?
C- Use the 2.5mm plastic spacers + rubber bushings and get longer servo mounting screws? (This would get both of the aileron servo balls directly under the swashplate balls).
D- Something else?

Thanks in advance!

[Ross Lawton]

Hi,

On my E7 which i am running as an E6 at the moment i am also running the Futaba BLS451 servos on the cyclic and i have them fitted with the rubber grommets and ferrules. The front cyclic servos on my E6 are almost perfectly aligned when using the rubber grommet and ferrules and the back elevator servo has a very small amount of offset in it but it doesn't seem to cause any issues.

I have attached a picture of my E6 so you can see the servo installation.

I hope this helps and if you need any further help just give us a shout! 


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[steffgiguere]

Mine are almost perfect also. Make sure your CF servo wheel is on the right side of the plastic wheel and also make sure your ball is facing the right direction.

[ElectricSheep]

Thanks guys - I think I figured it out: the rubber grommets/ferrules/etc. that I installed must have been for another set of servos. They're 2 pieces for each servo mounting tab, so there would be 4 for each servo. They're also slightly thinner; they must have been for some JR servos. I found the ones that are 1 piece for each tab just like Ross' so now the alignment looks just about right.

The CF servo wheel is also on the correct side, although I think Ross might be using M2x8 bolts (?), because the nuts on mine just fit to the end of the M2x6 bolts.

Again, thanks for the info and photo -- which caught my error. 

[Ross Lawton]

No Worries! It's good to hear you sorted out the problem, and if you need any further help just give us a shout.

My kit was pre-production and the bolts for the carbon servo arms were slightly longer so i have shortened them slightly.

[HelliYea]

Like the OP, my servo balls are not directly under the swash balls - see picture.  Is this OK or should I try and fix it?  How?  Thanks

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[stevehof]

Since different servo brands sit at different heights it would be impossible to design a kit such that every brand servo mounted up with the rods exactly at 90 degrees. The kit manufacturer would have to include several different size servo mount shims. The amount of offset shown in these photos will not affect the flying geometry at all. If it was off a little more you could just move the CF horn to the outside of the wheel but doing so with 451's would probably just make the small offset opposite of what it is now. Having said that, the fix for 'perfect' would be a mount shim of exactly the amount of offset and probably longer 2mm mounting hardware.

[HelliYea]

Thanks stevehof.  Good to know that the small offset will not affect the flying geometry.  I'll just leave it as is.

Cheers