Fusion Control Links

[waveydavey]

I'm in a bit of a dilemna. I'm using the Align metal servo horns which get you to 29mm centres, the centres on the bell cranks are 30. Now my way of thinking was to align the servo horns parallel with the servo and use the alignment pins to square everything up. Make the links adjusting for the slightly reduced distance on the horns and Bob's your uncle. Well no with the horn square and the alignment pins in the distance to each ball is different. Makes me think the servo cutout in the frame is slightly wrong.

What would you do, leave the servos centred and adjust the links slightly differently or set the links to the same length and trim the servo to suit. Which is best

[LipolyGone]

Are you on the outer holes on the bell cranks dave?
What I did on mine was use the align plastic wheels which on the outer holes are slightly smaller than the positions of the bellcrank holes.
I then put the pins in & set the servo wheels so the best position to 90 degrees was obtained I then adjusted my servo centres via the vbar
software & everything came good you will be amased that i have upto 30% of subtrim on some functions to get the geometry the vbar needs
so I'd just adjust your centres on subtrim the same mate.

[waveydavey]

Cheers Martin. I'm on the outer holes as they are 29mm as close as I can get. It was the unequal length of the links that I wasn't too sure about. To get the same length link I would have to have the servo none centered.

[Gate88]

Makes me think the servo cutout in the frame is slightly wrong.

I think you might be right Dave, I had the same issue on my Velo and went for centred servos and slightly different rod lengths.

[raptorheli2]

i don't follow this here, what does the servo cut outs have to do with anything? the links are made with the centre of the servo arm to the centre of the pivot point. it doesn't matter a hoot where the servo cutout is.

i'm obviously missing something here.

cheers

[Gate88]

i don't follow this here, what does the servo cut outs have to do with anything? the links are made with the centre of the servo arm to the centre of the pivot point. it doesn't matter a hoot where the servo cutout is.

Yes it does, The cut outs for the servos are at an angle and therefore the angle between the bell crank centre and servo wheel centre has to match, if it doesnt (and it doesnt on an N2 with Align servos) then you have to shorten the top rods by a couple of turns.

[waveydavey]

What he says, cheers Guy. As Guy says if the servos aren't exactly in line with the bellcranks you won't be able to centre the servo horn (in line with the servo) and have the same length link rods.

[LipolyGone]

I'd make the links the same length push in the pins then select the set of holes closest to lining it all up then adjust the servo centre so you can pop on the wheels mate.
Forget about making one pushrod longer it will lead to a slight binding & sap the juice even more or worse still pop a link off ending in an arrival.

[raptorheli2]

ok i understand what your saying now- if you pin the bellcrank then yes it matters but i didn't catch you meant that-apologies.

cheers

[coolice]

Hey guys.

Im reading this problem and am with Raptor2heli, as even if the servo is offline the output splines are still going to be X distance from the centre pivot point of the bellcrank. A much more realistic theory is that on the bell cranks one steel ball position is different to the other side.
The above is no different to using sub trim to line the servo splines upwith the servo disk/arm to allow for/an offline servo ouput spline.

Ive just re-read the problem, with the arms pinned level the control arms off of them do not match with the servo horns? Bad bell crank design?

I get it, the arms arent machined with the same angles to match the servo cutouts.
.

[waveydavey]

I still end up with the same problem though Ian. I don't suppose it matters though it just means that the servo horns end up off centre. Cheers. I just like everything how it's supposed to be

[Andy from Sandy]

I can see that with the bell crank set for mid stick in order that the link rods describe a 90 degree angle as they should the servo then needs to be in a certain place. If it isn't then the angles will be wrong. What I don't know is whether that matters or not?

[waveydavey]

Just checked and with the alignment pins in the control balls on the bell cranks aren't in line (square) with the servo centre. What's the point of that then

I think I'll just go ahead and do it the way I think it should be done.

[Gate88]

Here is a rather rough digram of how a slight change in angles at either end radicaly changes the relationship between the rods.



I drilled my own holes into the servo wheels but I still ended up having different size rods, the only other options were to have the balls slightly off set or not in line with the servo body. There is probably a mathematical answer whereby one ball could be slightly nearer the centre thus achieving equal rods, central servos and lined up pin holes but at 11:30 last night I couldnt work it out. (Mind you at 11:30 last night I couldnt even get my blade grips on the right way round!)

[waveydavey]

Described exactly as it is Guy.