Solved Simple Cub build: I don’t have enough up elevator

[Douglas]

This is my first FT build. I have installed my servos, but when I pull the stick back to give it up elevator, I’m not getting nearly enough up elevator. It doesn’t come close to either the high or low rates indicator. I tried adjusting where the control arm connects to the servo, but that didn’t do it. Ideas?

 

[Douglas]

Another question...in the simple Cub build video, Josh cuts three arms off of a 4-arm servo control arm. Those servos were different from what I received, and the servos I received included a single arm control arm along with the four-arm control arm. I put on the single arm and did not cut anything from the 4-arm. Am I using the wrong control arm??

 

[SlingShot]

Another question...in the simple Cub build video, Josh cuts three arms off of a 4-arm servo control arm. Those servos were different from what I received, and the servos I received included a single arm control arm along with the four-arm control arm. I put on the single arm and did not cut anything from the 4-arm. Am I using the wrong control arm??

The control arm is fine. On your throw problem, did you zero the servo before making your pushrod?

 

[Douglas]

Since I don't know what "zero the servo" means, then my answer is no. However, I suspect it means, "in the neutral position the servo needs to be halfway between full up elevator and full down elevator." If that's what it means, then I'd say it's pretty close to zero. Perhaps I used too much of the purshrod to make my z-bends, and thus I have a too short of a pushrod. Or perhaps I glued he servo too far forward.

 

[MacandRita]

Ok. The amount of throw is determined by which holes in the arm and the control horn the push rod is placed. To get more throw you need to move the control horn end into a hole closer to the hinge or move the servo end into a hole further out from the servo or both. This will increase the amount of travel on the elevator for the same travel arc on the servo. Depending on your transmitter you may be able to increase the end points of the servo travel. On my Flysky I6x I can go out to 120%. If you have turned on your transmitter and the evelator control is in the center of it's travel then the servo will be centered. The arm should be approximately at 90degrees to the servo sidewall so the arm should travel the same distance forward as backwards. The advantage of using the four piece arm is that you can keep rotating the arm until you find the setup that is closest to 90degrees. The hub that pushes on to the gear on the servo is not symmetrical so there will always be a better position and then you can cut the others off.
Hope this helps.
Mac

 

[Merv]

I agree with @MacandRita.

You should be getting about 90 degrees of movement from the servo arms, 45 one way & 45 the other way. If not check the settings in your Tx to increase the throws.

Are your hinges too stiff? They could be preventing the servo from moving. When servos are stalled, try to move but can’t, they make a grinding sound.

Are the control rods flexing? You may need to support them to prevent flexing.

 

[Douglas]

Ok. The amount of throw is determined by which holes in the arm and the control horn the push rod is placed. To get more throw you need to move the control horn end into a hole closer to the hinge or move the servo end into a hole further out from the servo or both. This will increase the amount of travel on the elevator for the same travel arc on the servo. Depending on your transmitter you may be able to increase the end points of the servo travel. On my Flysky I6x I can go out to 120%. If you have turned on your transmitter and the evelator control is in the center of it's travel then the servo will be centered. The arm should be approximately at 90degrees to the servo sidewall so the arm should travel the same distance forward as backwards. The advantage of using the four piece arm is that you can keep rotating the arm until you find the setup that is closest to 90degrees. The hub that pushes on to the gear on the servo is not symmetrical so there will always be a better position and then you can cut the others off.
Hope this helps.
Mac

Thanks. I did all three suggestions and now it is giving me the full throws I want.

 

[PsyBorg]

If you use spectrum gear I would suppose its more due to default end points being so short. Most modern radios go from ~ 980us to 2014us as default. When people set spectrum radios up in quads they have to extend end points to 147% to achieve that full range of 1000us to 2000us for maximum resolution.