Syncronizing/Balancing Multiple Servos

[Bartman]

OK, it's about time we get a thread going on how to get multiple servos to work with each other instead of against each other. I've managed to avoid this until now but with a Push/Pull on the rudder and dual servos on each aileron, it's time to learn something new.

So let's see what you guys have to say.....i'm sure there is an easy way and a complicated way and an even more complicated way. I've been reading about it this evening so I've got an idea of what to expect but let's get the thread started and see what everyone has to say.

Thanks!
Bart

 

[Terryscustom]

Depends a little on which radio system you are using. Some will use match boxes, some will use other electronic devices. I prefer to mechanically adjust as close as possible and then do the last little fine tune in the transmitter balance feature on the Spektrum and previously on JR radio.

I First do some measuring and adjust the inner arm and servo (with outer one disconnected). I adjust for max throws and equal up and down. Then without attaching, just hold the screw against the hole on the servo arm slowly move the stick and see how far off you are. Adjust mechanically until outside basically matches the inside. Then hook up an in-line amp meter like the Hangar-9 unit on the servo wire going to the outside servo. Finish mechanically matching or use the balance feature in the transmitter to finish setting it up.

First time I did it I think it was a couple hours, now it seems like any other 20 minute project once you get it down.

 

[Bartman]

thanks Terry, the comparing/matching technique was what I was going to try first and I'll have to check out the amp meter you mentioned. i read through some pretty complicated techniques but what you said with my Aurora 9 should be pretty easy. I was going to swap the two servos on the rudder out for one JR 8711 but figured I should give balancing a try finally.

 

[thurmma]

Like @Terryscustom said, make sure the mechanical part is setup before you plug the power in. A little extra time on this step will pay dividends ten fold in the long run

 

[jamesrxx951]

Since I went with the airwild unihubs everything went way easier. But prior I would have several different servo arms. First I would fit an arm and use my H9 angle meter and measure full up and full down. If one was higher, I would remove some of the higher number by turning the turnbuckle. Readjust for center using the transmitter. Once matched I will 0 out sub trim. Find an arm that will fit the closest to perfect center with no sub trim. Once I do that remeasure full up and full down. Sometimes adjustments are needed or after readjustment a new arm is needed. But the results are very little subtrim and pretty much no adjustment for travel adjust. I us a JR radio with servo balance feature and I rarely even need to use that.

 

[jamesrxx951]

The unihubs make it really easy because you rotate the hub to find the best center without having to have several different arms. I also use either a H9 amp meter ore fromeco quad meter to balance the servos if needed. I also love using the screw style control horns with a clevis because you can fine tune your throws to match evenly. The G10 styles are usually really close though.

 

[emtp275]

You can always program the servos and set the Tx subtrim to zero and throws to max and bam lol down fall is this limits you to the servos you get to choose from.

 

[jamesrxx951]

You can always program the servos and set the Tx subtrim to zero and throws to max and bam lol down fall is this limits you to the servos you get to choose from.

ive tried that with Hitec servos when I used to use them. The downfall I found with that was binding in the range of travel. Unless the geometry is correct you get binding. After a while I ended up just setting up proper geometry

 

[emtp275]

ive tried that with Hitec servos when I used to use them. The downfall I found with that was binding in the range of travel. Unless the geometry is correct you get binding. After a while I ended up just setting up proper geometry

This is true I left out the part where I get things as close as i can then program, Never tried swapping arms like you say but its a good Idea.

 

[jamesrxx951]

This is true I left out the part where I get things as close as i can then program, Never tried swapping arms like you say but its a good Idea.

with being able to program the servos swapping the arms probably is not even needed. Once geometry is set and even double checked you should not need to reprogram. Maybe move the arm a tooth to get the arm to hinge line close. Servo balancing is still nice. Im thinking a kit plane properly built you would not need to balance the servo's. But that is just a guess.