servo setup help

[drzoidberg]

Hi,

I am trying to set up my servos on my new rappy 50 titan. I have done the aileron and throttle servo and both seem good. I am now trying to set up the elevator servo and am running into trouble. I have been following the help at raptor technique and have hit a snag.

Here is what I have done so far.

I have installed the servo arm at 90 degrees (straight down), the elevator push pull lever is straight down. The balls on the servo arm are approx 11.5mm. (I had to move the out to get the proper throw) The balls on the push pull lever are where the manual says they should be. I have set up the neutral (middle) so it is level, I have been able to set up forward cyclic so it is reaching full deflection without binding but I am not able to get full backwards cyclic without having maxing out my ATV.

I have tried changing the lengths of all the rods but no luck. Also I am running Hitec 6975 servos and they sound as if they are binding even though I have made sure they are not. By this I mean when I give them full throw there is no binding but once it centres the buzzing starts. Is this normal?

ANy help would be appreciated.

Thanks

[Helirat]

Go back to raptor technique and click on the pic. in step 6
you will see the servo arm is not straight down but 90deg to the push-pull lever.

here is a pic of mine with the servo centered.
53246

[drzoidberg]

Thanks for the help, however if both arms are 90 and parallel to each other then this shouild not make a difference. Shuould it? I will try it again and let you know how I go.

[Helirat]

You want the back elevator arm (short rod to push-pull lever) to be straight down swash leval the push-pull to the servo parallel to each other and the servo centered.

[Helirat]

like this

53249 53250

[drzoidberg]

Thanks helirat, I seemed to have sorted out my iusse with the elevator. I am still having the buzzing noise problem though. I think it may be my ball links. I think they may be too tight and I will go over them them with my resizing tool when I get the pitch settings right. When they recentre they buzz and when I give them a little nudge with my finger they stop buzzing.

Anyways, I have set up the remaining servos and have moved on to the pitch settingsin my radio. I am having another problem with getting the pitch values right. At the moment I have set up one blade with pitch values -10 to +10 (I will set individual flight modes later) The other blade however is not playing the game.I have set up the long link and the short blade grip link so they are equal to the blade with the right pitch values. However I amnot getting the same values: -10 to +10. I get -9 to +11. I have tried changing the link lengths and have had no luck. Any ideas?

[BarracudaHockey]

First, digital servos buzz, thats not unusual.

Second, swap the blades, if it follows the blade one of them is warped.

[forjer]

Please make sure that the buzzing is NOT because of tight links or binding. Once you're set up, pop the links off the servo and make sure they move smoothly and with little resistance. If not, pop off one link at a time checking its fit to one ball at a time and resize as needed. Don't forget to check the link(s) on the servo itself.

Tight links are one of the gremlins that will bring a heli down either due to a weak servo not being able to recenter or being burnt out, or to extra mAh draw draining the battery a lot faster than you think.

[drzoidberg]

Thanks for the reply guys,

BaracudaHockey I know digital servos buzz I was just concerned that when they centre they continue to buzz. Forjer has hit the nailon the head though, I believe that I may have some tight links and this is causing the buzzing at centering. I will check the links once I have set my pitch correctly. I will try your suggestion by swapping the blades however I dont think this is the case as I was using the one blade to set the pitch values. Also they are newish blades from my T600 and they have never been a problem on that bird.

Thanks again.

[drzoidberg]

Ok I have now spent another good hour or so trying to get my pitch set up correctly.
I started with one blade and set the pitch eactly the way I wanted, I checked and rechecked and re-rechecked the values at low mid and full stick and they were all excellent.

I moved onto the next blade after making sure both the long and short blade links were the same size as the other side. I started with zero pitch at mid stick, this was good.Then I went to full stick and the value was off, same with low stick. They were almost the opposite to the first blade. (ie -11 at bottom and +9 at top) After trying different lengthsand adjustments I could not get the same pitch settings. I check the first blade again to see if the settings were still good and they were not. They had become all wrong. After pulling all my hair out I finally gave up for the night. This is not the first time I have set up a heli but it is my first nitro heli. I think the links on my bird are way too tight and causing issues with the servos. I think I will go over them all and resize them. Atleast then they willall stop buzzing when they centre.

Any other help would be appreciated.