• This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn more.

Help with tricopter servo needed

#1
I have just built a new tricopter and the tail moves freely with no stress (it seems) on the servo. I am on the verge of ditching my tri and getting a quad built instead as I have stripped 2 servos in 6 flights.
I thought I'd upgrade to something that seemed a little more durable and ended up with the hitec hs-65mg and still no joy. Does anyone recommend any servos or any tips about where I might be going wrong?

Thanks
Brad.
 

Aquanot

Junior Member
#2
Hi Brad!

maybe give us some more info about your setup (pic?)
what settings are you using in your controller?
what has failed at the servo? the gears? the motor?

i used on my tri also a metal gear servo as there will be a lot cyclic loads.

maybe you get some force onto the servo from landing? or does it fail in the air?
is it suffering from vibration coursed by the inteference of the controller and the setup? (if you use a kk2 increase the servo filtering value about 30 or more)

help will come soon
Aquanot
 
#3
Hi Brad!

maybe give us some more info about your setup (pic?)
what settings are you using in your controller?
what has failed at the servo? the gears? the motor?

i used on my tri also a metal gear servo as there will be a lot cyclic loads.

maybe you get some force onto the servo from landing? or does it fail in the air?
is it suffering from vibration coursed by the inteference of the controller and the setup? (if you use a kk2 increase the servo filtering value about 30 or more)

help will come soon
Aquanot
my setup is shown here: http://forum.flitetest.com/showthread.php?6216-My-New-Tricopter

and also i dont know what you mean by settings on the controller
and it is the gears that have failed

the tail moves extremely smoothly so i dont fully understand the problem

thanks so far for your help.
 

Aquanot

Junior Member
#4
my setup is shown here: http://forum.flitetest.com/showthread.php?6216-My-New-Tricopter

and also i dont know what you mean by settings on the controller
and it is the gears that have failed

the tail moves extremely smoothly so i dont fully understand the problem

thanks so far for your help.
i am quite ne to the world of tri;
what i have learnd from 15years of rc is, that
if the gears of a servo fail you always got a strong hit on too the gears.
I quite often broke the gears when turning the servo arm.

i could imagin that the weight of the lifting motor is coursing a peak load to the servo when landing it and the motor ist still in some angled position (as it usualy will be)

a servo with metal gears should help here - but no gurante from my side.
your hs-65mg has 1.6/1.9 kg/cm that seems ok - but i can be wrong here
(i used a servo with 1.9/2.2 kg/cm )

maybe some one more experienced has another idear what is happening
 
#5
i am quite ne to the world of tri;
what i have learnd from 15years of rc is, that
if the gears of a servo fail you always got a strong hit on too the gears.
I quite often broke the gears when turning the servo arm.

i could imagin that the weight of the lifting motor is coursing a peak load to the servo when landing it and the motor ist still in some angled position (as it usualy will be)

a servo with metal gears should help here - but no gurante from my side.
your hs-65mg has 1.6/1.9 kg/cm that seems ok - but i can be wrong here
(i used a servo with 1.9/2.2 kg/cm )

maybe some one more experienced has another idear what is happening
Thanks. The HS-65MG is all metal gear (except 1 gear) and i forgot to mention that its useually during flight the servo fails (luckily hasnt caused a crash yet).

My new bearings for the tail have just arrived so hopefully that would further increase the smoothness of the already extremely smooth tail mechanism. (its already as smooth as butter mealting in a pan). no issues like this with a quad... still might build one anyway but hobbyking are out of stock on kk2 boards.
 

Cyberdactyl

Misfit Multirotor Monkey
#6
Hmm, if you say the yaw mechanism's movement is liquid smooth from stop-to-stop, and the servo's max internal stop-to-stop is not more the the yaw mech and is not torquing at the stops, (which is very doubtful you're doing that). . . it's really hard to say. One thing that IS possible is you have the servo filter set much too low. This CAN burn out a servo, but your in-flight jitter would be very noticeable.

I have an extremely small misalignment on my tri, (shown below). It probably would be an issue if the servo was mounted absolutely, completely 'solid'. It 'feels' smooth, but the every-so-slight movement allowed by the zip ties allows the servo to 'swing' the necessary ~0.5mm somewhat freely. I've exaggerated the scale to show the loopy movement.

So, are you absolutely sure there is no sticking position in the entire rotation from stop-to-stop?

 
Last edited:
#7
Hmm, if you say the yaw mechanism's movement is liquid smooth from stop-to-stop, and the servo's max internal stop-to-stop is not more the the yaw mech and is not torquing at the stops, (which is very doubtful you're doing that). . . it's really hard to say. One thing that IS possible is you have the servo filter set much too low. This CAN burn out a servo, but your in-flight jitter would be very noticeable.

I have an extremely small misalignment on my tri, (shown below). It probably would be an issue if the servo was mounted absolutely, completely 'solid'. It 'feels' smooth, but the every-so-slight movement allowed by the zip ties allows the servo to 'swing' the necessary ~.05mm somewhat freely. I've exaggerated the scale to show the loopy movement.

So, are you absolutely sure there is no sticking position in the entire rotation from stop-to-stop?

if by sticking position you mean it catches slightly?
if so i can confirm it moves freely without any sticking positions and also it is mounted completely solid.

would a picture of my servo/tail mechanism help?
 

Cyberdactyl

Misfit Multirotor Monkey
#8
Sure. . . can't hurt. But it's going to up to you to confirm it rotates completely smooth. But you've already said that, so I'm somewhat at a loss.
 
#9
Sure. . . can't hurt. But it's going to up to you to confirm it rotates completely smooth. But you've already said that, so I'm somewhat at a loss.
A bit mucky but thats from the rough landing due to the servo gears failing:

IMG_0313_zps89196520.jpg
IMG_0312_zpsece6d0e3.jpg

the wire is just to securely bind the servo arm to the metal plate (no slop at all)
 
#10
Spinning bicycle wheel in high school physics class....for the sake of full disclosure I am not a multirotor guy but this stripped servo issue is a big one out amongst rc forum land. I will say I stay away from Hitec "mighty micro", don't consider it to be one of their better offerings.
 
#11
Spinning bicycle wheel in high school physics class....for the sake of full disclosure I am not a multirotor guy but this stripped servo issue is a big one out amongst rc forum land. I will say I stay away from Hitec "mighty micro", don't consider it to be one of their better offerings.
Thanks. what would you recommend as a replacement for the hs65mg?
 
#12
Thanks. what would you recommend as a replacement for the hs65mg?
Typically I am not the guy who drops in a thread, tells you all your components are crap and leaves without offering solutions.....but in this case I am lol. As stated in my first post I am not a multirotor guy so not prepared to make yaw servo suggestions....fortunately there are many other forum member here on FT that can. I just have experience with the hs65 in conventional rc applications, personal experience has been poor at best and other forum posts both here and elsewhere reaffirm that position. That being said I am not down and out on all HiTec servos, just believe there is something inherently wrong with the hs65 in particular. I suggest you add servodatabase.com to your rc bookmarks. It's a great place to get both reviews of tons of popular servos and sometimes slightly more honest specs than the often inflated numbers vendors offer. When looking for servos for special applications I often start at servodatabase to find several well reviewed options with the specs I am seeking and then look for a place to purchase rather than other way around.
 
#13
ok... im done 3 servos now IN 8 FU**ING FLIGHTS.

-a new set of bearings no slop on the tail at all
-cleaned all tail/servo mechanism
-new prop (no vibrations)
-new servo gears for HS-65MG
-greased gears (made sure it moved smooth)
-no rough landings at all
-no crashes

all these factors still didn't make a damn difference in ensuring the servo wouldn't fail (gears stripped).
I can safely say that I am building a quad now. This experience has put me off for now for sure.

I have done everything to ensure it wouldn't fail and it still happened. If I'm missing something major out here please somebody let me know. I just cant understand why this is happening.

at least with a quad I already have 80% of the parts, no servos to worry about, and I can put a DJI NAZA on it.
BUT, I would still miss my tri for sure.
 

xuzme720

Dedicated foam bender
Mentor
#14
Sorry about your troubles. I had those same hitecs on my T-rex450 and they didn't last long on there either. And that was just hovering and normal flying, no 3D or anything. Not sure what the weak point is on them but they do have an issue. David uses these on his tri's...maybe they would work better than the HS-65's.
 
#15
So after three servos you are calling it quits huh? I am more of a tough love sort of guy for which I hope you don't take offense. Know this, if you think quads are a walk in the park then you are reading the wrong forum threads. The cornerstone of this hobby IMHO is not so much the joy of flight but the challenges overcome with each new thing learned....the flying bit is just the cherry on top. Would you like to venture a guess as to how many of my scratch built models for which weeks had been spent building ended up in as piles of rubbish after only a few seconds of rather unsuccessful "flight"? Yes it can be disheartening but you can't allow your "give up botton" to be pushed so quickly. Again for me multirotors are like black magic, I can only imagine the forces I acted upon a tri yaw servo...they must be huge given the little I know about centrifugal force. Take a step back and think, if you have the funds to finish another quad project, you most certainly can afford trying a few other servo options. I do wish I could be more assistance from a technical aspect but will ask all the other FT members that are experienced with tri to offer their suggestions and I am willing to bump this thread until they start chiming in. Don't give up on this yet man....it seems to be as simple as finding the right servo for your application.
 

Craftydan

Hostage Taker of Quads
Moderator
Mentor
#17
Brad,

Try a v-tail. It's got a much better yaw and swoosh than the quad and less moving parts to break. (servos have way more moving parts than motors)

It's a better flying experience than a quad with higher reliably than a tri.
 

kah00na

Senior Member
#18
I've broke the plastic gears on one of the Hi-Tec servos, then burned out the motor in another Hi-Tech. I got tired of spending $20 on servos, so I bought the VWINRC TREX 450 Spare Parts Metal Gear Digital Servo MG90D from banggood.com. I liked it so much I bought a second to use on my second tricopter and then bought a 3rd to use as a backup. However, after 3 months, it is still sitting in the package because the first two haven't failed yet. I won't ever use anything but a digital metal-gear servo again on my tricopters.

You can see my servo in use in this video. :)
 
Last edited:
#19
sorry to revive this old thread of mine but I have info that may be helpful to others (or not) but I replaced the servo with the exact same Hitec one as previously mentioned but haven't had any issues since and the only thing I can recall changing is the servo filtering setting on the KK2 board. hope its useful to someone. from this experience I can only assume there was jitter due to a low servo filtering setting that was ripping the teeth on the servo gears to pieces. Thanks again to anyone who helped along the way.
 

crlock

Senior Member
#20
You need a servo with metal gears and at leas 3kg of torque, i use the HS5085 and it works awesome. that is the only way to stop striping your gears.

cheers