DS 821 servos

[trillian]

So what's the consensus on the DS821 servos?

I have the four that came with my DX7 and have not used them yet. I read somewhere that they have had shaft breakage problems or something.

I was surprised to hear that because I'm pretty sure Bob used them on his Gaui 500 build.

So should I use these or is there a problem with them or was that a myth?

[fogger]

I have hundreds of flights on mine in a trex600 with no issues. I did strip -one- out in a pretty bad crash that I'm certain was due to a lockout. I ended up putting in all new gears and bearings just to be on the safe side. I recommend some metal output arms just to be sure you don't have to worry about the output shaft issues some have had, but honestly, when I was trying to get the old bearings off (to see how I'd get the new ones on) I found that the carbonite gear material is extremely strong and quite hard to break.

-Fog

[Jan-DK]

Hi.

I have not yet had my first fligth with my Heli. Today I went to the flying club and prepared for flying. But we experienced that one of the servo's had a broken shaft.
I played with my Tx and the swash plate stopped moving :arggg:

[Tommy Norman]

i have about 18 flights on my heli with these servo's and no problems yet although i'm only hovering.

[Drew816]

I've snapped two in the #1 position on my Gaui 550; I didn't know that this was a 'known problem' with these servos.

So what's the cure, longer screws and if so what size and where can you get them???

Thanks and Happy Flying!

[Pinecone]

JR/Spektrum recommends them up to 600 size electrics, but only up to .30 size nitro helis. The vibration can cause the output shaft to break.

One thing that helps is JR has longer screws available, which helps support the output shaft.

Personally, I will not use them on over 30 size electric (500 - 500 mm blades), and not on any nitro heli. I will use them in planks.

[nouse094]

JR/Spektrum recommends them up to 600 size electrics, but only up to .30 size nitro helis. The vibration can cause the output shaft to break.

One thing that helps is JR has longer screws available, which helps support the output shaft.

Personally, I will not use them on over 30 size electric (500 - 500 mm blades), and not on any nitro heli. I will use them in planks.


GLAD I READ THIS I AM A NEW FLYER AND A RECENT CRASH (OR TWO) HAD STRIPED A GEAR AND I WAS LOOKING FOR A GEAR KIT WHEN SOMEHOW STARTED READING THIS FOURM. NOW REALLY THINKING ABOUT GETTING A NEW SET OF SERVOS FOR MY NITRO 600 TREX. WONDERING IF ANYONE HAS SOME RECOMENDATIONS FOR ME??:thumbup:

[Pinecone]

First turn off the all caps, it is like SHOUTING.

How much money do you have to spend? How much performance can you afford? :)

The top of the line for speed are the JR DS8717s. But they are about $140 per servo unless you find some used ones. The Hitec HS6965 is a very nice fast servo at a much lower price.

Futaba S9252 or S0452 is very common on 50 nitro helis. Equivalent Hitec or JR would also work well.