Hs-81!

[CactusJackSlade]

I made the MISTAKE of using the HS-81's (plastic gear) for the first time in my foamie Bandit just because they came with a flight pack I was traded. I stripped one servo just because I turned on my Rx before the Tx on tiime then I stripped the other servo after a medium soft belly landing.


I put new gearsets in both of them and hope to sell them to someone who doesn't know any better! Any takers?

CJS

[thepilotbruss]

Since your getting some gear sets would you please pick up a couple for me. :rolleyes:

[Doc Data]

Why not replace the gear sets with the metal ones if you're going to keep the servos?

Dave

[vario]

replacing the gears to metal seems to be a regular event these days for hs 81 servos,seems a shame that hitec makes even more money on an obvious problem!

i say;;; stop the madness,,i myself wont buy anymore hitec servos at least until they fix there problems

hey guys ,there is strength in numbers




my 2 cents ,,,,,,,vario

[Daemon]

I, and several other people have had a different problem with the HS-81s. They'll work fine for a while and then one day.. poof.. no response, and they heat up like something is shorted.
They may center when you power up the TX, but then get stuck in one position as the resistor at the bottom gets burning hot. I had this happen to *four* HS81MG servos in different gliders before I stopped using them completely. All in foamies though. I've still got 2 in a crunchie tha work fine, but they're also very well protected from the elements.

As for stripping plastic gears. Welcome to micro servos. I don't see it as a design flaw, just a miss application of that servo type.

ian

[CactusJackSlade]

I was actually going to put metal gears in them, even had them in my hand but the guy at the hobby shop here locally said they would not interchange... I looked at both the metal and the plastic and the cases look exactly the same... different internal space?

I guess I will pull them apart and see for myself...

Maybe you CAN on the newer ones and CAN'T on the olders models???

ANybody know?

[vario]

i dont know about old verse new but im pretty sure you can just replace one gear to metal.

its always the smallest gear that gets chewed,
,,,vario

[KEZ]

This has been discussed in electric heli forum:
http://www.rcgroups.com/forums/showthread.php?s=&threadid=89168&highlight=HS81

Initially I thought mine failed because I was pushing it to the limit with a gyro for the tail rotor. Now I am going to replace all my HS81's in my gliders as well. If the servos go when I am in a thermal, I would not see my glider again.

Kez

[Daemon]

I've never had one fail in the air (wouldn't worry about that too much), but I've had one fail on a pretty mild foamie style landing, pick it back up and throw it into the air, and realize it wasn't responding any more. My theory is that it picks up dust from somewhere and it gets into the position pot and throws it off. I've tried cleaning with spray contact cleaner, and I think I had one recover, but it failed again later. I just don't trust em for foamies at all any more, which is too bad, because the HS81MG is perfect size and weight for a lot of light weight foamies.

The two in my Nemesis sloper have been fine, but they're under low stress and well protected inside the fuse.

As for the gears. They are interchangeable.
However.. you'll have to change to the machine screws (no biggie), and be very very careful when you put the main servo gear back on (the last big one the servo arm hooks to). It has a plastic D-shaped hole (even in the metal version), and the top of the position pot pin is D shaped. If they aren't perfectly lined up when you press it on, it'll deform the hole, and you'll get slop, that causes it to never center in the same place. And that can only be cured with a new gearset. I killed one one of my new metal gears that way, so switched just that large gear back to the plastic one I had taken out (it's never the one that fails anyway).

ian

[Hostage-46]

So what would be a good low cost alternative?

I've had good luck with FMA servos ...

[webguyjv]

I guess I'm a slow learner, but I still strip them after three years of flying. Most of the servos I use are HS-81s. I have become mildly proficient at replacing the nylon gearsets. It's pretty easy.

I have on a few occasions installed the MG gearsets in the HS-81s that I purchased with nylon gears and it works perfectly! This is a good solution if you have the servos laying around and don't want to go out and buy new MG servos.

If you're wondering why I haven't started using a different brand of servos yet, here are the two reasons that work for me...
1) The HS-81s are cheap and have been pretty reliable for me
2) I've started sending them in for service when the problem isn't gears, and in EVERY case, Hitec has fixed them and sent them backto me, free of charge! In EVERY case!!!

OK, so I'm brand loyal. In short, yes, you can swap the nylon gears for the metal gears.

Happy Flying ;-)

webguyjv