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Did i just kill my servo??????

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Old 10-06-2004, 12:37 PM
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FlyingPika
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Default Did i just kill my servo??????

Hi ppls,
I was testing the strength of my hitec HS-5645, i applied force til it gave in about 3 times, however, when i switched the power off i noticed that when you move it by hand, it has a defeniate kink at the point where i resisted it.

Did i strip the gears at a certain point??? I would open it up but i r such a RC newbie X_x
It stil works, but does it now have a dead band at a certain point???

I feel like i keep killing my model....
Has this happened to any of you guys???
Any helps = greately appreicated
Mike

*goes and criez in a manly, testosterone filled sorta way*
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Old 10-06-2004, 12:55 PM
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Default RE: Did i just kill my servo??????

Hmmm... Do you test balloons by sticking pins in them?

It's hard to say if damage has been done or not without actually seeing/feeling it for myself. but it could be that you knocked a tooth out of a gear. Have someone (like another club member) have a look at it.

And don't do any "tests" with your receiver or transmitter
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Old 10-06-2004, 03:22 PM
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Default RE: Did i just kill my servo??????

In metal geared servos the first two gears are plastic. Mechanical force can cause those gears to break as they are the weakest link. You have a high leverage on those gears when you force them. You can buy the plastic gear set for the servo and just replace the plastic gears retaining the metal gears. Its much cheaper than buying the metal gear set.
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Old 10-07-2004, 09:41 AM
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Default RE: Did i just kill my servo??????

FlyingPika, u mentioned u feel a kink at the point where u forced the servo arm? I am quite certain u have sustained at least one broken tooth or stripped tooth and it'll prob be on one of the plastic gears. My advice is to remove the 4 screws and take the top off and give the gears a good visual inspection. Its quite straight forward and I don't think u'll face any problems. Just remember the positions of the gears and shafts. Plastic gears are cheap and once u've opened the servo, at least u'll know whether its the gears or something more expensive. Oh, and u really shouldn't be verifying the manufacturer's torque claim by forcing the arm...
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Old 10-07-2004, 05:07 PM
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Default RE: Did i just kill my servo??????

ORIGINAL: MeanMustang
Oh, and u really shouldn't be verifying the manufacturer's torque claim by forcing the arm...
That's true - but wouldn't it be nice to know which servos (manufacturer/model) really meet their published specifications and which do so without incurring damage?

I'd really like to know if my brand x servo will bust its cogs at its rated torque -- because in my book that means they're not actually the servo they claimed to be.

In this competitive marketplace, I suspect that most manufacturers are tempted to over-state the specifications of their servos.
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Old 10-07-2004, 11:56 PM
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Default RE: Did i just kill my servo??????

When you grasp the output arm of the servo you have a great mechanical advantage on the motor. When you move the output arm the motor must turn over many hundred times for every degree you move the output arm. In a servo with the three pole motor like the 5645 the motor resists turning over and if you persist you will most likely break one of the gears. With a servo with a coreless motor you will probably get away with it unless the motor has a load on it.
If you want to test a servo hang the rated load on the output arm-gently.Then move the control and see if it moves it.
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Old 10-08-2004, 01:18 PM
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Default RE: Did i just kill my servo??????

ORIGINAL: dirtybird
If you want to test a servo hang the rated load on the output arm-gently.Then move the control and see if it moves it.
Yes, I remember reading somewhere that that's the correct way to load-test a motor/servo...Can't recall where I read it though[&o] I probably learnt that in high school physics many many years ago.
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Old 10-08-2004, 01:45 PM
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Default RE: Did i just kill my servo??????

ORIGINAL: MinnFlyer

Hmmm... Do you test balloons by sticking pins in them?

And don't do any "tests" with your receiver or transmitter
lol,
*resists the urge to test the crash resisitance of his model*

Thanks guys for ur help, ill open it up now.
I recall reading something about when u test a servo, u let it pull up a weight, and as it winds up the cord increases the effective lerverage until the point it does pull the weight up anymore, then u just check the distance.
sound like u gotta hack them tho for a test.
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Old 10-09-2004, 11:14 PM
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Default RE: Did i just kill my servo??????

Flying Pica
One of the editors / contributors to RCMicroFlight magazine frequently publishes tests of servos he's performed. He's described his process in considerable detail a couple of times. If you want to continue, he'd be worth checking out. He does use the process others have mentioned, which is to set up a dead weight lift and see if the servo can lift the weight. He starts at a lower weight and increases it until the servo stalls. It's an interesting technical exercise but I'm not sure how much it all means to most of us. When I perform the "lawn dart" maneuver, its not due to servo problems.
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Old 10-12-2004, 12:23 PM
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Default RE: Did i just kill my servo??????

i was just tryin to get a hands on feel ^^
i opened up the gear box and as far as i could see all the gears had there teeth, took me ages to get it baq together tho!!
By kink at a certain point i mean, the resistance to being turned manually increases rapidly, then quickly drops off at a certain point.
Strange'ness yo~!

Mike
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