Best and economic servos for Shock Flyer F3A

Ted shuffled out of his cave and grunted these great (and sometimes not so great) words of knowledge:

Check out the Blue Bird servos.

I use them almost exclusively now. I have not had any problems and, IMHO, they are a great buy for the money - very compact and powerful. For instance, a

50 oz torque (4.8 volts) metal gear servo that is about 2/3 the size of a HiTec 85 for less than $20 I run these in my Freedom 3D with a Mega motor, 16x10 prop and 10 cells 3300 nimh. They have smaller (also less powerful ) servos that are less money also.

Hi Ted, I was checking out the Bluebirds and saw this warning: "WARNING: Using the servo arm to turn the servo motor may cause the gears to break or jump and the servo will stop functioning correctly. This is true for all servos regardless of servo manufacturer. Balsa Products assumes no responsibility once this kind of damage. This can also occur as a result of crash damage or hard landing. Once you install and use a servo Balsa Products assumes no responsibility any damages that may occur."

The price is right but could the gear material be inferior? I know it's not a good idea but I don't recall seeing the warning on JR, Hitec, or FMA servos??

That is a general rule with all servos. They have simply reduced it to writing. I have some of these servos and they're tough little buggers! I don't think for a minute that there is anything inferior about the gear material.

>>

Ed,

That's true for ANY servo. The motor itself has very little torque. It's multiplied by the gear train to the output arm. When you twist on the arm, the opposite happens. The torque you apply is DIVIDED by the gear train, so in order to move the motor, you need to apply a tremendous amount of torque, sometimes more than the gear train can take.

The tiniest servos are the worst for this.

in article K snipped-for-privacy@giganews.com, Ed Forsythe at snipped-for-privacy@hotmail.com wrote on 3/7/05 8:41 AM:

I've read it's not good to do this for *any* micro servo. The gears are smaller/lighter and can be stripped easier. Kudos to Balsa Products for the heads up.

Morris

OK Guys, I'm afraid I must disagree.. I've been turning servos to aid in installation, adjustments, or even to check for broken teeth for years. You must be aware that they are is attached to a gear train and apply just enough force (gradually) to start movement. A micro gear train is by definition more fragile than a larger servo *but* it will take significantly less force to move it. To verify my suspicion that the quality of the Blue Birds may not be up to par I called FMA and asked if there was any concern about moving *any* of their servos manually. The answer was "No we do it all the time, that's how we set the throws on our digital servos." Then I called the JR troops at Horizon and asked the same question. The answer was "you really should make your adjustments at the clevis or subtrims but you won't damage the servo by moving it manually." He further explained that you should know what you're doing (my words) and apply reasonable force. The last sentence in the HoB disclaimer is "Once you install and use a servo Balsa Products assumes no responsibility any damages that may occur." To me that indicates that no matter what goes wrong with the servo they are off the hook. IMHO, they may have had problems with returns because of stripped gears. Cheap can be just as good (rarely) but in this case I think "You get what you pay for." is appropriate. That's my story and I'm stickin' to it ;-)

Gad, I want to wince, cringe, and avert my eyes every time I see someone back-driving a servo, though I realize it's routinely done all the time.. like running a transmitter with the antenna collapsed. It's brutal on the final gear in the servo, and brutal on the output device in the Tx, but apparently incurs no damage.

Bill(oldcoot)

| It's brutal on the final gear in the servo, and brutal on | the output device in the Tx, but apparently incurs no damage.

Oh, it's not that brutal on the final stage of the TX. After all, it's only 250 or so mW tops that's being absorbed by the finals. And the manufacturers make sure it can easily dissapate this much energy for hours at a time -- otherwise they'd get lots of warranty returns.

Now, your 100 watt ham radio rig ... leaving it on transmit with the antenna not plugged in (or just really really out of tune), the magic smoke will escape very quickly if the radio cannot detect this and turn off.