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Old 08-05-2003 | 08:23 PM
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squareloop
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From: BLUE, HI,
Default Servo torque (physics question)

Originally posted by mglavin

Lets see some numbers. I have a 100oz-in torque rated servo with a 1" arm.

.75" servo arm nets 133ozs of FORCE
1.0" servo arm nets 100ozs
1.25" servo arm nets 80ozs

.75"SA x .75"CA nets 100oz-in
.75"SA x 1.0"CA nets 133oz-in
.75"SA x 1.25"CA nets 166oz-in
1.0"SA x .75"CA nets 75oz-in
1.0SA x 1.0"SA nets 100oz-in
1.0"SA x 1.25"CA nets 125oz-in
1.25"SA x 1.25"CA nets 100oz-in
1.25"SA x 1.5"CA nets 120oz-in

Then there is this thing known as the Final Ratio...
So the net torque is what is important. I didn't realize that at .75" at both arms would net less torque. Force is gained going in on the servo arm but where it's attached on the control arm is of great significance. Now if I can only remember when to divide and when to multiply the variables in the equation!

Mike (re: surface deflection), using the spreadsheet I plug in 1" at both arms to get a certain deflection of the surface. Then I plug in .75" (or any other number) at both arms and still get the same deflection (?). I had to check because I'm picturing in my mind that the deflection shouldn't change as long as the (D)istance from the pivot points are identical. Am I missing something here? (not a first!)