How does using a high strength shaft vs a regular shaft affect power and speed of a mechanism?

So I want to use a high-strength shaft for its, of course, strength. However, I’m at a loss for understanding how the thickness of it affects the power or speed of something. Example: you put a gear on the high strength shaft and turn it with a motor. Will it turn slower or faster with more or less power than compared to a regular shaft? And more importantly, why? What is the mathematical explanation behind it?

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Not sure about speed. However, if you were to try to lift a heavy object with a normal shaft, it would turn into a twizzler shaft(search it up on the forum.) On the other hand, a high strength shaft would be able to support it. Think about it like if you tried to break a pencil versus if you tried to break a tree.


That is because it does not. A HS shaft doesn’t have any more power, torque, or speed than a LS shaft. In fact, a HS shaft might even give you less power, as it is harder to get low friction on a HS shaft than a LS shaft. The benefit of a HS shaft is that it will have a significantly harder time twisting or bending. Under high torque loads, a LS shaft can bend or twist. A HS shaft will almost never do this.


Perfect. This is exactly what I needed.

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Only one small addition to what @9MotorGang said is that the extra weight of it might affect the acceleration of the mechanism ever so slightly. This difference is pretty small because the shaft will be at the axis of rotation, and really isn’t necessary to account for.

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To my knowledge, I have not seen significant real world differences between the two other than 1/8" shafts being more prone to bending. Mathematically speaking, the high strength shaft is actually carries more mechanical advantage than a regular 1/8" shaft. When a shaft drives a wheel, the IMA (ideal mechanical advantage) is always less than 1. However, you are effectively doubling your IMA by using a high strength shaft because it is twice the radius of the 1/8" shaft. This would explain why it is commonly used in applications where there are large loads. You don’t typically use them on something like a drivetrain because it adds a lot of unnecessary weight for something that can be accomplished with a 1/8" shaft.