Material question.

gear cutter said:

Can anyone recommend a grade of steel to make a torsion bar from. It will be approximately 50" long and be splined on both ends. Maybe 1" to 1-1/4" O.D. It will have twisting force put on it but nut much bending or arching over it's length.

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gear cutter said:

Can anyone recommend a grade of steel to make a torsion bar from. It will be approximately 50" long and be splined on both ends. Maybe 1" to 1-1/4" O.D. It will have twisting force put on it but nut much bending or arching over it's length.

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triumph406 said:

What's the torsional stress?

Choose a steel that has a greater torsional yield strength than req'd + safety factor (1.5-2.0)

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gear cutter said:

How would I calculate torsional stress?

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Erich said:

1. Get mechanical engineering degree.
2. Contract with an ME to do the design work for you.

If you can't calculate the stress how do you know what diameter to make the bar? Or choose the correct material?
Do you have any idea how to size the bar to get the spring rate you need for the application?
"A man's gotta know his limitations" Harry Callahan

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Rigor said:

Wow.....you're a lot of help.

Instead of guiding him, you push him off the edge of a cliff.

Torsional stress= length of lever(inch) x weight. So 12 inch lever multiply's the weight at the fulcrum 12 times (Torsional stress) if bar is placed at pivot of lever.
t......

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Erich said:

If you are going to help at least get it right. You described Torque.
Stress refers to whats going on inside the shaft. It captures the effect of shaft diameter.

Max Shear stress= Torque*Radius/J J is the torsional moment of inertia. For a solid round bar it is PI*D^4/32

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Rigor said:

Wow.....you're a lot of help.

Instead of guiding him, you push him off the edge of a cliff.

There are thousands of variables that can affect the size or type of steel needed. You failed to mention how it will be used. Is it attached at the pivot point of a lever or slightly offset?....how much weight on the lever, in static and in a dynamic state. What is the length of the lever???
What are the constraints you have to work with?
Torsional stress= length of lever(inch) x weight. So 12 inch lever multiply's the weight at the fulcrum 12 times (Torsional stress) if bar is placed at pivot of lever.
People here would gladly help you if only you would give them a fighting chance, by giving them some specifics.

Oh and BTW, There are many free online calculators.
Good luck with your project......

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NAST555 said:

EN19 T or EN24 T dependent on the application. Make sure it's condition T. Not sure what your equivalent there would be.

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