Shaft Critical Speed Calculator
First whirling speed from static deflection (Rayleigh).
Half a millimetre of rotor sag = 1,340 rpm critical โ a 2-pole motor would sit right on it. Run 30%+ away from critical; turbines deliberately run ABOVE and sprint through it.
Formula
Shaft Critical Speed Calculator is a free critical speed shaft for mechanical and machine-design engineers โ instant, accurate and 100% client-side, with the governing formula and reference shown next to the result so the number can be defended, not just quoted.
About Shaft Critical Speed Calculator
First whirling speed from static deflection (Rayleigh). The calculation implements N_cr โ 946/โฮด(mm) rpm (= 60/2ฯยทโ(g/ฮด)) (Rayleigh; Den Hartog, Mechanical Vibrations). Half a millimetre of rotor sag = 1,340 rpm critical โ a 2-pole motor would sit right on it. Run 30%+ away from critical; turbines deliberately run ABOVE and sprint through it.
How to use Shaft Critical Speed Calculator
- 1Enter Static deflection at mid-span in mm (From beam tools with rotor weight as load).
- 2Read Critical speed, Safe ceiling (รท1.4) instantly โ no submit button needed.
- 3Need US units? Flip the SI/Imperial toggle and every field converts.
Why use Shaft Critical Speed Calculator?
- โImplements the standard formula โ N_cr โ 946/โฮด(mm) rpm (= 60/2ฯยทโ(g/ฮด))
- โReference cited on-page: Rayleigh; Den Hartog, Mechanical Vibrations
- โOne-click SI โ Imperial toggle โ values convert in place, physics stays in SI
- โLive worked example: the substitution recomputes from your numbers
- โRuns entirely in your browser โ nothing uploaded, free forever
Frequently asked questions
What formula does the Shaft Critical Speed Calculator use?+
It computes N_cr โ 946/โฮด(mm) rpm (= 60/2ฯยทโ(g/ฮด)), per Rayleigh; Den Hartog, Mechanical Vibrations. The formula is displayed under the result along with a worked example substituted with your own inputs.
What should I keep in mind when using this calculator?+
Half a millimetre of rotor sag = 1,340 rpm critical โ a 2-pole motor would sit right on it. Run 30%+ away from critical; turbines deliberately run ABOVE and sprint through it.
Is this suitable for machine design coursework?+
Yes โ these are the exact Shigley/Machinery's-Handbook formulas, with the substitution shown step by step, so you can follow the worked example into your own calculation sheet.
Is the Shaft Critical Speed Calculator free to use?+
Yes โ completely free, no sign-up, no limits. It runs client-side in your browser, so inputs stay private and results are instant even on slow connections.
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