Open Tools · Mechanical, machine design
Gearsmith: free online machine-element design calculator
Gearsmith is a set of machine-element design calculators on one screen: pick a module, edit the inputs and read the safety factors as you type. It covers spur and helical gears, shaft stress and fatigue, shaft deflection and critical speed, rolling-bearing life, helical compression springs, bolted joints, fillet weld groups, and press fits and keys.
Every method states its source, every chart-based input is tagged so you know what you must supply, and the tool lists what it does not do. Results run in your browser, with a printable report and CSV export.
What Gearsmith can do
- Spur and helical gear stress and safety factors
- Shaft stress, fatigue, deflection and critical speed
- Rolling-bearing life and spring design
- Bolted joints and fillet weld groups
- Press fits and keys
- SI and US units, printable report and CSV export
How we verify Gearsmith
Gearsmith is checked against 197 independent reference cases. Where a reference answer exists you can run every check yourself on the Verify page, and the Gearsmith user guide documents every feature and limitation.
The separate Python generator includes same-formula recomputations of Kv, Km, Marin, beam and spring fits. These check implementation agreement and are not independent validation. Independent routes include integrated frustum compliance and weld properties, displacement compatibility for press fits, hand-derived boundary cases and bisection of fatigue intersections. Confirmed manufacturer values are identified by source. Unconfirmed tables and worked examples remain PENDING SOURCE with no reference value.
Gearsmith is part of Open Tools, the free engineering tools that run in your browser.
Professional use. Results are for education and preliminary design. They must be checked by a qualified professional, and they are not a substitute for code-compliant design or licensed engineering judgement.