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New · Free engineering tools Spring calculator and shaft power drive sizing. Animated, with charts and PDF export. Open tools →

Why I Wrote The Sheet Mechanic (And Why Calculations Aren’t Enough)

For engineers who already know the math—but still lose projects. For the last few years, I’ve been sharing technical guides here on Mechanical Design Handbook —how to size a motor, how to calculate fits, and (as you recently read) how to choose between timing belts and ball screws. But after 25 years in industrial automation, I realized something uncomfortable: Projects rarely fail because the math was wrong. They fail because: The client changed the scope three times in one week. A critical vendor lied about a shipping date (and no one verified it). The installation technician couldn’t fit a wrench into the gap we designed. University taught us the physics. It didn’t teach us the reality. That gap is why I wrote my new book, The Sheet Mechanic . This is not a textbook. It is a field manual for the messy, political, and chaotic space between the CAD model and the factory floor. It captures the systems I’ve used to survive industrial projec...
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Engineering Tools

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Free calculators for machine designers and automation engineers. Every tool states the equations, the source, and the limits it is valid for, so you can check the result instead of trusting a black box. Nothing is uploaded; the math runs in your browser.

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Calculators

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How these tools are built

  • Named sources. Each tool cites the textbook or standard behind its equations and material data, with table and equation numbers.
  • Stated limits. Each tool lists its assumptions and where the result stops being valid.
  • Checked before release. Each tool's math is tested in code: the spring calculator against Shigley's published worked problems, the drive tool against exact unit definitions and an energy balance.
  • Shareable. Tools with Copy link save the full design in the URL, so you can bookmark it or send it to a colleague.

Results are design estimates. Confirm critical parts with your supplier or a qualified engineer.

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