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Showing posts from May, 2009

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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 Calculations Online: Wolfram|Alpha vs. Generative AI

I first wrote about this topic back in 2009. At that time, finding a reliable "computational engine" online was a revelation. Today, while the tools have evolved significantly, the need for quick, accurate engineering calculations remains the same. Advertisement The Classic Powerhouse: Wolfram|Alpha Figure 1: Wolfram|Alpha parsing a natural language query for spring force. Wolfram|Alpha 's long-term goal is to make all systematic knowledge immediately computable and accessible to everyone. Unlike a standard search engine that gives you links, Wolfram|Alpha gives you answers based on structured data and physics formulas. For a mechanical engineer, this is incredibly useful. You can simply type a natural query like: "spring force k=500 N/m x=20mm" And it will instantly compute the result using Hooke's Law ( F = kx ), handling the unit conversions (mm to m) automatically. It serves as a d...
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Numerical Methods - The Newton-Raphson Method (Part 2)

In the previous post , we talked about several root finding techniques. In this post, we're going to see how we can use Microsoft Excel VBA to find the roots using the Newton-Raphson Method. Advertisement Figure 1: The Newton-Raphson method rapidly converges on a solution using the function's derivative. The Logic As we know, the Newton-Raphson Method is the most widely used of all root-locating formulas. It uses the slope ( first derivative ) of the function to find the root. That means, in the VBA code, we have to calculate the first derivative of the function. We already discussed how to find the first derivative using numerical methods , and we will incorporate that logic here. Figure 2: Geometric interpretation: The tangent line points to the next approximate root. The Iterative Formula: The method uses the Taylor series to approximate the next position (x N ) based on the curre...
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Calculate First Derivatives with Numerical Method Using Excel VBA

In the previous post, Numerical Methods - First derivative using Excel formula , we learned how to calculate the first derivative of functions using standard formulas in the spreadsheet grid. While effective, that method can be cumbersome to set up for repeated use. In this post, let's see how we can simplify the process by creating a reusable custom function using Excel VBA (Visual Basic for Applications) . Instead of downloading a pre-made file, follow the steps below to build this powerful tool yourself. Advertisement The VBA Code Solution The following code implements the Five-Point Stencil method for high precision. It defines the mathematical function f(x) and a derivative function fDeriv(x) . Step 1: Open Excel and press Alt+F11 to open the VBA Editor. Step 2: Go to Insert > Module . Step 3: Copy and paste the code below into the module window. ' ================================================ ' Created ...
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