Shelle Parsons Ohm’s Law: V = IR Ohm’s Law is to electrical engineering what F = ma is to mechanical. Three variables, one equation, and an enormous amount of practical power. What It Means V — Voltage (volts, V) — the “pressure” pushing electrons through a circuit I — Current (amps, A) — the flow rate of … Read more
Newton’s Second Law: F = ma If there’s one equation that defines mechanical engineering, it’s F = ma. Force equals mass times acceleration. It sounds simple — and it is — but its implications reach into every corner of engineering, from sizing a motor to designing a bridge. What It Means A force is what … Read more
GD&T Reference Guide (ASME Y14.5) Geometric Dimensioning and Tolerancing symbols and definitions. 1. FORM (No Datums) Symbol Name & Definition Straightness: 2D straightness of a line element. Flatness: Surface must lie between two parallel planes. Circularity: Roundness of a 2D cross-section. Cylindricity: Roundness + Straightness of a 3D cylinder. 2. ORIENTATION (Datums Required) Symbol Name … Read more
Imperial Bolt Strength Chart (SAE & ASTM) Standard strength ratings for carbon and alloy steel bolts up to 1″ diameter. These are the grades you’ll encounter on 99% of US engineering drawings. Grade Head Marking Material Proof (psi) Yield (psi) Tensile (psi) SAE Grade 2 No markings Low carbon steel 55,000 57,000 74,000 SAE Grade … Read more
What is ISO 286? ISO 286 defines the system of limits and fits for holes and shafts. If you’ve ever seen a callout like H7/g6 on a drawing and wondered what it actually means, this is your guide. The metric system uses a code-based approach instead of explicit ± tolerances. Once you understand the logic, … Read more
What’s the Difference? Cutting taps and form taps both create internal threads, but they do it in completely different ways — and they require different drill sizes. Confusing the two is one of the most common (and costly) mistakes on a shop floor. Cutting Taps (Chip-Producing) Cutting taps work exactly like you’d expect: they have … Read more
Common Structural Steel Shapes Structural steel comes in standardized shapes that are designed for efficient load-carrying. Here are the dimensions and properties for the shapes you’ll encounter most in machine design, fabrication, and construction. Steel Angle (L-shapes) Size (legs × thickness) Weight (lb/ft) Area (in²) Ix (in⁴) Iy (in⁴) L1×1×1/8 0.80 0.234 0.022 0.022 L1-1/2×1-1/2×1/8 … Read more
Retaining Ring (Snap Ring) Reference Retaining rings hold components on shafts or in bores without threads, pins, or adhesives. They sit in a machined groove and provide a shoulder. The two main types are external (on a shaft) and internal (in a bore). External Retaining Rings (Shaft Rings) Shaft Ø (in) Ring Thickness (in) Groove … Read more
What is Stress Concentration? Every time a part changes cross-section — a shoulder on a shaft, a hole in a plate, a groove for a retaining ring — stress multiplies at the transition. The stress concentration factor (Kt) tells you how much higher the local stress is compared to the nominal stress. Actual peak stress … Read more
Quick Metric ↔ Inch Conversion This chart covers the conversions you’ll use most often — common metric sizes and their nearest fractional inch equivalents. Perfect for when you’re working with mixed-unit drawings or trying to find the closest standard tool size. Millimeters to Inches — Common Sizes mm Decimal (in) Nearest Fraction Notes 1 0.0394 … Read more