Machining

Drill Size Chart — Fractional, Letter, Number & Metric (Master Reference)

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The Complete Drill Size Reference Why does this chart exist? Because someone at some point decided that drill bits should come in four completely different naming systems — fractional inches, letter sizes (A–Z), number/gauge sizes (#1–#97), and metric. And engineers need to convert between all of them constantly. This master chart lists all standard drill … Read more

Surface Finish Guide for Machined Parts — Ra Values & Specifications

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Why Surface Finish Matters Surface finish (or surface roughness) describes the texture of a machined surface. It affects sealing, wear, fatigue life, coating adhesion, and appearance. If you’re designing parts that mate, seal, or slide against each other, you need to specify surface finish on your drawing. Common Surface Finish Values Ra (µin) Ra (µm) … Read more