THE ENGINEERING REFERENCE LIBRARY

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Drill diameters, thread pitches, clearance holes, fastener tooling and sheet-metal inserts—organized around the dimension you need to check.

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Practical references for engineering, machining and manufacturing.
TECHNICAL REFERENCE SERIES 01 — 04
01 / LOOK UP

Start with the operation and hardware family, then confirm the standard, fit class, tolerance and manufacturer specification before releasing production work.

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DIRECT REFERENCE LINKS

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Hole & drill sizes

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Drill diametersDrill bit size chartFractional, number, letter and metric drill diameter reference.1/4 in = 6.35 mmOpen reference Hole clearanceClearance hole size chartCheck metric and inch fastener clearance classes.Fine · Medium · CoarseOpen reference

Threads & tapping

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Tap drill selectionTap drill size chartCutting and forming tap starting holes for metric, UNC and UNF.Cutting ≠ formingOpen reference Thread pitchMetric thread pitch chartCoarse and selected fine pitch series for ISO metric threads.M10 × 1.5Open reference

Fasteners & sockets

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Fastener toolingBolt wrench & socket sizeNominal hex head across-flats size by fastener family.ISO · ASMEOpen reference

Sheet-metal hardware

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Clinching hardwareSelf-clinching hardware holesHole sizes and minimum sheet requirements for PEM SP nuts.PEM SP onlyOpen reference Rivet nutsRivet nut installation holesManufacturer-specific hole and grip ranges for Avdel 9658.Avdel 9658 onlyOpen reference

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