Standards & Technical Documentation
Complete reference guide to international screw thread specifications, mathematical calculation formulas, and engineering data sources.
Computational Methodology & Data Verification
The Fasteners Standards computation engine utilizes a dual-layer approach combining exact digitized table lookups for nominal series dimensions with rigorous dynamic formula evaluation for tolerance limits and deviations:
Exact Standard Table Lookups
Standard pitch and diameter pairings, designation strings, and preferred choices are queried directly from the digitized catalogs of ISO 261 and ASME B1.1.
Dynamic Tolerancing Formulas
Pitch diameter tolerances (Td2, TD2), fundamental deviations (es, EI), and crest/root limits are calculated dynamically using the exact mathematical formulas specified in ISO 965-1 (Section 5) and ASME B1.1 (Section 8).
ISO Metric Standards (ISO 68-1, 261, 965, 5855)
International Organization for Standardization • 60° Symmetric Flank Angle
ISO 68-1:1998
Second EditionBasic Profile — Metric Screw Threads
Specifies the basic profile for ISO general-purpose metric screw threads with a nominal 60-degree included flank angle.
ISO 261:1998
Second EditionGeneral Plan for Metric Coarse & Fine Series
Defines the standard selection of nominal diameters (from 1 mm to 300 mm) and associated pitch combinations across first, second, and third choice series.
ISO 965-1:2013
Fourth EditionTolerances — Principles and Basic Data
Specifies fundamental deviations (e, f, g, h for external; G, H for internal) and tolerance grades (4 to 8) for pitch, major, and minor diameters.
ISO 965-2:1998
Third EditionLimits of Sizes for General Purpose External & Internal Threads
Provides exact dimensional limits for commercial quality tolerance classes, including the standard commercial fit (6H / 6g).
ISO 5855-1:1999
Third EditionAerospace — MJ Threads
Defines metric MJ threads with enlarged root radiuses (0.150P to 0.180P) engineered for high-fatigue aerospace fasteners and airframe components.
ASME Standards (Unified Inch, ACME, Stub ACME)
American Society of Mechanical Engineers • 60° Unified & 29° Trapezoidal Profiles
ASME B1.1-2019
Standard RevisionUnified Inch Screw Threads (UN, UNR, UNC, UNF, UNEF)
Covers geometry, limits of size, and tolerances for 60-degree Unified Inch screw threads across standard classes: 1A/1B (loose), 2A/2B (commercial), and 3A/3B (precision).
ASME B1.5-1997 (R2014)
Reaffirmed 2014ACME Screw Threads (29° Flank Angle)
Specifies 29-degree trapezoidal power transmission threads for leadscrews, jacks, and linear actuators. Covers General Purpose (2G, 3G, 4G, 5G) and Centralizing (2C, 3C, 4C, 5C) classes.
ASME B1.8-1988 (R2016)
Reaffirmed 2016Stub ACME Screw Threads
Specifies low-clearance 29-degree trapezoidal threads with approximately 42% reduced depth. Ideal for thin-walled tubing, structural spatial constraints, and high core shaft stiffness.
ASME B1.13M-2005 (R2020)
Reaffirmed 2020Metric Screw Threads: M Profile
American national standard governing metric screw threads conforming geometrically to ISO 68-1 and ISO 261 standards.
Key Geometric Equations (60° V-Profile)
Fundamental Triangle Height: H = P × (√3 / 2) ≈ 0.866025 × P
Pitch Diameter (d2, D2): d2 = d - 2 × (3/8 H) = d - 0.649519 × P
Minor Diameter (d1, D1): d1 = d - 2 × (5/8 H) = d - 1.082532 × P
Tensile Stress Area (At): At = (π / 4) × [ (d2 + d1) / 2 ]² ≈ 0.7854 × (d - 0.9382P)²
Tap Drill Hole (Cut Tap): D_drill = Nominal Diameter - Pitch
SolidWorks Thread Profiles (.SLDLFP)
Our downloadable SolidWorks Thread Profiles (.SLDLFP Library Feature Parts) are modeled strictly around the crest and root truncation boundaries defined in ISO 965 and ASME B1.1. They enable accurate 3D helical sweeps for additive manufacturing, CAM toolpath generation, and finite element stress modeling.
Legal, Trademark & Manufacturing Disclaimer
The technical documentation, formulas, and data provided by Fasteners Standards are for educational, engineering design, and reference purposes only. While every effort has been made to ensure rigorous mathematical fidelity to ISO and ASME standards, this platform should not replace verified engineering sign-offs. Users are strictly advised to consult official, authoritative publications from ISO and ASME before physical CNC machining, aerospace fabrication, or structural assembly. The operators assume no liability for errors, omissions, or physical manufacturing discrepancies.
Trademark & Non-Affiliation Notice: ISO is a trademark of the International Organization for Standardization. ASME is a registered trademark of the American Society of Mechanical Engineers. SOLIDWORKS® is a registered trademark of Dassault Systèmes SolidWorks Corp. Fasteners Standards is an independent technical engineering resource and is NOT affiliated with, endorsed by, or sponsored by ISO, ASME, or Dassault Systèmes.
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