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Technical Information

Technical Information
  1. General Data
  2. Specifications
  3. UN UNS UNC UNF UNEF Series Gages
  4. Cylindrical Plain Gages
  5. Metric Series Gages
  6. National Pipe Thread Gages
  7. Variable Style Gages
  8. Threaded Hole Centerline Location Gages
  9. British Standard Gages
  10. Medical Luer Fittings Gages
  11. Step Pin Gage Design Page
  12. Articles about threads mostly written by others
  13. Thread Data Charts
  14. ACME Screw Threads
  15. API American Petroleum Institute

General Data

  1. American Gage Design (AGD) Standardized Components
  2. Dynamics of Gauging
  3. Calibration/Recalibration Frequency Intervals
  4. Certification of Conformance vs. Long Form Certification
  5. Deep Hole Thread Measurement
  6. Gage Care Maintenance and Storage
  7. GO does not GO and NOGO does GO
  8. Minor and Major Diameter Questions
  9. Pitch Diameter
  10. Questions with no specific category
  11. Ring Gage Adjusting
  12. Ring Gage Calibration by Direct Measurement
  13. Ring Gage Solid vs Adjustable Styles
  14. Sealing Wax
  15. Set Plug Tolerances
  16. Set Plug Usage
  17. Terminology Related to Nuts and Bolts
  18. Thread Gauging Reference Guide
  19. User's Manuals for Variable Thread Measurement Systems
  20. Why Gages Grow
  21. Out of Business and/or Sold Screw Thread Gage Makers


  1. Authorized Resellers List
  2. A-A 59158 (STI) Unified Screw Thread Inserts
  3. AS8879 (ANSI/ASME/SAE) J-series
  4. AS71051 (ANSI/ASME/SAE) ANPT-series
  5. B1.1 (ANSI/ASME) UN-series part threads
  6. B1.2 (ANSI/ASME) UN-series thread gages
  7. B1.5 (ANSI/ASME) ACME Screw Threads
  8. B1.7M (ANSI/ASME) Screw thread nomenclature and letter symbols
  9. B1.8 (ANSI/ASME) Stub ACME Screw Threads
  10. B1.9 (ANSI/ASME) Buttress Screw Threads
  11. B1.10 (ANSI/ASME) Miniature Screw Threads
  12. B1.11 (ANSI/ASME) Microscope Objective Screw Threads
  13. B1.12 (ANSI/ASME) Interference-Fit Screw Threads
  14. B1.13M (ANSI/ASME) M-series Metric Screw Threads
  15. B1.16M (ANSI/ASME) M-series Metric Screw Thread Gages
  16. B1.20.1 (ANSI/ASME) American General Purpose Pipe Screw Threads - Parts and Gages
  17. B1.20.2M (ANSI/ASME) American General Purpose Pipe Screw Threads - Parts and Gauges (metric version)
  18. B1.20.3 (ANSI/ASME) Dry Seal Pipe Screw Threads
  19. B1.20.4 (ANSI/ASME) Dry Seal Pipe Screw Threads (metric version)
  20. B1.20.5 (ANSI/ASME) Dry Seal Pipe Screw Thread Gages
  21. B1.20.6M (ANSI/ASME) Dry Seal Pipe Screw Thread Gages (metric version)
  22. B1.20.7 (ANSI/ASME) Hose Connection Screw Threads
  23. B1.21M (ANSI/ASME) MJ-series Screw Threads
  24. B1.22M (ANSI/ASME) MJ-series Screw Thread Gages
  25. B107.17M (ANSI/ASME) Hex Wrench Opening Gages
  26. BS-21 R-series British Standard Pipe Tapered (BSPT)
  27. BS-93 BA-series British Association Screw Threads
  28. BS-919-3 Screw gauge limits and tolerances - Part 3: Specification for gauges for screw threads of ISO metric form
  29. BS-1580-1 Unified Screw Threads; Part 1; 1/4" and larger
  30. BS-1580-2 obsolete
  31. BS-1580-3 Unified Screw Threads; Part 3; smaller than 1/4"
  32. BS-2779 obsolete
  33. C81.61 (ANSI/ANSLG) Electric Lamp Bases
  34. C81.62 (ANSI/ANSLG) Electric Lamp Holders
  35. C81.63 (ANSI/ANSLG) Electric Lamp Bases and Lampholders
  36. C81.64 (ANSI/ANSLG) Guidelines and General Information for Electric Lamp Bases, Lampholders, and Gauges
  37. DIN 405 Rd-series Knuckle Screw Threads for General-purpose
  38. DIN 420 Whitworth Screw Threads (same as BS-84)
  39. DIN 513 S-Series 3°/30° Metric Buttress Screw Threads
  40. DIN-2999 withdrawn
  41. DIN-6063-1 Threads, mainly for plastic containers - Part 1: Buttress threads, dimensions
  42. DIN 15403 Rd-series Knuckle Threads for Lifting Hooks for Hoists
  43. DIN 20400 Rd-series Knuckle Threads for the Mining, Threads with Large Load-Bearing Depth
  44. DIN 40430 Pg-series Steel Conduit Thread
  45. EN 1707 Luer Connections for Needles and Syringes
  46. EN 10226-1 British Standard Pipe (R-external to Rp-internal)
  47. EN 10226-2 British Standard Pipe (R-external to Rc-internal)
  48. EN 10226-3 R-series British Standard Pipe Gages
  49. EN 10241 Steel Threaded Pipe Fittings DN6 to DN150
  50. EN 13544-2 Respiratory Therapy Tubing and Connectors
  51. EN 20594-1 Luer Connections for Needles and Syringes
  52. GB 8335 Chinese Gas Cylinder Neck and Valve
  53. HIMA MD 70.1 expired
  54. ISO-7-1 R-series British Standard Pipe Screw Threads
  55. ISO-7-2 R-series British Standard Pipe Screw Thread Gages
  56. ISO-228 G-series British Standard Pipe Screw Threads
  57. ISO-594/1 Withdrawn in 2016.
  58. ISO-594/2 Withdrawn in 2016.
  59. ISO-2853 Stainless Steel Threaded Couplings for the Food Industry
  60. ISO-5145 Cylinder Valve Outlets for Gases and Gas Mixtures
  61. ISO-5356-1 Anesthetic and Respiratory Equipment – Conical Connectors
  62. ISO-5408 Screw Thread Vocabulary
  63. ISO-8185 Humidifiers for Medical Use
  64. ISO-8637-1 Extracorporeal Systems for Blood Purification
  65. ISO-8637-2 Extracorporeal Systems for Blood Purification
  66. ISO-8638 Withdrawn in 2018.
  67. ISO-18250-1 Medical Reservoirs
  68. ISO-18250-3 Enteral Reservoirs
  69. ISO-80369-1 Medical Small-Bore Connectors
  70. ISO-80369-3 Enteral Connectors
  71. ISO-80369-6 Neuraxial Connectors
  72. ISO-80369-7 Connectors with 6% (Luer) taper for intravascular or hypodermic applications
  73. ISO-80369-20 Common Test Methods for ISO 80369
  74. MIL-S-7742 and How It Relates to Thread Gages
  75. MIL-S-8879 obsolete J-series
  76. MIL-T-21309 obsolete Screw Thread Inserts (STI)
  77. SAE Numbering Paradigm
  78. Unified National Thread: ANSI vs. BS vs. ISO vs. JIS
  79. V-1 (ANSI/ASME/CGA) Compressed Gas Cylinder Valve Outlet and Inlet Connections

UN Series Gages

  1. 2AG Class-of-Fit
  2. 3BG Class-of-Fit
  3. Controlled Root Radius on External Screw Threads
  4. Controlled Root Radius on Internal Screw Threads
  5. N vs. UN
  6. STI Gage Before or After Inserted
  7. STI Gage Class-of-Fit
  8. STI Gage Tolerances
  9. Unified National Thread: ANSI vs. BS vs. ISO vs. JIS
  10. UN vs. UNC vs. UNF vs. UNEF vs. UNS
  11. UNJ vs. UN
  12. UNR vs. UN

Cylindrical or Plain Gages

  1. Gage Maker's Tolerance Calculator and Charts
  2. GO or NOGO or Master
  3. Nominal Size

Metric Series Gages

  1. Pitch Diameter Charts
  2. STI Gage Before or After Inserted
  3. STI Gage Class-of-Fit
  4. STI Gage Tolerances

National Pipe Thread Gages

  1. Designations of American National Pipe Types
  2. Before Plate NPT Gages (National Pipe Taper)
  3. Calibrate NPT-L1 Work Plug Gage using NPT Master Ring Gage
  4. Calibrate NPT-L1 Work Ring Gage using NPT Master Plug Gage
  5. Calibrate NPTF-L1 Work Plug Gage using NPTF Master Ring Gage
  6. Gages: Pipe Plug
  7. Gages: Pipe Ring
  8. How many steps should a Pipe Gage have?
  9. How to Use: NPT; ANPT; NPTF
  10. NPSF into NPTF (Dry Seal Combination)
  11. NPT vs. ANPT (Aeronautical National Pipe Taper)
  12. NPT vs. NGT (National Gas Taper)
  13. NPT vs. NPTF (National Pipe Taper Fuel)

Variable Style Gages

  1. MTG Catalog
  2. Snap Gages, Threaded, Knife Edge Style, Maintenance
  3. Starrett no longer sells thread comparators
  4. Starrett Technical Info
  5. User's Manuals for Variable Thread Measurement Systems
  6. Why Use Thread Snap Gages

Threaded Hole Centerline Location Gages

  1. Overview
  2. Flexible Style
  3. Solid Style
  4. Tapered Style
  5. Lead Lock Style
  6. Variable Style

British Standard Gages

  1. BS-2779
  2. BS-21
  3. BS-21 Rp into R (Dry Seal Combination)
  4. BS-21 System A vs. System B
  5. DIN-2999
  6. EN-10226
  7. Gage Certifications do NOT Match the Gage Specification.
  8. ISO-7
  9. ISO-7 Rp into R (Dry Seal Combination)
  10. ISO-228
  11. ISO-228 Class A vs. Class B
  12. Rp vs. G
  13. Rs vs. G
  14. Full Form vs. Truncated or Modified
  15. ISO-7 vs. BS-21
  16. Designations of British Screw Thread Types
  17. DIN-240-1923 vs BS-84
  18. Whitworth Thread Form

Articles about threads mostly written by others

  1. Hot glue, the new sealing wax.
  2. JIS (Japanese Industrial Standard) Screw Thread Specifications
  3. Are You Beating Your Gages to Death?
  4. Screw Thread Design
  5. Cut costs on UNR threads.

ACME Screw Threads

  1. The World of ACME Screw Threads
  2. Centralizing ACME Screw Threads
  3. General Purpose ACME Screw Threads
  4. Stub ACME Screw Threads
API American Petroleum Institute
  1. API Home Page
  2. BTC Buttress Casing per API Spec 5B
  3. CSG Round Casing per API Spec 5B
  4. LP Line Pipe per API Spec 5B
  5. NC Numbered Connections per API Spec 7-2
  6. NU Non-Upset Tubing per API Spec 5B
  7. TBG (EU/EUE/EUT) External Upset Tubing per API Spec 5
This website is funded by the sale of screw thread measurement tools. It will help us continue to offer this data if you allow us to have the opportunity to sell our tools to your company. If you find this information useful, please work to get Gage Crib Worldwide Inc. on the bid list for future purchases of screw thread measurement tools.
This data is provided for general information only. The intention is to provide accurate information; regardless; errors may exist in the supplied information. If accuracy is critical, base your final decisions on the data provided in the official industrial specificaions; which are copyrighted documents. To purchase copies visit an Authorized Reseller.
Original Posting: 1/10/1999
Last Revision: 10/20/2020
Error corrections in, or comments about, the above data can be sent to: office@gagecrib.com
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Gage Crib Worldwide, Inc.
6701 Old 28th St SE, Suite B
Grand Rapids, MI 49546-6937
Phone: 001-616-954-6581 • Fax: 001-616-954-6583

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