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API 7-2 Second Addition

Companies working to the latest API 7-2 standard had until JUne 6 2017 to comply with the latest specification. Gagemaker, a leading developer and manufacture of precision mechanical inspection equipment for the Oilfield, Mining, Water Well, and General Machining industries has highlighted some key points below.

Requirements of indicator resolution have been updated for all lead, height, and taper gages. (API 7.4.1, 7.5.2, 7.6*) Now gages with
alternate indicators may not meet the new API requirements and must be replaced. Gagemaker recommends that you check your gages ASAP. Gagemaker has compiled a complete list of indicators and their compliant replacements at

  • New Bevel Diameters
  • Tables for connection bevel diameters have changed. (5.2.2)
  • Drawings Require New Angles All RSC box drawings now require a 30°max back-of-the-box angle. (6.3.3 Fig 10)

New Emphasis on the Effects of Lead Error.
The effects of lead error on standoff and pitch diameter can no longer be ignored. Greater emphasis has been placed on mandatory lead inspection. (7.2.1)

Gap on Hand-tight Parts Allowed If all of your element inspections are within tolerance, a gap between shoulders is allowed when parts are made-up hand-tight. (7.2.3 Fig. 14)

* API (American Petroleum Institute) maintains 685 standards and recommended practices. Many have been incorporated into state and federal regulations; as well as adopted by the International Organization for Standardization.

Thread Check Inc. is an authorized distributor for all Gagemaker products.

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Thread Check Inc., Achieves New ISO 9001:2015 Certification

Thread Check Inc. is pleased to announce today that it has earned certification for the new ISO 9001:2015 standard. The comprehensive system audits covered every aspect of operations.

Thread Check is an industry leader in gaging and measuring instruments.

Any company that has been through the certification process knows that achieving ISO 9001 certification is demanding. Each individual in our operations must be wholly dedicated to the pursuit of quality. By scrutinizing our enterprise at every level, we assure that our customers are receiving superior customer service and the highest quality products.

ISO 9001 is a quality management system standard that was developed by the International Organization for Standardization. ISO is an association of governmental and nongovernmental organizations from many countries. The ISO 9001 standard is utilized to certify quality management systems that focus on continuous improvement, customer satisfaction and the active involvement of both management and employees in a process based approach.

Fulfilling the strict requirements of the ISO 9001 standard highlights our focus and commitment to deliver total customer satisfaction.

To achieve this certification, we demonstrated the management and operational practices to ensure that what we deliver to you adheres to the standards you expect. Our quality management system emphasizes service and support because your satisfaction is important to our business.

To us, ISO 9001 certification is much more than just checking a box. Certification represents our commitment to continuously improving our performance for our customers.

Thread Check Inc.'s customer service team is led by expertly trained sales engineers and supported by some of the industry's most talented manufacturing engineers and gauging experts.

ISO 9001 Certificate

Thread Check Inc.



Thread Check Inc. Introduces Technical Video Series

Video on How to Use Thread Plug Gages

Thread Check Inc. has introduced a technical video series on gaging and measuring instruments. The first 3 videos with cover the basics of how to use thread plug gages, ring gages, and Thread Check's digital thread depth gage. The videos will help in answering the common question the company has received over 30 years. Thread Check plans to release more educational videos in the near future. The videos will assist Thread Check's customers' with gaging and measuring applications. All videos will be available on Thread Check's web site as well as posted to Thread Check's You Tube account. The videos are being produced by Ofer Cohen of Rabbit Foot Productions. Ofer Cohen is an accomplished videographer and independent filmmaker with over 30 years of extensive and diversified experience in global events, travel, adventure, and industrial work.

The first video on How To Use Thread Plug Gages explains the basic thread nomenclature specified on gages and handles and discusses the importance of calibration, handling and storage of the gages. The video provides clear detail on the basics of gauging a part with both the go and the no go gage members.


How to Use Thread Plug Gage Video



Flex Hole Location Gages

Thread Check Flex Hole Location gages

Flex Hole Location Gages by Thread Check Inc.

Flexible hole location plug gages also referred to as centerline hole location plugs are used to determine the true centerline to centerline distances of threaded holes. The flexible hole location gage is slotted at 90° increments to ensure positive location on the thread flanks regardless of hole size. This feature provides a firm locating grip without pulling the shoulder of the plug up against the hole face thus avoiding any squareness error being transferred to the centerline measurement. The center is concentric to the threaded section within .0002” TIR for probe location of coordinate measuring machines as well as plate inspection setups as “overpin” measurements. The flexible hole location gage can also be used with vee blocks to check concentricity to other diameters. Thread Check stocks flexible hole location gages in unified and metric sizes.


  • Positive grip on flanks regardless of hole size.
  • Center is concentric with threaded section within .0002” T.I.R. for probe location of coordinate measuring machines.
  • The .2500 +/- .0001(6.35mm +/- .0025mm) shank is concentric to the threaded section within .0002 T.I.R. prior to slotting and may be used with micrometers or plate inspection setups as “overpin” measurement.
  • Used with vee-block, concentricity checks can be made with other diameters.
  • Sizes #10 (M5 Metric) and smaller are solid tapered thread form from low limit to high
    limit of class 2B pitch diameters.

Gage sets are available. Thread Check’s expert sales engineers can assist you with selecting the correct gages for your application.
Tel:631 231 1515



Thread Check ISO Certification Audit

We are pleased to announce that Thread Check Inc. passed its 2016 ISO 9001:2008 Audit with a perfect score.

ABS Quality Evaluations conducted a full 1 day audit of Thread Check' quality management system. There were no major or minor non conformities found during the audit. This is the 7th year in row with zero nonconformities. This is a testament to our organization's continued commitment to customer satisfaction, employee empowerment and continuous improvement.

I would like to thank and congratulate all of our employees for their commitment to the quality management system.

Thread Check Inc. is now planning on implementing ISO 9001: 2015 for the coming year.


New Thread Check Catalog

Thread Check Inc., is proud to announce the release of our 2016 Precision Gage Solutions catalog with over 180 pages of precision gages, measuring instruments and technical information. Our new catalog is available for download or in an electronic book format for easy use. The new catalog has links to where our customers can shop on line, request quotes and view hundreds of technical articles. Use the table of contents to quickly turn to the product selection of your choice. Use electronic book marks for the pages you visit frequently. The new electronic catalog works across all platforms including tables and smart phones.

Thread Check Catalog 2016 Cover




Root Relief in Thread Ring Gages

All Thread Check Inc. thread ring gages are root relieved for longer gage life and more accurate gaging. Thread ring gages are manufactured with a root clearance in the major diameter which eliminates the possibility of interference from the full form section of the thread setting plug and major diameter of the part being gaged. This critical feature assures that the thread flanks are making proper contact.

Root Relief in Thread Ring Gages


Alternate Size Thread Measuring Wires

It is possible to use standard 60 degree thread measuring wires to calibrate 55 degree British thread plug gages and external product. Thread Check often receives inquiries for special thread measuring wires to calibrate Whitworth/British 55 degree threads. Although Thread Check Inc. can certainly supply these special thread measuring wires, the cost is higher and the lead time to manufacture is typically 4 weeks or more. The best solution is to select a standard 60 degree thread measuring wire which is close to the 55 degree thread measuring wire diameter and simply adjust the constant value. This alternative set of thread measuring wires with an adjusted constant for the 55 degree thread angle will achieve the same exact results. The same method can be applied to 29 degree Acme and 45/7 degree buttress threads.

All “Best Size” thread measuring wires have a maximum and minimum wire diameter that may be used to measure pitch diameter. Maximum and minimum thread measuring wires should be used which are safely within the limiting dimensions given by the formulas below.


Include Thread Angle Max. Best Min.
60° 1.010362p .57735p .505182p
55° .82573p .563692p .50568p
29° Acme .650013p .51645p .487263p

P=pitch  n=TPI   P=1/n

The wide range of standard wire diameters in stock found within the 60 degree inch and metric sizes and the 29 degree acme sizes makes it possible to find a wire diameter very close to a required British or special size. The measurement of pitch diameter is least effected by an error in the included angle of the thread by a wire diameter which is closest to the calculated best size wire.

Related topics regarding thread measuring wires:

Thread Check’s expert sales engineers can assist our customers with selecting the correct wire size and calculating the new constant value to ensure accurate measurements.

Thread Check Inc
900 Marconi Ave
Ronkonkoma, New York 11779
Tel: 800 767 7633



ISO 9001: 2008 Audit Completed

We are pleased to announce that once again Thread Check Inc. passed its 2015 ISO 9001:2008 Audit with another perfect score.

ABS Quality Evaluations conducted a 1 day audit of Thread Check Inc. There were no major or minor non conformities found during the audit. This is the 6th year in row with zero nonconformities. This is a testament to our organization's continued commitment to customer satisfaction, employee empowerment and continuous improvement.

We would like to thank and congratulate all of our employees for their commitment to the quality management system.



Blunt Starts, Higbee Cuts, and Depth Notches

Thread Check can add many custom features to our thread gages such as depth notches, blunt starts, blunt points or chamfers that are
beneficial for several applications including thread depth gaging and short or shallow threads

Blind Hole – A hole that goes partially through a part.


Blunt Point –The removal of a male center point from threads smaller than #6 (M4).
This does not allow the gage to be face ground to within .5P.
This is not a Blunt Start. See Convolution below.


Chamfer – An angle ground on the front of a gage that allows for easier assembly with the mating part


Convolution – Removal of the incomplete thread back to the first full thread. Also
known as a “Blunt Start” or “Higbee Cut” per ASME B1.7 – 2006


Depth Notch – Measure from the centerline of the first full thread to the flat step of the notch.
A depth notch is only used on a go plug gage and is used to measure thread depth.


Grind Face w/in .5P - A convoluted thread plugs face is ground back to the base of
the first full thread. This permits the gage to inspect a blind hole to the bottom of the thread.

Contact Thread Check Inc for more information

800 767 7633 or 631 231 1515