In Gage Threadcheck's Official Blog

Go to Threadcheck

Gagemaker offers new and improved MRP 1000 gage models

The Gagemaker MRP-1000 model number was updated / superseded by an improved version of the gage.

The model numbers for the MRP-1000 series now follow the same naming convention as the MRP-2000 series.  MRP-1001 is configured for external measurement, the MRP-1002 is configured for internal measurement, and the MRP-1003 is configured for both internal & external measurement.

In addition, a lifting lever has been added to the pivot arm.  The diameter of the upper and lower arms has both increased from 0.375” to 0.500” for improved resistance to deflection and to enable more travel.  We also upgraded the indicator from an AGD 1 (1” diameter dial) to a standard AGD 2 (2” diameter dial).

Legacy MRP-1000 series upper arms, lower arms, and blocks with a 0.375” hole are no longer available through Gagemaker.  If you require replacement arms for a legacy MRP-1000 gage, you can purchase new 0.500” arms and new blocks with 0.500” holes to accommodate them.  Legacy upper, lower arms and blocks with 0.375” can be procured by contacting us.

Thirty years ago, Gagemaker introduced the MRP® crest diameter and ovality gage which forever changed the industry. Today, the MRP® series of gages is the industry standard worldwide. Whether you call it Crest Diameter, Root Diameter, or Ball PD, Pitch Diameter governs the strength of the actual thread assembly and ensures API dimensional measurement specs are met. (Check out the new carbon fiber MRP AIR.)

The Gagemaker MRP® crest diameter gages measure the internal and external pitch diameters of tapered threaded connections. Any slight variations in diameter or ovality are immediately detected with these precision gages allowing the operator total control over the quality in the threads they are producing . MRP® crest diameter gages are extremely versatile with 3 models that can can easily adjust to measure thread diameters ranging from 1½” – 20”. The ability to inspect and measure a range of internal and external diameters with one gage, eliminates the need for heavy, cumbersome, and expensive fixed limit ring or plug gages.

The gage uses two pivoting shoes that rest on the crests of the threads during inspection. Any variations in pitch diameter detected during inspection are shown on the gage’s indicator.

Gagemaker offers both rod style setting standard and frame style setting standards which can be used to preset the MRP® Crest Diameter Gage.

Thread Check has a team of technical experts that are ready to help you with all your gauging and measurement requirements.

Contact us at  or 800 767 7633


Filed under: Gagemaker No Comments

JSS Tubing and Casing Inspection

Tubing & Casing JSS® Thread Inspection System

Thread Check Inc. offers Gagemaker’s JSS® Tubing & Casing Thread Inspection System which takes the guesswork out of inspecting tubing  and casing. The Gagemaker Tubing & Casing Thread Inspection system inspects all required thread elements – Insert Identification, Thread Form, Crest Diameter & Ovality, Thread Lead, Thread Height, and Thread Taper – all with the precise accuracy required in today’s demanding industry.

  • Optimize performance for tubing and casing.
  • Extend longevity of tubing and casing.
  • Scrutinize all thread elements with greater precision and accuracy.
  • Inspect all types of tubing and casing connectors including API round thread, long thread, short thread, line pipe, and buttress.
  • Protect against mechanical forces such as tension and leakage that tend to destroy tubing & casing connection.
  • Inspect both standard and non-standard connections – all using the same gages.
  • Ensure proper thread interference with pipe and coupling make-up.
  • Pinpoint thread errors that cause expansion of the coupling and compression of the pipe end



Insert Identifiers

The first step in the quality process is to ensure the threading insert being used is correct for the job.
Use the JSS™ Thread Insert Identifier Template to quickly verify that the correct threading insert has been selected as well as check the full topping profile of both internal and external inserts.



Inspection Setup

TDWIN Taper™ is the only software program dedicated to the manufacturing and inspection of downhole tubular connections. It has everything you need to machine, inspect, and document tubular connection threads. TDWIN Taper™ relies on API and industry standard tables and tolerances. TDWIN Taper™ displays connection drawings, inspection gage information, and setup and inspection reports. Simply, it is a must have for any machine shop.

Thread Form

Thread form accuracy is important if two connectors are to make-up properly. Using a JSS Thread Profile Gage and a JSS Thread Addendum Gage provide a quick check of the thread to ensure that the form is correct. Thread form verification ensures form accuracy. Also, checking thread form will ensure the first imperfect thread is fully deburred.
Thread form is defined as its profile in an axial plane for a length of one pitch. Most importantly, verifying thread form is a recommended inspection for API connections and ensures form accuracy.


Thread Lead Inspection

API Mandated Requirement

Thread Lead is one of the most important thread elements to monitor. Not only is lead inspection an industry wide practice for rotary shouldered connections, it is an API mandated requirement. Lead error is most commonly generated by manual and CNC lathes not cutting properly.

Verifying thread lead is within tolerance is a required inspection according to API specification. Application of a Gagemaker Lead Gage to a setting standard and then to the product confirms that the lathe is cutting properly. Lead variation has a direct effect on pitch diameter and how two connectors go together when made up.

Thread lead is the distance between threads, measured on a plane parallel to the centerline of the threaded part. Lead error has a direct effect on functional diameter, stand-off, and thread flank engagement.

Gagemaker’s lead gages inspect pin and box connections for multiple pitches and thread forms. The gages provide dimensional verification of product print data on the thread’s true integrity.

  • Interchangeable contact points allow inspection on a variety of thread forms and sizes.
  • Inspect RSC threads as well as Tubing and Casing threads
  • Requires presetting using Gagemaker’s lead gage setting standards.



Crest Diameter & Ovality Inspection

  • Thirty years ago, Gagemaker introduced the MRP® crest diameter and ovality gage which forever changed the industry. Today, the MRP® series of gages is the industry standard worldwide. Whether you call it Crest Diameter, Root Diameter, or Ball PD, Pitch Diameter governs the strength of the actual thread assembly and ensures API dimensional measurement specs are met. (Check out the new carbon fiber MRP AIR.)
  • The Gagemaker MRP® crest diameter gages measure the internal and external pitch diameters of tapered threaded connections. Any slight variations in diameter or ovality are immediately detected with these precision gages allowing the operator total control over the quality in the threads they are producing. MRP® crest diameter gages are extremely versatile with 3 models that can easily adjust to measure thread diameters ranging from 1½” – 20”. The ability to inspect and measure a range of internal and external diameters with one gage, eliminates the need for heavy, cumbersome, and expensive fixed limit ring or plug gages.

Thread Taper Inspection

API Spec. 5B Mandated Inspection

Tapered threads are a signature feature of API Tubing & Casing connections. Measuring thread taper is not only an industry wide practice, it is an API Specification 5B mandated inspection. During the manufacturing process, taper must be accurately measured and quantified to stay within the required specification limits. When subjected to a service load, taper error on threaded tubing and casing connections can lead to galling, improper fit, and reduced performance.

For the most accurate taper inspection, use Gagemaker taper gages to verify both the threaded pin and coupling meet all customer and industry requirements. Gagemaker’s taper gages are the best choice for measuring and controlling both pin and box taper values.



Thread Height Inspection

API Required Inspection

The correct thread height maximizes the performance of any threaded connection and is a required inspection by the API. Thread height affects both the interchangeability and integrity of a thread assembly. Thread height is the distance between the crest and the root, normal to the axis of the thread.

Gagemaker Thread Height Gages provide immediate feedback on how the thread height compares to the specification requirements. A shallow thread height may allow the connection to pull apart under critical loads.

Inspecting thread height can also help to detect a chipped tool. Gagemaker Thread Height Gages inspect both internal and external thread height for a variety of thread forms and provide immediate feedback on the integrity of your threads.














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.

For more information on Gagemaker instruments please visit

or email us at





STI Thread Plug Gages Manufactured to ASME B18.29.1

STI thread plug gages made to ASME B18.29.1 - Helical Coil Screw Thread Inserts--Free Running and Screw Locking (Inch Series), will have a different no go major diameter than STI thread gages made to MIL-T-211309/A-A-59158.

ASME B18.29.1 does not list tables of gage sizes, but instead states to make the gages per the formula in ASME B1.2.

The major diameter of a no go plug is made to the standard formula of “NoGo P.D. + 0.43301270P.

Since the major diameter of a no go plug gage is only a clearance dimension and does not check anything, either gage standard is correct and completely functional.

For more information on STI thread gage and other types of thread gages, contact or visit



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



Barcor Chamfer Gages

Digital Chamfer Gages

The BARCOR CHAMFER GAGE is a precision instrument specifically designed to measure the top (major) diameter of a chamfer, countersink, center drill, or tapered hole. Just press the spring loaded, conically ground, precision 3-blade Gaging Plunger into the chamfer or countersink and instantly read the dial in .001" or .01mm/.02mm diameter increments.

The BARCOR CHAMFER GAGE is a direct reading instrument. The Barcor Chamfer gage does not require a setting master or standard. To "Zero" the gage or check the setting, press the base of the gage against flat ground surface and adjust the dial to read the "Set To" number stamped on the back.

The CHAMFER GAGE is offered in two angular ranges:

  • 0°-90° for angles of 90° or less,
  • 90° - 127° for angles greater than 90° but less than 127°.
  • Models for angles larger than 127° can be priced on request.

The BARCOR CHAMFER GAGE is supplied with a hardened tool steel gaging plunger. Optional Solid Carbide Gaging Plungers with a LIFETIME wear guarantee are also offered. Other options include .0001" reading Super CHAMFER GAGE, External Models, Micrometer

Models, HALF SIZE Models, Electronic Models with SPC capabilities, Masters with long form calibration traceable to N.I.S.T..

The chamfer gage is ideal for measuring chamfers in piston rings, shaft centers, bushings, stampings, valve seats, rivet seats and tube flares, hydraulic fittings, and screw machine parts.

Thread Check offers over 320 standard chamfer gage models in inch, metric, O.D., solid carbide, and high precision readoutBarcor Inc





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



New Chamfer Gage

Chamfer Gage

Thread Check offers the GSG chamfer gage which is an innovative easy to use gage for accurately measuring chamfers. The indicator features a hard programmed ratio measuring mode which accurately calculates the chamfer size. The instrument includes one digital indicator, 1 collet assembly, 1 attachment housing and 1 thumb ring. Individual anvils and chamfer ring masters are offered in a wide range of standard and custom sizes. 3 Piece chamfer gage sets in 3 lengths and 4 included angle sizes are also available. Anvils are offered in standard sizes of 62°, 92°, 120°, and 135° as well as custom angles priced on request. The lengths include 2.0”, 4.0” and 6.0”.

Chamfer master ring gages are available in A2 steel and carbide. Chamfer master ring gages are supplied in class X tolerance and include a long form calibration report


How to Use Thread Plug Gages

Thread plug gages are very easy to use. The user must first select the correct size thread plug gages for the corresponding externally threaded product. Thread plug gages should be clearly labeled on the handle but also on the gage members when possible. This is obviously critical but sometimes difficult as drawings and specification requirements are frequently missing, incomplete, or incorrect. The user of the thread plug gages should ensure that the correct major diameter, TPI/pitch, Class of fit, and any special pitch diameters are clearly specified.

The user should also confirm that the gages conform to the proper national or international standard. In the USA it is commonly assumed that metric thread plug gages conform to the ANSI/ASME B1.16M but this may not be the case particularly when working with an international customer or a globally recognized company with manufacturing facilities located in the USA and engineering located in Asia or Europe. Other metric standards like ISO or JIS may be required. It is also important to confirm that pitch diameters on the gages match the part specification. For example a part gaged prior to plating will have special pitch diameters. The thread plug gages selected should be engineered and made correctly to the preplate or before plate pitch diameters.

Thread plug gages should be marked with B/P or P/P designation for quick and easy identification. Finally the inspector should confirm the gages are calibrated. It is always advisable to recheck the thread plug gages prior to use regardless of the calibration sticker’s current status. Many companies arbitrarily select annual frequencies of calibration rather than basing frequency on usage. This can be dangerous as thread plug gages can be worn out of tolerance or damaged during the course of a production run. Thread Measuring wires or a 3-Wire Thread Measuring System can accurately measure pitch diameter and confirm the thread plug gage is still within tolerance.

The best thread plug gaging practice utilizes several sets of thread plug gages. One or two gages can be used for in process inspection while another gage can be used for final inspection and a master thread plug gage retained for dispute in the event that gages fail to correlate on acceptance or rejection.AGD thread plug gages are designed with a chip groove for sizes above .164” (#8). The chip grooves purpose is to clean the threads of the work piece but it should really not be relied on. It is highly recommended that the work piece be as clean and burr free as possible to reduce friction and wear on the gage. A clean thread prior to gaging will provide the inspector with more sensitivity of thread fit.

Thread plug gages should be cleaned with solvent or air and then frequently recoated with a rust preventative/gage preservative. In clean room environments Isopropyl alcohol may be substituted to help reduce friction on the gages. Thread plug gages should be protected in plastic tubes or coated in wax when not in use to prevent nicks to the threads. All gauging whenever possible should be done over an inspection table in the event that the gage is accidentally dropped. If a gage is dropped it should be immediately re-inspected for damage.The go thread plug gage should engage the internal threaded part with very little force used. The engagement should be smooth.

There is no specification regarding torque or pounds of pressure for using thread plug gages. Common sense should be applied based on factors of thread size, pitch, and application. If the gage starts to bind, the inspector should stop before damaging the part or the gage. The part may be undersized or tapered. Other possibilities include lead error or a damaged thread. With fine threads the inspector should be careful to not cross thread the parts.

It is important to use the no go gage as it checks pitch diameter exclusively. It is unaffected by other conditions in the screw thread as it is intentionally truncated on the crests and with greater clearance applied on the roots of the thread. The no go thread plug should not enter the part more than 3 turns although in practice it is advisable to limit the amount of turns to 1 ½ - 2 turns max. The user just simply counts turns. The end user should review the applicable thread specification in detail as there are variations to the above practice.