Adjustable Thread Ring Gages vs. Solid Thread Ring Gages

What is the background of a Thread Ring Gage & Thread Plug Gage?

The screw thread in a thread ring gage consists of many different in depth features all turning around a central point or shaft. As screw threads blew up in america and around the world, it became very crucial to check every manufactured screw thread. This was done to see if that particular screw thread met the industry standard. Through trial and error, it was determined that the task of checking the correctness of each screw thread was way to intense a test to do on the factory line. Do to this great need in the industry, thread ring gages were invented. 

Thread Plug Gages

There is no definite information to be found but it is thought that thread plug gages were designed before thread ring gages. This is greatly due to the fact that testing an internal threaded hole in a part / product is almost impossible to precisely measure. Thread plug gages are very straight forward to produce due to the fact that the threads used to inspect other products are on the outside diameter of the thread plug gage ends (Go / No Go). At this location it is very possible and simple to measure the thread plug gage specifications.

Solid Thread Ring Gages

Most think that the original thread ring gages produced were solid thread ring gages. This is because they share a shocking similarity with a standard threaded nut. That being said, a thread ring gage is much different than the standard threaded nut. This is because a thread ring gage is made of a hardened material, in order to extend it's life of checking parts / products. Another difference is that thread ring gages need to be machined to much tighter tolerance. These tight tolerances in the world of thread ring gage manufacturing, is a cause for a lot of the thread ring gages to be scraped during the manufacturing process. This tight tolerances that are needed to be met are ISO-1502, BS-919, and many other industrial specifications.

Adjustable Thread Ring Gages

Around the time of World War I (WWI) and World War II (WWII) the adjustable thread ring gage was designed by a US company by the name of Pratt & Whitney. The employees name was Mr. Johnson, who then worked for Pratt & Whitney at the time of his design. The need for this product was great because production accuracy was critical, reduced costs of production, and speed of manufacturing. The new design had many benefits over the other option on the market, a solid thread ring gage. 

Here are a few reasons that adjustable thread ring gages are more favored than solid thread ring gages:

1. Much less scrap thread ring gages in the thread ring gage manufacturing process. Which in turn sped up the thread ring gage production and drove down the cost of thread ring gages.
2. A much lower / more reasonable cost for any special thread ring gage
3. The final products have a much tighter tolerance allowing more manufacturing leeway for the end product which ends up reducing the cost of the final thread ring gage.
4. A adjustable thread ring gage has a longer life vs. the standard solid thread ring gage, because an owner of the thread ring gage can readjust or have a calibration lab readjust the adjustable style thread ring gage. This allows an out of tolerance thread ring gage to become an in tolerance thread ring gage again.
5. The overall ability to reasonably / inexpensively rework a worn or damaged thread ring gage to renew its usefulness in the industry.

This small list of benefits is just the beginning of the reasons that adjustable thread ring gages swept across the entire USA and the world. 

Where are Adjustable & Solid Thread Ring Gages Today?

Today both adjustable and solid thread ring gages are in use around the world. In the US, the use of adjustable thread ring gages is very popular, with the rest of the world still using solid thread ring gages but growing toward the adjustable thread ring gages.

What Are The Cost Differences Between Solid & Adjustable Thread Ring Gages?

A solid thread ring gage will be a cheaper and more affordable option vs. an adjustable thread ring gage. This is not the case when it comes to special size thread ring gages though. In that case, it will be the exact opposite. .

What Are Some Reasons That The Solid Style May Still Be Preferred?

After reading all of the above advantages of going with adjustable thread ring gages, why would a customer still insist on purchasing and using a solid thread ring gage? Here are some ideas:

1. Their customer may be using a solid thread ring gage and they want to use the same style of gage that way their tests and inspections will match
2. They may fear that the adjustable will always be out of round (this could be due to them knowing how their employees will handle the gage) 
3. They fear that the adjustable thread ring gage will go out of tolerance and will still be used to check a threaded part / product. 

Disclaimer: To the best of our knowledge, the information contained herein is accurate and reliable as of the date of publication; however, we do not assume any liability whatsoever for the accuracy and completeness of the above information. M & J Tooling LLC makes no warranties which extend beyond the description contained herein. Any information given in this statement does not constitute any warranty of merchant ability or fitness for a particular use. It is the customers' responsibility to fact check and confirm any of the above information in order to satisfy themselves as to the suitability of the products to their particular purpose.