Adjustable thread ring calibration has some nuances that most calibration companies and assessors just don't want to talk about or hide the details in the fine print. Who reads the fine print?
Simply put: Direct Measurement Of Adjustable Thread Rings.
We thought it would be beneficial to put together a resource focused on adjustable thread ring calibration in an effort to allow consumers of calibration services to make a more informed choice.
Direct Measurement of Adjustable Thread Rings
As we mentioned in a previous article, there are inherent problems when using direct measurement for the calibration of adjustable thread rings. Gage Crib published an excellent explanation of these problems in Ring Gage Calibration by Direct Measurement. We strongly encourage to read this article. They specifically mention the deficiencies of using a coordinate measuring machine -CMM in regards to helix offset and why a master setting plug is the preferred method.
You might also want to check out Thread Ring Realities in Quality Magazine- "The ASME standards to which these gages are made require them to be verified by their fit on an appropriate setting plug. There is no other option on the smaller sizes but different hardware for directly measuring pitch diameter is often used to get around the costs of a setting plug for non-stocked gages. Each method takes a different approach to the situation and because they are not the same from a metrology point of view, the ‘answers’ they produce are rarely the same either."
No need to do a Google Search. We have compiled a list of resources for you to check out.
Indirect Measurement of Adjustable Thread Rings
This approach is very intriguing from a calibration point of view. Wouldn't it be great if you could somehow "look" at an adjustable thread ring and calibrate it! Visual measurement methods are used in a variety of manufacturing settings, but the current standard for thread rings does not support this approach. Larry Borowski has written an excellent article - Setting Adjustable Thread Rings- that explains why you really do need to send in your master setting plug when you have your adjustable thread rings for calibration.