Pin Gauge Terminology

[Kyle Schultz]

The blurb below is from the Meyer Gage Co. website. It explains the difference between a Go and a No-Go Gauge. Makes perfect sense to me.





Now, if I look at the McMaster-Carr website at their pin gauges I find the following options.




The specs on their Go gauges are described as being 0" to 0.0002” and their No-Go as -0.0002” to 0”. In other words, a Go gauge is oversized relative to a No-Go gauge. And, based on the McMaster table, I would describe the Go gauge as a “Plus” gauge and a No-Go as a “Minus” gauge.

To my thinking, that is exactly opposite what the Meyer folks are saying. The No-Go should be larger than the Go, just like it is with headspace gauges. Do you see my confusion. What am I missing? Thanks.

 

[PatMiles]

My humble opinion is the GO is the undersized guage pin while the NO GO is the oversized guage pin. I'm basing my thought on the hole being dead nuts on so the larger of the 2 pins would not fit in the hole.

 

[RegionRat]

In a metrology or inspection lab, none of those names are important because they are arbitrary.

How we apply the pins, is more important than what somebody calls them. Sometimes we use the pin the way they are named, and sometimes we don't.

My advice is to select your gage pins on their actual size, and ignore the names. After all....

A rose by any other name....

ETA:
https://www.newmantools.com/meyer/pluggage_ABC.htm

 

[X-Caveman]

Your go/ no go are not the same nominal size and you have to use both on any given hole. In a production environment, they are functional checks in lieu of actual measurements.

As an example, If the hole is .250” +/- .002”, your Go gage is .248” and your No Go is .252”. Since everything has a tolerance, you want your No Go (must not fit) to be dead nuts or a hair under. You know you are catching the big holes if it fits. Likewise, you want you Go gage (must fit) to miss big. Otherwise, it may fit in a hole that’s a tiny bit undersized. In other words, McMaster-Carr’s listing makes sense to me. Did I keep all that straight?

 

[Oso]

Everything you could want...

Vermont Gage Company

 

[Kyle Schultz]

Your go/ no go are not the same nominal size and you have to use both on any given hole. In a production environment, they are functional checks in lieu of actual measurements.

As an example, If the hole is .250” +/- .002”, your Go gage is .248” and your No Go is .252”. Since everything has a tolerance, you want your No Go (must not fit) to be dead nuts or a hair under. You know you are catching the big holes if it fits. Likewise, you want you Go gage (must fit) to miss big. Otherwise, it may fit in a hole that’s a tiny bit undersized. In other words, McMaster-Carr’s listing makes sense to me. Did I keep all that straight?

Yes. I see says the blind man. Thanks Travis!

 

[X-Caveman]

Green = gotta go
Red = must not go

 

[divingin]

Don't the terms "Go" and "No-Go" depend on what you're measuring? In other words if your has to be a minimum size, "Go" would be the opposite than if the hole could not be larger than some measurement?

This is one of the times I am glad I'm not a machinist.