Information on GD&T Symbols, what they mean, and how to inspect features

[CMfgT]

Hello everyone,

I am new to GD&T and I am trying to find a good resource online to explain GD&T symbols and what they mean, and how to check/inspect them. I can find a ton of information on what they mean, but I can not find how to check them with inspection equipment. I am trying to get pictures of how to inspect GD&T features.

For example, I saw a pictures for roundness. The bar stock was placed on a vee block and rolled with an indicator on the diameter. Thats kinda what I am looking for - for the basic GD&T symbols.

Any help would be appreciated

[Wes Bucey]

In Reply to Parent Post by CMfgT

Hello everyone,

I am new to GD&T and I am trying to find a good resource online to explain GD&T symbols and what they mean, and how to check/inspect them. I can find a ton of information on what they mean, but I can not find how to check them with inspection equipment. I am trying to get pictures of how to inspect GD&T features.

For example, I saw a pictures for roundness. The bar stock was placed on a vee block and rolled with an indicator on the diameter. Thats kinda what I am looking for - for the basic GD&T symbols.

Any help would be appreciated

OK. The plain and simple fact is you probably should already own a recent edition of Machinery's Handbook which most machine shops consider the Bible of the trade. The GD&T symbols are explained. Gaging methods are shown, plus all sorts of wonderful stuff is contained. With tax and shipping it will cost less than $100 and will earn that back for you in time saved trying to find something for free on the internet which is already contained in this handbook.

Frankly, unless you are running a lab which does 2nd and 3rd party inspections, with the Handbook, you won't need a current version of ASME 14.5 (the Standard for GD&T - it's available from ASME)

Disclaimer:
I have no financial connection with ASME or Industrial Press (publisher of Machinery's Handbook), but I heartily recommend owning both the Standard and the Handbook if you are an inspection lab for hire.

[Kingsld1]

Gary Griffith put out a book a few years ago called "Measuring & Gaging Geometric Tolerances" Prentice Hall is the publisher.

The ISBN # on my 10 year old copy is 0-13-374042-0. I believe that there is
a newer edition out that may have a different ISBN #.

It gives a brief explaination of each symbol and 1 or 2 methods to check it with a surface plate setup. (including pictures)

[justncredible]

I found this awhile back......

[Coury Ferguson]

In Reply to Parent Post by justncredible

I found this awhile back......

Thanks for the attachment. It is useful.

[Stijloor]

Friends,

Be cautious with "quick solutions" to GD&T verification problems.

Make sure that the methods comply with the actual definitions in the respective ISO and ASME GD&T Standards.

For example, if you carefully look at the definition of "roundness" and "circularity", you'll conclude that putting the part in a Vee Block is not the proper way for verifying this.

Just my

Stijloor.

[tjwoolno]

I found this website useful when I was doing some research on GD&T. Hope it is helpful.

www.etinews.com/gdt_glossary

[justncredible]

http://www.tec-ease.com/gdt-tips.htm

Has some good information as well.