GD&T Examples

[richardpaulfox]

Hi

I have a basic understanding of the principles of GD&T but I am left clueless of how and when to apply it.

Though I can find info on the principles - I can't find any 'realistic examples'.

I guess it must be like learning to ride a bike but I feel that I need a helping hand to get me going.

Can anyone please point me in the right direction.

Thanks in advance.

Richard

 

[3DDave]

It's applied in a manner similarly to any other programming language - the difference is that programming uses an uncaring compiler or interpreter to generate usually singular answers. Since FCFs are used to link multiple features together and the tolerances represent ranges of values, the outputs are rarely singular - mostly they are more reasonably seen as statistical distributions, except for trivial limits calculations.

Datum feature and FCF application users typically don't have access to such tools unless they have a license to VSA or some other tolerance analysis software.

The problem with examples without the analysis being described step by step, is their limited value.

The best self-study is to make up paper models with exaggerated variations, such as fitting tolerances of 5mm on 50mm features, and seeing what happens when they are assembled together. Once you have an intuitive understanding, then it's easier to move to analytical/numeric analysis and understand the calculations in the standards and tutorials and derive them for new cases.

Only after gaining this understanding can one start to craft applications and understand when to apply it.

 

[Belanger]

The goal is to not just make drawings that can be understood, but to make drawings that cannot be misunderstood. (I'm paraphrasing a quote from elsewhere.)

So if you create a non-GD&T drawing that cannot possibly be misunderstood, then you don't need to add GD&T. But be careful -- a very simple part that seems to be super-clear is probably not idiot-proof.