Stop in for a cup of coffee
Hey Karl, what is your GD&T homework?
GD&T is basically the new way of tolerancing drawings. It's been growing in popularity since the mid 90's. It's the latest update to of ASME Y14.5 (2009) drawing standards.
I'm taking AutoCAD classes at the local comm college to get up to date with the latest drawing standards to help get back to work. I've had AutoCAD 2D & 3D classes, and the new Inventor 3D right now. Inventor is a higher level version of AutoCAD that is easier to model in 3D and make drawings after the model is done... Each language has it's benefits and limits.. AutoCAD is a first level CAD, Inventor is a second level CAD.
If done properly with GD&T, the mating parts will always fit together when made to print specs. It also maximizes the amount of acceptable variation for a part to help keep costs as low as possible. In the old tolerancing standard some parts could still be acceptable/functional, but were not to print spec... By using circular tolerance zones instead of rectangular ones, you can accept 57% more parts that will still work where by the old standards, they would be out of spec and no good... It also helps reduce tolerance stack-ups which add more variation to the parts....
I like to think of it as tolerancing catching up to CAD design.
Many companies like to have a GD&T expert in each design group. If I can learn it good enough, it can bring more $$$ to my paycheck when I get back to work... I can also take the certification test from ASME to get certified and put on their national certification list. You have to re-apply for certification every 3 years to stay current.