What do mechanical engineers do?

1) Check the print and spec/stds per the print and PO, GDT (and understood by all parties, including internal and external sources. BTW do YOU understand what needs to be done for successful part, and delivery?
2) Confirm that part(s) are made to the above with data and documentation (independent inspection reports with numbers, not "OK", certs are useful, material and any inspection certs (NDT, etc)
3) Confirm that part(s) are assembled OK without problems by the team members who will do the actual work on various shifts
4) Write up any feedback from the team members on issues, problems, improvement, track all of them and give feedback/update to the team members/group (in the loop) and dates when the issues will be resolved.
This does not cover design review to make sure the design itself can be accomplished or needs special tool, requirements, std:)

I'm a mechanical engineer and done a wide variety of engineering tasks from; work studies, process improvements, building modifications, managed several maintenance departments, been an operations manager, managed environmental issues and headed a regional (NA) engineering group. On the other hand, I have a friend that is also a mechanical engineer, and he worked his whole career designing combustors for a major jet engine manufacture. If you pursue a niche market, mechanical engineers tend to do more specific tasks, metallurgy, stress analysis and parts design etc. A broader type of engineering is as a project engineer (any engineering specialty can be a project engineer), you could manage all aspects of a project using a team of specialist to accomplish the task/project. Engineering is about problem solving, exploring solutions and making improvements. If you get a good education and keep your option open the opportunities are endless. We can always use another talented engineer. Good luck.

Mechanical engineering involves the research, design, development, building prototypes, test devices. These devices include tools, switches, manufacturing equipment, machines, etc. This engineering discipline applies the principles of engineering, physics, advanced mathematics, and materials science for the design, analysis, manufacturing, and maintenance of mechanical systems.