Getting defensive: CMM Inspection

Machining has been the foundation of my career since entering the workforce in 1993. I am fortunate to have had the opportunity to work in several industries, and I have had access to many different growth opportunities.

Unlike many craftspeople, I did not get my education from a structured program, such as a vocational school or an apprenticeship. I learned my trade at the machine shop that my father owned. Unlike most shop owners, Dad was not a machinist. He was a salesman who found himself with a shop. A series of unfortunate events left us short-handed with a significant backlog, forcing me to jump in. This challenging situation introduced me to a trade that quickly became a passion. I read old machining books, studied the work of experienced people and looked for opportunities to try new things.

After several years of running Dad’s shop, life led me in another direction, and I arrived at an aerospace manufacturing company as a manufacturing engineer. That is when my reeducation in machining began.

At the family shop, we made things like pump parts for dishwashers and seat parts for bass boats. The aerospace company that I moved to made high-performance components for military aircraft like the F-16, A-10 Warthog and Apache helicopter. The transition from a small shop to a Department of Defense contractor was difficult.

The transition from a small shop to a Department of Defense contractor was difficult.

Dishwasher parts are probably more complex than one might think but not by much. At the family shop, we usually worked with dimensional tolerances in the ±0.127 mm (0.005″) range with an occasional dip into the ±0.0127 mm (0.0005″) range. We did not know anything about geometric dimensioning and tolerancing. So the dimensional requirements of work at the shop were not very challenging.

At the new company, we made high-performance hydraulic pumps and motors for military aircraft. Operating pressures of 5,000 psi were common in many of these units, and the entire pump was sealed by mechanical fit. There were no O-rings, rubber seals or gaskets used in the assembly process. Seals were made by machining the mating components so flat that high-pressure oil could not find a gap. Flatness requirements were below ±0.001016 mm (0.00004″) and had to be measured with light-emitting optics. To say my transition was challenging would be an understatement.