Electrical engineer John Chidgey joins us in this episode of The Engineering Commons to talk about ladder logic, podcasting, and an engineer’s role in making the world a better place.
An open invitation to discuss general engineering issues got Jeff started in the world of podcasting.
Carmen, Brian, and Adam became trapped involved as co-hosts on this podcast when Chris Gammell left the show.
Our guest for this episode is electrical engineer John Chidgey, who has worked in several engineering domains, including RF hardware, systems engineering, and the oil & gas industry. He also produces a weekly podcast, Pragmatic, and authors the Tech Distortion website.
Carmen and John are fans of making coffee with the Aeropress.
Citizens band (CB) radio served to interest John in electrical engineering.
John notes that there is a general trend toward standardization, as the costs of customization are too high for many companies.
For a while, at least, John had a job that may (or may not have) required a security clearance.
Our guest moved into the controls industry around 2003, installing programmable logic controllers (PLCs) for industrial clients.
Many PLCs can be programmed using ladder logic, which originally was nothing more than a schematic for wiring together electromechanical relays.
John has had some bad experiences programming PLCs with software implementing function block diagrams.
“Where there is a choice, there is a problem.”
After testing out several other podcast concepts, John launched the Pragmatic podcast to cover engineering topics in a practical and actionable manner.
John mentions the Hypercritical blog, written by John Siracusa.
A live chat room has recently been added as a feature of the Pragmatic podcast. Jeff doesn’t think he could handle the additional cognitive load while recording interviews.
We’ve gone meta with a podcast about podcasting!
John occasionally gets requests for career advice, although many times engineers write in to simply point out technical errors.
According to our guest, engineers can change the world by providing reliable services and infrastructure that will improve people’s lives.
We discuss some of the considerations that go into choosing a threaded fastener in this episode of The Engineering Commons podcast. It can be more complicated than you might think!
Carmen has a tendency to make up words every now and then; this leads to quizzical reactions from his co-workers.
For many years, Jeff has used the Machinery’s Handbook as his reference for most issues related to threads and threaded fasteners.
We let slip a million-dollar idea; a blank book that lights up with content when turned on. How many years until this becomes a reality?
The primary reason for using a threaded fastener is to allow for the assembly and disassembly of components.
Despite the differing definitions about what constitutes a screw and what constitutes a bolt, we go with a distinction in usage: a bolt needs a nut, while a screw does not.
When selecting a screw or bolt, one usually starts by looking at the strength needed in two places; the fastener itself, and the threaded connection.
Plain washers are used to distribute forces that might deform or mar one of the clamped components.
The cylindrical portion of a bolt that extends from the underside of the head to its point or end is called a “shank.”
Lead is the linear advance of threaded fastener as it makes one complete rotation about its longitudinal axis. Pitch is the spacing between adjacent threads on a threaded fastener.
“RightTighty, Lefty Loosy” is a mnemonic device for remembering which way to turn a threaded fastener so as to tighten or loosen the connection.
Measuring the diametric distance across the tops (or “crests”) of an external thread reveals the “nominal” or “major” diameter of that thread.
A notation of “M10 x 1.5” designates a thread that has a major diameter of 10 mm, and a lead of 1.5 mm.
While metric fasteners identify the lead directly, English threads give the inverse of the lead. Thus, the notation “1/4-20” indicates a thread having a major diameter of 0.25 inches, and 20 threads per inch (a lead of 0.05 inches).
Most of the world uses the ISO standards for thread forms and sizes.
When selecting a threaded fastener, it’s good practice to use a coarse pitch unless you have a good reason for not doing so. Fine pitch threads are normally reserved for those cases when vibration might tend to loosen the threaded connection.
In the American system, sizes below 1/4 inch are identified by numbers that decrease as the nominal diameter decreases.
A rule of thumb is that the axial thread engagement should be at least 1x the nominal diameter for steel, 1.5x the nominal diameter for cast iron, brass or bronze, and 2x the nominal diameter for aluminum or zinc.
A “blind” tapped hole allows for an internal thread that doesn’t go all the way through a component.
Many different head types are available in threaded fasteners.
In a lively discussion of how to best prepare today’s engineering students for tomorrow’s engineering challenges, we talk with Dave Goldberg and Catherine Whitney about their new book, A Whole New Engineer.
Any “dot-com” dreams that Brian harbored during his college days have long since dissipated.
Carmen suggests that ridiculous buyout amounts are now measured in units of “Instagrams,” with one Instagram equaling one billion US dollars.
Engineers must constantly expand and refine their skills; Jeff notes that over his career he has moved from drawing prints on a drafting board, to working with 2D CAD packages, to implementing 3D models.
Our first guest for this episode is Dave Goldberg, who appeared previously on Episode 37, in which he talked with us about the evolution of engineering roles over time. Dave leads ThreeJoy Associates, a consulting firm that advises educational institutions.
Our second guest is Catherine Whitney, a New York-based writer who has previously written or co-written more than forty books on a wide range of topics, including nutrition, social issues, and entrepreneurial success.
Dave argues that the “old engineer” was entirely appropriate in a time of expertise and narrow technical focus. However, a “new engineer” must reach across disciplinary boundaries, and solve problems in domains that lack recognized experts.
Dave makes a passing reference to disruptive innovation, a term coined by Clayton Christensen to describe the manner in which existing markets and institutions may be displaced through the introduction of new technologies.
Current technological trends have led to people “bowling alone,” a phrase the describes how individuals are disengaging from the social and political networks that comprise local communities.
The story of Jack Andraka is offered as an example of how academic expertise is being undermined over time.
Jeff notes differences between “just-in-time” and “just-in-case” learning.
Dave notes that more than one version of the Grinter Report (pdf) was proposed back in the mid-1950s.
Our guests mention a study by Kristen Wolfe, later referenced by Woodie Flowers of MIT, that looked at the skills used by mechanical engineers five years after they graduated from college.
Dave was involved in establishing iFoundry at the University of Illinois, while co-author Mark Somerville was (and is) a faculty member at Olin College.
Electrical engineer John Chidgey joins us in this episode of The Engineering Commons to talk about ladder logic, podcasting, and an engineer’s role in making the world a better place.
