The Art of Fixing
Repair, don’t toss.
By Chris Rogers
As 3D printers, laser cutters, CAD/CAM, and microprocessors take a lead role in undergraduate engineering education, what tools and skills are getting replaced? Clearly, the scumbag, drafting and lookup tables, and slide rules have essentially disappeared—not a loss in my mind. But so too has learning how to “fix what you got” as opposed to reprinting or recutting. The joys of a beautifully planed surface, perfect joint, or smooth router cut (spinning blade router, not a network one) are also disappearing. We’ve lost the feelings of dread as that router skips or the joint does not fit.
Often these imperfections and blunders would lead to innovations in the effort to make them almost disappear. This skill is still alive and well in engineering companies, which require fixing or optimizing imperfections in products when it is cost-prohibitive to redo them. But how can we get this learning in our college classes when it is so easy to simply fix the CAD drawing and reprint?
One place where I still see students trying to fix rather than redo is in my Design and Performance of Musical Instruments class, in which students design and build from scratch their own musical instruments. These range from copies of existing instruments (for instance, lutes, violins, drums, bells, clarinets, and flutes) to their own inventions. They then compose for them, perform on them, and analyze the resulting sound.
I have found instrument manufacture a particularly compelling engineering problem. First, because the students are required to deal with imperfections in their instrument (and they get to use a router). Second, because there is a fun balance between perception and science, in that if you believe a million-dollar Stradivari violin is better than a $50,000 one made today, you might actually play better (and sound better) despite the fact that a scientific investigation found no difference between the instruments (https://bit.ly/3wPKQoh). Third, because the science behind how the sound is produced and what we hear is complicated and still developing. In the case of the violin, grain patterns, wood density and thickness, curvature and shape, and varnish all have subtle (or not-so-subtle) effects on the sound—making instrument design a great opportunity for student creativity and innovation. It also means that iteration needs to happen at the workbench rather than at the computer terminal, as simulations in this area are still developing.
How does one know where to drill holes, shave off material, or add strengtheners? Most models underpredict. Tables and charts offer guidance—but every instrument is different, and it is amazing how slightly thinner (or thicker) surfaces can change the timbre of the note. Does the student want a “fuller” tone or prefer the more muted low-frequency dominance? What happens when you go too far (and the pitch changes, the high frequencies dominate, or the instrument just does not stay in tune)? Suddenly the art of fixing becomes important.
In our design classes, we often talk about a minimum viable product (MVP) with our students, to get them to be able to invent, fabricate, and test in a semester timeframe. Unfortunately, sometimes the MVPs are held together by duct tape and zip ties because of last-minute mistakes. How can we better teach the skill of fixing these defects, making them disappear so that the beauty of the invention is not marred by tape? In senior capstone design, I have started requiring products to be completed two weeks before class ends (much to the dismay of the students) so that they have time to reflect and focus on the look and feel (usability) of their invention. Since I implemented this timeline, students have turned in products that are noticeably better—in how they both work and look.
As automation continues to advance, the types of mistakes will change (issues like bad pixels in a camera and bugs in firmware will replace skips with a router), and therefore the innovative solutions will change alongside (software updates, digital correction, or just selling the products with more defects at a cheaper price). But the need to “fix what you have” will remain, so we must find ways of teaching the ability. As one of my college mentors told me, the skilled craftsperson is one who knows how to fix and hide imperfections, not one whose work doesn’t have them. The same applies to the skilled engineer.
Chris Rogers is a professor of mechanical engineering at Tufts University.