Segmented bowls and punched cards

The vase pictured above is a prize-winning example of a segmented turning created by Ken Cowell. It is composed of 2,977 separate pieces of wood all glued together and then turned to final shape.  For the curious, Google “segmented turning” to see more examples, or look at this page on how to construct a relatively simple bowl.

I’ve been wanting to take the plunge into segmented turning for a while now. Last year I turned a couple of relatively simple bowls (literally using only 6 or 8 separate pieces of wood).  Recently I turned my first staved bowl, which had (gasp!) 13 separate pieces of wood glued together.  Right now I’m working on a house-warming gift for a friend that will have (let me think…) approximately 43 separate pieces.

The basic technique for construction involves creating a 12 or 16-sided “ring” by gluing very precisely cut pieces end-to-end. The ring is flattened to eliminate any minor warping, and then glued onto a stack of previously glued up rings.  Rinse, repeat.  For the style I’m working on, I can’t glue up the entire ring in one sitting. For my 12-sided rings, I need to glue pairs first, then 3 pairs into a 6-sided half, then (after some quick sanding to make sure the halves mate properly) a full ring.  Since I’ve been letting the glue dry overnight for each gluing phase, that’s three nights to put together a single ring.

Segue to punched cards.  In the “old days” (1970’s), a popular medium for storing computer programs was the punched card.  The programmer would write a line of code and have it punched out on a card (one column per character); a stack of cards corresponded to lines of code.  When it was time to have the program run on the mainframe, one carried the deck of cards to the operator, who then queued them up for submission.  The deck of cards plus any printed output would be waiting at a pick-up window hours (or days) later.

I’ve written before about how the change from punched card storage to high-speed magnetic storage and personal computing changed the nature of programming. A beginning programmer now can write lines of code, run them instantly, and if s/he made a mistake, immediately fix the error and re-run the code again, seconds later.  In the old days, a mistake meant losing several hours (or days) to a badly run job. Programmers had to double- and triple-check their code before submitting to the machine room; it was the programmer’s version of “measure twice, cut once.”  Nowadays students can “hack” at code (a different meaning of “hacker” from its more nefarious usage) until it works; only when programs grow to several pages do people need to acquire the discipline to design their program up front, break it into manageable chunks, and follow principles to ensure a bug in one section doesn’t require re-writing code throughout the program.

I have never had to write code on punched cards; I came of programming age in the early days of magnetic storage.  But creating a segmented turning is giving me a good taste of what it must have felt like.

I can turn a bowl from a solid piece of wood (a half of a log, for example) in a single evening.  After dinner, a split log.  By bed time, a bowl resting on the bench with the finish drying.  If I make a mistake, it’s usually no big deal – the wood is often found (read: free), and I try to learn from my mistakes. I have to admit, I enjoy the rapid turnaround of an evening-long project. As much as I enjoy the process of turning, I like having something to show for it at the end.  Pen making feels the same way – I can go from raw materials to finished project in an evening.

Creating a complicated segmented turning requires as much planning and prep work as building a house. The “fun part” (the actual turning) is actually relatively perfunctory.  The overall shape has already been determined by the relatively width of the rings – the only point of turning it on a lathe is to smooth over the corners and thin down the material.

So I’m a little torn.  I love the intricacy and beauty that segmented turning opens up. Some of the gallery examples I’ve seen are simply breathtaking. But creating them is literally an act of brick-laying, fitting one piece after another carefully together, layer by layer. I have to say, I don’t really enjoy the execution. The design process is fun, as is the final product, but the middle portion?  Punched-card programming.

Here’s a question I should ask myself – would I have majored in computer science and become a software engineer if I had been introduced to programming on a punched card system? How much of the initial thrill and engrossment of high-school programming was due to the immediate feedback of magnetic storage and a timesharing system?  It’s quite possible I would have found the whole process frustrating and found other outlets for immediate gratification. There are lots of implications in that insight for education in general, but that’s going to have to be a future blog posting.

For now, I’m going to continue to explore the world of segmented turning, and remain mindful of how I’m being in that process. I suspect I’ll only take on an occasional project in this medium, when a particular design occurs to me and I simply have to see what it would look like. What clearly is not helpful is to beat myself up for not having the patience and discipline (if I really want to do a number on myself, I’ll use words like “maturity”) to enjoy segmented turning.


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