the Carpentry Way: Computer Numeric Re-Considerations (III)                                                          

Computer Numeric Re-Considerations (III)

I've been enjoying the lively discussion emerging from the previous two posts in this thread, and continue to chat about the issue with other woodworkers. I might be starting to approach the 'broken record' phase for all I know, but I am still engaged in this topic. In fact, repetition is one of the most appealing reasons I can think of for making use of CNC.

When I was a teenager I worked in my father's business on weekends, which manufactured aluminum sailboat masts. One of my jobs was to work on the metal lathe turning sheaves for the mast heads. Sheaves are another term for pulley, in case you hadn't heard it before. I remember the machining sequence well - face off the end of the stock, drill the center for the bronze bushing, turn the outside down to the diameter required, machine the groove in the sheave for the rope, part off the sheave, press in the bronze bushing and it's pretty much done. The first one you make is an intriguing challenge - by the 4th or 5th one you are starting to get the hang of it, after a dozen you could say you have it down. After 20 or 30 of them you can do it in your sleep pretty much.Soon, you might be starting to dread making another goddamn sheave. I think these sorts of highly repetitive sequences of work, where each part really needs to be identical to the one before, are perfect applications for automation. It's simply not interesting work, and certainly not work with significant opportunity for artistic exploration. Repetition of that sort is a little inhuman actually.

I was thinking more about machinist's work today I visited a local machine shop run by a retired shop teacher, named Tim, who must be around 70 years of age. I have my Oliver jointer fence apart at the moment as I am planning to get the fence re-machined in the near future. There are a few pieces of the fence hinge mechanism that will benefit from some fiddling that only a machinist can provide. I paid a visit to see Tim and ask if he could take a look at the fence hinge parts sometime next week. While chatting with him, I noticed he had a couple of CNC-lathes, both Japanese. He had conventional metal working equipment as well of course, and much of that was Japanese as well. I was thinking to myself, it doesn't seem like machinists have much issue with using CNC equipment. And then thinking of making those sheaves again reminded me of how pleasant it would be to have such parts made on a CNC.

Academics like Sōetsu Yanagi might romanticize the unconscious excellence of the mass produced Korean tea bowl that is the most esteemed piece of among chanoyū cognoscenti. He liked the fact that its beauty was the product, not of deliberate intent on the part of the artisan, but as a by-product of their automata-like perfection of skill. That might be an ideal from an academic view, however such is not always the case for the maker.

A lot of people romanticize woodworking I think, with images of the craftsperson out in their warm and toasty shop, trusty dog snoozing nearby on a cushion, wisps of shavings falling from the board as they construct one perfect surface after another and effortlessly assemble another beautiful creation with pride and satisfaction in a job well done. Well, it might be like that sometimes folks, but a lot of the time its not quite so romantic. A lot of tasks in fact are highly repetitious - in my typical sequence it might be: re-saw the boards, joint the boards, plane the boards, trim the boards to dimension, mark out the joints, sharpen the tools, cut the joints, sharpen the tools, wear some skin off your finger tips and bleed all over everything most inconveniently, make some jigs, test the jigs, adjust the jigs, cut some more joints, profile edges, test assemble, adjust, assemble, adjust, assemble, sharpen tools, finish plane, sharpen tools, finish plane, have some tear out, let out a few curses, try some scraping, start the finishing work, rub oil until you think you are going to lose your mind.

Now, out of the tasks I typically need to undertake on a given project, 95% of them I have had considerable practice with and in some cases no longer find the work all that interesting. For example, running 20 boards through the planer half a dozen times each board, is three hours of time I find, at best, meditative. Now, I really enjoy laying out and cutting joints, really enjoy sharpening and planing, edge profiling, jointing, and so forth. I am no fan of finishing work, and running the shaper I find at times a bit on the scary side.

Importantly, one can not zone out when doing certain of these repetitive tasks as unfortunate outcomes can soon eventuate. As me how I know.

While there is much repetition of a given skill in woodwork, be it sawing a straight line, chiseling out a mortise, planing an edge true or a face flat, it is when faced with the making of numerous identical copies of a given object that the work becomes more, well, machine-like.

It's no surprise that one of the first woodworking specialties to take up the CNC with gusto is the stair-making branch of the trade. Stairs, by nature, are composed of units which repeat, and I'm sure after making 50 bannisters/balusters the intrigue wears off a bit, never mind when making hundreds and hundreds of the same thing as a component stair manufacturer would. While the odd variation in a piece might be delightful in the products of the hand, when you have 5o balusters lined up, the irregular ones stick out and do not look pleasing in most cases. What is called for is absolute uniformity - at least by most clients for such pieces. And it is that sort of work where the repetition of making moves well away from any hope of artistic expression.

As an aside, only peripherally related to the topic at hand today, I read recently that more geometrical stairs are being built today than in the golden age of 19th century stair-building due to the advent of 5-axis CNC machining.

I think a lot of people might associate CNC to some sort of situation where the wood is fed into one end of a giant machine and out the other comes the completed piece. To be sure, there is a good amount of CNC work done along these lines. In such a case, the only interesting job is going to be the designing of the product, and maybe programming the machine, as the other workers in the shop will be doing little other than loading, unloading and packaging. Of course, some might like that sort of work but it isn't typically the sort of environment where those of a more artistic bent would tend to flourish.

However, when looking at the work done by Karl Holtey and others, we can see that the CNC is only forming a part of the overall process - the artisan is choosing the most appropriate tool for the job at hand out of the equipment available. Sometimes the 'best' tool is going to be CNC-based for reasons of the precision afforded - Holtey's employment of CNC milling to cut the multiple oblique dovetails for the wooden-soled planes he makes would be a good example. He avers that it wouldn't be possible to make that joint any other way, and I would have to agree. Sometimes the CNC is going to be the best choice when the work to be done is highly repetitive and not terribly creative - like cutting plywood to shapes which will interlock to form some sort of chair, for example. I certainly wouldn't be too excited by a job where I did nothing all day but cut plywood patterns and trim them. Some would find that work fun, but not me.

I think when the work revolves around the CNC and not much else, the craft disappears for all those except the programmer and designer. And that's a loss. I have more to say yet in relation to the blue collar/white collar ramifications of CNC, and will be looking at that topic a bit more in the next post.

Thanks for coming by today. --> on to post IV