Hand Tools

Re: Planecraft and the Cap Iron *LINK*

TM Stock
Until the aerospace industry settled on the decimal inch in the 1930's, the finest grad on a rule was commonly 1/64", and discussion of mils or thousandths was not common outside of the engineering and machinist's communities. In look through older woodworking books, the discussion of the cutting list, thicknesses, etc. is generally fractional inches, so I am not surprised that 1/64" seems to be the smallest increment noted.

For those involved in more precise work with tighter tolerances (miniaturists, model makers, luthiers, some cabinetmakers), working to the nearest thousandth in wood is not uncommon, but Audel's and other books of the time were aimed as much at framing carpentry (where 1/8" was a fairly tight tolerance) as trades where 1/32" or 1/64" was more common. I suspect that several things happened along the way between the craftsman's utterances and their translation to paper by author and editor:

- The nebulous 'as close as possible' for fine work in difficult grain probably ended up being stripped out of some book drafts as editors sought to avoid the extremes of overly vague 'about a pinch/just a smidge' common units or seemingly persnickety, unfamiliar measurements such as 'thousandths of an inch' or 'tenths of millimeters' when editing books for as broad an appeal as possible.

- When confronting new drafts, and with authors sometimes weeks away in terms of correspondence or off contract and onto their next project, those same editors may well have looked to competing texts to sanity check their own. This is not limited to craft - once an error or omission is made in a text or other frequently referenced guide, undoing the damage can be quite painful.

- Science and engineering practice typically couples the 'why' of a practice to the 'how', if for no other reason than that degree of formalism is the minimum accepted standard for most written work. Craft knowledge is quite different in nature, because too often the 'why' of a practice is fully separable from the 'how' of the thing when the guidance is in the form of annotated, bulleted text - especially where an 8 page magazine article is an exception and guides such as Audel's were expected to be both comprehensive across the field and very concise on any one topic. Look at any engineering structures text and you'll see each new topic developed from first principle to actual practice, thus, coupling the 'why' and the 'how'. Look at most craft texts - especially the ones produced as series at set-piece rates, and that formalism is lacking. Further complicating the issue is the fact that often, authors were - like many of us - talented amateurs in the craft of interest, attempting to relay the rudiments of what had been learned from primary sources.

My observation after 40 years of teaching complex tasks and the last ten teaching instrument building and repair is that once the 'why' of something is separated from the 'how' of the thing, it only takes a further magazine cycle of 7-8 years or a book publishing cycle (closer to 10 years) to lose both.

While the craftsman instructor may continue to provide rationale for choices made or techniques used, those beyond his or her immediate circle of students effectively loses access to both technique and rationale. The knowledge may continue forward, but it becomes more and more difficult to access - especially where research skills rely more and more on digital media versus the talents of reference librarians and first print editions carefully held away from the public.

On the subject of Audel's economy:

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