It is often hastily assumed by employers that artisans wearing glasses are not so well fitted to do certain classes of delicate work as those who depend exclusively upon their natural eyesight. This notion, it would appear, is a mistaken one, and in a recent work on the subject, Mr. R. B. Carter mentions one very remarkable proof of the harmlessness of using glasses—and even of employing a single glass.
Among watchmakers it is an unavoidable necessity of their calling to work by the aid of a single glass, and they appear to enjoy an enviable immunity from eye diseases. It is, he says, exceedingly uncommon to see a working watchmaker among the patients of the opthalmic department of a hospital, and he entertains little doubt that the habitual exercise of the eye upon fine work tends to the development and preservation of its powers.
The persons who suffer most, according to Mr. Carter, from popular prejudice and ignorance on the subject of spectacles, are men of the superior artisan class, who are not engaged on work which requires good eyesight, and who, at the age of 50 or sooner, find their power of accomplishing such work diminishing.
It is, he tells us, a rule in many workshops that spectacles are altogether prohibited, “the masters ignorantly supposing them to be evidences of bad sight, whereas the truth is they are not the evidences of bad sight at all, but only of the occurrence of a natural and inevitable change, the effects of which they entirely obviate, leaving the sight as good for all ordinary purposes as it ever was.”
Mr. Carter adds that “in many shops in which they are not prohibited they are still made an excuse for a diminution of wages; and the result of these practices is that hundreds of good workmen struggle on, perhaps for years, doing their work imperfectly, when a pair of spectacles would instantly enable them to do it as well as at any former period. In the present state of knowledge there is no excuse for rejecting a man’s services, or for diminishing his payment, because he requires spectacles, unless it can be shown that, even when he is furnished with them, his sight is below the natural standard of acuteness.”
Persons who are condemned to the use of spectacles will thank Mr. Carter for thus coming forward as their champion.
Carpentry and Building – August 1880
Quotations from:
Eyesight, Good and Bad: A Treatise on the Exercise and Preservation of Vision
Robert Brudenell Carter – 1880
The painting is John Cuff and his assistant (1772) by Johann Zoffany, commissioned by George III. John Cuff (1708-72) was a Fleet Street optician, maker of spectacles and microscopes.
Flitch-cut cherry log, showing end-grain splits (the boards are 2″ thick)
I recently returned from a week and a half in Colombia. While there, I got to experience some of the temperature and humidity extremes that we subject our furniture to: We traveled from the warm, humid llanos at Villavicencio, to the cool, wet cloud forests near Bogotá and in the Santa Marta range, to the hot, near-desert thorn forests of La Guajira. Fortunately, I personally contain very little cross-grain construction, so I emerged without any significant structural damage, save for a few mosquito and chigger bites.
Water exists in wood in two forms: Free water is water that occupies the voids in the wood, and generally behaves like a liquid. Bound water is water contained within the solid structure of the wood itself, and behaves more like a vapor “dissolved” in the wood. For our purposes, free water isn’t very interesting, as it moves freely (duh) via capillary action, and doesn’t contribute significantly to moisture-related wood movement. There is, however, some evidence that movement of free water is hindered when the surface of a piece of wood is very dry, which may be another contributor to the why-won’t-my-thick-slab-dry? phenomenon. As Chris noted previously, thick slabs often act as if the dry surface wood somehow seals in the moisture in the bulk of the wood, and it may be the case that free water is being trapped.
Bound water moves via diffusion. Imagine a large room containing 500 drunken woodworkers (e.g., the banquet hall at Woodworking in America). They’re all in there, randomly staggering around. We draw an imaginary line through the middle of the room, and discover that there are 450 woodworkers on one side of the line, and only 50 on the other side. Why? Guess which side of the room contains the open bar?
When the bar closes, the distribution begins to even out. This doesn’t happen because the woodworkers are purposefully trying to move away from the bar; it’s just that anything moving around randomly is more likely to move from an area of high density to an area of low density than the other way around, simply because there’s more “stuff” in the high-density area.
If the room has open doors, then some of the woodworkers will occasionally exit and end up in the hallway. As long as there aren’t very many woodworkers out there already, there will be more woodworkers exiting than coming back in. Eventually, a point will be reached where there are as many woodworkers randomly coming back in as randomly leaving, and the system will be in equilibrium. This is diffusion in a nutshell.
In a future installment, we’ll get into the nuts and bolts of diffusion, but for now we’ll skip all that and look at some wood, namely three boards, each 8′ long and 20″ wide, and 1″, 2″ and 4″ thick, respectively:
Imagine that you’re a molecule of bound water, located smack dab in the center of a board. Your quickest escape is through the face of the board, as the edges and ends are too far away. If you’re in the 4″ board, you have to travel four times as far (2″) to get out than you would if you were in the 1″ board. Remember from last time that the drying rate in this case goes as the square of the board’s thickness, meaning that it’s going to take you 16 times as long to go four times as far.
Now imagine that you’re a molecule of bound water very close to the end of a board. Your quickest escape is through that end. As we go from the 1″ board to the 2″ board to the 4″ board, your local environment doesn’t change; you’re still very close to the end of the board. In other words, the rate at which you leave the board is independent of the board’s thickness. And this is what gives dry kiln operators nightmares (and why many of them won’t touch thick slabs): The disparity between drying rates at the center and ends of a board increases dramatically as the board gets thicker, and along with that disparity comes increased stress in the board. The rapidly drying ends shrink faster than the center, with end splits being the inevitable result, as in the photo above.
This also applies to the faces and edges of the board, but as we will see next time, it’s usually less of an issue there, except for certain species, such as oaks, that have a strong tendency to develop surface checks, especially on tangential (flat grain) faces.
Even though some of the boards in the photo aren’t cracked at the ends, they nevertheless contain a substantial amount of built-in stress, leading to an increased likelihood of cracking after the board is placed into service. Knowing how the board’s neighbors behaved, and depending on how it will be used, I might inset a butterfly key on the underside of such a board to help restrain it. If I’m really nervous about it, I might even cut the board in half lengthwise, plane the cut edges and then glue it back together, just to be on the safe side.
We can reduce the drying rate disparity by covering the ends of the board with a substance that retards diffusion. (Again, slowing moisture loss from the end grain is usually more important than slowing loss from face or edge grain.) People have used a lot of different materials for this. In my own experience, latex paint offers some protection, but seems to be more or less worthless in the long term. I currently use a commercial water-based wax emulsion product, Anchorseal from UC Coatings, with good results. The absolute best product for eliminating moisture loss that I’ve tried is Leak Stopper aerosol roof sealant, but it’s a bit messy and kind of on the expensive side. I’ve also heard that oil-based aluminum paint works well, but I haven’t tried it.
Next time: The scary-looking diffusion equation! (You may want to ask small children and sensitive adults to leave the room before reading.) Also, we’ll answer the question of whether or not it makes sense to drill holes in a thick slab to hasten drying.
Compared to last year, my 2014 teaching schedule is a cakewalk. But that’s like comparing the various Boer wars, the First, Second and Third Reichs and Fried Pickles v. Lots-a-tots at Hooters. In other words: It’s all brutal.
I teach classes because I know that it’s good for my research and writing. I meet fascinating people, and I get to visit interesting places. But most of the time, I’d prefer to crawl under the sink unit at the Hampton Inn in the fetus position.
I am a natural hermit.
So here is my 2014 teaching schedule, with a promise that 2015 will be even more limited.
Jan. 18-19, 2014 Kansas City Woodworkers Guild I’m teaching a two-day class on building a Dutch Tool Chest and giving a presentation on Jan. 18 on something (relating to woodworking, promise). This club is very impressive. Well-organized. They have an excellent facility and passionate members. Contact them if you’d like to attend the free Saturday night program.
Feb. 22-23, 2014 Alabama Woodworkers Guild During this weekend seminar, I’ll build a six-board chest entirely by hand and attempt to do a massive brain dump on handwork in the process. Visit the club’s site for details on attending the seminar.
Mar. 17-24, 2014 William Ng Woodworking School I’m teaching two classes at this California school. The first is on making Roorkee chairs; the second is on making a Dutch tool chest. Both classes are lots of fun (for me, at least!).
April 25-28, 2014 The Alaska Creative Woodworkers Association It’s my first visit to Alaska, and I am very excited about it. During my trip there I’ll be teaching a class in making layout tools and the Dutch tool chest. Plus I’ll be giving a presentation to the club.
May 5-9, 2014 The Woodworkers Club, Rockville, Md. During my first teaching gig in this area, I’ll be teaching a class in building the Anarchist’s Tool Chest, and speaking to the local SAPFM chapter and doing some other cool stuff I can’t mention just yet.
June 9-13, 2014 Marc Adams School of Woodworking, Franklin, Ind.
French Workbench. If you want to build an epic French workbench, this is the class to take. We have lined up some excellent ash for the class and the facility and machinery make it an incredible week.
June 18-20, 2014 The Woodwright’s School, Pittsboro, N.C.
I’m teaching the Dutch tool chest at Roy Underhill’s school during these three days. If you’ve ever been to a class with me and Roy, then you know you are in for an intense session of teaching, gesticulating and eating of scones.
July 5-6, 2014 Lie-Nielsen Toolworks, Warren, Me. In my attempt to spread awesome Dutchness across our great land, I’m teaching an intense two-day class in building a Dutch tool chest at the inspirational Lie-Nielsen facility.
July 21-28 Mystery England Classes I’ll have a lot more to say about these two classes in England – my first teaching assignment in England ever. So stay tuned. Or take a liver holiday and sign up for them now.
Oct. 4-5, 2014 Marc Adams School of Woodworking, Franklin, Ind.
This is the annual handplane weekend class I teach at Marc Adams’ school with Thomas Lie-Nielsen. It is a fun on a bun – an annual ritual of indoctrinating new hand tool woodworkers that I don’t ever want to miss.
There are a couple of other club events and shows that I am still working on, plus a couple of Lie-Nielsen Hand Tool Events that I’ll be adding to this calendar in the coming weeks. But if you seek to abuse/amuse me in 2014, the list above is fairly complete.
I have worked at coopering in all its different branches off and on for about thirty years; have seen it in its prosperity and felt its adversity. I have known the cooper who worked journey work to have a kit of tools weighing 100 to 150 pounds, and many curious-shaped tools they were, among which the only machine in use was a boring machine. Twenty staves from the rough were called a set and made a load to carry into the shop— rough heading four or six pieces—often causing the cooper to go back and make a second load to get a complete set for a barrel.
Old-time coopers will remember how a new man was broken into the traces; then, when his staves were equalized, shaved and jointed by hand, and heading made into a head, all of which required a mechanic to do the work, and our journeyman had his first barrel raised, there would go up from every cooper about the place a yell, “blockwash, blockwash!” that, only for the difference in the way it was done and the word itself, you would think there was fire in the next yard. The new cooper understood the rules, and if he hadn’t the money he got the boss to help him out, and the nearest saloon got the benefit of his first earnings by furnishing the ingredient (blockwash). (more…)
The folding bookstand in A.-J. Roubo’s “l’Art du menuisier” is nice, but not nearly as fancy as the one I unearthed today while reorganizing my office.
This bookstand is shown in “L’Enseignement Professionnel du Menuisier” (book 1) by Léon Jamin. Jamin is listed at an “ancien collaborateur au Roubo,” but I don’t know enough about Jamin to say what that really means.
I purchased an original copy of the plates from this 19th-century book for professional woodworkers, and it is a delight to page through. One of the owners of the book performed all the recommended exercises on the backs of the plates, which are almost as fascinating as the plates themselves.
In this plate, No. 32, the author is illustrating how to draw the bookstand in perspective. The three images here are joined to one another at the edges, making for a complete exploration of all the details of the bookstand.
I don’t own a copystand (yet) for my camera, so I have included three high-resolution scans here for you to play with. Feel free to stitch the images together.
