The frequent inquiries in the Correspondence columns of Carpentry and Building indicate that there is a dearth of knowledge as to the proper method of sharpening a scraper. Without any disposition to assume superior knowledge in this connection I am constrained to remember that we cannot clean our floor without sharp tools, and will give your readers the benefit of my experience along this line.
I presume that every reader understands that the cutting edge of the scraper is formed by turning over a “burr” or wire edge, which does the cutting when applied to the wood. This burr is made by rubbing against the edge of the scraper with a tool called a burnisher, which may be made of any piece of steel of convenient form but which must be harder than the scraper. (more…)
The general demand for finely finished floors of hard or soft wood in modern residences has given rise to such a variety of tools and finishes designed for this special purpose that natural confusion arises as to the best tools, finishes or methods to employ in this highly important branch of the trade.
The growing demand for the conveniences of the city residence in the homes of the smaller towns and the rural districts often brings the carpenter and the painter up against this sort of work, demanding methods of treatment with which they are unfamiliar, and many a good job of floor has been spoiled or indifferently treated by otherwise good mechanics, simply because they lacked the knowledge or experience so essential to success.
It has been the fortune of the writer to have a somewhat extended experience in the better grades of modern floor finishing, and it is with the hope of affording some degree of general information to the craft that this discussion of the topic is undertaken. For convenience in treatment the subject will be considered with reference to the following elements:
1. The carpenter.
2. The tools required.
3. The laying of the floor.
4. Preparation of the surface.
5. The painter’s work.
6. Different varieties of finish.
7. Relative cost of floors and finishes.
8. Suggestions as to estimating. (more…)
Freshly-cut red oak, destined to become Roubo workbench legs
A few days ago, Chris broke one of the cardinal rules of this blog: he began a sentence with, “You should…” He said to me, “You should be writing about this stuff…as a full-on blogger.” I agreed, then explained that the reason I don’t is that I find writing to be painful. So what does he do? He offers to let me write on his blog. I suppose I should be thankful that he didn’t kill me outright, like poor Raney. On the other hand, Raney’s death was quick and presumably fairly painless. Mine will more likely be slow and lingering.
Wood and water. From the woodworker’s point of view, not exactly a match made in heaven. Why is it that thick slabs of wood take so %$#@! long to dry? You may have heard the old air-drying rule of thumb, “one year per inch of thickness.” I remember reading it for the first time many years ago and thinking, That can’t be right. From basic geometry, doubling the thickness of a piece of wood should quadruple, not double, the drying time, and my own experience with drying wood since then has at least approximately confirmed that. There are two factors that cause thicker pieces of wood to dry more slowly: one, there is simply more water to remove through the same amount of surface area, and two, the water has to travel further, on average. Both of these factors are proportional to the wood’s thickness, and they’re multiplicative, so in the simplest approximation the drying time goes as the square of the thickness.
I’ll skip the physics lecture (for now, but there might be an exam later) and show the results of some computer simulations that I ran for water loss in wood, from fully saturated to near equilibrium, using a few assumptions (physicists are all about making simplifying assumptions). The assumptions I made are:
the board is wide and very long compared to its thickness, so I only have to worry about water movement through the faces of the board, and not the edges or ends,
the temperature is a constant 52°F (the year-round average for southeastern Ohio, where I live), and
the equilibrium moisture content is 12% (a typical outdoor value for this climate).
Here are two graphs (click to enlarge), showing the computed change in moisture content over time in red oak, in a 1″-thick board (left) and 6″-thick board (right), subject to the above assumptions and using published data for the various water transport parameters:
As the graphs show, the 1″-thick board settles down in a couple of years, while the 6″-thick board takes over 70 years to equilibrate to the same degree. Apart from the 36-fold difference in time scales, the graphs are nearly indistinguishable. In other words, there’s no significant qualitative difference between thin and thick boards; they both behave more or less the same, just on very different time scales.
So that’s at least a partial answer to the puzzle. In part 2, we’ll look at the role that end grain plays in drying (there’s good news, and there’s bad news), and examine Chris’s hypothesis about how “being surrounded by so much dry wood keeps the moisture in” (hint: he’s at least partly correct).
These first two are fairly non-technical, but they focus on the what and have little to say about the how and why.
Baronas R et al. (2001) Modelling of Moisture Movement in Wood during Outdoor Storage, Nonlinear Anal. Modell. Control6:3-14.
Includes an excellent comprehensive overview of the theory of moisture movement in wood; requires a working understanding of partial differential equations.
Simpson WT (1993) Determination and use of moisture diffusion coefficient to characterize drying of northern red oak (Quercus rubra), Wood Sci. Technol.27:409-420.
Source for the data used in the computer simulations.
Our audiobook version of “The Joiner and Cabinet Maker” read by Roy Underhill was a grand experiment. (Is there another woodworking audiobook?) We love the result – I’ve listened to it three times now. But we made a mistake in pricing the CD version. It’s too expensive.
So effective immediately we have cut the price by 50 percent (to $13.50) and are offering free domestic shipping on the three-CD set. This price cut is permanent until we run out of the CDs. After that, the audiobook will be available only as a digital download.
We’ve also reduced the price of the digital download to $13.
The superior processes introduced into industry, in modern times, by the knowledge of chemistry, has led to the establishment of various branches of manufacture, and made them of great importance, though they deal with articles which were formerly either entirely unknown, or disregarded as of no value.
Glue, in the modern industrial world, is a case in point. Like many of the important things in industry, it has heretofore been overlooked; and though the world would suffer, to-day, much less in its comforts and conveniences of living from a loss of all its gold and silver than from that of its glue, yet this fact would be most probably overlooked by the large majority of those whose well being is so intimately dependent upon its abundant and cheap supply.
Yet, in fact, glue is absolutely indispensable to the arts of modern industry, and as yet no substitute has been found to take its place. Without it, turpentine and petroleum would escape from the barrels which now contain them, and be lost. The very paper on which we write would, but for glue, make nothing but a series of blots; and so on through all the series of domestic or household arts. (more…)
