Appendix 6: Evolution of Woodworking's "Cutting Edges"

Working notes and images for a conceptual framework of the origin and evolution of cutting edge assemblies in hand and power machinery tools

Disclaimer: this piece is not intended as a "history"; instead its intent is to set out a brief account of how I understand the cutting edge of woodworking tools evolved.

Moreover, recently -- about three years after the Evolution of Woodworking's 'Cutting Edges' concept occurred to me -- I discovered a chapter in an almost 50-year old book, by James J Hammond, et al, "Topic 40: Theory Underlying the Design and Action of Cutting Tools", Woodworking Technology Bloomington, IL: McKnight and McKnight, 1961, pages 92-95. The gist of the chapter -- and much of the book's contents -- focuses on a "theory" that, essentially, woodworking tools do one major operation: cut and/or shape wood, basically, the same as what my theory is, as outlined in the narrative below, but more fully developed. I say "more fully developed" because Hammond and his co-authors -- all talented instructors in the Industrial Arts movement -- buttress their arguments with evidence that includes well-drawn, clear, schematic diagrams that show the cutting and shaping functions of major hand and power woodworking tools. I have reproduced several below.

Well, shall I cry? Or, laugh? Cry, because my theory wasn't as original as I thought it was. Instead of "inventing the wheel", I end up "re-inventing" the wheel.

I can laugh, too, though, for at least two reasons:

first, this book confirms the validity of my theory, which I find consoling. Nothing like being out on limb with a theory that everybody views with suspicion.

Moreover, as good as the Hammond, et al "Theory Underlying the Design and Action of Cutting Tools" is, as you'll note below,

second, I found reason to question part of their "theory", specifically their claims about the operation of the "knife wedge". For me, their ideas about the "knife wedge" merely constitute a variation on their "chisel wedge". Their claims about the knife -- as a "double bevel" wedge -- does not have enough distinctiveness to stand alone.

Moreover, throughout their narrative, as an example, the authors only mention "knife wedge" once, and in that particular context, knife wedge figures only in a minor way.

But, I am jesting. As amateur woodworkers, we are not in a competition. Instead, for us, more than anything else, woodworking is "fun"; if it wasn't fun, to occupy our leisure hours, we would find some other hobby that really was fun.)

First, as I note at the top, much of the bibliography for the existing scholarship on the history of early hand tool development exists in anthropology and the history of technology.

(Have yet to search Technology and Culture intensively yet, but my initial foray into it was disappointing: it's annual bibliography is arranged in a highly classified order, but strangely this classification scheme lacks a category for woodworking, which means that to pick up articles on woodworking, you must go to the index and look individual topics. Have yet to look for a digitized database version of it.) History of technology is especially useful because they published an annual bibliography since 1964, and its digitized, but my academic library doesn't subscribe to it.)

Conceptual Framework: Woodworking as an Evolving Art and Craft

For readers not familiar with either the objects or the vocabulary of woodworking, I offer this section as an "introduction" of this online book. As both a craft and an art, woodworking traces back to the earliest points of man's habitation on earth.

By beginning with the birth of woodworking, we can show the connectivity that traces through these beginnings to the present day. I especially want to impress you, the reader, about the empirical and experiential aspects of woodworking, its intuitive sweep, and the "bottom up" nature of its development. Woodworking is, in truth, one of mankind's most admirable achievements. The text and illustrations below introduce some basic woodworking concepts.

My intent is simple: explain how woodworking tools function when cutting and shaping wood. And to make these concepts clear, the ideal perspective I believe is one that shows their evolution from rudimentary tools that helped primitive humans survive and -- increasingly -- flourish.

Except for the initial chisel, all tools introduced in this section exhibit one characteristic, i.e., cutting with multiple sharp edges.

Evolution of Woodworking's "Cutting Edges"

1. Single Wedge-Shaped Cutting Edge:	1. The Chisel
2. Multiple Wedge-Shaped Cutting Edge:	2. The Toothed Saw
3. Single, Elongated Wedge-Shaped Cutting Edge:	3. The Hand Plane
4. Single Cutting Edge, Elongated, Profiled Wedge-Shaped Edge:	4. The Profile Plane
5. Multiple Cutting Edges, Rotary Action, Short Wedge-Shaped Cutting Edge:	5. The Drill Bit
6. Multiple Cutting Edges, Rotary Action, Short Wedge-Shaped Cutting Edge, Straight Edge:	6. The Circular Saw Blade
7. Multiple Cutting Edges, Rotary Action, Elongated Blade, Wedge-Shaped Straight Edge:	7. The Jointer and The Planer
8. Multiple Cutting Edges, Rotary Action by External Power, Elongated Blade, Wedge-Shaped Profiled Edge:	8. Router Bits, Shaper Cutters and Jointer and Molding Heads

My narrative begins with the theory underlying the operation of woodworking's cutting edge. Then, to illustrate, walks through eight stages -- more-or-less successive, historically -- in the development of woodworker's cutting edges.

The narrative covers (1) the chisel (single wedge-shaped cutting edge), then progresses through (2) the toothed saw (multiple wedge-shaped cutting edges), (3) the hand plane (single, elongated wedge-shaped cutting edge), (4) the molding plane (single cutting edge, elongated, profiled wedge-shaped cutting edge), (5) the drill bit (6) the circular saw blade (multiple, short, cutting edges, rotary action, narrow wedge-shaped cutting edge),(7) the rotary cutterhead (multiple cutting edges, rotary action, elongated blade, straight wedge-shaped edge), (8) the shaper cutter, the router bit, the molding knife (multiple cutting edges, rotary action, elongated blade, profiled wedge-shaped edge).

Along the way, I will offer definitions and illustrations.

The Theory Underlying the Operation of Woodworking's Cutting Edges

In "cutting" and/or "shaping" wood — whether it's sawing, planing, boring, shaping, routing, sanding — the purpose of the operation is to systematically sever material along a workpiece's length, width, or thickness.

1. Every wood cutting tool is a wedge-shaped cutting edge or series of wedge-shaped cutting edges, with a single bevel.

Chisels, plane irons, turning tools, gouges, drawknives, spoke shaves, scrapers -- and sandpaper -- are all modified chisels or gouges, with single wedge-shaped cutting edges, as are jointer, router, shaper, molding, and thickness planer knives.

The two wedge-shaped cutting edges of an auger bit are, in effect, two chisels set up with the blades pointing in opposite directions -- see below. When the bit is rotated, the "lips" cut in a clockwise direction. The twist drill has its cutting edge on an angle, but the effect is the same.

In the case of a tool like the cross-cut saw, the double bevel on each tooth, in effect, makes two wedge-shaped cutting edges See below .

2. In cutting wood by any method, stock is removed through the shearing action of the wedge-shaped cutter or series of cutters. The wedge-shaped cutting edges shear the fibers of the workpiece, and -- as shown in the image on the left -- the incline of the face of the wedge causes the fibers to be separated from the workpiece, producing shavings, chips, or dust.

3. The shearing is accomplished by the cutting edge of the blade (or teeth) being wedged into the stock in a sliding motion, and at a depth controlled by the tool's operator.

4. The wedge or wedges are driven by hand or machine power and engage the stock in a given plane, arc, or angle.

5. The wedge-shaped cutting edges may be pushed or pulled into the workpiece-- as with a Radial Arm Saw's rotating blade --, or may revolve or reciprocate in the workpiece -- as with a Lathe or Jig Saw, or the workpiece may be pushed into or revolved against the wedges -- as with a workpiece fed into a Table Saw's rotating blade or a rotating log sheared into veneer sheets.

6. The smoothness of the cut is determined largely by the shape and content of the wedge-shaped cutters -- carbide teeth, the number of wedge-shaped cutting edges -- an 80-tooth carbide-tipped blade, the angle at which it is inserted into the stock, the depth of the cut, the moisture content, and the grain pattern. The smoothest cuts usually result in shavings. (Under a microscope,the finest sawdust appears as minute shavings.)

7. The most effective angle of approach of the tool's cutting edge to the wood fibers is approximately 30°, and each type of tool is so designed that in use, the wedge-shaped cutter's edge enters the stock at that approximate angle. At certain angles the wedging action is erratic because the cutting edge of the tool tears and breaks the fibers ahead of the cut.

8. The lip clearance is the relief given the wedge-shaped cutting edge so that it may enter the material to be cut. Much of the effectiveness of the cutting edge depends on the correct lip clearance angle. If no clearance angle was provided, the cutting edge would be prevented from entering the work. Too great a lip clearance angle weakens the cutting edge. The angle may range from 6° for metal cutting tools to 35° for woodworking tools.

9. The rake angle is the angle at which the face of the cutting edge enters the work. This angle partially controls the tightness with which the shavings are curled. A large rake angle requires a great force to drive the tool. Too small a rake angle results in a thin cutting edge. Tools such as the plane, auger bit, and saws are designed by manufacturers for maximum stiffness and most efficient cutting angle.

(The images above and the text are adapted from "Topic 40: Theory Underlying the Design and Action of Cutting Tools", James J Hammond, et al, Woodworking Technology Bloomington, IL: McKnight and McKnight, 1966, pages 92-95. Pages 92-93 have illustrations of the operational physics of the hand scraper, the rip saw, cross cut saw, the auger bit, and the combination circular saw tooth.)

(1) The Chisel: single wedge-shaped cutting edge

Man began fashioning tools at least a half million years ago (Jones and Simons, 1961). In man's long history, estimated to stretch 20,000,000 years, the use of chisels, however primitive, come into evidence very early. (C. D. Darlington, Evolution Of Man And Society, 1969, page 22; The Story of the Saw, a 1961 publication issued by the saw blade manufacturer, H. Disston, and Sons Inc., also informs my account of multiple cutting edges. The authors are Peter d'Alroy Jones and E N Simons.)

As specialized woodworking tools, the anthropologist, W L Goodman, The History of Woodworking Tools, 1964, citing numerous sources, shows that the chisel, the axe and the adze, trace back to the Stone Age, i.e., about 50,000 years ago. (Goodman, pp 12ff, 195-198).

Refinements on the chisel followed. In early classical times (i.e.,,, period of Roman Empire), at about the beginning of the Christian era, a cutting tool which could be easily adjusted and which depended less on the skill of the craftsman plane, was in use. (Figure 1) Although no examples are extant, tradition suggests that the tool dates back to the Greeks. (Goodman, 39-109).



Before 1200 BC, tools used as chisels consisted of flint or other similar, naturally occurring, hard substances. But, in his conference paper, "Development of materials for wood-cutting tools," E. K. Spring, [Chief Metallurgist, Henry Disston & Sons, Inc., Philadelphia, Pa. Proceedings Of The Wood Symposium: One Hundred Years Of Engineering Progress With Wood, The Centennial Of Engineering Convocation, Sept 3-13,1952 Chicago, Illinois, need page no] argues that "records indicate the use of steel articles prior to 1200. B.C."

For Spring, the iron industry, "the basis of our civilization," grew on man's longing for a superior weapon. At about 1200 BC, Spring elaborates, man began "crudely smelting iron ore." He points out, for example, that when the invading Romans arrived in and around Toledo (Spain), ca, 192 B. C., they found evidence of the working of iron. Out of these discoveries emerged the so-called "Toledo blade," a device that soon acquired a reputation as a superior military weapon. The Catalan forge, the first use of mechanization in the smelting of iron ore, evolved in Spain, about 1300 A. D. (For me, these developments prove – once again the regrettable irony in our history that major technological advances accompany and follow the intensification of research and development during major wars. Proof of this latter point will become evident when we look at the decade, the 1920s, following WWI, and the 1950s, following WW II, for examples of major advances in woodworking, especially for amateurs.)

After these advances in smelting, continues Spring, a long period elapsed before we see the beginnings of modern steel, so essential for refining woodworking tools. Around 1740, in England, Benjamin Huntsman, designed the first crucible furnace capable of producing steel. Huntsman "remelted the carburized cement or blister bar, which when cast into a mold, resulted in a fairly homogeneous piece of steel." The first tool steels for the working of wood and other products, according to Spring, were of "plain carbon steel."

Later, about 1855, well into the Industrial Revolution, another Englishman, Robert Mushet, created a "special" steel, high in carbon, with quantities of tungsten, designed to resist against the softening from the heating that develops during operation, as we'll see below, very important in woodworking saw blades, especially those large, narrow, circular ones designed for the bandsaw.

2. Multiple Wedge-Shaped Cutting Edge: The Toothed Saw

My concept of the early appearance of uses of "multiple wedge-shaped cutting edges", i.e., the hand saw, comes my conviction that "crude and un­even notches or serrations in the edges of flint flakes" are merely elaborations of the single edged chisel. Jones and Simons (1961) argue that the principle of "sawing" dates to the "pre-metal age."

(I also consulted H., Disston, and Sons. The Saw In History. 8th edition. New York, 1926. The era in which these developments about "sawing" occurs, the "pre-metal age", is labeled the Neolithic Age, ca. 4700-2000 BC. Neolithic is a term coined in 1865 by the Englishman, John Lubbock, but given more validity in 1925 by the English archaeologist, V. Gordon Childe, The Dawn Of European Civilization, 1925. The Neolithic Age is characterized as the period when man mastered the processes required to supply his own food, through domesticating animals and cultivating plants, and skills in fashioning tools.

Neolithic man adapted as tools the objects he found around him; as an early form of the multi-toothed saw, for example, really just a variation on the chisel, the Neolithic man cut crude and un­even notches or serrations in the edges of flint flakes. For more background on the Neolithic Age, see ch 4 of Darlington, The Evolution of Man and Society, 1969.)

The action of a single tooth in a saw is represented below, in this diagram adapted from W F M Goss, Bench Work in Wood, rev ed, 1905, page 30, but for greater detail, click here.



Ancient man, driven out of necessity -- survival -- his imagination limited to found objects, but pragmatic, empirical -- education not needed -- visualized in due time, that, simply by multiplying the "edges" of a chisel multiplied geometrically the efficiency of the chisel for cutting and shaping wood and stone.



And crude though they be, very slow and laborious in action, acting like multiple chisel edges, the saws make their appearance in the Copper or Early Bronze Age. (W L Goodman, 110-159). Says Goodman, "It is fairly obvious that only a metal saw would have any advantage in working life and economy of material over the existing stone axes and other cutting tools," and consequently the first real saws evidently were created ca 1490 B C, in Egypt.



In these images of the action of today's crosscut hand saws, the wedge-shaped cutting action occurs in two distinct directions:

(1) back-and-forth, where, the side points on either side of the saw -- the first set of wedge-shaped cutters -- score parallel lines. This action is wedge-shaped cutters operating in a back-and-forth motion.

(2) As the sawing action continues, the cutting edge on the inside of the teeth -- the second set of wedge-shaped chisel cutters -- comes into contact with the wood, shearing it out of the kerf.

When a full bite is taken, the points of each tooth score the outsides of the kerf, and the sharpened, beveled sides of the teeth, wedge-shaped, shear the wood between the side wedge-shaped cutters.

In the cross-cut saw, the teeth are set, alternately, to the right and left, so that the cut, or kerf, is wider than the thickness of the saw blade. This off-setting of the teeth is known as "set."

(Editorial Note: These images are adapted from James J. Hammond, et al, Woodworking Technology Bloomington, IL: McKnight and McKnight, 1966, 2d ed., pages 96 and following. However, in opposition to Hammond and his co-authors, who claim that the "scoring" of the back-and-forth action is a "knife wedge", rather than a "wedge-shaped" chisel, I claim that the back-and-forth action is "wedge-shaped" cutting, a conclusion drevied from an analysis of the "point" on each tooth. Rather than having a "knife" shape, for me, the point of each tooth is the point of a "wedge". A knife's elongated edge is distinctly not a point. However, such differences of opinion are merely that, differences of opinion, and need not become an obstacle to understanding how saw teeth operate as wedge-shaped cutting edges.)

[not yet completed] One of the greatest single events in the history of mankind — the invention of the wheel — may well not have been possible without the earlier invention of the metal saw.[Vere Gordon Childe New Light on the Most Ancient East 1952 "wheel can hardly be made without a metal saw Page 110; JJones and Simons story of the saw 1961 selections.doc] forbes, r j, studies in ancient technology, 1955 and tunis, Edwin, wheels, 1955]

3. Single, Elongated Wedge-Shaped Cutting Edge: The Hand Plane

From earliest times on through successive ages, along with as bench planes for smoothing and dimensioning wood, woodworkers of all sorts have used special planes "for cutting rebates, grooves, and moldings of various shapes."

(Above, plane with a single, straight edge, the so-called Roman-Silchester plane.)

The Romans, for example, employed a variety of planes, including ploughs, rabbet planes, hollows and rounds. In the medieval period, much shaping of work was achieved with molding planes, while in the 15th and 16th centuries, the linen-fold panels [get picture], very popular, needed to “have been worked with sets of hollows and rounds, and the panels themselves let into ploughed grooves or rebates. The lathe, or turned work, uses straight- and curved-edge chisels. Turned work appeared in the eastern Mediterranean in the second millennium B C. While there evidently no lathe artifacts of this period, speculation suggests that power was created by the bow-drill, “in which the object of be turned was the stock of the drill, rotated by a bow between two fixed points."

James J. Hammond, et al, Woodworking Technology Bloomington, IL: McKnight and McKnight, 1966, 2d ed., pages 92 -- the physics of the plane's components are set out: the rake angle, the cutting angle, the lip clearance.

4.Single,Profiled Wedge-Shaped Cutting Edge: The Profile Plane

These images by Aldren Watson, Country Furniture New York: Thomas Y Crowell, 1974, page 173, give us several views of the ways in which planes with profiled Irons shape Moldings

































My Sargent Combination Plane No 1080 confirms the concept of profiled cutting edges.

5. Rotary Action, Wedge-Shaped, Multiple Cutting Edges: The Drill Bit

Soon, we move into the era of powered tools. But first, we will examine the early twist drill bits, or auger, that evolved from one edge to two-edges. Arbitrarily, I am calling crude bits or augers, "multiple-edged" cutting tools, although that label is debatable. Augers first appear in Roman times. These crude bits or?

Recently a "revolutionary speed bit" was introduced for electric drills. Actually it is an adaptation of an early "button bit" (A) and (B) and has the same design as the "center bit" (c. 1794) with which the pioneer American started trunnel holes in his buildings. For shallow holes or to start a boring, it cut downward without pulling shavings upward as the big spiral bit does. Center bits, therefore, which were never put on bar handles, were used with a brace.

The four typical wooden bar handles shown are generalizations; because so many men made their own handles, it is difficult to pinpoint the date of a handle from its design. I have worked out these estimates, from the handles in my own collection, in the hope that this information might be helpful in dating tools in other collections.

It seems incredible that a man could turn the huge bits that some augers have. The job was made easier in the by a two-handled drill (shown opposite) ; an adjustable model came out in the 1860's that drilled at any angle.

Drills, for drilling holes in wood, were spoon-shaped. If you look at the pictures below carefully, you will detect that they do indeed have two cutting edges, but how effective is the second edge? Augers with twists were used in Russia between the 10th and 13^th centuries. In realtiy, though, augers or drill bits with two effective cutting edges did not appear until much later. The screw auger No 208, featuring two cutting edges, was invented in Connecticut ca 1800. is the earliest representation … of the modern twist bit. (W L Goodman, 165-166). (See illustration, Figure 5, in lower right image.)



In the three images from Goodman -- on the left, and below -- the first features examples of Russian augers, dating from the 10th to 13th centuries. The second, with tools of much later period, the nineteenth century, includes -- the second auger from the bottom -- the example of a twist drill/auger with two cutting edges. In the third, round holes are drilled into wood by a twisting action, with each of the two cutting edges removing wood.













Sources: W L Goodman, History of Woodworking Tools, London: G Bell and Sons, 1964, pages 166 and 170; Garrett Wade, Tools: A Complete Illustrated Encyclopedia New York: Simon and Schuster, 2001, page 168 and following.

Bentham's Rotary Cutterhead Preceded Auger Bit

One would think that, with its two cutting edges, the auger bit would have preceded the rotary cutterhead of the planer and jointer. Not true, though, as the rotary cutter head concept preceded the two-edged auger bit by a century. Samuel Bentham, labeled by some the "father" of the modern woodworking machine, is credited with inventing the rotary cutterhead. For evidence about this anomally, historians can cite two sources:

The determination of when and to what extent technological innovations made an impact on the furniture industry is at best problematic. The value of patent records for dating machinery is extremely limited because of the frequently significant lag between invention and commercial application. Samuel Bentham, for example, received a landmark English patent in 1793 for a broad range of woodworking machines including rotary planers, molders, dovetailers, an automatic lathe, and a reciprocating mortiser. (Parenthetically, most of these did not see general use for at least forty years.) Source: John Richards, Treatise on Woodworking Machines, 1872, pages 5-6, as cited by Michael Ettema, "Technological Innovation and Design Economics in Furniture Manufacture", Winterthur Portfolio 16 1981, note 20.

6. Multiple Cutting edges, Rotary Action by External Power: Circular Saw Blades and Bandsaw Blades

Two examples of saw blades exist in this group: circular saw blades and bandsaw blades.

[introduce some of Richard's account of the development of band saw blades.]

6.a Circular Saw Blades

The concept of the circular saw blade was used in England by the scientist, Robert Hooke, in about 1670, while even earlier, in the Netherlands, C. C. Jonge Calff patented something like a circular saw on 25th June, 1645. However, circular saws proper were not refined and patented until the second half of the 18^th century, by Samuel Miller and Walter Taylor. (Jones and Simons, 1961). The operations of mechanical flattening and tensioning, incident to manufacture and servicing in the field, limited the hardness of the blade or body of the saw. High-Speed Steels

The next advancements of the wood working industry was the adoption of another product of the steel metallurgist, the so-called "high-speed steels." and the carbide-tipping of saw blades (The beginning of a treatemnt of hss is in glossary H, but needs much more work)

6b Bandsaw blades

Bandsaw blades, evidently are close to an engineering miracle, especially since they when/where developed, however crudely, circa mid 19^th century.

Some notes to complete in the future"

The miracles are -- in creating the continuous metal band -- first, creating a blade that is both thin and flexible and, second, solving the problem of "welding" the two, opposite ends of the blade together with sufficient strength to withstand the enormous pressure needed for the teeth to "saw" large workpieces, as shown in the image below, on the left.) According to E K Spring, [need source-- a member of the asme, spring's article appeared in the asme's proceedings in about 1952] band saw blades have continued to be made of mildly alloyed steels. Will later incorporate John Richard's history of woodworking machinery at least note that the concept of the "edge" is implicit. Ex: Force can be used in any degree: force is the first and main element wanting; by increase of force we increase the cutting edge, and the result is greater accordingly.]

Need also to show multiple cutting edges, rotary action, elongated blades; i.e., planer and jointer cutterheads. Cannot find a dramatic enough illustration of a jointer cutterhead to use. Need to show readers the length of the jointer/planer knives. My intent is to demonstrate that the jointer/planer cutterhead is merely a refinement of the circular saw blade, an elaboration of the "width of cut" or "kerf"; i.e., today, the "width of cut" of the typical carbide-toothed circular saw blade is 1/8". (Note the distinction between a circular saw blade's "teeth" and a jointer/planer's "knives"? -- The width of a jointer knife is usually 6", but ranges upward to 16-20 inches, which compared to the kerf of a saw blade, gives the six-inch jointer knife a kerf of six inches.)

7. Multiple Cutting Edges, Rotary Action by External Power, Elongated blade, Straight edge: The Jointer and The Planer Cutter Head

On the left, is a Dado Set, the blades, Chippers and Bushings lined out on a rod (smaller in diameter than an actual Arbor), designed to operate on either a Table Saw or Radial Arm Saw, which in operation would hold the dado set during rotation.

Don't be fooled, however; in actual operation, the blades in the dado set are tightly held together, so that an accurate dado "groove" can be achieved. The underlying concept of a dado set, though, is a Circular Saw Blade, but its Kerf stretched out, to make a Dado Cut.

On the right, is the Jointer Cutterhead for my 1947 Shopsmith 10E. The concept is the same as the Dado Set on the left, to show the Cutting Edge stretched out, enabling a wider "Kerf"; very rarely, though, is the "cut" with jointer or planer knives in excess of 1/8 inch. For the most part, the depth of cut is less than 1/16th inch.

8.Multiple Cutting Edges, Rotary Action by External Power, Elongated Blade, Profiled Edge: Router Bits, Shaper Cutters and Jointer and Molding Heads

The molding head -- image on right, above -- is a variation on, first, the molding plane, with its profiled cutting edge, but also, second, the circular saw blade.

Likewise, above, on my shop-made shaper/router table -- the three-lip Shaper Cutter is bored for an Arbor or a Spindle. Arbors and Spindles both are devices designed to securely hold devices with cutting edges that rotate at speeds ranging from a few hundred revolutions-per-minute (rpms) up over 20,000 rpms. Regardless of rotation speed, Runout factors critically into the equation, in the sense that the rotation must remain constantly accurate, or otherwise there will be an uneveness in the resulting cut, especially if the operation involves a profiled edge, like a Router Bit designed to cut the edge in one pass a Raised Panel. [10-23-07 -- more on this later] Shaper Cutters include lock-edge style shaper cutter assemblies.

On the left is an image of my (unused -- note the rust) lock-edge shaper cutter assembly. The set-up is part of my purchase at an estate sale of a vintage bench-top shaper, of unknown ancestry -- there are absolutely no identifiable markings on anything -- but likely a 1930s Delta (or knock-off of the same era)

<sup>This lock-edge assembly is a smooth-edge slot, but the preference is for serrated slots, because they allow precisely setting the cutters, so that the cut each makes is uniform with the other, and one cutter is not doing all the work.<

On the right -- courtesy < oella_saw_and_tool -- is an image of the lock edge with the serrated grooves, allowing precise setting of the two cutters.</sup>

Router Bits

On the left is a three-edge bead router bit.

What Next?

[note to self 8-22-08] Nathan Rosenberg's ch America's Rise to Woodworking Leadership should be used as part of a theme setter. WWU book, Brook Hindle, America's Wooden Age: Aspects of Its Early Technology , 1975: pp 37-62, 197-202; Rosenberg also wrote the 86-page intro to the reprint of the American system of manufactures, originally published in 1855, and 1854. The following is a scan of rosenberg's pp 38-39 – but the whole ch should be copied.

Techniques for cutting and shaping wood continue to evolve. The discussion above is limited to the cutting edge.

Another method of shaping wood is Sandblasting (although like the action of sandpaper itself, particles of sand actually "cut" the wood).

However, Lasers are used for cutting and shaping wood, and achieve this action without a cutting edge. lasers are the tool of the future, for certain, but it is unlikely that lasers will entirely displace the cutting edges discussed above.

Sources: (not complete) Vere Gordon Childe New Light on the Most Ancient East 1952; W L Goodman, The History of Woodworking Tools London: G Bell, 1964; page 105; Cyril Aldred, “Furniture: To the End of the Roman Empire,” in Charles Joseph Singer, et al, eds., A History of Technology, v2, Oxford University Press, 1956, page 232; Garrett Wade, Tools New York: Simon and Schuster, 2001