under construction 1-11-10
The Bandsaw BladeThe band saw [blade] is an endless steel belt running over wheels and revolved continuously. It is pliable, so as to conform to the faces of the wheels, and is serrated on one edge. The ends are joined together by solder and by neat clamps. Arrangements are made for straining [read: "tensioning"] the saw [blade] by regulating the relative distance of the wheels....
Source: Edward Henry Knight Knight's American Mechanical Dictionary: A Description of Tools, Instruments ... 1876, Volume 1, page 226
Rather than offer my personal definition (above), instead, I adapted my definition of "bandsaw blade" from an authoritative source, the 1876 classic, affectionately known as Knight's Mechanical Dictionary.
To the uninitiated, the bandsaw remains a rather strange machine. Because it performs several operations key to dimensioning rough workpieces -- primarily Resawing, Ripping, and cutting curves and other shapes -- its versatility in woodworking is legendary. Nonetheless, its origins continue to remain rather shadowy. As Keith Rucker (owwm.com) notes,
The band saw was first invented (or at least conceived) back around 1808. However, the machine was impracticable because technology at the time did not exist to weld the ends of the blade together strongly enough to withstand the pressure placed upon the blade while cutting.
Not until the early 1860's did A. Perin & Company of Paris France develop a blade and a welding method strong enough to hold up under the pressures placed on the blade while cutting wood or other materials. Perin & Company also manufactured band saws and -- after much trail and error -- succeeded in developing a blade to sell with their saws.
Early band saws blades were usually welded together with silver or German silver solder. The blade's two ends were "scarfed" in such a way that, when the ends were laid one on top of the other, the blade's thickness remained constant. Most early band saws were sold with a special jig that allowed the user to clamp the two scarfed ends together and hold them in place while welding. A thin piece of silver solder was placed between the scarfed ends, and heat applied until the solder melted. The weld was then cooled using tool that looked very similar to blacksmith tongs but with blocky ends that served as a heat sink to cool the part quickly.
More Investigation Needed
I will continue my quest for locating the background on when, finally, welding bandsaw blades reached a standard that eliminated most breakages from the strain while it cut material.
In the meantime, I find Manfred Powis Bale's extensive account of the bandsaw up to 1880, Woodworking Machinery, both interesting and informative, primarily because his description is more thorough than Richards' Treatise -- see Sources at bottom, while -- because of a paucity of results -- my investigations in NewapaperArchive.com and the two versions of digitized books and periodicals of the nineteenth century -- Making of America -- were disappointing.
Bale writes (in 1880) on about the problems bandsaw manufacturers had with their blades in the nineteenth century.
The following sections are adapted from Bale's Chapter 39, "Band or Ribbon Saws". (-- for bandsaws in general, more details in glossary entry bandsaws -- Bale's Woodworking Machinery is online, fulltext)
Writing in 1880, M Powis Bale -- considered both at the time and by scholar's today as an authority on woodworking machinery technology -- argues that, in the creation of bandsaw blades, "recent advances" -- primarily in France led to impoved bandsaw blade [operation]" not so much from the quality of the steel employed, but more likely from advanced method employed in tempering, "which ensures to the blade a considerable amount of hardness combined with toughness". The manufacture of these saws on an extensive scale has never been carried out in this country, the method of tempering successfully 'being kept more or less a secret.
When cutting wood or other material, band-saw blades are subjected to considerable strain. For Bale, in 1880, the chief strain is "a bending or torsional strain, especially heavy work, with sharp curves". Drawing on metallurgical theory of the time, Bale alludes to the prevailing idea that, while cutting timber, "the expansion and contraction in the blade [that ] friction [creates] ... seems in a great measure to alter the fibre or granular structure of the steel..." The results, constant breaking of the blade, says Bale, has driven potential users against adopting "this method of sawing".
To solve the problem, Bale himself tried to fashion a blade combining hard-tempered teeth, but "the blade's main body was left soft... his [attempt], however, owing to the difficulties of tempering and the unequal expansion and contraction, was a failure". (Bale was himself a prominent figure in English woodworking circles.)
Credit for improvements in the manufacture of band-saw blades goes ot M. Perin, of Paris. Nonetheless,
"[p]lenty of scope for improvement still exists, especially in saws of stout gauge and considerable width -- say, above 3 inches. Wide band saws are valuable for certain classes of heavy bevel sawing, such as the curved forms required for ships' timbers or the backing for armour-plated vessels. Their use for these purposes, however, is much retarded, owing to the heavy loss sustained even by the breakage of a single saw, as when once broken it is a matter of considerable difficulty to braze efficiently wide saws of stout gauge.
In 1856 Mr. W. Exall took out a patent for improvements in the manufacture of band-saw blades. These improvements consisted chiefly in heating the blade by means of blow-pipes or lamps whilst it was being passed through the rollers or dies used for the purpose of reducing the blade to its proper thinness, and in giving the blade its proper temper by continually rolling it between hard rollers or by repeated drawing through dies, as in drawing wire. He also claimed another plan of tempering the blade when joined ready for work by heating it in a suitable oven and then plunging it into oil or other fluid.
A patent for an improved machine for setting the teeth of band saws was taken out by Mr. L. Orton in 1876.
In this invention two pulleys hold the saw taut, and the two limbs of a forked frame suspended on a short shaft carry each a punch, that operates, as the frame is oscillated by the handle, to set the teeth from opposite sides, the saw being fed along by a pawl on a bell-crank lever, that is actuated by a cam fixed upon the frame.
For sawing very hard wood or iron the teeth should be made shorter, and with at least one-third more points to the inch, than in blades for sawing soft wood, as they will stand little or no setting; for a clearance for the saw they are made to taper from the points of the teeth to the back of the saw. The teeth of band saws should be set by blows in preference to bending, which, unless very carefully performed, is more liable to buckle the blades and prevent them running true.
Saw blades of too hard a temper, where the steel has crystallised, or where the blades have been subjected to imperfect or sudden tension, break readily, the fractures usually commencing from the roots of the teeth. A good saw-blade should be elastic in its temper, without hardness; the gauge, width, and toothing should be uniform throughout. Care should be taken in jointing the saws that they are not made thicker at the braze, as when in work, if this is the case, they will be found to jump and not run true on the saw wheel, breakages being the result. The operation of brazing or jointing band-saw blades with a little practice is easily performed. The modus operandi is as follows:
Take each end of the blade and file down a taper on the opposite sides of the saw of about three teeth points, so that when the two ends of the saw are made to overlap each other the joint, when cleaned off, will be the same thickness as the rest of the blade. Secure the overlapping ends of the saw well together by small hand vices, and tie them with fine iron wire. Over this bind tightly with brass wire the full length of the overlap. Moisten the joint with water and cover it with powdered borax. Either take a large tongs and make it red hot, or place the saw in a small forge fire made of charcoal and keep it there till the brass is well melted. Let the saw cool gradually, and file the joint to the same gauge as the rest of the blade and finish it with emery cloth. If this operation is well performed the joint will scarcely be distinguishable. Some prefer to moisten the saw with diluted muriatic acid, we presume to remove any grease; but we have always found plain water answer very well. Care must be taken that when brazed the overlapping ends of the saw press well together.
It is difficult to distinguish by inspection the quality or temper of a saw blade. A blade either too soft or too hard is comparatively useless. By bending the blade you can in a degree judge by its elasticity as to its temper, but users must, however, necessarily be more or less in the hands of the manufacturer.
The expansion and contraction of the saw blade is a fruitful cause of breakages. This can be somewhat lessened by lubricating the blade well, keeping the leathers on the saw wheels true, and slackening the tension of the saw immediately after finishing work. The bed plate and column of the machine should be of sufficient section and area, and fixed on a foundation of sufficient firmness to prevent any jar or vibration even when sawing the heaviest timber of which the machine is capable. We have found saw blades of a thin gauge to stand better than stout ones. They should always bend easily over the pulleys, as if the angle is too sharp for the gauge or temper of the saw they will invariably break.
Although we are aware they are thinner than those usually employed, after considerable experience we can recommend the following thicknesses of saws as the gauges most suitable for sawing pine and the softer kinds of wood of the Pinus family. The lengths of the blades are given in feet, and the thicknesses by Birmingham wire gauge:-
We give herewith illustrations of the saw teeth we have found most suitable for band-saw blades for cutting all ordinary classes of wood. Figs. 43 and 44 are well suited to most of the woods of the Pinus family, except pitch pine; for working this wood we can recommend fig. 45, the teeth of which should be coarsely spaced and set. In addition to this, owing to the clinging properties of the resin, a, small brush should be attached to the machine, so arranged that the saw blade is constantly swept by it; an occasional application of grease to the blade is also an advantage, as the resin is more readily removed. We can recommendfor durability saws with gullet teeth--i.e. teeth rounded out at the root, similar to figs. 44 and 47-as they are much less likely to fracture in working than saws with the roots running to an angle, as the fracture in the blade is found almost invariably to commence at the point of this angle. Owing, however, to small gullet teeth being more troublesome and expensive to sharpen, the angle teeth are still more generally employed.
After several experiments we have found the teeth shown by fig. 46 very suitable for sawing oak, ash, elan, and other hard woods, and by setting the face of the teeth farther back-i.e. slightly out of the perpendicular-the cutting action is improved.
These figures must not, however, be considered as arbitrary, but can be modified according to circumstances. The smaller the diameter of the saw wheel, so should in ratio the gauge of the saw be reduced. This, however, does not apply to those machines of the smaller class in which the saw blade runs over three wheels instead of two, as in this case the blade does not impinge on the, periphery of the saw wheel at so sharp an angle as when two wheels only are employed.
For cutting the harder and closer-grained woods, such as oak, beech, &c., the thickness of the saw should be increased about one gauge, the teeth should be more upright and spaced finer, and the set also should be reduced. For woods of a woolly fibre, such as English poplar, the teeth of the saw should be of coarse space and set, to effect a clearance and overcome its clinging properties. For cutting metal the thicknesses given may be increased about three gauges, the teeth of the saw being very finely spaced-say, twenty points to the inch-and set slightly with a hammer. These saws are made to taper towards the back of the blade for clearance.
For heavy curved sawing, such as the timbers used in ship-building, the backing of armour-plated vessels, &c., for all saws above 24 inches wide we can strongly recommend the gullet tooth, as shown in fig. 47. In fig. 48 are teeth adapted for cutting iron and metals ; they should, however, be somewhat stouter at the root than those shown in sketch.
The figures are not drawn to scale, but are intended to illustrate the shape or form of the teeth.
Snippet in Amateur Mechanics August 1883, page 246
Brazing Band-Saw [Blades] -- A large proportion of the users of band-saws are occasionally puzzled as to the method of repairing easily. The only really satisfactory way is to make a thick, heavy pair of tongs bright red hot, and clamp the joint with them. The heat melts the spelter instantly, and makes a good joint without scaling or damaging the steel. For a joint which has to stand constant heavy strains and bending, it is better to use an alloy of equal parts of coin[?], silver and copper, melted together and rolled out thin. This alloy, it is said, never bums, cannot be overheated, and makes first-rate joints which will stand hammering and bending to almost any extent.
Source: [Anonymous], Amateur Mechanics August, 1883, page 246
When I showed the passage above to my friend, Roland Johnson, contributing editor at Fine Woodworking, he responded with:
I've never heard of someone simply fusing the two parts together with hot tongs using spelter (zinc-copper alloy) as the bonding agent. I guess it would probably work....maybe. The second part refers to silver soldering, which is often used to join the ends of the band. Other authors have addressed this method, but I avoided any recommendation of it in my book simply because it's tough to get the blade ends parallel (if the blade isn't straight it's pretty much useless) and the potential for personal harm is high if the blade should break. Silver-soldering is not the simple, fool-proof process the others pretend it is. Bandsaw blades aren't that expensive that we need to risk damage to ourselves or equipment by trying to bond a broken blade.
I know there are some folks who buy bulk blade stock and make their own blades, at least they claim they do. I'll let the pros do it for me. Induction welding is a good means of bonding a blade. Typically this is what's done with mass-production blades. Bandsaw blade breakage should be nearly non-existent with wood cutting bandsaws, there simply should not be that much stress put on a blade. I haven't broken a blade in years.
Metal cutting bandsaws are a whole different animal. High friction heat and high pressure often result in broken blades, the reason so many old DoAll bandsaws (and other brands) had induction welders mounted right on the saw frame, plus the fact that metal-cutting bandsaw blades tend to wear quickly and bulk blade stock is often used in manufacturing settings. The relatively low speed a metal cutting bandsaw works at reduces the danger of blade breakage and the less aggressive teeth won't do the damage a wood-cutting blade can do. It's more of an annoyance than a physical danger.
Crescent Machine Company, Leetonia OH circa 1900
Keith Rucker gives us some brief background on how, ca 1900, the just-formed Crescent Machine Company of Leetonia OH achieved success in creating a new compound for welding bandsaw blades, but -- according to Rucker -- this information is sketchy. (Rucker's study of Crescent is in "A Short History of the Crescent Machine Company Part I - 1894 to 1920," The Chronicle 60, no. 4, pages 137-157.)
According to Metallurgist, E K Spring, writing in the 1950s, band saw blades have continued to be made of mildly alloyed steels.
Anne Pauline Crepin
Anne Pauline Crepin, a woman in early 19th century French aristocracy, is worthy of more investigation.
In 1995, Women Studies scholar, Autumn Stanley, wrote Mothers and Daughters of Invention: Notes for a Revised History of Technology.
An image from page 319 of this study is reproduced on the left. As one of her sources, Stanley cites the 1924 book, A Popular History of American Invention, a two-volume set -- authored by Waldemar Kaempffert -- published by C. Scribner's Sons. A Google Books search, "Waldemar Kaempffert" and "crepin", yields only snippets, but enough to make out the evidence on page 194, where Mlle Crepin's name is mentioned.
Bandsaw Blade Anatomy
Below, one on top of the other, are two images of bandsaw blades. On the top, the image shows blade tooth "set", or "clearance"; below the top image is an image that shows terms employed to identify specific blade parts
The top image -- on bandsaw blade anatomy -- locates positions and terms associated with the anatomy of bandsaw blades. The lower image adapted from USDA
Sources: John Richards, "Wood-Working Machinery," Journal of the Franklin Institute, 3d ser. 60, no. 3 (Sept. 1870): 174-76; John Richards A Treatise on the construction ... of Wood-working Machines. London: Spon, 1872, pages 149-161; Manfred Powis Bale, Woodworking Machinery, Its Rise, Progress, and Construction London: Crosby, Lockwood and Son, 1880 (1894); Joseph M. Wilson, History, Mechanics, Science, volume 3 of The Masterpieces of the Centennial International Exhibition Philadelphia: Gebbie and Barrie, 1877, pages 107-9; "The Endless Band Sawing Machine," Journal of the Franklin Institute, 3d ser. 59, no. 1 January 1870), pages 6-11; E K Spring, "Develpment of Materials for Wood-Cutting Tools", Proceedings of Wood Symposium: One Hundred Years of Engineering Progress with Wood, The Centennial of Engineering Convocation, September 3-13, 1952, Chicago IL; Charles Singer, ed., A History of Technology Oxford: Clarendon Press, 1958, volume 4, page 437; Polly Anne Earl, "Craftsmen and Machines: The Nineteenth-Century Furniture Industry", in Ian M. G. Quimby, and Polly Anne Earl, eds., Technological Innovation and the Decorative Arts Charlottesville: University of Virginia Press, 1973, pp 307-329; Chandler Jones, Bandsaws: Wide Blade and Narrow Blade Types Seattle: Privately Printed, 1992; Keith Rucker, "A Short History of the Crescent Machine Company Part I - 1894 to 1920," The Chronicle 60, no. 4, pages 137-157. In their respective manuals on the bandsaw, both Mark Duginske and Lonnie Bird provide many destails, suggestions and illustrations useful for bandsaw users, especially newbies. For citations to Duginske and Bird, and more on bandsaws, see my bandsaw syllabus for more info and images see my bandsaw syllabus