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In the beginning, there were weights, wedges, and wraps.
Egyptian tombs provide the first illustrations of clamping devices or techniques, applied to gluing boards by their edges. The boards would be held vertical by two uprights, and weighted down, until the glue set.
For more oomph, the boards might be placed horizontal, and wedged between an upright and a wall. The wedging action might come from bent sticks, or from opposed inclined planes.
The boards could also be bound with cord. By inserting a stout stick into the cord and twisting, significant additional holding power could be gained in little space.
All these techniques are useful and versatile, and have continued to the present. In fact, almost every one has used the twisted cord technique when repairing chairs, gluing up stringers between chair legs.
The screw, because of its many applications, is probably the most important of the mechanical elements. The screw--actually an inclined plane spiraling around a central shaft--offers enormous mechanical advantage.
It is said to have been invented by Ardeytas of Tarentum, a Pythagorean philosopher and mathematician, about 400 B.C., but is generally associated with Archimedes who died in 212 B.C. Both Hero and Pliny have described wooden screws as having been applied to presses in the first century A.D., but do not appear to have left a description of how these screws were made.
Screw-based presses squeeze the juice of grapes and the oil of olives more effectively than weights or levers alone. With slight modifications, they remove the water from hand made sheets of paper, and apply the ink to news print and books.
With further simplification of the frame holding the screw, they become holding devices. The earliest of these are named for their application, window, pianoforte, and door clamps; the latest are named for their generic shapes as bar clamps. In all of these, the force is applied along the axis of the screw.
If a block rides freely along the screw in a framework, then the force can be applied more conveniently off the axis of the screw. This is the fundamental design of the bench vise. If the block is lengthened, and with a pivot at one end, then further leverage can be obtained from a screw. This is the fundamental design of the leg-vise.
Another advance is the use of multiple screws. In the bookbinder's press, or in luthier's clamps, two or more screws in parallel apply force more evenly along a long jaw, either straight or curved in shape.
With two screws acting oppositely to each other, we get both the pivot action (hence leverage) of the leg vise, and control over the spacing. We have arrived at the hand screw, or clamp.
A fundamental problem is actually making a screw. For the male screw of a big press, it is possible to use a length of tape wrapped around a cylinder to mark the path of the screw, and then to chisel it out. Tedious work.
Leonardo da Vinci has recorded the use of the screw both in the making of other screws and the construction of machines, but whether or not his screw-making machines were ever made seems uncertain. Nevertheless, in this matter he was clearly capable of very original thought so, as he was demonstrably much in advance of his time, it seems that he owed little of this to his contemporaries.
It fell to Henry
Maudslay, a British mechanical genius, to achieve the first effective
screw-cutting lathe, in the late 1700s, building on the work of his predecessors
over previous centuries. The history of this development is fascinating, and
may debunk the
Great Inventor
syndrome.
Henry Maudslay, 1771-1831, was employed originally by Bramah, the 'locksmith', but left his services in 1797 following a dispute over rates of pay. Bramah himself was a prolific inventor, numbering amongst his designs the hydraulic press and the beer engine, but there is little doubt that he owed much to Maudslay, as a practical mechanic, who perfected Bramah's locks.
The end of the century saw the production of two other lathes equipped to produce screw threads; one in 1795 by a Frenchman named Senot, the other by David Wilkinson, an American, who introduced his machine in 1798.
It was many decades before screw lathes became perfected, made cheaply, and used widely.
(Much of this information was taken from A HISTORY OF MACHINE TOOLSby Ian Bradley. This book has much more information on early machinery and lathes, and I recommend that you get a copy, if you can find one. It is out of print. Other links are available from the links above.)
Wood was plentiful, easily worked, and adequate to the tasks.
The makers of wooden clamps have brown bars in the time line below.
The Industrial Revolution brought the strength of steel and precise thread-cutting techniques to the manufacture of clamps. The problem isn't to cut a thread; it is to cut a uniform thread over a long distance, repeatedly.
The makers of composite clamps have black bars in the time line below.
The time lines below shows those American firms for whom dates are known. Links to a history page can be found with each bar and its 2 or 3 letter abbreviation.
Wooden clamp makers are in dark brown; composite clamp makers are in black. Users are in light brown. Dealers are in green.
Thick bars indicate times when a firm made, used, or sold clamps; thin bars indicate times when the firm existed, but was not involved with clamps.
The square brackets indicate definite dates for begin and end. The angle brackets indicate indefinite dates. Vertical lines indicate important events in the history of the firm.
The codes are explained elsewhere.
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This major section provides further information about makers, dealers, and users. The subsections are
last revised and validated
Copyright © 1996- Wooden Clamp Journal