Blockmaking

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The Royal Portsmouth Dockyard was a scene of intense activity in 1801. The long war with Republican France had raised to unprecedented levels the need for English fighting ships, and severely taxed the material and labor resources of the nation. In the previous 5 years, fleet size had increased by more than 200 vessels, bringing the total number to 864. That the yard accomplished as much new construction, repairs, and refitting as it did was in large part due to the astounding efforts of English shipwrights. But they had the aid at this, the dawn of the Industrial Revolution, of technical developments like the steam engine and circular saw.

The man responsible for the installation of those devices in Portsmouth was Sir Samuel Bentham (1757-1831), a forward-looking naval engineer and shipwright who in 1796 had been appointed to the office of Inspector-General of Naval Works. He was a rare combination of inventor, practical artisan, and able administrator who, against some opposition from a conservative Admiralty, completely re-organized the dockyard. His improvements greatly increased efficiency, but he was still faced with a perplexing bottleneck in block production.

At this time, the Royal Navy required upwards of 100,000 blocks per year; one 74-gun ship, for instance, carried no less than 922 blocks, and that was just a third-class ship. But production lagged behind demand, since the methods then in use required many skilled laborers performing fairly involved steps. Each was made by cutting stock to appropriate dimensions, making a mortise for the sheave, drilling for the pin on which the sheave would turn, scoring for the strop, and finally rounding all edges and corners of the shell, first with a stock shave, then with a spoke shave. Some use was made of horse or water-power and jigs, but the process was to a great extent done by hand.

Into this situation came Marc Isambard Brunel (1769-1849), a man who was later to be knighted for prodigious engineering accomplishments, including the building of the first Thames tunnel. He was born in Normandy, but because of Royalist sympathies he fled France at the outbreak of the Revolution and traveled to America, where he practiced civil engineering, eventually becoming Chief Engineer of New York. In that capacity he designed and supervised the construction of fortifications, an arsenal, and a foundry. But he had a personal project: he was fascinated by the concept of an automated assembly line, and saw the need for large numbers of uniform-sized blocks as a perfect design opportunity.

In 1798 he moved to England to marry Sophia Kingdom, whom he had met in France. For the next three years he continued to develop his ideas, and in 1801 took out a patent on blockmaking machinery. The next step was the construction of models to show to prospective manufacturers. A fellow immigrant introduced him to Henry Maudslay, a young engineer and machinist who had a reputation for solid engineering know-how, innovation, and an obsession with precision.

One of the first people to see Maudslay's completed models was Sophia's brother, at the time Undersecretary to the Navy Board. He offered to contact one Samuel Taylor, the head of a Southampton family business that had been the leading supplier of blocks to the British Navy since 1759. In what must be one of the most shortsighted appraisals of all time, Taylor dismissed the designs as not worth bothering with.

"My father", he wrote, "has spent many hundreds a year to get the best mode, and most accurate, of making blocks, and he certainly succeeded; and so much so that I have no hope of anything ever better being discovered, and I am convinced that there cannot. We are, as you know, so much pressed, and especially as the machine your brother-in-law has invented is wholly yet untried. Inventions of this kind are always so different in a model and in actual work.
Believe me dear Kingdom,
Yours in great truth,
Samuel Taylor"

This was a setback, but only a temporary one; Brunel had an effective, revolutionary system, no shortage of demand for his product, and the most talented machinist of his day to translate his diagrams into reality. All he needed was an appreciative, influential person who could see to it that the production line was given a fair chance.

That person turned out to be Samuel Bentham, who examined the models and immediately set about convincing the Admiralty that it would be folly not to install the machinery at once. On his recommendation, Brunel's proposals were accepted, and construction begun. Four years later Brunel's machines were making all of the British Navy's blocks. One can imagine Taylor's surprise.

It is difficult to overstate the significance of this, the world's first large-scale automated production line. The particulars were highly specialized, even obscure, but the effect on the nature of manufacturing was appreciated even then.

Martin Hill, writing in the Circle of the Mechanical Arts (England 1818) called Brunel's system, "The most complete piece of mechanism in England, or perhaps in the world." Reese's Cyclopedia, published in 1819, devoted 18 pages and 7 plates to it, and the Oxford Companion to Ships and the Sea (Oxford University Press) notes that, "Brunel's machines not only produced a greatly improved article but made them quicker and cheaper, the annual savings when his machines were in full production being estimated at $24,000."

Quicker and cheaper - ten unskilled workers replacing one-hundred-ten skilled ones. - was putting it mildly, and was only part of the story. Brunel pioneered not just in production concepts, but also in materials and mechanical innovations. The Portsmouth machines were the first powered tools of substantial size to be constructed entirely of metal, resulting in a degree of accuracy that redefined standards of precision. And all the designs represented either important developments of existing tools (lathe, drill, circular saw), or were new inventions (mortising machine, shaper, conical clutch, split nut, etc.) Ultimately these devices would profoundly affect the nature of the smallest home shop as well as the largest factory. Forty-five machines were installed at Portsmouth. What follow are descriptions and backgrounds of some representative examples.

The Machines

1. Circular Saw

A modern woodworking shop would not be considered complete without several forms of this tool; it is nearly indispensable. Examples of it date from the 17th century in Europe, and Sister Tabitha, an American Shaker, discovered it independently in the U.S. But the circular saw did not come into widespread use until Brunel's refinements made it practicable for other than limited applications, i.e. small machinery for clockmakers, and crude larger machines, such as those used by William Dunsterville, another early supplier of blocks to the Royal Navy.

A variety of circular saws were used at Portsmouth. For instance, a pendulum saw was used to crosscut logs into scantlings in the first step of the block making process. Pendulum travel vertically and horizontally was controlled by rods that pivoted on the pendulum at one end and meshed with pinion gears on the upright at the other. With this arrangement the saw could cut to the limit of its blade depth on one face of the log, then be elevated for the same depth cut along the top, then lowered to cut into the log from the other side. Thus a log of greater diameter could be cut than would have been possible with a fixed blade.

A similar principle was used on the machine that cut lignum vitae logs into disc-shaped blanks for the sheaves. The log was clamped upright onto a pedestal base which could be raised by means of threaded rods built into the machine's uprights. The blade was mounted horizontally, on a pivot, at about the operator's eye level so that it could be swung into the log for the cut. A crank connected by pulley to the base simultaneously rotated the log past the cut, in much the way that a lathe rotated the work past the knife. As with the pendulum saw, thicker logs could be cut than would have otherwise been possible for the size blade used.

A corner saw was used to trim the edges of the blocks preparatory to shaping. The inclined table slid on two parallel bars past the saw blade. The ledge, which the block rested on during cutting, could be adjusted for different block sizes. A line shaft drive transmitted power from a steam engine to this and the other machines.

Drilling Machines

1. Round Saw

The sheave blanks were rounded to appropriate diameter and drilled for the coak (see below) on which the pulley would rotate on the rounding saw. The pin hole bit rotated inside a tube which passed through the plug-cutter type rounding bit. The blank was braced between the tube and the faceplate, and both bits were advanced together by the lever turning beneath and up the back of the machine. The two different-sized pulleys allowed the bits to be powered independently, at the best speed for each.

The blank was then taken to the coaking drill, which made three recesses to accommodate the ears of the coak, a metal sleeve in which the sheave pin would ride. One can see in this machine the combination of style and good sense, which typifies the collection. Sheaves eventually came to be made entirely of metal, which made this particular unit obsolete, but most of the production line was in use right through the 1800's, and many of the tools are still in usable condition. Clearly the exquisite artisanship was not a luxury but an excellent investment, especially when one considers that the machinery paid for itself in only 3 years.

A third piece of drilling equipment called simply "the boring machine" made holes in the squared block blank, one in the center of the broad face for the sheave pin, the other near the top of the longer narrow face as a startling point for the sheave mortise. Using it was a simple matter of pulling first one lever, then another to move the two drills, and there is no doubt that, like most of its fellows, it was a boring machine.

There is one interesting detail, though: the clamp which holds the blank in place impressed two marks, on its ends. The marks are locators for the clamps of the mortising and shaping machines.

The Mortising Machine

This, one of Brunel's most significant and fascination inventions, cut block sheave mortises. Two chisels mounted in a sliding frame at the front of the machine, moved at 400 strokes per minute, with vertical motion provided by a crank at the end of the drive shaft (illust). A cam in the middle of the same shaft moved, with each revolution, a lever hitch pivoted on an adjacent horizontal support. The lever engaged a ratchet wheel which rotated on a lead screw* at the base of the machine. By means of this screw the carriage to which the block was clamped was advanced 1/24" per chisel stroke, and one double or two single blocks was neatly mortised in a matter of seconds. An automatic stop was provided by another lever mounted on the side of the machine's base. Its upward-curving after end contacted the lead screw, and the other end rested on the carriage, overhanging it by a length equal to that of the desired mortise. The carriage gradually moved to the right until it came out from under the lever end, which dropped down, raising its other end, striking a bar, which disengaged the pawl from the ratchet wheel. And people wonder where Rube Goldberg got his ideas.

The modern Oscillating Chisel Mortiser, and metal Slotter (the latter used to make keyways in wheels) are both direct derivations from the Mortising machine. As if that were not enough, its pulley assembly contained the first know conical clutch, by means of which the operator could disengage the drive shaft without affecting the speed of the flywheel. Today conical clutches are used in power take-off couplings for gear run intermittently from a continuously-rotating shaft (driving pulley, hoisting drums, etc.) and for machine tools requiring rapid direction reversal.

Shapers

These machines were functionally a cross between a lathe and a Ferris wheel: ten blocks were clamped at the perimeter of the double wheel, or "chuck", which was set in motion by the pulley at the side. A gouge mounted on an arced former was moved from one side to the other, the arc of the former thus being reproduced on one face of the block .

Three more faces remained to be turned on each block, and this was accomplished by a system of worm-and-bevel gearing, which ran from the block, clamped at one end to a crown wheel and on the shaft at the other. When the machine was in operation the crown wheel ran free, but when it was time to present a new face to the gouge, a stop was moved into position, which held the crown wheel stationary. The operator then moved the Ferris wheel through four revolutions, causing the bevel gears to turn on the stationary crown, thus turning the blocks 90°.

The mortise and cheek sides of the blocks had different curves; different formers were used for each curve.

The Scoring Machine

A circular rope strap called a grommet encircled the block at right angels to the mortises, providing means to suspend the black. The grommet was tightened by the seizing between thimble and block, and rested in scores made by the scoring machine. Two blocks were treated at the same time. They were first clamped to a hinged table, then swung into position beneath a pair of rotary cutter heads set in a hinged frame. Cutting depth was controlled by the ingenious use of a template mounted upright between the two blocks. As the block table was swung forward the cover of the driving pulley came into contact with the template and slid along it, causing the cutters to describe the template curves in the blocks. Then the base pivoted 180° to bring the other ends of the blocks to face the cutter heads, to score the block's other ends.

Blocks eventually came to be made differently, with an internal metal strap projecting from a metal, plastic, or wooden shell. But some sailors still favor the traditional look feel of rope-stropped block.

Lathe

The lathe is an ancient and universal tool, but the sharply increased demand for machined parts - especially threaded parts - that occurred in the eighteenth century, led to a number of important lathe innovations.

The Traversing Mandrel, introduced around 1700, was an early method of turning threaded stock. The mandrel slid axially in its bearing, its rate of travel controlled by a master screw. The stock moved past the cutting tool, producing a thread identical to that of the master screw's. Since the mechanism was mounted inside the lathe bed, however, its travel was limited and could only produce short threads.

Throughout the 1700's inventors came up with a series of jigs, stops, and chucks, but it was Maudslay, Brunel, and their immediate successors who provided us with the most significant lathe developments.

Henry Maudslay first gained a wide reputation for his invention of the lead screw (used in the Lignum saw), the basic component of the modern screw-cutting lathe. A series of changeable gears connects the Mandrel to the lead screw, which runs the length of the lathe bed. The tool saddle travels along the screw and can cut a wide range of thread pitches for a length limited only by the length of the bed. The lathe was thus made useful for more than just cutting threads; even without the use of a cross-feed device, moving the cutter in and out, opportunities for production of standardized parts were obvious. Brunel was not one to ignore them.

Maudsley's lead screw principle was employed not only in the lathes but as we have seen, in the Mortising Machine and Lignum saw. He did not have a hand in the design of this or any other Portsmouth machine, but his expertise was no doubt responsible for the quality of construction.

A number of Maudslay's associates later gained fame in their own rights, including Richard Roberts, who invented the back gear clusters for lathes, which made possible low speeds without loss of power.

Joseph Whitworth, another Maudslay and Sons alumnus, patented the lead screw split nut, and gained a considerable income from it. As we have seen, Brunel used it much earlier on his Mortising machine, but then he could afford to be generous with his inventions.

Conclusion

Long, large-scale wars with France, America, and other countries kept the Portsmouth yard busy right through the 18th century and well into the 19th. Brunel's machinery made a significant contribution toward maintaining the British Navy's dominance of the seas, and this fact was much-appreciated in its day. But important as its immediate effects were, the machinery's long-term and value proved to be even greater.

In a sense, its greatness, proved to be its own undoing: the mortising machine, all-metal frames, split-nut, cone-clutch, lead screw, and many other ideas, tied together by the principle of an automatic production line, were adapted to metal-working machines to produce larger, more efficient steam engines (and the gear they drove) than had been previously possible. By 1845 the British fleet was no longer purely sail-powered, and the subsequent rise of propeller-driven craft quickly reduced by 97% the need for ship's blocks, leaving the Portsmouth machinery an obscure historical curiosity by the end of the 19th century. Today, few people even know of its existence, but every factory, machine shop, lumber yard - any place that uses machine tools - is a monument to Brunel's extraordinary burst of innovation.