I’ve never worked in a sawmill, but the technology fascinates me. Most tractor shows have an operating sawmill and I enjoy watching as the spinning blade reduces a log into usable lumber in no time. The most elaborate mill I’ve seen is the Briden-Roen steam sawmill at the Western Minnesota Steam Threshers Reunion in Rollag, Minnesota. A huge, high-production mill, it is powered by a Case 110 hp skid steam engine and several smaller units, including one used to hoist logs into the mill. If you ever get a chance to see it, don’t miss it.
Sawmills are still very much in use (that’s where all those boards for sale in Lowe’s and Home Depot come from, just in case you wondered). There was a portable mill just down the road from me a year or two ago, and lots of permanent mills remain in operation, especially in nearby Holmes County, Ohio.
Water wheels an early power source
No one really knows when the first tree trunk or limb was split into a more-or-less flat plank, shingle or clapboard. The broad axe was used to hew one or more sides of a log into a flat surface. To make a board, a log was laid over a pit or on a raised framework. The tiller man stood atop the log and lifted a long, straight saw on the upstroke, while guiding it along a chalk line. Beneath the log (often wearing a wide-brimmed hat to keep sawdust from falling down his neck) stood the pitman, who pulled the saw down on its cutting stroke.
When water wheels came into being, they were used to power sawmills, among other things. Often a gristmill and a sawmill shared power from a single water wheel. Archeologists have uncovered evidence that Romans used a water-powered saw to cut stone as early as the third century A.D. By the 14th century, water-powered sawmills were common in Europe.
A contemporary account of such a mill was written by an English bishop visiting Lyons, France: “The sawmill is driven with an upright wheel, and the water that maketh it go is turned into a narrow trough which delivereth the same to the wheels. The wheel hath a piece of timber put to the axletree end and fastened to the end of the saw, which, being turned by the force of the water, hoisteth up and down the saw that it continually eateth in... Also the timber lieth as it were upon a ladder, which is brought by little and little to the saw with another device.”
Two styles of early sawmills
The up-and-down sawmills were of two types. A sash mill had one or more straight saw blades stretched under tension inside a rectangular frame (sash or gate) driven by the pitman from the crank on the power source. A sash saw with multiple saw blades could cut several boards from a log at the same time and was called a “gang saw.”
A variation of the gang saw – a “slabbing gang” – had just two blades, with one movable to adjust the distance between the blades. When run through the slabbing mill, a slab was removed from each side of the log, leaving it flat on both sides. A log so flattened was called a “stock” and was then cut into boards or planks on a standard gang or circular mill.
The mulay saw (also called a muley saw) typically had a single vertical blade that was driven directly by the pitman between wooden guide blocks at the top and bottom, and its blade was made of heavier steel than that of the sash saw. The mulay saw required less power than the sash saw because the weight and friction of the heavy framework that held the saw was dispensed with.
Solving the problem of waste
Steam engines began to replace a few of the water wheels as sawmill power in the U.S. around 1830, but as the population grew, demand for lumber increased and the slow vertical mills were hard-pressed to keep up. In about 1850, circular sawmills capable of handling large logs were introduced, although the blades were as much as 1/2-inch thick and, as one account put it, “so little was known as to the proper method of dressing and handling such saws that their product more nearly resembled washboards than lumber.”
A new form of rolling carriage was developed that was moved back and forth by a wire rope powered by the engine, and the rack-and-pinion method of moving the log sideways into the saw by a graduated scale was invented.
The waste in sawdust of a good quality log cut by the heavy circular saw blades of the day was an important concern, driving lumbermen to search for ways to make thinner saws. New methods of metallurgy, along with the discovery of ways to hammer a thinner saw blade so it ran true, allowed the old 1/2-inch kerf to be reduced by half. This still resulted in a lot of sawdust, however, and as trees for lumber became scarcer and demand increased, band saw mills with their thinner blades came into use.
Highly sophisticated modern processes
Today, the modern sawmill is a technological wonder. Incoming logs are debarked and scanned by lasers, presenting each to the saw so as to yield the maximum number of usable boards. The flexible band saw blades are often double-edged. Cuts can be made in both directions, and the newly sawn boards are automatically sorted, sized and stacked by machines that are controlled by computers, lasers and digital cameras. The slabs are ground and the sawdust is saved for use in making particle board and other products. Everything is monitored by barcode systems and the handful of workers involved don’t have to wrestle heavy logs or carry boards. Instead, they push buttons, read computer printouts and intervene occasionally if there’s a glitch.
It’s all very efficient, but I still prefer the old circular sawmill driven by a steam engine that gets its power from burning the slab wood produced by the mill. There’s something mesmerizing about watching the big, low rpm saw blade eat its way through a large oak or poplar log, a sight that one can see at most steam and tractor shows. FC