Woodworking machines are made to do a wide variety of jobs. For any one job there are usually a number of makes, sizes, and styles of machines from which to choose. They are not standardized. Only a brief classification and outline of specifications for fairly typical machines of the more important types is attempted here. Small light machines of the home workshop size are not included.
Woodworking machines may be divided into three broad classes based on function: sawmill, planing mill, and industrial plant machinery. The function of sawmill machinery is to cut the log into rough, green lumber. The planing mill takes the rough lumber (usually dry), and prepares it for general construction uses, such as flooring, siding, shiplap, or framing. The industrial plant cuts up lumber and makes it into doors, furniture, boxes, or other fabricated products.
Several types of sawmills are available for making the log into lumber, and the type that is most suitable in any given instance will depend upon such factors as the size of the timber and the desired output. Nearly all the cutting the sawmill is done parallel to the grain. In the United States this is done with saw teeth of the chisel type with cutting edges that are at right angles to the plane of the cut both on top and on the front. The teeth are widened at the cutting edge usually to about 6 gages thicker than the rest of the blade for softwoods and 5 gages thicker for hardwoods. The first saw for cutting parallel to grain that the log encounters when it enters the mill is referred to as the headsaw, regardless of whether it is a band saw, gang saw (frame saw), or a circular saw. There may or may not be several other saws depending upon the size of the sawmill
The band headsaw is in common use in most medium and large mills today. Band saws may be fitted with teeth on both edges, but this is the exception. A band mill of the size used for making logs into lumber seldom has wheels less than 6 feet in diameter, blades less than 9 inches wide, or weight less than about 12,000 pounds. Band mills used for large West Coast timber may have wheels 10 feet in diameter, blades 18 inches wide, and a weight of 50,000 pounds, The horsepower required varies from 50 to 250, and the speed of the motor is so adjusted as to give the saws a speed of about 10,000 feet per minute when cutting softwoods and about 7,000 feet per minute for hardwoods. Dimensions of typical sawmill band saws are as follows:
Nearly all small sawmills, as well as many of the medium-sized ones, use the circular saw to break down the log. The saw blades may be either of the solid-tooth or inserted-tooth type, but the latter are much more common owing to greater ease of upkeep.
The gang saw cuts by means of a series of parallel saw blades mounted in a frame that moves up and down as the wood is slowly fed through the machine. Typical gang saws turn out accurately sawed lumber with a minimum of waste. They are common in the medium and larger plants where they can be used to advantage.
The edger is used to square up lumber by removing bark edges, to reduce it to standard widths, and sometimes to sip extra wide material to narrower widths. Like headsaws, edgers vary widely in size and capacity. They usually have one stationary circular saw and one or more circular saws that can be moved laterally on the arbor so as to permit ripping different widths. Saws may be either solid-tooth or inserted-tooth and many more.
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