Types of Sawmills
Not a sawmill, of course, but a pit saw was used by two sawyers to convert a log into boards using muscle power. This would not be the method of choice if there is a sawmill available (although the first sawmills in England were destroyed by pitsawyers rioting against potential job loss). Note the similarity between the frame-type pit saw and a sash sawmill. Also known as a whip-saw.
Images from Whitney's Century Dictionary, 1897, vol VI, p. 4518.
In an up-down (or Sash-type) Sawmill, a single straight saw blade is held inside a wood sash (or frame) that is driven up and down by the mill. This is a photo of the Ledyard sawmill from the 1930s with the wooden sash highlighted in brown. (The lower ends of the blade and sash are below the floor in this picture.)
Up-down sawmills are also called: frame sawmill; English gate sawmill, upright saw. The straight saw blades were often referred to historically as millsaws or long saws.
A muley saw is also a type of up-down sawmill, but the blade is not in a frame. Rather, the straight saw blade slides between wood guides at the top and bottom. Muley saw blades are made from a heavier gauge steel than sash sawmill blades. The name may have originated from the German mühl-sage (mill-saw).
See more in the Sash sawmill glossary entry for muley saws.
Image from Appleton's Cyclopaedia 1891 vol. 2 p. 708.
A gang saw has multiple straight blades held inside a frame and moves up and down – several boards can be cut in one pass of a log or squared beam through the mill.
Image from Grimshaw on Saws 1880, fig. 22.
The circular sawmill has the familiar modern blade which is a disc with teeth around its circumference. The picture shows a circular sawmill with an additional top blade and the log carriage.
Image from Grimshaw on Saws 1880. fig. 80.