Dating spear jackson saws
The Spear And Jackson Cockerill hand saw is fitted with a quite distinictive Beech handle.The handle is secured to the blade with five brass buttons, one of which is faced with a 'Warranted Superior' medallion or possibly a 'S & J'' medallion.A small saw industry survived in London and Birmingham, but by the 1820s the industry was growing rapidly and increasingly concentrated in Sheffield, which remained the largest centre of production, with over 50% of the nation's saw makers.Highly productive industries continued in Germany and France.It was so-named because it was typically operated over a saw pit, either at ground level or on trestles across which logs that were to be cut into boards.
The industry gradually mechanized all the processes, including the important grinding the saw plate "thin to the back" by a fraction of an inch, which helped the saw to pass through the kerf without binding .
This force may be applied by hand, or powered by steam, water, electricity or other power source.
An abrasive saw has a powered circular blade designed to cut through metal or ceramic.
Diagram showing the teeth of a saw blade when looking front-on.
The teeth protrude to the left and right, so that the saw cut (kerf) is wider than the blade width.