Keyhole saw
From Wikipedia, the free encyclopedia
A keyhole saw (also called a pad saw, alligator saw, jab saw or drywall saw) is a long, narrow saw used for cutting small, often awkward features in various building materials. There are typically two varieties of keyhole saw: the fixed blade type and retractable blade type.
The retractable blade variety is usually found to have either a cast iron handle or, less commonly, a wooden handle. The facility to retract the blade to an optimum length serves to prevent unwanted flex to the blade should the full length of the blade be obstructed in some way. In both types the blade is typically secured by one or two holding/thumb screws.
The fixed blade type, often being cheaper to manufacture and purchase (due to fewer parts) is therefore more commonly used in the modern construction trade. With the advance of certain building methods and materials, designs specific to these trades have been developed. One such modification being a sharpened point at the tip of the blade which can be pushed or ‘jabbed’ through soft materials such as drywall without pre-drilling a hole for the blade.
Two power tools serving largely the same function but which work more quickly and with less effort are the jigsaw and spiral saw.
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[edit] Maintenance
Maintenance of the saw blade will depend on the type and or age of the tool. Older key hole saws with filed crosscut teeth will require the craftsman to manually set and sharpen the teeth by hand. For contemporary versions of the retractable blade variety replacement blades are readily available thus removing the skills, tools and time that would otherwise be required to manually sharpen the blade. Mass production of cheap throw away versions of the fixed blade type make it cost effective for the tradesman to do exactly that and purchase a new replacement when the teeth become blunt.
