A keyhole 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

Cast iron

Cast iron is derived from pig iron, and while it usually refers to gray iron, it also identifies a large group of ferrous alloys which solidify with a eutectic. The color of a fractured surface can be used to identify an alloy. White cast iron is named after its white surface when fractured, due...

 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 cheaper fixed blade type is more commonly used in the modern construction

Construction

In the fields of architecture and civil engineering, construction is a process that consists of the building or assembling of infrastructure. Far from being a single activity, large scale construction is a feat of human multitasking...

 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

Drywall

Drywall, also known as plasterboard, wallboard or gypsum board is a panel made of gypsum plaster pressed between two thick sheets of paper...

 without 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

Jigsaw (power tool)

A jigsaw is a tool used for cutting arbitrary curves, such as stenciled designs or other custom shapes, into a piece of wood, metal, or other material. It can be used in a more artistic fashion than other saws, which typically cut in straight lines only. In this way, it is similar to the rasp and...

 and spiral saw.

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

Artisan

An artisan is a skilled manual worker who makes items that may be functional or strictly decorative, including furniture, clothing, jewellery, household items, and tools...

 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

Mass production

Mass production is the production of large amounts of standardized products, including and especially on assembly lines...

 of cheap throw away versions of the fixed blade type make it cost effective for the tradesman

Tradesman

This article is about the skilled manual worker meaning of the term; for other uses see Tradesperson .A tradesman is a skilled manual worker in a particular trade or craft. Economically and socially, a tradesman's status is considered between a laborer and a professional, with a high degree of both...

to do exactly that and purchase a new replacement when the teeth become blunt.

External links

• Vintage Saws - Pete Taran