Radial arm saw

A radial arm saw is a cutting machine consisting of a circular saw mounted on a sliding horizontal arm. Invented in 1923, the radial arm saw was the primary tool used for cutting long pieces of stock to length until the introduction of the miter saw in the 1970s.

In addition to making length cuts a radial arm saw may be configured with a dado blade to create cuts for dado, rabbet or half lap joints. In addition some radial arm saws allow the blade to be turned parallel to the back fence allowing a rip cut to be performed.

Origins

Unlike most types of woodworking machinery, the radial arm saw has a clear genesis: it was invented by Raymond De Walt of Bridgeton, New Jersey. De Walt applied for patents in 1923, which were issued in 1925. De Walt and others subsequently patented many variations on the original, but De Walt's original design (sold under the moniker Wonder Worker) remained the most successful: a circular saw blade directly driven by an electric motor held in a yoke sliding along a horizontal arm that is some distance above a horizontal table surface.

Before the advent of the radial arm saw, table saws and hand saws were most commonly used for crosscutting lumber. Table saws can easily rip stock, but it is awkward to push a long piece of stock widthwise through a table saw blade. In contrast, when a radial arm saw is used for crosscutting, the stock remains stationary on the saw's table, and the blade is pulled through the stock.

Beginning about the late 1970s, the compound miter saw began to replace the radial arm saw somewhat, but only for crosscuts and miter cuts since it is unable to perform rip cuts. The radial arm saw can be less safe when used by an inexperienced or untrained operator, but is not dangerous when used properly. In the hands of an experienced operator, the radial arm saw can safely cut compound miters necessary for picture and door frames, rip lumber precisely to width, cut tongues and grooves, and make variable dadoes. Most cuts are followed with a fit and require more material be removed, sometimes a tiny amount (which is easy to do). Like the compound mitre saw, the radial arm saw can make these cuts with absolute precision, but is capable of making a wider variety of cuts, including more complex ones.

In the home shop the radial arm saw is an alternative to the table saw. Both machines can rip, crosscut, do simple and compound miters, dado, mold or shape, make tenons, make open mortises, taper cut, and rabbet. The radial arm saw requires less clearance or space in the shop to handle long stock. An arm saw only requires clearance on the sides, whereas a table saw needs clearance to the sides, in front, and in back. The arm saw is perfectly efficient backed up against a wall, where as the table saw wants to be placed in the center of the shop to give all around clearance. With some accessories the radial arm saw can be used as a shaper, a disk or drum sander, a grinder, a surface planer, or a horizontal boring machine, whereas a table saw's secondary uses are limited to shaper and disk sander. The major shortcoming of most current radial arm saws for home-use is that most radial arm saws that have been built after the early 1960s are manufactured with stamped sheetmetal parts and are machined to loose tolerances, and hence, they are not precise for doing accurate work without 'tuning'. A high-quality radial arm saw has carefully machined trackarm ways and locking mechanisms, and a motor that runs very smoothly; under 'no-load' conditions most of the sound and vibration will originate from the whisper/whistling and the imbalance of the sawblade upon the arbor.

Safety

For safest operation, you should use a saw blade with a "negative" hook on a radial arm saw. A negative hook angle will slow the feed rate and will also inhibit the blade's tendency to "climb" the material being cut. Radial arms saws and sliding compound miter saws require a blade with a very low or negative hook angle, to inhibit overly fast feed rate, binding, and the blade's tendency to try to "climb" the material.

External links

* [http://woodworking.about.com/od/toolsequipment/p/RadialArm.htm Woodworking Tips: Using Your Radial Arm Saw] at About.com
* [http://www.radialarmsawrecall.com Revised guard system and recall of older Craftsman brand radial arm saws]
* [http://www.cpsc.gov/cpscpub/prerel/prhtml06/06212.html Recall of some models of Ryobi brand radial arm saws]