Cutting Tools - Aircraft Structure Repair

Powered and nonpowered metal cutting tools available to the aviation technician include various types of saws, nibblers, shears, sanders, notchers, and grinders.

Circular-Cutting Saws

The circular cutting saw cuts with a toothed, steel disk that rotates at high speed. Handheld or table mounted and powered by compressed air, this power saw cuts metal or wood. To prevent the saw from grabbing the metal, keep a firm grip on the saw handle at all times. Check the blade carefully for cracks prior to installation because a cracked blade can fly apart during use, possibly causing serious injury.

Kett Saw

The Kett saw is an electrically operated, portable circular cutting saw that uses blades of various diameters. [Figure 1] Since the head of this saw can be turned to any desired angle, it is useful for removing damaged sections on a stringer. The advantages of a Kett saw include:

1.                  Can cut metal up to 3⁄16-inch in thickness.

2.                  No starting hole is required.

3.                  A cut can be started anywhere on a sheet of metal.

4.                  Can cut an inside or outside radius.

Pneumatic Circular Cutting Saw

The pneumatic circular cutting saw, useful for cutting out damage, is similar to the Kett saw. [Figure 2]

Reciprocating Saw

The versatile reciprocating saw achieves cutting action through a push and pull (reciprocating) motion of the blade. This saw can be used right sideup or upside down, a feature that makes it handier than the circular saw for working in tight or awkward spots. A variety of blade types are available for reciprocating saws; blades with finer teeth are used for cutting through metal. The portable, air-powered reciprocating saw uses a standard hacksaw blade and can cut a 360° circle or a square or rectangular hole. Unsuited for fine precision work, this saw is more difficult to control than the pneumatic circular cutting saw. A reciprocating saw should be used in such a way that at least two teeth of the saw blade are cutting at all times. Avoid applying too much downward pressure on the saw handle because the blade may break. [Figure 3]

Cut-off Wheel

A cut-off wheel is a thin abrasive disc driven by a high-speed pneumatic die-grinder and used to cut out damage on aircraft skin and stringers. The wheels come in different thicknesses and sizes. [Figure 4]

Nibblers

Usually powered by compressed air, the nibbler is another tool for cutting sheet metal. Portable nibblers utilize a high speed blanking action (the lower die moves up and down and meets the upper stationary die) to cut the metal. [Figure 5] The shape of the lower die cuts out small pieces of metal approximately 1⁄16 inch wide.