Rivet guns vary in size and shape and have a variety of handles and grips. Nearly all riveting is done with pneumatic riveters. The pneumatic riveting guns operate on compressed air supplied from a compressor or storage tank. Normally, rivet guns are equipped with an air regulator on the handle to control the amount of air entering the gun. See figure 13-10. Regulated air entering the gun passes through the handle and throttle valve, which is controlled by the trigger, and into the cylinder in which the piston moves. Air pressure forces the piston down against the rivet set and exhausts itself through side ports. The rivet set recoils, forcing the piston back. Then the cycle is repeated. Each time the piston strikes the rivet set, the force is transmitted to the rivet. Rivet sets come in various sizes to fit the various shaped rivet heads. Rivet set retainer springs must be used on all pneumatic rivet sets to prevent the set from being discharged from the gun when the trigger is pulled. Several types of pneumatic riveters are in general use. They are the one-shot gun, slow-hitting gun, fast-hitting gun, corner riveter, and the squeeze riveter. See figure 13-11. The type of gun used depends on the particular job at hand, with each type having its advantages for certain types of work. Small parts can be riveted by one person if the part is accessible for both bucking and driving. The greater part of riveted work, however, requires two people.

The size and the type of gun used for a particular job depend upon the size and alloy rivets being driven and the accessibility of the rivet. For driving medium-sized, heat-treated rivets that are in accessible places, the slow-hitting gun is preferred. For small, soft alloy rivets, the fast-hitting gun is preferable. There will be places where a conventional gun cannot be used. For this type of work, a corner gun is employed.

Larger rivets require greater air pressure. The approximate air pressures for four of the most common rivet sizes are given in table 13-1.

ONE-SHOT GUN. The one-shot gun is designed to drive the rivet with just one blow. It is larger and heavier than other types and is generally used for heavy riveting. Each time the trigger is depressed, the gun strikes one blow. This gun is rather difficult to control on light-gauge metals. Under suitable conditions, it is the fastest method of riveting.

SLOW-HITTING GUN. The slow-hitting gun has a speed of 2,500 bpm (blows per minute). As long as the trigger is held down, the rivet set continues to strike the rivet. This gun is widely used for driving medium-sized rivets. It is easier to control than the one-shot gun.

FAST-HITTING GUN. The fast-hitting gun strikes the rivet with a number of relatively lightweight blows. It strikes between 2,500 and 5,000 bpm and is generally used with the softer rivets. Like the slow-hitting gun, it continues to strike the rivet head as long as the trigger is depressed.

CORNER RIVETER. The corner riveter is so named because it can be used in corners and in close quarters where space is restricted. The main difference between this riveter and the other types is that the set is very short and can be used in confined spaces. See figure 13-11.

SQUEEZE RIVETER. The squeeze riveter differs from the other riveters in that it forms the rivet head by means of squeezing or compressing instead of by distinct blows. Once it is adjusted for a particular type of work, it will form rivet heads of greater uniformity than the riveting guns. It is made both as a portable unit and as a stationary riveting machine. As a portable unit, it is larger than the riveting guns and can be used only for certain types of work that will fit between the jaws. The stationary, or fixed jaw, contains the set and is placed against the rivet head in driving. The rivet squeezer shown in figure 13-11 is the pneumatic type.

As is commonly known, drills are used to bore holes. In the following paragraphs, the correct use and some common errors in the usage of drills are presented. Additionally, a brief description of pneumatic and angle-drive drills is included.