A DRIVE SLIP JOINT is a method of joining two flat sections of metal. Figure 2-61 is the pattern for the drive slip. End notching and dimensions vary with application and area practice on all locks, seams, and edges.

"S" joints are used to join two flat surfaces of metal. Primarily these are used to join sections of rectangular duct. These are also used to join panels in air housings and columns.

Figure 2-62 shows a flat "S" joint. View A is a pattern for the "S" cleat. View B is a perspective view of the two pieces of metal that form the flat "S" joint. In view C, note the end view of the finished "S" joint.

Figure 2-63 shows a double "S" joint. View B is the pattern for the double "S" cleat. View A is one of two pieces of metal to be joined. Note the cross section of a partially formed cleat and also the cross section of the finished double "S" joint. his is a variation of

Figure 2-61. - Drive slip pattern and connections

Figure 2-62. - "S" joint or slip pattern and connections.

Figure 2-63. - Double "S" joint (cleat) pattern.

the simple flat "S" and it does not require an overlap of metals being joined.

Figure 2-64 shows a standing "S" joint. View B is the pattern for the standing "S" cleat. View A is one of the two pieces of metal to be joined. Note the cross section of the finished standing "S" cleat and standing "S" joint.

Seams

Many kinds of seams are used to join sheet-metal sections. Several of the commonly used seams are shown in figure 2-65. When developing the pattern, ensure you add adequate material to the basic dimensions to make the seams. The folds can be made by hand; however, they are made much more easily on a bar folder or brake. The joints can be finished by soldering and/or riveting.

When developing sheet-metal patterns, ensure you add sufficient material to the base dimensions to make the seams. Several types of seams used to join sheet-metal sections are discussed in this section.

There are three types of lap seams: the PLAIN LAP seam, the OFFSET LAP seam, and the CORNER LAP seam (fig. 2-66). Lap seams can be joined by drilling and riveting, by soldering, or by both riveting and soldering. To figure the allowance for a lap seam, you must first know the diameter of the rivet that you plan to use. The center of the rivet must be set in from the edge a distance of 2 1/2 times its diameter; therefore, the allowance must be five times the diameter of the rivet that you are using. Figure 2-67 shows the procedure for laying out a plain lap and a comer lap for seaming with rivets (d represents the diameter of the rivets). For comer seams, allow an additional one sixteenth of an inch for clearance.