Many tools other than the ones already presented in this chapter are currently used to help create technical drawings. A variety of drafting machines (not in the draftsman kit) are available at several shore-based support activities. Dependent upon the requirements of that particular activity, an EA assigned to staff or independent duty may also be exposed to a more advanced and sophisticated computer-assisted drafting method. 

The standard drafting machine combines the functions of a parallel ruler, protractor, scales, and triangles. Various drafting operations requiring straight and parallel lines may be performed advantageously with a drafting machine.

The majority of drafting machines are constructed so that the protractor head may be moved over the surface of a drafting table without change in orientation by means of a parallel-motion linkage consisting of two sets of double bars. Figure 2-33 shows a rigid metal connecting link or arms, commonly called pin-joint linkage. Another type of drafting machine has two steel bands enclosed in tubes working against one another (fig. 2-34) (although this type may also

Figure 2-33.-Drafting machine with rigid arms.

have the bands without the tubes). If these bands become loose through wear or expansion, the tension can be increased on them. This type of drafting machine is superior to that with pin-point linkage because there is less lost motion. 

To learn more about other tools and their uses, refer to chapter 1 of the field manual FM 5-553, General Drafting, published by the Headquarters, Department of the Army, and other civilian publications.

Figure 2-34.-Drafting machine with enclosed steel bands.