Hand tools layout

Wood adhesive can also be used, but is not essential. These are typical practical issues, which the teacher has to manage through a clear plan of action suitable to the working environment. Thus, the classroom layout should enable pupils to remain at a work station rather than move around the room, unless they require materials and tools, in which case they should work to the established routines for these tasks. Hand tools will suffice throughout and pupils should work individually or in pairs. The skills required to use the tools should be rehearsed and demonstrated to pupils. They should be drawn into demonstrations of how to saw, how to drill and how to shape the materials. Children should wear aprons. 

Hand tools are designed and built based on the properties of simple machines (see Chapter 10). Hand tools use the mechanical advantages of simple machines to help us perform various tasks. Before performing some of these tasks, a technician uses measuring tools to layout the prototype. 

Layout Tools The first step in prototype fabrication is transferring measurements from the drawing and laying them out on the material. Figure 8-13 shows common hand tools—a steel rule and a tape measure—used for measuring and layout. These measuring tools are typically graduated in. 1/16-inch measures. Tri squares or combination squares are used to transfer perpendicular lines to the material. For lumber, the transfer is marked with a pencil. If the material is metal, a scratch awl is used. 

The task requirements will determine critical layout characteristics of the workstation. The relative importance of the screen, keyboard, and hard copy (i.e., source documents) depends primarily on the task, and this defines the design considerations necessary to improve operator performance, comfort, and health. Data-entry jobs, for example, are typically hard copy oriented. The operator spends little time looking at the screen, and tasks are characterized by high rates of keying. For this type of task it is logical for the layout to emphasize the keyboard, mouse, and hard copy, because these are the primary tools used in the task, while the screen is of lesser importance. On the other hand, data-acquisition operators spend most of their time looking at the screen and seldom use hard copy. For this type of task, the screen and the keyboard layout should be emphasized. 

Separating Tools Once layout is complete, the material must be separated. Common hand separating tools either remove chips (for example, a saw) or shear the material (for example, a pair of scissors) (see Figure 8-14). Common handsaws include the handsaw, the hacksaw, the coping saw, and the hacksaw. We can cut thick metal with a hacksaw, and we can shear thin metal with aviation... 

It should be obvious by now that the semicustom design approach makes heavy use of software tools. These tools eliminate the tedious and error prone task of hand layout, provide accurate circuit simulation, and help with issues such as testability. Their power and sophistication make transparent the complexity inherent in the design of integrated circuits. 

---