4.1 DESIGNING 74 Go online and find information about graphite grades on which the hardness of pencils depends. 2H & 4H are used for first drawings and construction lines. The best types of pencils for sketching are the HB, 2B, and 6B. Vellum paper was used traditionally for drafting and came supplied in rolls. More recently, drafting paper, standard paper sheets, or tracing paper have become more common as they are less expensive. MANUAL DRAFTING Manual drafting or hand drafting is the practice of creating drawings by hand with pencil or ink on a media such as paper or polyester film using drafting instruments and equipment. Proper line width and darkness are necessary to produce a quality drawing; in addition, symbols and sizing to scale are used to convey placement of objects, surfaces, sizes and other relevant information about the space being designed. Hand drafting was the preferred choice among professionals for a very long time. But the advent of more efficient and effective software technologies including computers, man-machine interface devices, and sophisticated software such as CAD have made design and drafting easier and less time consuming. Equipment for manual drafting The accuracy of drawings depends greatly on the quality of the instruments and tools used. The equipment includes: a drawing board, typically with a parallel motion, which allows consistent drawing of parallel lines. Drawing boards can often be adjusted in height and angle to suit the user; drafter: disegnatore, progettista drafting tape: nastro adesivo di carta drawing board: tavola da disegno masking tape: nastro in carta per mascherature sheet: foglio to sketch: abbozzare sizing to scale: dimensionamento in scala stencil: normografo T square: riga a T vellum papers: carta velina specialised pencils with varying lead hardness. Consider that the harder the pencil type, the lighter the drawing, and the softer the pencil type, the darker the drawing; technical drawing pens of varying sizes used to overwrite the pencil lines and give permanent lines. One of the most common technical pens is the rapidograph, used to make lines of a constant width; scale rulers, used for measuring lengths and transferring measurements at a fixed ratio of length; set squares, shaped like a triangle and used for drawing straight lines and angles; T-squares, used primarily as a guide for drawing horizontal lines on a drafting table; compasses, used for drawing circles or arcs; protractors, used for measuring angles between 0 and 180°; templates or stencils, allowing for the easy drawing of certain objects, symbols, common shapes, or text; stainless steel clips, to secure the corners of the sheet to the board; drafting paper , erasers, sharpeners, drafting and masking tape. Advantages and disadvantages + The low cost of equipment compared to CAD hardware and software. + The clarity achieved due to the fact of seeing all the shapes, sizes and angles on one sheet. + The ability to bring creative style and expression to drawings. A large amount of space for the drawing process, storage and viewing. Drawings cannot be linked to digital information. Drawings can take much more time to prepare in comparison to software drawings, and they are more difficult to correct. It is more complicated to create threedimensional representations. 164 EnginEEring MechPower.indb 164 30/01/24 17:08