Summary
Highlights
Engineering drawings are crucial for representing objects like buildings and machines, specifying their size, shape, and materials. While software exists, drawing on paper remains relevant for certain applications. Drawing is a universal language, allowing designs to be understood across different cultures. This video introduces fundamental instruments for engineering drawing.
A drawing sheet is the white paper on which objects are drawn. It must be of good quality, white, uniformly thick, tear-resistant, and smooth. Common sizes include A3 and A4. The drawing board, typically made of soft wood and rectangular, supports the drawing sheet, with its size matching the sheet.
The mini drafter is a versatile instrument with adjustable arms and a perpendicular scale set. Fixed to the drawing board, it's used for drawing various lines and angles. The t-square, made of wood or plastic, is used to draw horizontal and vertical lines on the drawing sheet, with its head attached to the board's edge.
A compass draws arcs or circles of known dimensions. It has two legs, one with a needle and the other holding a pencil, with the pencil tip adjusted slightly above the needle's tip. A divider, similar to a compass but with two needles, is used to divide lines or curves into equal parts and to check measurements.
Set squares are used for drawing lines at specific angles (30, 45, 60, and 90 degrees), simplifying common drawing tasks. There are 45-degree and 30-60-degree set squares. A clinograph, also known as an adjustable set square, draws parallel lines to inclined lines by allowing its wing to be set at a required angle.
A protractor, a transparent semicircular plastic tool, draws and measures angles with one-degree accuracy. French curves, irregularly shaped plastic tools, are used for drawing irregular curves that a compass cannot create. Templates are plastic or wooden boards with pre-cut shapes or letters, facilitating the drawing of non-dimensional shapes or specific fonts.
Pencils are essential, with their hardness determining the line's appearance. Pencils are classified into 18 grades (from 9H to 7B), with specific grades recommended for different line types in engineering drawings (e.g., 3H for construction lines, H for object lines). An eraser removes mistakes; it must be soft and of good quality to avoid damaging the paper.
To keep the drawing sheet fixed on the board, paper holders, board pins, or masking tape are used. Care should be taken when removing these fasteners to prevent tearing the sheet.