Engineering Drawing For CNC Machining – Introduction, Applications & Drawing Instruments

Drawing Board: It is rectangular in shape and is made of wood about 25 mm thick, it is cleated at the back by 2 battens to prevent warping. The surface of the board should be smooth and is used to keep the drawing paper. There is a working inch at the side of the drawing board. 

Drawing Paper: While selecting a drawing paper, we have to be sure that the size of the paper is smaller than the drawing board. 

Pins, Clips & Adhesive Tapes: To hole destroying paper, we use pins or clips or other save tapes. 

Pencils: They are basically used to draw, the accuracy and appearance of a drawing depends on the quality of the pencils used. The grade of pencils H2H and HB are mostly used.

T-Square: T-square is made of two parts: the stock and the blade which are joined together at right angles by means of screws and pins. T-square is fitted at the side of the drawing board and its along the edge of the board and is used to draw horizontal straight lines. 

Set Square: It is triangular in shape with one of the angles as right angle. Two forms of the set square are generally used, one having angles 45 and 90 degree and the other is 30, 60, 90. Set square is a combination with t-square, is used to draw lines at an angle. 

Scale: A scale is used to draw lines of specific lengths. 

Protractor: It is flat and semicircular in shape, it’s circumferential edge is graduated to one degree divisions and is numbered and every 10 degree interval and is readable from both the ends. The protractor is used to draw or measure angles.

Drafter: The combination of a t-square, a set square scales and a protractor is a drafter. It’s one end is clamped by means of a screw at the edge of the drawing board. The other end is adjustable, it has a scale which is at 90 degree and also has a protractor which can be rotated at certain angles. This scale can be moved anywhere we want within its limits.

Roller Scale: It has a roller in it. It is used for drawing vertical lines, horizontal lines, parallel lines, angles and circles.

French curve: They are made in various shape, used for drawing curves which cannot be drawn with a compass, it is used to draw curves like ellipse, parabola, hyperbola, etc. 

Compass: A compass is used to draw a circle of a specific radius and an arc at a specific distance. 

Eraser: Soft Indian rubber is widely used to erase pencil drawings, the eraser should be such that it does not spoil the surface of the paper.