Standard principles of drawing ( tools & accessories).pptx

contains brief informations on engineering desighn principles

1. ENGINEERING DRAWING (Standard principles of drawing ( tools & accessories)

2. Basic Tools A draftsperson needs some basic tools to draw. These should include the following: ● A range of pencils ● Drawing board ● Ruler ● Clips or tape ● Set squares ● Rubber ● Compasses ● Dividers ● T-square

3. Drawing Board A drawing board is a flat, smooth board on which to attach paper for making drawings or designs. Traditionally, they are made of timber however, modern day boards are constructed out of plastic. The board can be purchased in A4 size although they are more commonly found in schools as an A3 size format.

4. Drawing Paper Drawing paper is the paper on which drawing is done on. Engineering drawings are made on sheets of paper of strictly defined sizes, which are set forth in respective standards. The paper should be smooth, uniform in thickness and fibers should not be disintegrated when an eraser is used on it.

5. Ruler A ruler is one of the most important pieces of drawing equipment. An opaque-type ruler should only be used to measure distances with lines being drawn with T-Squares and Set Squares. But it must be remembered that the edge of a ruler is not guaranteed to have a perfectly straight edge unlike a good T-Square or Set Square.

6. Pencils Pencil is used to draw on the paper. Pencils number ranges from 9H to 7B. These alphabets represets to the hardness of the pencil lead. The H stands for hard and the B stands for blackness. H pencils are harder and produce lighter lines because they contain more filler and less graphite. Pencils that fall into the B grade, on the other hand, make a darker mark because they're softer and don't contain as much filler.

7. Pencils & Grades

8. Grades and hardness of pencils. Grade of pencil Hardness of pencil 9H Hardest 6H, 5H, 4H Extremely Hard 3H Very hard 2H Hard H Moderately hard HB Medium hard B Moderately soft 2B Soft 3B, 4B, 5B, 6B Very soft 7B Softest

9. T-square T square is used to draw horizontal and vertical lines on drawing sheet. It made of wood or plastic and in T shape. The vertical part of T is called blade and horizontal part of T is called head. The edge of head is uniform level and attached to the edge of the board. The working edge is used to draw lines anywhere on the sheet by moving the instrument top to bottom.

10. Clips/ Tapes Clips/tapes are used to hold the drawing paper in position when drawing board is not available. They are designed to clip on to the edge of a table or portable timber board and hold the paper down firmly against the flat surface (Drawing board or table).

11. Protractor A protractor is used to measure angles. A typical protractor is a semi-circular piece of plastic with 180 degrees printed around its curve Also available for graphics is a full circle protractor which can be used to accurately measure angles greater than 180 degrees.

12. Compass A compass, also known as a pair of compasses, is a technical drawing instrument that can be used for inscribing circles or arcs. The distance between the legs can be adjusted to allow the changing of the radius of the circle drawn.

13. Divider The divider looks like a compass, but the difference is the two legs of divider are provided with needles. This is used to divide a line or curve into equal parts. It is also used to check the measurements.

14. Set Squares Set Squares are used to draw accurate angles. The most common set squares are 45 degrees and 60/30 degrees. When using set squares they should always be used along with a T-Square. The Set-square rest on the straight edge of the T-Square and this ensures that the angle is drawn straight and with accuracy.

15. French curve A French curve is a template which is generally made out of plastic and is composed of many different curves. They are used in manual drawing to draw smooth curves of varying radii. The curve is placed on the drawing material, and a pencil is traced around its curves to produce the desired result.

16. Rubber/ Eraser Eraser is used to remove the lines or spots which drawn by mistake or with wrong measurements. The eraser used should be of good quality and soft. It should not damage the paper while erasing