Drafting Instruments

1. Drawing Board

- it provides the smooth, flat surface needed for drafting. The tops of many drafting tables are designed for this purpose. Individual drawing boards are manufactured in a variety of sizes. The majority of them are made from selected, seasoned basswood. The right-handed draftsman will use the left edge of the board as the working edge; the left handed draftsman the right edge. The working edge should be checked periodically for straightness. Draftsmen often tape a piece of heavy paper or a special vinyl board cover to the working face of the drawing board to protect its surface. The vinyl surface is

easily cleaned.-Drawing board size:

Drawing boards are made in various sizes. The selection of Drawing board depends on the size of drawing paper used. The sizes of Drawing board recommended by Bureau of Indian Standards (B.I.S) is given below

The drawing board must always be kept clean before, during, and ater using it to avoid dirt to stay there or stick on your next works.

You should not let water spill on your drawing board since it is made of wood, it might have bubbles that will make your board ugly and not very useful anymore.

Do not leave any kind of marks on your board to retain its smoothness.

2. Drawing Sheet or Paper/Plate Paper

- where you draw or draft or make sketches.

- Drawing Sheets are available in two ANSI standard series: engineering and architectural and sized by the letters "A", "B", "C", "D", and "E". The chart below provides the dimensions of the sheets and the drawing shows the relationship of the sizes to each other.

- Drawing Sheet Sizes:

An ISO (International Standards Organization) metric standard also exists in industry. The chart below provides the dimensions of metric sized sheets.

Place on a dry area so it will not be damaged Draw lightly with a pencil so when you erase it, there are no markings Write/draw carefully so it will not be crumpled Place it in a plate holder when not in use so it will not be crumpled

It should be stored in rolled form.

3. Drafting Tape

- used to tape down drawing sheets/ plate papers on the table so it will not move while you are working or drawing.

Place it on a dry place so the sticky portion will still be there Place it on a clean place

4. Pencils

- The accuracy and appearance of a Drawing depends on the quality of Pencil used to make Drawing. The grade of a Pencil lead is marked on the Pencil. HB denotes medium grade. Increase in hardnessis shown by value put in front of H such as 2H, 3H etc., Softer pencils are marked as 2B, 3B, 4B etc. A Pencil marked 3B is softer than 2B and Pencil marked 4B is softer than 3B and so on. Beginning of a Drawing may be made with H or 2H. For lettering and dimensioning, H and HB Pencils are used.

Never sharpen the pencil over the drawing or close to any of your equipment.

Sharpen the pencil properly

Always keep the lead sharp.

Using the cleaner, spray the cloth and wipe the pencil's residue like oil from hands

5. Erasers

- are manufactured for use in the drafting room. The type of material being drawn upon paper, film or vellum, will determine the kind of eraser to be used.-used to remove pencil markings

Take the erasers and rub out any black marks. Do this by rubbing the eraser against a clean piece of paper until the black smudge has disappeared.

6. Erasing Shield

- used to erase smaII errors or drawing changes without soiling a large section of the drawing. Place an opening In the shield of the proper shape and size over the area to be changed and then erase. The erasure is made without touching other parts of the drawing. A popular shield is made from stainless steel. This metal can be made very thin and still be strong. It is also wear resistant and does not stain or "smudge" the drawing.

Should be kept together with other supplies to avoid losing it.

7. Sharpeners

- is a device for sharpening a pencil's writing point by shaving away its worn surface. Pencil sharpeners may be operated manually or by an electric motor.

Carefully use it so it will not break easily Only sharpen the pencils that fit in its hole

8. T- Square

- used to draw horizontal lines and to support the triangles. The T-square consists of two parts, the head and the blade or straight edge. The head is usually fixed solidly to the blade; however, a T-square with a protractor head and adjustable blade is also available. Clear plastic strips inserted in the blade edge of some T-squares makes it easier to locate reference points and lines.The blade must never be used as a guide for a knife or other cutting tool. If accurate line work is to be done, it is essential that the head of the T-square be held firmly against the working edge of the board.It is recommended that the blade be left flat on the board or suspended from the hole in its end. This will keep warping or bowing of the blade to a minimum.

Do not use the T-square for any rough purposes.

Never cut paper along its working edge, since the plastics can easily be damaged. Even light nick can ruin the T-square.

9. Triangles

- used to draw vertical and inclined lines. They are made. of transparent plastic

and are available in a number of different sizes. To prevent warping, the triangle should be left flat on the drawing board when not being used. Angles of 15 and 75 deg. can be drawn by combining the triangles as shown in Fig. 3-4.To draw vertical lines accurately, rest triangle solidly on the T-square blade while holding the T-square head firmly against

the working edge of the drawing board

Do not use the triangle for any rough purposes.

Never cut paper along its working edge, since the plastics can easily be damaged. Even light nick can ruin the triangle.

10. Rulers/ Scales

- constant use on the drawing board because almost every line on a mechanical drawing must be of a measured length. Accurate drawings require accurate measurements. Because of the diversity of the work that must be drawn, the scales used by the draftsman are made in many shapes, lengths and measurement graduations. They may be made of wood, plastic, or a combination of both materials. Graduations are printed on inexpensive scales, and are machineengraved on the more costly ones.

For convenience, scales are classified according to their common uses: >A R C H I T E C T S ' S C A L E

Each division represents one foot and is divided into twelve parts, each part being equal to one inch.>E N G I N E E R S ' S C A L E

Used mostly where large reductions are required. It is divided into 10, 20, 30, 40, 50, 60, 80 and 100 units (each represents one foot) per inch. >M E C H A N I C A L D R A F T S M E N ' S S C A L E

Most commonly divided into the following graduations: full size, and 3/4, 1/2, 1/4 and 1/8 in. to 1 foot.

Scales should not be pricked with needle points of either the divider or compass when measurements are taken.

11. Compass

- Compass is used for drawing circles and arcs of circles. The compass has two legs hinged at one end. One of the legs has a pointed needle fitted at the lower end where as the other end has provision for inserting pencil lead. Circles up to 120mm diameters are drawn by keeping the legs of compass straight. For drawing circles more than 150 mm radius, a lengthening bar is used. It is advisable to keep the needle end about 1mm long compared to that of pencil end so that while drawing circles, when the needle end is pressed it goes inside the drawing sheet by a small distance (approximately 1mm).

Use only the pencils that will fit on the pencil holder Do not play with it

12. French Curve

- used to draw curved lines that are not exactly circular in form- The curves are made of transparent acrylic plastic. They range in size from a few inches to several feet in length and may be purchased individually or as a set.

 Never cut paper along its working edge, since the plastics can easily be damaged.Even light nick can ruin the French curve.

13. Protractor

- is used to measure and lay out angles on drawings. They are usually made of clear plastic and may be either circular or semicircular in shape. The degree graduations are scribed or engraved around the circumference of the protractor.

 Never cut paper along its working edge, since the plastics can easily be damaged.Even light nick can ruin the protractor

should not be pricked with needle points of either the divider or compasswhen measurements are taken