Drafting Instruments Abie

7/28/2019 Drafting Instruments Abie

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WHY DO WE DRAW?

To communicate!!! To communicate!!!


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In the beginning of recorded history,people have used drawings torepresent the design of objects to bebuilt or constructed.

They used drawings to convey andexpress their ideas.

Everybody can understand drawing,and it is very important source of

their information.


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Although people around the worldspeaks different languages, auniversal graphic language hasexisted in the earliest of times-

drawing.

Drawing is a graphic representationof a real thing, an idea, or a proposeddesign for later manufacture orconstruction.-the act of creating blueprints anddesigns.


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Drawing (Drafting) is said to be theuniversal language.

Drafting develops both your manipulative(hands-on) and

intellectual (creativity)abilities.


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Freehand Drawing a type of drawing which does not use any tool

or equipment.

Mechanical Drawing a type of

drawing which uses drawing toolsand instruments.

TWO TYPES OF DRAWING


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Most people who think they cant never learnto draw has a usual apology of I cant even

draw a straight line .. This is a sense true, no one can draw a realstraight line without a guiding edge.

It is made in precision drawing instruments andrequire no artistic and special ability. Anyintelligent person can learn to execute goodmechanical drawing rapidly and skilfully.


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Typical Drawing Equipment

1. Accuracy

2. Speed3. Legibility

4. Neatness

OBJECTIVES INDRAWING


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ACCURACY No drawing is of maximum usefulness if it is not

accurate.


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SPEED Slow drafters will soon find themselves looking for

another while the fast drafter is usually mentally alert.


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LEGIBILITY Drawing student should realized that he/she is a meansof communication to others and that his/her work mustbe clear and legible in order to serve its purpose well.

Wrong Correct


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NEATNESS Ones work should be clean and free from any kind of dirt.

Wrong Very Wrong


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DRAWING INSTRUMENTSAND EQUIPMENT:

Prepared By:ABEGAIL V. DELA FUENTE

DRAFTING


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DRAWING TABLE

With inclined, flat and smooth surface.


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DRAWING BOARDS

The left edge and right edge of a drawing board has a truestraight edge.

For right-handed people, the

left-hand edge of the board iscalled the working edgebecause the T-square headslides against it.

For left-handed people, the

right-hand edge of the board iscalled the working edgebecause the T-square headslides against it.


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The T-square is made of a longstrip called the blade, fastened atright angles to a shorter piececalled the head.

The drawing paper should beplaced close to the working edgeof the board to reduce any error resulting from the bending of theblade of the T-square.

The paper should also be placedclose enough to the upper edge of the board to permit space at thebottom of the sheet for using theT-square.

Drafting tape is used to fasten thedrawing paper to the drawing

board.

T- SQUARE


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High-quality drawing pencils should be used in technical drawing, never ordinary writingpencils.

Many makes of mechanical pencils are available together with refill leads in all grades.Choose a mechanical pencil that feels comfortable in your hand.

DRAWING PENCILS


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DRAWING LEADS

HARD MEDIUM SOFT

9H 8H 7H 6H 5H 4H 3H 2H H F HB B 2B 3B 4B 5B 6B 7B

Hard leads are usedwhere extreme accuracy

is required. Generallythese leads are used for construction lines.

Medium leads are usedfor general purpose line

work in technicaldrawing.

Soft leads are used for various kinds of art work.

These leads are too softto be useful inmechanical drafting.

The first consideration in the selection of a grade of lead is the type of line workrequired. For light construction lines and guide lines for lettering use a hardlead. For all other line work, the lines should be BLACK. The lead chosenshould be soft enough to produce jet black lines but hard enough not to smudge.


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DRAWING LEADS


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DRAWING LEADS


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TASK LEAD GRADE LINE WEIGHTCONSTRUCTION LINES 3H, 4H, 6H THIN, LIGHTVISIBLE OBJECTLINES

H, F, HB THICK, DARK

HIDDEN LINES 2H, H THIN, DARKCENTER LINES 2H, H THIN, DARK

DIMENSION LINES 2H, H THIN, DARK

EXTENSION LINES 2H, H THIN, DARK

LEADER LINES 2H, H THIN, DARK

CUTTING PLANELINES H, F, HB THICK, DARK

PHANTOM LINES 2H, H THIN, DARK

LETTERING H, F, HB THIN, DARK

Drawing Lead ApplicationsDrawing Lead Applications


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DRAWING HORIZONTAL AND VERTICAL LINES

To draw a horizontal line, press the headof the T-square against the working edgeof the board with your left hand. Lean thepencil in the direction of the line at anangle of approximately 60 and draw theline from left to right. While drawing the

line, rotate the pencil to distribute the wear uniformly on the lead to maintain asymmetrical point.

To draw a vertical line, press the head of the T-square against the working edge of the board withyour left hand and place a triangle against the bladeof the T-square. Lean the pencil in the direction of the line at an angle of approximately 60 and drawthe line upward, rotating the pencil to distribute thewear uniformly on the lead to maintain asymmetrical point.


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TRIANGLES

Most inclined lines aredrawn at standard anglesusing the 45 x 45 triangleand the 30 x 60 triangle.

In addition to drawing anglesof 90, 45, 30, and 60,triangles can be combinedto draw angles of 15increments.


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SCALES

Scales are instruments used inmaking technical drawings fullsize or at a given reduction or enlargement.

Types of scales include metricscales, engineers scales,decimal scales, mechanicalengineers scales, andarchitects scales.

Scales are usually made of plastic or boxwood and areeither triangular of flat inshape.


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PIVOT COMPASS A compass used mainly to

draw circles and circular curvesof relatively short radius . The large pivot joint compass issatisfactory for drawing circles of 25 mm to about 300 mm indiameter without an extensionbar. The pivot joint provides enoughfriction to hold the legs of thecompass in a set position. One of the legs is equipped with asetscrew for mounting either apen or a pencil attachment on thecompass. The metal point extends slightlymore than the lead tocompensate for the distance thepoint penetrates the paper.


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BOW SETS

Giant Bow Sets

Giant bow sets contain variouscombinations of instruments.

Giant Bow Compass

The giant (large) bow compass has a

center wheel and can be adjustedsimply by opening or closing the legsof the compass while turning thecenter wheel.


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Using a Giant Bow Compass

1. Set off the required radius on one of the center lines.

2. Place the needle point at the exactintersection of the center lines.

3. Adjust the compass to the requiredradius

4. Lean the compass in the direction thatyou are going to draw the circle. Draw

the circle in a clockwise direction whilerotating the handle between the thumband forefinger.


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Sharpening the compass lead

A properly sharpened compass point isformed by rubbing the lead on the sandpaper pad.

A properly sharpenedcompass point consists of a single elliptical face.

A properly adjusted compass

The needlepoint extends abouthalfway into the paper when thelead touches the paper.


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EXTENSION BARS

Extension bars areavailable for large bowcompasses to draw largediameter circles.


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DIVIDER

Extension bars areavailable for large bowcompasses to draw largediameter circles.


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DRAFTING MACHINE

A drafting machine is adevice that attaches to thedrafting table and replacesthe T-square, triangles andprotractors. They increase theaccuracy and greatly

reduce drafting time. Most drafting machineshave a protractor.


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ERASING SHIELD

Used to protect the linesnear those being erase.


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FRENCH CURVE

Used to drawing curveswere the radius of curvatureis not constant.


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PROTRACTOR

Used for laying out anglesthat cannot easily be drawnby using triangles.


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TEMPLATES

Used to draw shape of details such as bolts, electricalsymbols, plumbing symbols and others.


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Pencil Drawing Techniques

A quality drawing is characterized by crisp black line work and lettering.

All finished pencil lines should be very dark. Construction lines should be madevery light so that they need not be erased when the drawing is completed.

Contrast in pencil lines should vary in the widths of the lines. Visible object lines

should contrast strongly with the thin lines of the drawing. .

Drafting Instruments Abie

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