TheThe UseUse andand CareCare ofof DraftingDrafting EquipmentEquipment
ChapterChapter 33
Sacramento City College EDT 300/ENGR 306
EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment 1 ObjectivesObjectives Learn to properly and efficiently use basic drafting tools and equipment to produce technical drawings.
2 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment BasicBasic ManualManual DraftingDrafting EquipmentEquipment Vocabulary • India ink • Irregular curves Acute angle • Obtuse angle Alphabet of Lines • Opaque
Angle • Protractor
• Right Angle Circumference • Scales Compass • Symmetrical Drafting Film • T-Square Erasing Shields • Transparent
Inclined • Vellum
• Vertex
3 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment BasicBasic ManualManual DraftingDrafting EquipmentEquipment Drafting Board • Architect’s, engineer’s and
T-Square or parallel-ruling straightmetric edgescale or drafting machine • Irregular curve Drawing sheets (paper, cloth, or film) • Drawing instrument set Drafting tape Drafting pencils • Brush Black drawing ink Pencil Sharpener Technical pens Erasing shield Triangle, 45o and 30o-60o
4 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment BasicBasic ManualManual DraftingDrafting EquipmentEquipment Drawing tables and desks Come in many different sizes and shapes Can be used standing or sitting Combination drafting table, desk and regular office chair is the most comfortable and efficient. See Figure 3-3.
5 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment DrawingDrawing BoardsBoards Drawing sheet is taped to the drawing board. Drawing boards usually measure: 9 x 12 16 x 21 18 x 24 Usually made of pine or basswood Made to stay flat and so the guiding edge will remain straight Hardwood or metal strips are used on some board edges to provide more durable edges.
6 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment TT--SquaresSquares A T-Square is an instrument that consists of a head that lines up with a true edge of the drafting board and a blade, or straightedge, that provides a true edge. Most have plastic-edged wood or clear plastic blades and heads of wood or plastic. If extreme accuracy is required, the T- square may be made of stainless steel. The blade must be very straight. The blade must be attached securely to the top surface of the T-head. See Figure 3-4.
7 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment CheckingChecking TT--SquareSquare AccuracyAccuracy To check the accuracy of a T-square On a clean sheet of paper, draw a sharp, thin line along the drawing edge of the T- square. Then, turn the drawing sheet around and line up the drawing edge of the T-square with the other side of the line. If the drawing edge and the pencil line do not match, the T-square is not accurate and should be replaced. See Figure 3-5.
8 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment DraftingDrafting MachinesMachines Two kinds are in use The arm or elbow type (Figure 3-6). The track type (Figure 3-9). The parallel bar type (Figure 3-9).
9 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment ArmArm oror ElbowElbow DraftingDrafting MachineMachine The anchor and two arms hold a movable protractor head with two scales. The scales are normally at right angles to each other. The arms allow the scales to be moved to any place on the drawing that is parallel to the starting position. Items are parallel when their edges are exactly the same distance apart at all points.
10 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment ArmArm oror ElbowElbow DraftingDrafting MachineMachine Most industrial drafting departments and many schools use drafting machines. Drafting machines combine the functions of the T-square, triangles, scales, and protractor. Allow you to draw more quickly and with less work.
11 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment TrackTrack--TypeType DraftingDrafting MachineMachine The track-type uses a horizontal guide rail at the top of the board and a moving arm rail at right angles to the top rail. An adjustable protractor head and two scales, usually at right angles, move up and down on the arm The scales may be moved to any place on the drawing that is parallel to the starting position. This type of drafting machine is easy to use on large boards or on boards placed vertically or at a steep angle.
12 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment OtherOther BasicBasic ToolsTools Triangles Drafters use two types of triangles in combination with the T-square to draw lines at various angles. Protractor A protractor is an instrument that is used to measure or lay out angles. Parallel-Ruling Straightedges Many drafters prefer this device to the drafting machine.
13 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment OtherOther BasicBasic ToolsTools Irregular Curves Also called French curves Used to draw noncircular curves They are made of sheet plastic Come in many different forms Sets are made for ellipses, parabolas, hyperbolas, and other special purposes. Flexible curves Curves which can be adjusted to complex curves that may be difficult to draw with other irregular curves.
14 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment DrawingDrawing MediaMedia Drawings are made on may different materials.
15 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment PaperPaper White, tinted, blue tint or pale green. White is used for drawings which will be photographed. Light colored papers reduce eyestrain and are less likely to soil.
Opaque drawing papers are used for Permanent records Master drawings. Maps. Any drawing that will be photographed.
16 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment TracingTracing paperpaper Tracing paper Is translucent drawing paper Name was derived from the practice of first making a drawing in pencil on opaque paper, then “tracing” in ink on a sheet of translucent paper. Translucent papers allow “bluelines” or copies to be made. Natural papers made strong and durable are not very transparent. Papers with high transparency are only moderately durable.
17 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment VellumVellum Vellum
Is tracing paper that has been treated to make it more transparent.
Vellum provides strength, transparency, durability (handling and folding) and erasability without “ghosting”.
18 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment TracingTracing ClothCloth Tracing Cloth
Is finely woven cotton fiber material cloth that has been sized with starch to provide a surface that takes pencil and ink. It comes in white for pencil tracings and blue for ink.
19 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment TracingTracing ClothCloth Tracing Cloth The working side is dull or frosted.
You can erase without damaging the surface by using a soft rubber or vinyl eraser.
Treated to provide a good working surface and good transparency.
Is considerably more expensive than paper media.
20 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment TracingTracing ClothCloth Tracing Cloth Is subject to expansion and shrinkage. The drawing should be completed all at once.
21 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment MylarMylar (Plastic(Plastic Film)Film) Best qualifications for drawing media. Best for longevity, dimensional stability, great resistance to tearing, easy erasing with soft eraser and high transparency. Waterproof. Will not become brittle with age. Drawing surface is matte (dull and rough). Other side is very smooth, and will not accept graphite.
22 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment DrawingDrawing SheetSheet SizesSizes Drawing sheets follow standards set by American National Standards Institute (ANSI) OR International Standards Organization (ISO)
23 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment ANSIANSI SheetSheet SizesSizes American National Standards Institute (ANSI) provides two sets of standards which are commonly called the US Customary series. Both are developed upward in size from smallest to largest. 8.5 x 11 series OR 9 x 12 series
24 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment ANSIANSI SheetSheet SizesSizes Series based on 8.5” x 11” sheet. A - 8.5” x 11.0” B - 11” x 17” (keep the longest dimension (11); multiply the smallest dimension by 2; 2 x 8.5 = 17) C - 17” x 22” (keep the longest dimension (17); multiply the smallest dimension by 2; 2 x 11 = 22) D - 22” x 34” (keep the longest dimension (22); multiply the smallest dimension by 2; 2 x 17 = 34) E - 34” x 44” (keep the longest dimension (34); multiply the smallest dimension by 2; 2 x 22 = 44)
25 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment ANSIANSI SheetSheet SizesSizes Series based on 8.5” x 11” sheet. A - 8.5” x 11.0” B - 11” x 17” C - 17” x 22” D - 22” x 34” E - 34” x 44”
26 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment ANSIANSI SheetSheet SizesSizes Series based on 9” x 12” sheet. A - 9” x 12.0” B - 12” x 18” (keep the longest dimension (12); multiply the smallest dimension by 2; 2 x 9 = 18) C - 18” x 24” (keep the longest dimension (18); multiply the smallest dimension by 2; 2 x 12 = 24) D - 24” x 36” (keep the longest dimension (24); multiply the smallest dimension by 2; 2 x 18 = 36) E - 36” x 48” (keep the longest dimension (36); multiply the smallest dimension by 2; 2 x 24 = 48)
27 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment ANSIANSI SheetSheet SizesSizes Series based on 9” x 12” sheet. A - 9.0” x 12.0” sheet. B - 12” x 18” C - 18” x 24” D - 24” x 36” E - 36” x 48”
28 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment ISOISO SheetSheet SizesSizes ISO Sheet sizes are developed downward in size from a base sheet with an area of about 1 square meter. (Remember that ANSI sizes are developed upward) Sheet sizes are based on a length-to-width ratio of 1 to square root of 2. Each smaller size has an area equal to one- half the preceding size.
29 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment SettingSetting upup aa DrawingDrawing onon thethe DraftingDrafting BoardBoard
EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment 30 FasteningFastening TheThe DrawingDrawing SheetSheet ToTo thethe BoardBoard Place sheet at least 2” from left edge.
Place sheet at least 4” to 6” from the bottom of the drawing table.
Line up sheet horizontally with drafting machine then place drafting machine over paper to hold in place.
Use strips of tape or round “draft-dots” to hold the sheet in place.
31 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment PencilsPencils Pencil “lead” is made from graphite, a form of the element carbon. It also contains clay, and some resins to hold it together Graphite pencils have been used for more than 200 years and are still the most important kind.
32 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment PencilsPencils Leads used in drawing pencils are manufactured by a special process designed to make them strong and capable of producing sharp, even density lines.
33 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment GraphiteGraphite PencilPencil GradesGrades ofof HardnessHardness 6B-softest and H-medium hard blackest 2H-hard 5B-extremely soft 3H-hard, plus 4B-extra soft 4H-very hard 3B-very soft 5H-extra hard 2B-soft, plus 6H-extra hard, plus B-soft 7H-extremely hard HB-medium soft 8H-extremely hard, plus F-intermediate 9H-hardest between hard and soft
34 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment ChoiceChoice ofof PencilPencil HardnessHardness The grade of pencil you used depends On the kind of surface on which you are drawing. The roughness of the drawing media Paper Vellum On how opaque (dark) and thick you want the finished line to be.
35 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment CommonCommon UseUse ofof HarderHarder LeadsLeads The softer grades of lead deposit more lead on the media and produce more opaque lines.
However, many drafters continue to use the harder grades because they produce sharper lines and do not smudge readily during drafting process.
36 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment ChoiceChoice ofof PencilPencil HardnessHardness Examples “Layout views on fairly hard-surfaced drawing paper”. 4H or higher Tracing paper/finished views to be reproduced. H or 2H
Grades HB, F, H are sometimes used for sketching, and for drawing arrowheads, border lines.
37 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment ChoiceChoice ofof PencilPencil HardnessHardness The exact grade depends on the drawing and the surface. Very hard and very soft leads are seldom used in drafting.
38 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment SharpeningSharpening PencilsPencils
EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment 39 SharpeningSharpening PencilsPencils To sharpen a wooden pencil, Cut away the wood at a long slope (Fig 3- 17A) or Use a drafter’s pencil sharpener Sharpen the end opposite the grade mark Leave about .38” to .5” exposed. Shape the lead to a long conical point Do this by rubbing the lead back and forth on a sandpaper pad, while turning the pencil slowly. Burnish the lead by rubbing on drafting paper. Never sharpen a pencil over a drawing board !
40 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment TwoTwo PencilPencil PointPoint TypesTypes Conical The conical point is used for general line work and lettering. It is shaped in a lead pointer
Wedge Used for drawing ling straight lines because it holds it point (edge) linger than the conical point.
41 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment LeadLead HoldersHolders Are widely used by drafters They hold plain sticks of lead in a chuck that allows the exposed lead to be extended to any length desired.
Generally are shaped just like pencils The lead is sharpened in a lead sharpener.
42 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment PencilPencil TechniqueTechnique
EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment 43 PencilPencil TechniquesTechniques Lines must ALWAYS be clean and sharp. must be dark enough for the views to be seen when standard line widths are used.
44 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment PencilPencil TechniquesTechniques Pencil pressure Too much and you will groove the drawing surface Not enough the line will be too light and will be “fuzzy”.
Sufficient pressure must be used to fill the drawing fibers with graphite.
45 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment PencilPencil TechniquesTechniques Pencil Strokes More than one pencil stroke is required to produce a line of proper density
The pencil MUST BE ROTATED as you are drawing the line.
46 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment PencilPencil TechniquesTechniques Develop the habit of turning the pencil between your thumb and forefinger when drawing a line.
This will help keep the line uniform and keep the pencil point from wearing unevenly.
47 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment ErasersErasers andand ErasingErasing Use soft erasers Vinyl type (only). Pink/green erasers are too abrasive. On film, only use a vinyl type of eraser.
On paper or cloth, erase across the direction of the line.
48 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment ErasingErasing ProcedureProcedure Clean eraser by rubbing on a clean scrap of paper. With your free hand, hold the drawing securely. Rub soft vinyl eraser lightly back and forth to erase detail or line.
For erasing deeply grooved pencil or ink lines, place a triangle under the paper for backing.
If necessary to protect details close by, use an erasing shield.
49 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment EraserEraser ShieldsShields Use eraser shields to prevent accidentally erasing nearby lines.
Erasing shields are made of metal, or plastic and have openings of different sizes and shapes.
Position the shield so only the part you wish to erase appears in one of the openings on the shield.
50 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment ElectricElectric ErasersErasers Use care not to remain in one spot too long, especially with film. You can “polish” the film to the point that it will no longer accept graphite. Use only soft rubber or vinyl erasers.
A very gentle pressure avoids overheating the drawing surface. You can use a piece of thin gauge copper, brass or aluminum sheet under the area to be erased to help dissipate the heat and reduce the possibility of damage to the drawing.
51 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment NeatnessNeatness InIn DraftingDrafting Neatness = Ability
The first impression is a lasting one. Practice cleanliness from the start. The primary source of “dirty” drawings is smeared graphite Sliding T-squares, triangles, shirt sleeves and hands across drawings.
Lift tools off your work; do not slide!
52 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment NeatnessNeatness InIn DraftingDrafting Wash your hands before starting, and occasionally during drawing if your hands tend to be oily.
Always wipe dust and dirt from instruments with a soft cloth before starting to draw and frequently during use.
Lay out all views with a hard pencil first. “Heavy-in” lines only when certain they are correct.
53 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment NeatnessNeatness InIn DraftingDrafting Remove graphite dust when it collects. After each line is drawn, blow loose graphite from the sheet.
Remove erasure dust with a brush, not your hands!
54 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment NeatnessNeatness InIn DraftingDrafting DO NOT slide instruments across drawing! Lift the drafting machine prior to moving.
Sharpen pencils away from the drawing.
Maintain an orderly drawing area. Keep only the tools you need on top of the desk Keep unused tools OFF THE SHEET!
55 EDT 300/306 - Chapter 3 - Use/Care of Drafting Equipment