Chapter 2: Sketching, Lettering, and Lines Sketching lines, circles, arcs and multiviews. Freehand...

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Chapter 2: Sketching, Lettering, and Lines Sketching lines, circles, arcs and multiviews. Freehand lettering and mechanical lettering equipment.

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Transcript of Chapter 2: Sketching, Lettering, and Lines Sketching lines, circles, arcs and multiviews. Freehand...

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  • Chapter 2: Sketching, Lettering, and Lines Sketching lines, circles, arcs and multiviews. Freehand lettering and mechanical lettering equipment.
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  • Sketching is Freehand Drawing Advantages: Fast visual communicator Helps to organize thought Minimizes errors on final drawings - Sketches help to record the stages of progress on a design - Useful for of illustration - Useful for laying out dimensions of a part
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  • The Quality of a Sketch Depends On its Intended Purpose Speed is the big key to sketching. A sketch is to be used to relate a design idea to someone quickly.
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  • Tools and Materials for Sketching Paper newsprint or graph paper Pencil- common #2 pencil or automatic 0.7mm or 0.9mm pencil with F or HB lead Eraser The best sketches are made when you can move the paper freely.
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  • Sketching Straight Lines Lines should be sketched in short, light, connected segments. Sketch light lines when you are first laying out the sketch. Darken the lines when you are ready to finish the sketch. Very long lines can be sketched using the edge of the paper or table as a guide.
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  • Steps to Sketch a Horizontal Straight Line Step 1: Mark the starting and ending positions with points. Step 2: Without touching the paper, sketch the direction of the line. Step 3: Sketch light short strokes between points keep your eye focused on the end point. Step 4: Darken the final lines.
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  • Sketching Circular Lines Quick Small Circles Box Method Centerline Method Hand-Compass Method Trammel Method
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  • Sketching Quick Small Circles These are easy to draw. It is just like drawing the letter O.
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  • Parts of a Circle
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  • Box Method for Sketching Circles Step 1: Sketch a square equal to the diameter of the circle using light lines. Step 2: Sketch diagonal lines across each corner of the square. Step 3: Establish marks on the diagonal lines out from the center of the square equal to the circle radius you want to sketch. Step 4: Create the circle by sketching arcs that are tangent to the sides of the square and go through the marks on the diagonals.
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  • Centerline Method for Sketching a Circle Step 1: Sketch very light horizontal, vertical, 45 degree lines that meet at the center of the proposed circle. Step 2: Mark the approximate radius of the circle on the centerlines. Step 3: Create the circle by sketching arcs that go through the marks on the centerlines.
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  • Hand-Compass Method for Sketching a Circle Step 1: Allow the paper to free rotate 360 degrees. Step 2: Use your index finger as the point of the compass. The pencil rests in your palm and makes contact with the paper as you pivot around your index finger. Control the pencil with your thumb. Step 3: Determine the circle radius by adjusting the distance between your index finger and the pencil point. Step 4: When drawing the circle, keep your hand and pencil point in one place, and rotate the paper with the other hand to create the circle. Step 5: Darken the final circle.
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  • Trammel Method to Sketch a Circle Step 1: Create a trammel larger than the circle radius out of 1 wide paper. Mark the radius with tick marks. Step 2: Sketch a straight line with tick marks (a & b) to locate the radius of the circle and the center of the circle. Step 3: Place the paper trammel on the line, lining up the radius tic marks. Pivot the trammel about the center mark (b).Lightly make tic marks as you rotate the trammel. Step 4: Solid in the tic marks to create the final circle.
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  • Sketching Arcs Technique is similar to sketching circles. Arcs are generally drawn with a radius. Sketch the arc with your hand facing the inside of the arc. An arc is part of a circle and forms rounded corners. The arcs creates a smooth connection at the point of tangency with the straight line.
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  • Sketching Ellipses An ellipse has a major diameter and a minor diameter. To sketch an ellipse, create a box equal to the major and minor diameter. Now sketch lines from the corners to the mid point of the major diameter lines of the box. From the cross points in the lines, use that radius for the end arcs of the ellipse. From the midpoints on the major diameter box lines, sketch an arc equal in radius to the sketch lines to the corners for the major arcs.
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  • Measurement Lines and Proportions All lines in a sketched object are related to each other in size and direction. The first line in a sketch is the measurement line and sets the scale of the sketch. All other lines are sketched in relation to the first line. The same relationship can also be applied to spaces.
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  • Block Technique in Sketching an Object Step 1: Visualize the object surrounded by an overall rectangle using proper proportions. Step 2: Using the lightly sketched rectangle, start sketching out areas of the object working from the edge of the rectangle. Step 3: Measure from the rectangle edges to locate interior features. Step 4: Darken final lines of sketched object.
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  • Sketching Irregular Shapes Step 1: Place the object in a lightly constructed box. Step 2: Draw a grid of equally spaced horizontal and vertical lines. Step 3: Establish a similar grid on the object you are transferring by sketch or visualize a grid on the real object. Step 4: On the sketch, reestablish a proportioned grid similar to the one over the original drawing. Step 5: Using the new grid, draw in the irregular object, placing the arcs and line in the same grid positions as the original drawing. Step 6: Darken final sketch.
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  • Creating Multiview Sketches Multiview projection is also known as orthographic projection. Multiviews are 2 dimensional views of a 3D object. Line of sight is perpendicular (90 degrees) to the surface of the object.
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  • Multiview Alignment Sketch the front view first in the lower left portion of the paper. Place the top view directly above the front view and the right side view to the right side of the front view. The choice of views depends on the object to be drawn.
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  • Establishing Isometric Axes Step 1: Sketch a horizontal reference line (ground level). Step 2: Sketch a vertical line perpendicular to the ground line. Use this line to measure heights. Step 3: Sketch 30 angular lines starting at the intersection of the first two lines.
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  • Making a Isometric Sketch Step 1: Select the best view of the object. Step 2: Set up isometric axes. Step 3: Draw an isometric rectangle in proportion to the object. Step 4: Lightly sketch in the features of the object. Step 5: Darken in all of the object lines.
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  • Placing Nonisometric Lines Step 1: Develop a proportional box. Step 2: Sketch all isometric lines. Step 3: Locate the starting and ending points of nonisometric lines. Step 4: Sketch in the nonisometric lines by connecting the points.
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  • Four-Center Method for creating Isometric Circles Step 1: Draw an isometric cube. Step 2: On each surface of the cube, draw lines that connect the 120 corners to the centers of the opposite sides. Step 3: Sketch arcs using the lines on each surface as the radius for arcs in the 120 corners. Step 4: Sketch arcs using the intersection of where the lines cross on each surface to establish the radius for the smaller arcs.
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  • Single Stroke Gothic Lettering Today this standard is conveyed by the American Society of Mechanical Engineers (ASME Y14.2, Line Conventions and Lettering). This is the standard for lettering established in 1935 by the American National Standards Institute (ANSI). Industry uses the upper case style as the standard.
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  • Other Lettering Styles Used in Drafting Inclined Lettering Lowercase Lettering Architectural Style
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  • Lettering Legibility ASME: Lettering size for dimensions numerals and notes -.125 in.(3mm) high ASME: Lettering size for titles, drawing numbers, section and view letters and captions -.25 in. (6mm) high
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  • Lettering Legibility (continued) Use only one style of lettering on a drawing. Lettering should be dark, crisp & opaque. Minimum space between letters -.06 in. (1.5mm) The space between words in a sentence is the same as the height of the letters. The minimum space between 2 numerals with a decimal point is 2/3 the letter height. Notes should be lettered horizontally on a page. Space between lines of letters is equal to the height of a letter. Vertical or inclined letters may be used.
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  • Vertical Freehand Lettering Standard for mechanical drafting Use lightly drawn horizontal guidelines. Use 0.5 mm automatic pencil with H,F,or HB lead. Each letter is composed of single strokes to make the letter. Fraction numerals are same size as other numerals. The fraction bar is most often drawn horizontally. The fraction numbers do not touch the fraction bar. Decimal points should be dark and clear with enough room around them to be clearly read.
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  • Making Guidelines Guidelines are drawn to the height of the letters. Use hard lead such as 6H or 4H lead, or use non-photo blue lead. Use an Ames Lettering guide for assistance.
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  • Lines All lines should be dark, crisp, sharp, and of correct thickness (ASME). ASME recommends two line thicknesses. Military standards require three line thicknesses: thick, medium & thin. Line standard relates to manual and computer- aided drafting. Thick lines 0.6 mm Thin lines 0.3 mm
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  • Line Conventions
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  • Types of Lines Construction and Guidelines Object Lines Hidden Lines Centerlines Extension Lines Dimension Lines & Leader Lines Arrowheads Cutting-Plane & Viewing-Plane Lines Section Lines Break Lines Phantom Lines Chain Lines Stitch Lines
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  • Pencil Line Technique All lines should be the same darkness. Wash your hands & equipment often for a cleaner drawing. Lay out the entire drawing in construction lines. Draw horizontal thin lines first, then draw vertical thin lines. Next, draw all circles and arcs. Last, draw all horizontal and vertical thick lines. Finish with all of the lettering and notes Always draw radii first before straight lines this makes for a smoother transition.
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  • Inking Technique Use the correct side of the media with the inking surface. Use template lifters to avoid smearing the ink. Maintain a clean pen to avoid ink blots and poor line quality. Make arcs first for ease of connecting to a straight line. Follow the same procedure for laying ink lines as with pencil lines (i.e. horizontal lines first, etc.). Hold technical pens 90 to the surface for proper ink flow and line definition do not apply too much pressure. Ink away from previous lines to avoid smearing. Move the pen at a constant speed do not decrease movement at the end of a line.
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  • Erasing Ink Electric erasers work well to erase ink on vellum in small areas. A smooth area will not take ink again. To erase on polyester film use: Ink remover Water on a cotton swab Ink eraser
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  • Pencil Skills with Polyester Lead Draw with a single line in one direction. Draft with a light touch. Draft over recommended backing material for a drafting board. Erase with the vinyl eraser. Use the electric eraser with care.
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  • Web Site Research http://www.asme.org/asme/8.html http://www.ansi.org http://www.adda.org