lesson a 3-1 planning and designing projects. problem area 3 construction systems
TRANSCRIPT
Lesson A 3-1
Planning and Designing Projects
Problem Area 3
Construction Systems
Lesson 1
Planning and Designing Projects
Interest Approach
l Ask students why a project needs to be planned on paper. Show copies of project plans and building blue-prints. Explain that planning “on paper” will help avoid costly mistakes and the purchase of unneeded materials. Lack of planning results in time wasted on trips to the lumber yard to buy one more board, a few more nails, or another pair of hinges.
Interest Approach
l “Paper planning” with scale drawings will help spot potential problems. Trial and error construction (unplanned construction) results in wasted time and materials. Stress to the students that when planning is done on paper, problems can be corrected with a pencil eraser instead of a hammer, wrecking bar, and saw.
Student Learning Objectives
l 1. Explain how to read project plans and blueprints.
l 2. Explain how to draw project plans.l 3. Discuss the development of a
cutting list and a bill of materials.
Terminology
l Architectural scalel Bill of materialsl Border linel Blueprintl Center linel Cleaning padl Compassl Computer aided
drafting (CAD)
l Construction procedure
l Cutting listl Dimension linel Dividerl Drafting paperl Drafting pencilsl Drafting tapel Drawing board
Terminology
l Dusting brushl Eraser shieldl Extension linel Fastenersl Finishl Full-size drawingl Hardwarel Hidden object line
l Isometric drawingl Mechanical drawing l Object linel Pencil block eraserl Pencil lead pointerl Protractorl Scale drawingl Sketch
Terminology
l T-squarel Templatesl Triangles
Reading or interpreting plans and blueprints
l Ideas come alive when it is transferred to the paper.
l Sketches and drawings are the written language that will tell you what must be built and the materials needed for the job.
Reading or interpreting plans and blueprints
l Lines, symbols, and dimensions convey the project to the mind of the builder.
l It is important to be able to read and draw sketches and scale drawings.
Sketches
l Sketch: Original idea put on paper in a rough form which is not drawn to scale.
Full-size drawing
l Full-size drawing: Drawing the exact size of the project to be built.
Scale drawing
l Scale drawing: Drawn proportionally to the size of the actual project with a label that indicates its size in comparison to the project.
–The scale might be ¼ inch to one foot.
Views
l Types of Views:
–One, two, or three views.
–If three views are used, they are generally the top, front, and right side.
–Isometric Drawings
Views
l When three views are used, they are generally the top, front, and right side.
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Isometric Drawing
l Isometric drawing: Three-dimensional drawing.
l Difficult to draw, especially to scale. l When isometric drawings are made the
corner lines are vertical and the front and side lines are drawn at an angle of 30 degrees to the horizontal.
Isometric Drawing
Picture Courtesy, Interstate Publishers, Inc.
Lines
l Several types of lines are used in drawings.
l Using the wrong type of line is like using an incorrect word.
l Types of Lines:
–Border line, Object line, Hidden object line, Dimension line, Extension line, Center lines
Border Lines
l Darker than any lines in the drawing and is used around the outside of the drawing like a frame for a picture.
Object Lines
l Darkest line of the drawing and stands out to show the exact shape of the object.
Hidden Object Lines
l Medium in darkness, and represents edge lines that can’t be seen.
Dimension Lines
l Marks the dimensions of an object such as length, width, thickness, and diameter of holes.
l Is a fine line with an arrowhead placed at each end and the number representing the dimension placed in the center of or on the dimension line.
Extension Lines
l Fine line placed at the end of the dimension line referring the reader to the part of the object being dimensioned.
Center Lines
l Light, broken lines of alternating short and long dashes.
Picture Courtesy, Interstate Publishers, Inc.
Picture Courtesy, Interstate Publishers, Inc.
Plans
l Typically prepared with an original and copies.
l Copies may be collectively known as plans.
l Types of Plans:
–Blueprint
–Computer aided drafting (CAD)
Blueprints
l Blueprint Copy of an original plan that is produced with a process that produces white lines and other images on a blue background.
l Being replaced with plans made by copying machines.
Blueprints
l These machines show lines and details in black or blue on white paper.
l Typical paper size is 18 × 24 inches but other sizes can be used, depending on the size of the drawing.
CAD
l Computer aided drafting generates drawings on a computer which are then printed with a laser printer or a machine known as a plotter.
l Some people refer to all large, detailed plans as blueprints regardless of how they have been prepared.
Reading Plans
lReading project plans are like following a road map. lYou know you can’t visualize everything you will see along the way, but if you follow the lines and symbols properly, you will arrive at your destination. lLearn to follow the plans step-by-step, and you will complete the project.
Common Plan Symbols
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Common Plan Symbols
Picture Courtesy, Interstate Publishers, Inc.
Anticipated Problem
What tools and procedures are used to draw project
plans?
Planning Tools and Procedures
l Mechanical drawing: Detailed drawing that is carefully and accurately drawn to scale using various drawing instruments.
l Such drawings are the means of communication between those who prepare plans and the people who are builders.
Planning Tools and Procedures
l Before attempting to draw a detailed plan, you must select suitable instruments and materials.
Common Tools
l Drawing Boardl T-Squarel Drafting Boardl Rulerl Architectural Scalesl Trianglesl Protractorl Drafting Pencil
l Pencil Lead Pointerl Compassl Dividerl Templatesl Pencil Block Eraserl Eraser Shieldl Dusting Brushl Cleaning Pad
Drawing Board
l A drawing board is a 20 × 24 inch piece of knot-free softwood.
l The drawing board should have square corners and straight edges so that the T-square can be used to square from the board.
T-Square
l A T-square is used to position the paper square on the board and as a straight edge to draw horizontal lines.
l When the head or short part of the square is held firmly against the board, the blade will extend squarely across the board.
Picture Courtesy, Interstate Publishers, Inc.
Drafting Paper
l Paper which drawings are done l Comes in white, cream, and light
green l Sizes ranging from 8½ × 11 to 17 ×
22.
Drafting Tape
l Used to fasten the paper to the drafting board.
l Not as likely to damage the paper when removed as scotch tape or masking tape.
Picture Courtesy, Interstate Publishers, Inc.
Measuring Devices
l Ruler marked in 16ths of an inch may be used for most drawings.
l Some drawings might be done in metric (millimeters, centimeters, meters) rather than the standard English measurements (inches, feet, yards).
Measuring Devices
l Architectural scale: Three-sided ruler with six different measuring scales often used by professionals.
Triangles
l Held tightly against the T-square to form a straightedge to mark vertical lines.
l Common Triangles:
–45–45–90 degree triangle
–30–60–90 degree triangle
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Protractor
l Used to measure angles from 0 to 180 degrees.
Picture Courtesy, Interstate Publishers, Inc.
Drafting Pencils
l Made in 18 different grades of hardness
l Have the grade stamped near the end of the pencil.
Picture Courtesy, Interstate Publishers, Inc.
Drafting Pencils
l Pencil has no eraser it could be sharpened from either end, but it should be sharpened from the unmarked end so the hardness grade is not removed.
l 2H pencils are recommended for beginning draftsmen.
Picture Courtesy, Interstate Publishers, Inc.
Pencil Lead Pointer
l Only a sharp pencil can produce accurate, clean-cut, dark lines.
l A dull pencil produces fuzzy, indefinite, sloppy lines.
l After sharpening, rotate the pencil on a piece of sandpaper, rough paper, or a fine file to finish the point.
Pencil Lead Pointer
l Professionals use a device called a pencil lead pointer that contains graphite.
l The pencil is rotated to finish the point and then the graphite particles are removed by sticking the pencil point in a piece of styrofoam.
Compass
l Compass: Adjustable device with a point on one side and a pencil on the other side and is used to draw circles.
Picture Courtesy, Interstate Publishers, Inc.
Divider
l Divider: Has a point on both legs and is used to transfer a measured distance to another location.
–It may be faster and more accurate than using a ruler.
Picture Courtesy, Interstate Publishers, Inc.
Templates
l Metal or plastic objects with a variety of circles or irregular curves that may be used to help draw circles and curves.
Removing Construction Lines
l Pink or red pencil block eraser: Used to remove construction lines and other un-wanted lines.
l Eraser shield: Piece of metal or plastic used to protect areas while unwanted lines are erased.
Picture Courtesy, Interstate Publishers, Inc.
Removing Construction Lines
l Dusting Brush: Small brush used to remove eraser fragments from the drawing.
Picture Courtesy, Interstate Publishers, Inc.
Removing Construction Lines
l Cleaning pad: Pad containing special cleaning powder
l When the drawing is completely finished use to help remove any remaining loose graphite particles from the drawing.
Picture Courtesy, Interstate Publishers, Inc.
Block Lettering
l A finished drawing should have the name of the project, your name, and scale used in legible, neat, well balanced, and attractive lettering.
l Block lettering is probably the most popular type of lettering.
Anticipated Problem
How are a cutting list and a bill of materials developed?
Drawing Dimensions
l Used to take the next step in the planning process.
l Order must be prepared for the lumber yard and instructions must be prepared for the builder.
Cutting Lists
l List of all pieces giving exact dimensions of each board needed to complete the project.
l Used by the builder to cut purchased lumber into the sizes needed to assemble the project.
Bill of Materials
l Listing of the kinds and amount of lumber, fasteners, hardware, and finish necessary for completing the project.
l Is in sizes and quantities that the lumberyard worker can use to fill your order.
Bill of Materials
l The plans should include the lumber dimensions, grade, and species of wood.
l Example: One 12 foot 2 ×4, construction grade, white pine.
Fasteners
l The fasteners section, sometimes referred to as rough hardware, needs to have the number, size, and kind of fastener (nails, screws, bolts, and glue).
l Example: 12 flat head standard slot 1½ inch eight gauge steel wood screws.
Picture Courtesy, Interstate Publishers, Inc.
Hardware
l Hinges, catches, knobs, handles, and locks are all classified as hardware or finish hardware.
l An example of hardware would be one pair of 2 inch brass tee hinges.
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Finish
l Finish is used to protect and beautify a project.
l It includes paints, stains, wood preservatives, and clear sealers.
Labor
l Optional as a fifth section of the bill of materials.
l Custom built projects are bid based on the cost of materials and the estimated hours needed to complete the project.
Labor
l Even if the project is to be built for yourself, estimating the hours helps to determine whether it makes sense to continue the plan to build the project.
Construction Procedure
l List of steps for making each part, assembling the project, and finishing it.
l Should be detailed enough for
someone else to construct the project.
Construction Procedure
l Developing the construction procedure teaches students to analyze tasks, solve problems, and organize solutions.
l Whether your project is large or small, you should develop a written step-by-step construction procedure.
Review
l How are project plans and blueprints read?
l How are project plans drawn?l How are a cutting list and a bill of
materials developed?