Create Proportional Views of Orthographic Figures Illinois CTE Curriculum Revitalization Initiative - Drafting and Design

Demonstrate techniques for applying proportion to orthographic figures. Employ the use of scale in technical drawings. Learning Objectives Illinois CTE Curriculum Revitalization Initiative - Drafting and Design

Terms to Know Blocking-in method Relative Estimated Scale Grid method Unitary Measured Terms to Know Illinois CTE Curriculum Revitalization Initiative - Drafting and Design

Proportion is an extremely important concept that must be mastered. Draw an object found in this classroom. How close is the proportion to being accurate? Use a scale to “size up the sketch.” Proportion is an extremely important concept that must be mastered. Proportion Illinois CTE Curriculum Revitalization Initiative - Drafting and Design

Objective 1 Demonstrate techniques for applying proportion to orthographic figures. Illinois CTE Curriculum Revitalization Initiative - Drafting and Design

An example to work from… You are working for a custom cabinet shop and a customer brings in a picture of a treasured family heirloom that was damaged in a fire. You have no object to measure or to take dimensions from, but the customer really wants this piece of furniture recreated. What do you do? An example to work from… Illinois CTE Curriculum Revitalization Initiative - Drafting and Design

Many skills/techniques are used in creating proportionate drawings. See the following examples of how to 1) estimate proportion in drawings and 2) create drawings using proportion to enhance accuracy Applying Proportion Illinois CTE Curriculum Revitalization Initiative - Drafting and Design

Applying Proportion Estimating Proportions Relative proportions Use an object like a pencil to identify and define proportional size and shape. It does not provide necessary dimensions; it provides a reference for what an object would look like with respect to length, height and width. It is best for objects that have simple geometry and may be quickly transferred to paper. Applying Proportion Illinois CTE Curriculum Revitalization Initiative - Drafting and Design

Applying Proportion Illinois CTE Curriculum Revitalization Initiative - Drafting and Design

Applying Proportion Unitary Proportions Similar to relative proportions Establish smaller arbitrary unit to base measurements on rather than addressing overall relationship of dimensions Similar to distance markings on outer edges of maps Provide reference point for finding or adding details Applying Proportion Illinois CTE Curriculum Revitalization Initiative - Drafting and Design

First identify a base unit (arbitrary) and then apply it as many times as necessary to illustrate the size and features of an object. One may not be able to identify actual dimensions but will be able to establish proportion between features and the object’s size. It is used where symmetry and uniform sizes and shapes are common. Applying Proportion Illinois CTE Curriculum Revitalization Initiative - Drafting and Design

Applying Proportion Illinois CTE Curriculum Revitalization Initiative - Drafting and Design

Applying Proportion Estimated proportions This is less precise than unitary and relative methods. It is created by maintaining an even distance from an object while holding a pencil at arm’s length. Adjust length of exposed pencil until it matches object’s dimensions. Transfer dimensions to paper; work in details as you go. Proportions are not accurate but convey what object looks like. Applying Proportion Illinois CTE Curriculum Revitalization Initiative - Drafting and Design

Applying Proportion Illinois CTE Curriculum Revitalization Initiative - Drafting and Design

Applying Proportion Working in Proportions Grid Method Create complex drawings Place a series of squares in a grid pattern over object Break complex or curved object into smaller units (reduce challenging problems to series of smaller details) Effective for scaling an object from smaller to larger or vice versa Does not give accurate dimensions, but are kept uniform Applying Proportion Illinois CTE Curriculum Revitalization Initiative - Drafting and Design

Applying Proportion Illinois CTE Curriculum Revitalization Initiative - Drafting and Design

Applying Proportion Blocking-in Method Starts with the least amount of detail and works in those that remain Used in relative and unitary methods of sketching Essential to work efficiently Start with major features, add details as you progress Applying Proportion Illinois CTE Curriculum Revitalization Initiative - Drafting and Design

Applying Proportion Illinois CTE Curriculum Revitalization Initiative - Drafting and Design

Applying Proportion Measured Proportions Possible when a physical part is present to base drawings on Appropriate measuring tools required Combine with blocking-in method to create accurate drawings Applying Proportion Illinois CTE Curriculum Revitalization Initiative - Drafting and Design

Applying Proportion Illinois CTE Curriculum Revitalization Initiative - Drafting and Design

Objective 2 Employ the use of scale in technical drawings. Illinois CTE Curriculum Revitalization Initiative - Drafting and Design

Another example to work from… Many times a draftsperson is asked to work on a project that is too small to clearly convey the details or too large to economically draw on paper. How do they maintain accuracy without wasting a lot of paper and time? Another example to work from… Illinois CTE Curriculum Revitalization Initiative - Drafting and Design

Scale Drawing objects at a specific ratio (larger or smaller than the real object) to provide details in an efficient, cost-effective manner Shows ratio between true size and shape as compared to what is drawn/printed Scale Illinois CTE Curriculum Revitalization Initiative - Drafting and Design

Difficult to print small objects out and rationalize design points E.g., circuit boards, small machine parts, nanotechnology Fine details cannot be printed effectively; adjusting scale on paper might make details recognizable. Large objects are ineffective to print at 1:1 scale. E.g., a blueprint for a house that is 50’ long by 20’ tall Scale Illinois CTE Curriculum Revitalization Initiative - Drafting and Design

Scale Can show large objects on a much smaller scale Details can illustrate essential features. Drawing/printing to scale is critical. Those creating objects need to reference the drawing for details that may not have been dimensioned. Scale Illinois CTE Curriculum Revitalization Initiative - Drafting and Design

Scale Illinois CTE Curriculum Revitalization Initiative - Drafting and Design

Common scales: 2:1 1:1 1:2 Drawing with ratio of 2:1 means object on paper is 2 times larger than its real size. Architectural scales range from 1” = 1’ to 1/32” – 1’, etc. Drawing at ¼” = 1’ means object will be 1/48 as large as in reality. Scale Illinois CTE Curriculum Revitalization Initiative - Drafting and Design