The Core Concepts of Technology

ETP 2006—Tanya MattsonThis material is based upon work supported by the National Science Foundation under Grant No. 0402616. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the view of the National Science Foundation (NSF).

Systems A group of interrelated

components designed collectively to achieve a desired goal.

Parts of a system: Input Process Output Feedback

Systems found in Technology

1. Mechanical2. Fluid3. Electrical4. Thermal5. Chemical

Systems often work together to make the technology work.

Systems are made up of related subsystems.

Technological systems often interact with each other.

Open-Looped System

Has no feedback and requires human

intervention

Closed-Loop System

Uses feedback

Resources Things needed to get the job done. Basic technological resources:

Tools and machines Materials Information Energy Capital Time People

Most systems and products have requirements placed

on them. These are the parameters often referred

to as CRITERIA and CONSTRAINTS

Designing is the process of applying creative

skills in the development of an

invention or innovation.

There is no perfect design

All designs can be improved

Ingredients of a successful technology design

1. Safe use of tools and machines2. Consider alternate solutions3. Test and evaluate solution4. Design a solution to the problem5. Integrate information from other

academic studies6. Build a solution to the problem

7. Receive formative and summative feedback from the teacher

8. Make sketches and drawings of potential solutions

9. Utilize a design or problem solving model

10. Assess the impacts and consequences of technology

Controls

The mechanisms or activities that use

information to cause a system to change.

Drafting Conventions

Line Weight Dimensioning

Line Weight

One can communicate more clearly by using varying line weights for different purposes.

Types of Lines

Border Line Object Line Hidden Line Dimension Line Extension Line Centerline

Dimensioning A few guidelines:

All lettering should be positioned so as to be read from the bottom of the drawing.

Most dimensions and notes should be presented next to the front view, and not be repeated on top or side views.

Information should be placed between the views, not on the object itself or outside of the views.

Place largest or longest dimensions farthest from the object.

If part is to be machined by a computer (CNC), all dimensions should reference x = 0 and y = 0 (lower left corner of the drawing).

Curved surfaces are described by radius. Circles or holes are described by

diameter.

Extension lines should not touch the object, but extend beyond the dimension line. Centerlines do touch and extend beyond the object.

Hand drawn dimension lines have arrowheads that are about 3 times as long as wide.

Hidden lines, represented by evenly spaced dots and dashes, do touch each other if they intersect, and also touch a visible line if they intersect.

Hidden lines and centerlines do not touch if they intersect.

Construction lines are drawn very thin and light, with the intention of being erased after serving as an alignment aid.

Guidelines are thin and light, drawn as an aid in creating uniform hand lettering.

If using a CAD system, one should choose a simple font that is highly legible with no frills—Helvetica Narrow or Arial are good choices.

Orthographic Projection

By tradition, the front, top, and side views are shown.

These 3 views are connected by imaginary lines so that one can see a correspondence between the views. Some features are hidden or fore-

shortened

View Selection

How do you choose the front view? The front of a complex object can often

be answered by choosing the side that reveals the most information.

If necessary, a special view is created. These are called an AUXILIARY VIEWS.

Oblique Projection This method is sometimes used in

both sketching and drawing. This is the simplest method of

pictorial representation. Typically, you begin with a full,

straight on front view, and depth is represented as fore-shortened, and at a 45 degree angle.

Isometric

There is no front view, as all views are foreshortened.

The viewer looks at a corner of the object, and only the height is shown to scale.

Perspective The most accurate method of

projection. The object gets smaller the farther

away it is. The artist/draftsperson chooses 1,

2, or 3 “vanishing points” off in the distance on the horizon. 1 point = easiest

Sketching

Sketching is probably the only approach to design expression that will permit one to focus on the design problem Either by hand or electronically

Good design practice demands that a number of options be considered.

Sketching

Only a grid sheet and pencil are allowed.

This is how great ideas first take shape.

Isometric Sketching

Most difficult to draw Three (3) basic types of elements

that one needs to be familiar with: Rectangular Cylindrical Sloped or angled surfaces

CAD/CADD

Could mean: Computer Assisted Drafting Computer Assisted Design Computer Assisted Design and

Drafting

How to Communicate the Design Proposal

1. Each member of the team makes their own sketch of the solution to the problem.

2. Team (group) discussion of the strengths and weaknesses of each solution.

3. The team might choose to develop a proposal that incorporates a number of features from each design.

4. A new sketch is made as a result of the group decision.

5. A prototype is built.6. The design would most likely be

modified AT LEAST once more before presenting it.

The design process also includes being able to effectively

present your solution.

In our everyday experience, designs are communicated

or “sold.”

How are they “sold?”

Presentation of the product Power Point A display Prototype of the product More realistic drawings that provide

much more information than the 1st crude sketches.

Etc.

Standards and Benchmarks 8: Students will develop an

understanding of the attributes of design. 8.E: Design is a creative planning

process that leads to useful products and systems.

9: Students will develop an understanding of engineering design. 9.F: Design involves a set of steps,

which can be performed in different sequences and repeated as needed.

Explain the 6 types of lines used in dimensioning and draw an example of each:

Border Line Object Line Hidden Line Dimension Line Extension Line Centerline

Explain what an Isometric drawing is. Explain what an Oblique drawing is. Explain what an Orthographic Projection is. Explain what Perspective Projection is. What are the 2 drafting conventions? What is Computer Assisted Design? List 3 ways you can “sell” a design proposal.

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