Technical DrawingAKA: Mechanical Drawing or Drafting 

OBJ #32– Define sketching.

• When you first get an idea for something you want to create, you may draw it roughly…without using instruments or accurate scales. This is called a conceptual sketch.

• conceptual sketch - A rough drawing, usually freehand, where instruments and tools are not used.

OBJ #33– Define lettering.

•Lettering – a process of forming standardized letters in technical drawings.

OBJ #34– Explain why lettering is important.

•Legible!•Uniform, standardized, consistent. •Unclear writings result in:

•Miscommunication•Wasted time•Costly errors

• Most common font used in drafting is GOTHIC. 

• Lettering is drawn freehand and are drawn within light horizontal guidelines.

• All lettering uses upper case letters.  Lower case letters are almost never used in technical drawings.

• There are three aspects of good lettering:  proportions and forms of the letters, composition and spacing, and practice.

• http://www.youtube.com/watch?v=Ky5p‐L_m6BQ&list=TLYG3KqUAAbEnu5A8qkgYHKwqa82OpX3DO

• https://www.youtube.com/watch?v=byQy0w5vr‐A

OBJ #35– Define technical drawing.

Technical Drawing - Creating plans that visually communicate how something is constructed.

• Presents all the information needed for the object’s construction.• Is done to scale (proportion)

Where is it used?

• Just about everywhere!

People who also use it:

‐ Architects

‐ Engineers

‐ Drafters

‐ Fashion designers

‐ Business owners

‐ Inventors

‐ Illustrators

‐ Landscape designers 

‐ Interior designers

‐ Product designers

‐ Software designers

‐ Graphic designers

‐ Industrial designers 

‐ Construction workers

‐ Plumbers

‐ Electricians

‐ Contractors

‐ Machinists 

‐ Anyone who builds or creates things!

OBJ #36 – Know the tools required for technical drawing.

• T-square – creates 90o horizontal & vertical lines.

• 45-90 Triangle – has two 45o angles and a 90o angle.

• 30-60-90 Triangle – has a 30o, 60o, & 90o angle.

OBJ #37 – Define orthographic projection.

Orthographic projection ‐Representing a 3D object in 2D using multiple views.

Viewing Objects

Unfolding the box produces an arrangement of the six views

OBJ #38 – Identify each view of a technical drawing.

•Front ‐ shows the most detail, contour, and/or features. 

•Top – the top of the object

•Side – the right side of the object

OBJ # 39 – Define the three major line types.

•Object Line ‐ defines the object.

Object Line

Hidden Line – shows interior detail that may not be visible from view.

Hidden Line

Center Line ‐definesthe center of holes. 

Center Line

OBJ # 40 – Define dimensions.

•Dimensions – used to show size and location. 

Dimension Line

Dimension Line

OBJ # 41 – Properly draw dimensions.

• Include extension lines!• Arrows on ends.• Measurement in middle.

Dimension Line

Dimension Line

Extension Line

Small Space

OBJ #42– Compare sketching to technical drawing.

• Ideas to be expressed quickly – rapidly drawn.

• Is prepared free-hand.• Is not done to scale.

• Serve as an official standardized reference to engineers.

• Uses drawing tools.• Accurately communicates

ALL information. • Absolutely clear, very little room for interpretation.

Sketch VS Drawing