CHAPTER 6, LESSON 3 of 3
GOAL: To further understand the elements of a good formal drawing, including the section view and scale.
Previous lessons have covered the three types of formal drawing one might encounter in woodworking, as well as the Orthographic Projection system of drawing for representing the design of a project. This lesson will focus on working drawings, including the section view and matters relating to scale.
| Understanding Sectional Views
|
|
 |
 |
| Front elevation
|
Full-size section on A |
Sectional end elevation on B |
|
|
| The horizontal cut on the grapefruit allows us to see a section in plan.
|
| |
 |
| The vertical cut allows us to see a section in elevation. |
| |
 |
| In this example of alcove drawers, the alcove is 89 1⁄2" tall. The scale of 3/16" to 1" allowed the maker to show the proportion of the drawer height to the whole alcove. |
 |
The Orthographic Projection system of drawing presents three views of a project: a front elevation, a side elevation and a plan view from the top.
As well as drawing what is visible as elevations and plans, we can also draw what would be visible only if the object were cut through. Such drawings are called sections.
Sections
The illustration to the right shows how section lines are drawn and identified. One end of the section arm has an arrow, identified by a letter, that shows which direction you are looking at in section. The arms indicate the “cut line” of the section, but neither arm touches the drawing. A section drawing can be positioned in any convenient place on the sheet.
Sections are particularly good at revealing what’s inside a joint. Drawing an elevation that shows the location of the section to 1/8 scale but drawing the section full-size reveals a wealth of joint detail.
There is one more step we can take with sections, and that is to draw the part that is cut and the parts that lie beyond it. In this way, the section is placed in context and is referred to as a sectional elevation or a sectional plan, depending on what part you have drawn.
There is never any doubt about which are the sections because they are identified by hatch lines drawn at 45°.
Scale
Scale is an important aspect of layout. A dining room table 72" long is clearly too large be drawn full scale. It must be reduced using a scale rule to fit a typical paper size. However, choose a scale that makes the object views as large as possible while still leaving room for any other necessary detail drawings, along with word specifications and a title block.
An orthographic drawing gives the best look at proportion — the proportions of the parts as well as the proportions of the spaces. For this reason, avoid writing or drawing in the form or space areas as much as possible.
|