Two Proposal Drawings

To clearly express the design of the conference table, a detail is drawn full-size. It would be lost if kept at the drawing's scale.

The use of varying line weights, with some lines thicker or darker than others, helps to more realistically portray the table.

Starting with a drawing like the one below, you can break out the angles to arrive at projections like the ones shown in the stack of drawings.

A drawing is a representation by lines or delineation of form without reference to color.

Above is an imagined object that displays examples of various line types. It’s normal to put the section as part of the elevation: it saves space, and the lines are already in place

The horizontal cut allows us to see the grapefruit in a plan view.

A vertical cut shows a section in elevation.

A vertical cut shows a section in elevation.

Exploded view drawings are another way of showing various parts and their relationships.

The focus of this lesson is on the sort of drawings an architect would make of a building, a machinist of a metal part or a woodworker of a piece of furniture. It's a drawing that appears at first to be straight lines and rectangular shapes set down in an orderly fashion.That regularized appearance has a history of development and can be described as a collection of lines, symbols and words put together by a draftsman that conveys the design intent clearly enough for a workman to construct the object. There are generally three drawing types associated with furniture: proposal, working and shop. A proposal drawing, sometimes called a client drawing, consists of scaled elevations sufficient to explain the designer's intentions to the client.

A working drawing has complete views and sections sufficient for the piece to be made in any way chosen by the maker, guided by the drawing details. From the working drawing, the maker can calculate the quantities and dimensions of the materials needed and create a cutting list.

A shop drawing has details that direct the maker to make the piece exactly as the drawing specifies.

Orthographic Projection

The proposal drawings at right were drawn using T-square and triangle. The next step is to make working drawings in a more formal style based on straight lines and right angles and a more standardized set of rules. The drawing system is called Orthographic Projection, which specifies where each part of the drawing is placed.

Most things we draw as furniture are box-like or will fit in a box. For that reason, we use the word "box" as the object, whether it be chair, table, etc. The first thing to note is that a box has six sides and we can only see three of them at any one time. We call these visible faces front, side and top. The best way to draw the box to record its shape and dimension is to draw each of the faces. To avoid confusion, the faces must be placed in a consistent relationship to each other. It seems simple enough until you realize that there is more than one way to position the views in relation to one another.

To understand these possibilities, imagine that you have the apparatus drawn here. The back is a fixed plane to which the vertical and horizontal planes are hinged so you can fold them flat as if they were a sheet of drawing paper.

Place the same box in each quadrant and project the three images onto the planes. When you fold the vertical and horizontal planes flat, you will see how the images relate to one another in each layout.

The diagrams below the apparatus at right show four possible layouts. Each one comes from placing the box in a different quadrant, which are named First Angle, Second Angle, Third Angle and Fourth Angle.

The image of the box is projected onto three surfaces. The two on the walls (vertical planes) are called front elevation and end or side elevation. The image on the floor or ceiling (horizontal plane) is called the plan.

The images on all three planes are what would be seen if you, the viewer, were standing outside the apparatus. Don't be confused by thinking that the projected image is the one facing the plane: it's the opposite side!

On a simple drawing it may seem obvious which image is which elevation or plan. Nonetheless, each must be named. The name is normally placed below, with the first letter aligned with the first line of the drawing.

Of the four layouts available in the system, the First Angle and Third Angle are the two commonly used, the difference being the location of the plan above or below the elevations. Here in the U.S., the Third Angle prevails.

Drawing Features: Lines

As stated before, a drawing is a representation by lines or delineation of form without reference to color. There are other components in a drawing - words and numbers - but here we'll start looking at lines.

Lines: We use three line weights: bold, regular and light.

Bold lines — used for outlines and baselines. They make the piece of work stand out.

Regular lines — the workhorse of the drawing: they delineate the parts and the details. 

Light lines — play a variety of support and informational roles. Normally they don't represent parts that you could touch on the real thing, and for this reason we want them to be in the background. Typically, dimension, break and hatch lines are all light lines.

Dimension lines — The measurement may be placed on, over or under the continuous dimension line so it's easy to read.

Witness lines — an extension of the dimension they record and are drawn to the liking of the draftsman. The preferred terminal is a 45° slash drawn freehand.

Break lines — indicate that the part continues beyond a particular point but that the continuation is not pertinent; also used to compress a long element — the dimension gives the true length.

Hatch lines — indicate the cut surface of a section. Drawn at 45°.

Broken lines — (sometimes incorrectly called dotted lines) show concealed parts.

Center lines — used when you want to increase the scale of a symmetrical drawing by drawing only half of the object; marked with the initials CL.

Section Views

As well as drawing what is visible as elevations and plans, we can also draw what would only be visible if the object were cut through. Such drawings are called sections.
The illustration below 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 the elevation that shows the location of the section to 1/8 scale, but drawing the section full-size, reveals a wealth of joint detail.

Sectional Views

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 to 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 on the paper size you're using. Leave room for any other necessary detail drawings along with word specifications and a title block. Creating a balanced layout that makes the best use of the drawing area isn't as simple as it may appear. Most people find it helpful to block in the areas with light, easily erased, lines to get a comfortable composition before committing to the real thing.

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, we avoid writing or drawing in the form or space areas as much as possible.

Exploded Perspective Drawing

Another useful method used is exploded perspective drawings. Their pictorial nature is easy to read and suits their purpose well, especially as the drawings are supported by photographs. However, unless you have the interest and the equipment to computerize your drawings this way, the orthographic system is easier to learn and will provide all the information you or another maker will need.

The other limitation of exploded perspective drawings is they are most suited to small or moderately complex subjects. The drawing of the table at right works quite well in an exploded perspective drawing. Now imagine an architect trying to draw a house in the same manner. It would quickly become impractical.