WORKING DRAWINGS AND SETTING OUT
The book rack set out in isometric projection (336) is turned into an orthographic drawing. A system is used that employs the undermentioned basic principles.
1 Most furniture is symmetrical about an axis, normally the centre line. Therefore often one half only will provide sufficient information.
2 Where a piece has a feature repeated more than once, to draw in full detail once is sufficient.
3 The craftsman's prime interest is how the component parts are joined together. Provided the length of the component is clearly indicated, it is the joints and the intersections between pieces that really matter.
4 A drawing such as figure 337 is intended for workshop use only, and can be written on, sketched on, and used as a visual diary of ideas.
5 Where the drawing is made in the workshop by the craftsman for his own use (337), labelling and lettering can be kept to a minimum.
On the example shown (337), the draughtsman should proceed as follows:
1 Draw a full size front elevation in outline, symmetrical about a centre line.
2 Using the heights already indicated, draw the end elevation in the position shown.
It is now possible to measure from the drawing the following information:
1 Overall length(s) 6 Width of back rail
2 Overall height 7 Thickness of bottom
3 Height of end 8 Thickness of ends
4 Width of end 9 The length, width
5 Position of back rail and thickness of foot. By turning the end elevation into a section the
thickness of the back rail can be indicated.
If the right-hand end of the drawing is left as it is, it will show the front elevation as it will be seen.
If the left hand of the elevation is referred to as the view from the back it can be shown how the back rail is joined to the ends.
Information is needed on the joint between the ends and the bottom. By superimposing part of an inverted plan on the end, the setting out of the joint involved can be shown.
The positions of the slot screws retaining the feet are also shown.
The three colour convention
These drawings, using views and sections that are superimposed, gain enormously in clarity and ease of reading if the front elevation(s) and sections are left black, side elevations and sections are drawn in blue, and anything that is plan or part plan is drawn in red.
True coloured pencils and not crayons (even if they are encased in wood) should be used and kept sharp.
When the drawing is on paper or plywood the use of this system is well worthwhile. Colours do not come out on dyeline machines (on some machines the blue or the red does not come out at all).
Figure 338 is the same drawing figure as 337, but is finished for another craftsman to make. Its dimensions are given and it is labelled to make it clearer to read. It is also dimensioned in millimetres which has the advantage of avoiding the use of fractions of an inch. Once the common sizes are memorized and immediately related to a specific length, width or thickness, it becomes a most convenient system to use.
ELEVATION OF BACK SECTIONAL END ELEVATION
ELEVATION OF FRONT
338 Drawn to give instructions to craftsman