This section is from the book "Modern Buildings, Their Planning, Construction And Equipment Vol1", by G. A. T. Middleton. Also available from Amazon: Modern Buildings.
For the proper production of architects' drawings it is essential to be provided with well-selected instruments and materials, in perfect adjustment, and properly arranged. An expert draughtsman will, certainly, produce good work under all sorts of unsatisfactory conditions, but for the inexpert to so handicap himself is to put himself to great disadvantage and to retard his progress.
As most men stand when drawing, the Drawing Table should be between 32 and 40 inches higher, and broad enough from back to front to take the largest drawing board which is likely to be used. In many offices the "tables" consist of nothing more than a pair of trestles with a large board resting on them (see Fig. 1). This arrangement covers a good deal of floor space which cannot be otherwise utilised, but the whole thing can be readily removed and folded up against a wall if necessary.
Fig. 1. Drawing Table on trestles.
Another form of table, much used, is one of which the under portion is formed into a nest of shallow drawers for the reception of drawings and paper. The top should, however, project considerably in front of the drawers, to give knee space, especially when sitting on a high stool (see Fig. 2), but drawers of some sort are essential, and it is an economy of space to put them here. They rarely need to be more than 2 1/2 inches deep, except that which is to contain the unused paper, but ought to be encased on all sides, with cupboard doors to the front, so as to exclude dust; and each should be labelled with the name of the building the drawings relating to which are contained in it. The drawers should be of such sizes as will contain comfortably the drawing papers most generally used in the office.
There are several patent drawing tables made with sloped or adjustable tops, but the plain flat table is as good as any, as pencils, etc. will not roll off it as they will off a sloped surface, while the drawing board can be sloped at any desired angle by inserting small supports under it - such as 4-inch cubes of wood or specially made fir wedges (see Fig. 3).
Fig. 2. Chest of drawers & drawing Table combined.
Fig. 3. Slope block for drawing table.
It is a very common practice to place the drawing table directly in front of a window, but this is exceedingly bad for the eyesight, especially if sunlight be admitted - though generally a window is chosen which faces north, or nearly so, if there be the opportunity of selection. In any case the light, impinging on the white drawing paper, is reflected to the draughtman's eyes, causing in time a species of blindness. It is better, therefore, to place the table sideways to the window, with the light a little forward, and preferably upon the left-hand side, so as to cast no shadow either from the body or the hand upon the work. Any artificial light should be similarly placed for similar reasons - or green glasses would in course of time have to be worn.
Drawing Boards are almost always made of Canadian pine, a soft wood which warps little and shrinks evenly. Common ones are merely clamped at the edges, but those in most general use are made as shown in Fig. 4. The angles are rounded so as to avoid splitting, while the effects of warping and shrinkage are minimised by broad and deep saw-cuts from end to end along the back, alternating with short saw-cuts through the edges at the ends - where a strip of ebony is inserted - while the backs are clamped with mahogany battens attached with brass screws working in brass slots.
Fig. 4. Drawing Board.
The principal requirements are perfectly straight edges and freedom from warping. It is sometimes useful to be able to work from two edges which are known to be at right angles with one another, but this is not essential. Surface warping is easily detected and remedied with the plane; but a twisted edge is less discernible. It should be tested for occasionally, as any inaccuracy may affect a drawing to a considerable extent.
A good T-square should have a bevelled edge and a tapering blade, balancing well when in use. This can only be tested by experiment, but a long straight blade is almost sure to drag. Many are made of pear-wood, which is light but easily damaged, so that the best are of mahogany with a working edge of ebony (see Fig. 5). The edge of the blade should be exactly at right angles with the cross-piece, to the face of which it should be screwed, so that in work the cross-piece does not rise above the surface of the drawing board. Experience will show that comparatively few T-squares retain the exact right angle between cross-piece and blade for any length of time; and this is of little account so long as the same T-square is employed on the same drawing, all lines drawn by its aid being parallel if the edge of the drawing board is true. If, however, another T-square be applied to the same drawing without altering its position on the board, and either or both these T-squares be inaccurately set, the lines drawn with the aid of the one will not be parallel to those drawn with the aid of the other. Consequently, so long as the drawing remains pinned in one position on a board, all the work done upon it should be by the aid of the same T-square; or, if T-squares are changed, the paper should be re-set to correspond.
Fig. 5. T Square.