HORIZONTAL LINES

The draftsman’s horizontal line is constructed by drawing from left to right along the workingedge of a T square, as shown in figure (view A). This working edge, when true, is perpendicular to the working edge of the drafting board. When you draw horizontal lines, keep the working edge of the T square head in firm contact with the working edge of the drafting board. The pencil should be inclined to the right at an angle of about 60 degrees, with the point close to the junction of the working edge and the paper. Hold the pencil lightly and, if it was sharpened with a conical point, rotate it slowly while drawing the line to achieve a uniform line width and preserve the shape of the point. Normally, when a series of horizontal lines is being drawn, the sequence of drawing is from the top down.

ATTACHMENT OF PAPER TO THE BOARD

Now that you have become relatively familiar with your equipment and materials, it is time to get started by attaching your drafting paper to the board. The sheet should be placed close to the left edge of the drafting board. Working in this area makes the T square easier to handle and reduces the likelihood of error because of T square “swing.” The drafting sheet should be far enough from the bottom of the board (about 3 in.) to ensure firm support for the head of the T square when you are drawing at the lower part of the sheet. A drawing sheet properly attached to the board on which a T square is used. After aligning the drawing sheet, smooth out any wrinkles and fasten the four corners with short strips of drafting tape. If you are attaching large sheets, you should place additional strips of tape at the top and bottom edges of the sheet. Drafting tape has a lighter coating of adhesive than does masking tape. Consequently, it will hold the drawing firmly, yet can be removed without tearing or marring the drawing. If you use masking tape or transparent tape, leave a large margin in the event you tear the paper when removing the tape. When placed diagonally across the corners of the sheet, the drafting tape offers little obstruction to movement of the T square and triangles. Avoid the use of thumbtacks; they will eventually ruin the drafting board. If you are using a parallel straightedge or draft- ing machine instead of a T square, the procedure just described is the same with one exception. Instead of placing the paper close to the left edge of the board, you should place it approximately at the midpoint of the length of the parallel straightedge or in the center of the drawing board surface when you are using a drafting machine.

SHARPENING A PENCIL

To sharpen a pencil, cut the wood away from the unlettered end (view A) with a draftsman’s pencil sharpener or a penknife. The lettered end should be left intact so that the grade of pencil can always be identified. The cut should be started about 1 1/2 in. from the end, leaving a half inch of lead exposed. To produce a conical or needlepoint (view B), which is best for general use, rotate the pencil between the fingers at the same time as the exposed lead is rubbed back and forth across the full length of the sandpaper pad (view C). Many draftsmen prefer to use a mechanical lead pointer instead of the sandpaper pad. The mechanical pointer quickly produces a uniform conical or needlepoint. However, the sandpaper pad must still be used to produce other types of points. The resulting needlepoint should be dulled slightly by drawing it lightly across a piece of scrap paper several times. Avoid sharpening pencils near your drawing. Graphite particles will cause smudges that are difficult to erase. A cloth or tissue be used to wipe away graphite particles that cling to the pencil after it is sharpened. A wedge point (view D) will aid an experienced draftsman in the extensive drawing of straight lines. This point is produced by sharpening a pencil to the conical point just described, then flattening both sides on the sandpaper pad. For an elliptical point, hold the pencil firmly with thumb and fingers and cut the lead on the sand- paper pad by a back-and-forth motion, keeping the pencil at an angle of about 25 degrees to the pad. Continue until a flat ellipse is formed, as shown in figure (view E). A good draftsman never uses a dull pencil. Some draftsmen prefer to use mechanical drafting pencils instead of wooden pencils. The lead of a mechanical pencil is sharpened in the same manner as the lead of a wooden pencil. However, the length of the mechanical pencil is not depleted as the lead is sharpened. This is an advantage over wooden pencils that become difficult to use when they are less than 3 in. in length. When leads for the mechanical pencil are exchanged, ensure that the changeable lead grade designator on the mechanical pencil corresponds to that of the lead used.