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DRAFTING TABLES WITH BOARDS Most EA shops are furnished with standard drafting tables with drafting boards, as shown in figure 2-6. The majority of this furniture is easily adjustable to the users needs. The height of the table should be such that if you desire to work in a standing position, you can do so without stooping or holding your arms in a raised position. Hinged attachments for the drafting board are provided to adjust the incline so that your line of sight will be approximately perpendicular to the drafting surface. Your drafting stool should be high enough in relation to the table for you to see the whole drafting board but not so high that you are uncomfortably seated. The drafting boards contained in the drafts-man kit are constructed of joined strips of softwood, usually clear white pine or basswood. They are equipped with hinged attachments for securing the board to a table or fabricated base. If suitable bases are not available, table bases may be constructed at the unit carpenter shop. You should consider only the left-hand vertical edge as a working edge for the T square if you are right-handed (the right-hand edge if you are left-handed). The T square should never be used with the head set against the upper or lower edge of the board, as the drafting board may not be perfectly square. The drafting board should be covered. A variety of good drafting board cover material is available. Available cover materials are cellulose acetate-coated paper, vinyl, and mylar film. The vinyl drafting board covers have the added advantage of being able to close up small holes or cuts, such as those made by drafting compasses or dividers. In general, these covers protect the drafting board surface by preventing the drafting pencil from following the wood grain, by reducing lighting glare, and by providing an excellent drafting surface. Since you will be constantly using your eyes, it is important that your working area be well lighted. Natural light is best, if available and ample, although in the majority of cases acceptable natural light will be the exception rather than the rule. Drafting rooms are usually lighted with overhead fluorescent fixtures. Ordinarily, these fixtures are inadequate in quality and intensity of light. Adjustable lamps will improve the lighting conditions. The most popular type of adjustable lamp is the floating-arm fluorescent fixture that clamps onto the drafting Figure 2-6.-Drafting tables with boards. table. Arrange your lighting to come from the front-left, if you are right-handed; from the front-right, if you are left-handed. This minimizes shadows cast by drawing instruments and your hands. Never place your drafting board so that you will be subject to the glare of direct sunlight. North windows are best for admitting daylight in the Northern Hemisphere. Conservation of vision is of the utmost importance. You must make every possible effort to eliminate eyestrain. |
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