Datum Points

in a separate drawing made upon the other side of the rod (see Fig. 2) ; all the. vertical dimensions are shown on the " height rod," Fig. 4. Thus with these three drawings the joiner can obtain all the dimensions of every straight piece in the job. The curved portion requiring special treatment will be referred to presently. No broken lines must be made in the length of a section. Obviously, if this is done, the rod is useless for its chief purpose, the actual laying down of the stuff upon it, and the transference thereto ot the shoulder lines, etc.

The breaks in the examples at A, Fig. 4, and B-B, (Figs. 2 and 3, page 183), are introduced to avoid making the drawing to such minute scale that the details would be indistinguishable, but, of course, in actual settingout. this would not need consideration. When a job is so large that more than one rod is required to accommodate its length, as, for example, a dado framing for a 30-ft. corridor, the adjacent ends should be squared, and correspondingly numbered or lettered with;n circles, and the exact distance between two near points in the framing should be figured in, as a check, in case the rod should get accidentally cut short. The wall or other " fixed point " should always be shown on the width rod, and the floor line upon the height rod, and these datum points are the ones to commence with.

In setting out linings to openings, or frames to fit into them, lay down the dimensions of the opening first, as ascertained upon the building or from other data, and build the traming, as it were, around or in them ; by this method the danger of making a fitting either too large or too small for the opening will be avoided.

Work from the face, or best side of the job- -i.e. from the inside of a window or the more important side of a door. Where two opposite sides of a job are alike, as the two boxings of a sash frame, do not set out each independently, but set out one side completely, then carefully gauge each line from the face edge and run it to the opposite side and

JOINERS' RODS 183

complete the section therefrom, which ensures accurate duplication.

Setting Out Rods Joinery
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  • ofelia
    How to use datum points in technical drawing?
    8 years ago

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