![]() Figure 3 (a-b) can be used to illustrate the datum impact on the assembly variation. It is ideal to treat the two hinges as the datums so that the inspection results can directly indicate the assemble-ability, shown in Figure 2(b).ĭatums provide common ground between Design and Production for assembly manufacturers.ĭatums are often used in Assembly Strategies as locating features. Before a door is installed to a car body by the hinges, the door component will be inspected. Take a door component as shown in Figure 2(a). ![]() (2) Datums are derived from actual datum features, not reference points, lines, or planes.ĭatums are used to ensure components are assembled as intended. (1) Datums are the origins from which the GD&T and Measurements are established. ![]() In other words, Datums have the following characteristics. The definition of a Datum from the Dimensioning and Tolerancing Standard ASME Y14.5-2009 is:Ī theoretically exact point, axis, line, plane, or combination thereof derived from the theoretical datum feature simulator. Datum Design is integral to Assembly Strategies, GD&T (Geometrical Dimensioning and Tolerancing), and Measurement and Inspection Plans. In a dimensional engineering procedure, datum design is the second critical task, right behind objective specification. 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 andĬomplete the section therefrom, which ensures accurate duplication.Dimensional Engineering – Datums are Important from the inside of a window or the more important side of a door. Work from the face, or best side of the job-i.e. 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. 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. 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. 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. 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. 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. No broken lines must be made in the length of a section. The curved portion requiring special treatment will be referred to presently. Thus with these three drawings the joiner can obtain all the dimensions of every straight piece in the job. vertical dimensions are shown on the " height rod," Fig. In a separate drawing made upon the other side of the rod (see Fig.
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |