The object represented on the drawing cannot be made with the necessary degree of accuracy, without knowing its geometrical sizes and maximum deviations. Besides, values of the sizes allow to estimate a real type of an object, considering the scale in which nachercheno its image.
It is required to you
- - the computer from the established CAD and the electronic file of the drawing;
- - a ruler and a pencil if the drawing is executed on paper;
- - a tracing-paper or paper, the printer or the plotter for the printout of the drawing (if it is necessary).
1. Define constructive bases of a product from which the sizes will be affixed. It needs to be done so that a nacherchenny object could be made and checked. In total all sizes have to reflect all geometrical measurements of a product, at the same time their quantity has to be minimum.
2. Distribute the sizes which need to be put, by types of the drawing. On each look there has to be approximately identical number of the sizes, it is better to show some of them on cuts and sections. If it is required to put the sizes of any structural element, for example a groove or a ledge, them it is necessary to have on that look where the image of this element most informatively, that is gives complete idea of its form.
3. Draw a dimensional line parallel to a rectilinear piece which size needs to be put. Locate portable lines perpendicular to the dimensional line. Draw them continuous thin lines, and on the ends of dimensional lines arrange dimensional arrows. When drawing size of diameter draw a dimensional line through the center of the represented circle, at the same time it is allowed to do break of the line next of the center of a circle.
4. Observe the minimum distance in 10 mm between the main line of a contour of a product and the dimensional line, between parallel dimensional lines – 7 mm.
5. Specify the valid value of the size in millimeters, having figure parallel to the dimensional line. Do not forget to specify maximum deviations or the main deviation with number of quality in accordance with GOST 25346-89.
6. Note the help sizes on the drawing the sign "*", at the same time include point in the text of technical requirements "* the Size(s) for reference". At emergence of additional questions use the rules stated in GOST 2.307-68.