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8 READING AND DETAILED DRAFTING OF ASSEMBLY DRAWINGS
8.1 READING OF ASSEMBLY DRAWINGS

To read an assembly drawing means to understand setting, structure, principle of work of the
represented article. Thus co-operation, methods of connection and shape of every part are taking
into consideration.
The name of an article and the scale of a representation are finded out after title block. Due to
the representations and parts list by the part numbers we determine from what parts and what
amount article consists of, what kind of parts are drawn on every representation, how they are
joined and co-operated. Thus a special attention should be paid to fragmentary views, sections, and
detail sections.
Having found out the setting of an assembly unit and principles of its work, the geometrical
shape of separate parts are analyzed. For this purpose all representations of a part on the drawing
should be attentively learned, projection connection between representations, position of cutting
planes with the help of which sectional views and sections are executed by should be found out. It
should be remembered that shading of sections of the same part is identical on all of
representations.
The final stage of reading a drawing is to determine the sequence of assembling and
disassembling of an article.
The main place while reading the assembly drawing occupies the study of a shape of every
separate part.
When determining a geometrical shape of a part it should be remembered that it can’t be fully
found out from the representations. It is explained by the presence of general view of an article of
row of simplifications, legalized standards, on the drawing.
So chamfers, fillets, grooves and similar elements are not drawn on the drawings of general
view. But these elements must be drawn on detail drawings of parts.

8.2 DETAILED DRAFTING OF ASSEMBLY DRAWING

Detailed drafting is drawing of separate parts according to the drawing of an assembly unit.
It is recommended to begin the process of detailed drafting with drawings of basic parts of an
article. The drawing of every part is done in the following order.
1. Read the assembly drawing thoroughly. Do not concentrate too long on one part, but pass
on to the adjacent part and come back to first part, if necessary. Determine the minimum number of
views required to adequately represent each part. Locate the sectional planes, if necessary.To
choose main view. It must give a complete picture of a shape and sizes of part.
2. To set the location of sectional views, sections, auxiliary views and other representations on
the drawing; thus unnecessarily to adhere to the same location, as on the drawing of general view.
3. To choose a scale for the representation of a part, according to State Standard 2.302 - 68.
4. Separate small elements on a part are advisable to draw as detail sections.
5. To choose necessary format according to State Standard 2.301 - 68.
6. Use the following sequence for drawing:
– Draw the axes of symmetry and block in the overall dimensions of the views;
– Draw the main outlines;
– Make sectional views and sections, and cross-hatch them;
– Draw the dimension lines and arrow heads;
– Put in the dimension figures and check the dimensions of mating parts.
7. To put denotation of roughness of surfaces. One of the most important moments in the
process of implementation of the detail drawing of a part is dimensioning and designation of
roughness of its surfaces. Putting the denotations of roughness of surfaces of a part should be done
according to State Standard 2.309 - 73.

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