Engineering III

 

 

A. Assembly drawings guide workers in assembling parts properly and for general reference throughout the shops.

 

 

 

 

 

 

 

 

 

 

 

 

 

B. Assembly drawings show the assembled machine or structure, with all detail parts in their functional positions.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

C. In selecting views for an assembly drawing, the drafter must keep in mind the purpose of the drawing, which is to show how the parts fit together and to suggest the function of the entire unit.

          1. The assembly should not describe the shapes of individual parts.

          2. The views selected should be the minimum views or partial views that will show how the parts fit together.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

D. A subassembly is used with large or complicated machines when it is not possible to show all parts in one assembly and a separate drawing is needed.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

E. Title strips are the same for an assembly drawing as a detail drawing except for the addition of the word assembly in the title.

 

 

 

 

 

 

 

 

 

 

 

F. A parts list may be placed on a separate sheet or in any convenient open corner on the drawing. It is preferred to be read up from the title block or down from the upper right corner.

          1. The parts list includes the part number, name, material, and number of pieces required.

          2. Each part is identified on the drawing by lettering the part numbers in .438 or .500 diameter circles near the assembly, and drawing leaders to each part where it is clearly shown.

          3. The circles should be arranged in groups and in vertical or horizontal rows.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

G. Assembly sections.

          1. In an assembly drawing where several adjacent parts are sectioned, it is necessary to draw the section lines in different directions              to distinguish the pieces clearly.

                    a. The first large area is section-lined at 45 degrees.

                    b. The next large area is then section-lined at 45 degrees in the opposite direction.

                    c. Additional areas are section-lined at 30 degrees or 60 degrees with horizontal.

                    d. If necessary, to make any area contrast with the others, any other angle may be used.

          2. Section lines do not meet at the visible lines separating the areas.

          3. For small areas the lines are drawn closer together.

          4. In sectioning very thin parts, when there is not enough space for section lining, the sectioned parts may be shown solid.

          5. It is customary not to section parts that would make the drawing less clear, such as bolts, nuts, shafts, keys, ribs, gear teeth,                      spokes, screws, nails, ball and roller bearings, and pins.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

H. Design assemblies or layouts.

          1. One of the initial drawings created by the designer, usually drawn to full scale to enable the designer to visualize the part more                  clearly.

          2. Includes the views necessary to show the size and shape of each part of the mechanism, but dimensions are omitted.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

I. Outline assembly or installation assembly

          1. The purpose is to give general information regarding the character and size of the unit and how it fits in its environment.

          2. In an outline assembly there is little or no section lining.

          3. Only the principal overall and center-to-center distances needed to clarify questions of installation are given.

          4. Outline assemblies are sometimes referred to as exploded assemblies.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

J. Working drawing assembly

          1. A working drawing assembly combines detail and assembly drawings giving complete dimensions and notes for all parts.

          2. Used in place of separate detail and assembly drawings for simple parts.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

K. General assembly

          1. Shows how the part fits together and how the assembly functions.

          2. Chief use is in the assembly shop where all finished parts are received and put together.

          3. Views shown may be regular, sections, auxiliary, and partial.

          4. No dimensions are usually given on a general assembly.