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Mechanical Engineering Technology

MEC 1011


MEC 1011 - Design Communication I
Assignment 3
Assembly Documentation

Due at the end of our First meeting in Week 3
All items drawn with pencil on
8 ˝ x 11 paper

Concept Sketch:

  1. Produce a concept sketch of a simple assembly (like a zero-g doughnut holder). Sketch freehand on plain paper using any combination of orthographic or isometric views. Consider using an exploded isometric view as in L&J Figure 3.47. Your design should include at least two custom parts (meaning you can’t buy them through a catalog) and at least one standard fastener. Further, your design must demonstrate a clearance fit and an interference fit (see L&J page 518). Include general and specific notes. Also include a title at the top, some reference to size, material, how it will work and how it will be made. Sign and date it. Here’s an example that meets most of the above requirements. Here’s a concept sketch from an old electromechanical senior project.

Working Drawings:

  1. Produce a complete part drawing for each custom part in your assembly. Use rectangular graph paper and include the necessary views (at the maximum convenient scale), projection/miter lines (lightly as called for), dimensions (see rules in L&J Figure 12.48), tolerances, title block (see L&J Figure 12.35), border, and pertinent notes.
  2. Produce a complete assembly drawing. Use isometric graph paper to construct an exploded isometric view (like L&J Figure 12.7) at the maximum convenient scale. Include balloons (alias ‘ball tags’ or ‘bubble numbers’) as in L&J Figure 12.5. Include a parts list like L&J Figure 12.9, a title block and a border.


1.    Keep it simple!

2.    To determine the maximum convenient scale, lay out a plan for your view(s) as though your object(s) was a simple rectangular block (see L&J Figure 3.17 for iso or L&J Figure 4.27 for ortho). You might even consider sketching a rough draft of each drawing to make sure you have accounted for dimensions etc.


Consider identifying a supplier for your standard fastener. This can assist you by giving you tolerances to design with. For example, a typical ground steel dowel pin has a diameter tolerance of +0.0002 – 0.0000.