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mec222:drawing_rules

Drawing Rules

These are some rules regarding technical sketches and CAD drawings in MEC222.

All of the following rules MUST be followed on ALL sketches. Failure to follow these rules will result in a significant grade reduction.

Refer to Chapter 5 of the textbook for more.

Page formatting rules

Proper Paper
All manual drawings are done on blank (i.e. unlined) paper.

  • You can use quad paper under the blank page to help guide your drawing.
  • All sketches - and only sketches - are to be done in pencil.

Proper Border
Draw a 1 cm border around your page. All writing/drawing must be within the border.

Proper Title Block
A proper title block is needed to identify the drawing, even if it is just a technical sketch.

  • Solidworks: Template files specific to MEC222 will be provided for you to use. In an absolute emergency, you may use the default title blocks that Solidworks generates, but you will have to explain to your TA/instructor why you had to use the default. A poor rationale will result in a grade penalty.
  • Manual drawing: Just draw a 1cm tall box across the bottom of your page — inside the border — and divide that box into 5 parts (side by side), containing:
    • your name & student ID,
    • your course and section number,
    • a title for the drawing (and drawing number, if it's part of an assembly),
    • the scale of the drawing1) and units of measurement, and
    • the units of the drawing.
  • Hint: You may draw one good empty template (per example below), photocopy it onto blank paper, and use the photocopies for in-class and take-home sketching assignments.
  • The border and title block are not technically part of the drawing, so you can use a ruler to draw them.
  • Here are examples of a typical Solidworks drawing template:

mec222swtemplate-b.jpgmec222swtemplate-a.jpg

  • Here is a sample of what your manual drawing sheet can look like:

typicalsketch1.jpg

Proper Lettering
Try to get as close as possible to engineering block.

Proper lines

Different line styles must be distinguishable.

  • Lines must be consistent darkness and thickness.
  • Construction lines must be very faint.
    You can use a light blue, “non-photo”, pencil (like this) to draw construction lines2).

The following figures come from Fundamentals of Graphics Communications, 6/e.

alphabetoflines1.jpg alphabetoflines2.jpg alphabetoflines3.jpg

Proper view layout

Principal views must be properly laid out.

  • Generally, one draws on the paper in “landscape” mode.
  • Generally, one draws views to fill the page leaving at least 1cm (usually 2cm or more) between the page border and the view itself.
  • Generally, one divides the page into quarters, where
    • the front view goes in the bottom left quarter,
    • the top view goes in the top left quarter, and
    • the side view goes in the bottom right quarter.
  • It is good to leave construction lines so that we can see what you were thinking.
  • Actually drawing construction lines to partition the page into quarters is good practice for beginners, because these lines can constitute the folding lines3).
  • Adjust the size of the page quarters to suit the proportions of the part you are drawing.
    • EG: a long thin part will likely have a small side view, so move the vertical folding line to the right. This helps ensure you can draw the part to the best possible size. In the example below, the quarters have been sized to accommodate a longish, squat part.
      typicalsketch2.jpg

Proper front view

Rule-of-thumb: the best front view is the view that (1) takes advantage of a part's “natural” bottom, and shows (2) the most interesting geometrical features and (3) the fewest hidden lines.

  • It may be that in some cases the most interesting geometrical view does not have the fewest hidden lines (or vice versa), so some flexibility is allowed here. Nonetheless, students are expected to show good judgement in selecting the front view. See the FAQ for more information.

Dimensioning rules

Rules for dimensioning have been moved to this Google Doc.

1)
If the scale is 1:1, then no scale needs to be specified. If the scale is anything else, you must specify what it is.
2)
The light blue is often used in industry because it does not show up on scan and photocopies - so it saves you the trouble of having to erase them.
3)
Refer to the textbook for an explanation of folding lines.
mec222/drawing_rules.txt · Last modified: 2020.03.12 13:30 (external edit)