More Rules of Tech Drawing

My final notes for this class have been collected here. But all the rules can be found in the Australian standard for industrial design technical drawing AS1100.101

BOM = Bill of Materials

Diagonal Hatching = section view
Use different hatching against angles + spacing to make separate components clear.
Hatch angle should be 45 degrees for Australian industrial design standards.
Don’t hatch fasteners (hinges, nails, bolts)

Tolerances: Decimals matter!
.0 = ± .5
.00 = ± .05
.00 = ± .005
(this all adds up in either mistakes or costs of precision.)

Draft is the slight angle of the sides on moulded parts:

Depth symbol:

TYP = a typical measurement for this kind of feature
PLCS = places
eg. (depth symbol) 55 TYP 3 PLCS = the depth is 55mm for this one and the other two like it.

⌀ = diameter
R = radius
S⌀ = spherical diameter
SR = spherical radius
use diameter wherever possible. don’t use radius for full circles.
circumference = diameter x pi (yes, i’m terrible at maths so i do need this note.)
concentric = same centres
pitch circle = a guiding dimension for features that are in circular symmetry.

Pitch Circle Diameter.JPG

Threads can be drawn as follows:
a 3/4 circle around the outside of the hole (or inside of the bolt)
parallel lines along the outside of the hole (or inside of the bolt)gewinde-darstellung-01kl
M9 = metric 9mm thread form (a standard thread size)

For assembly labelling, balloons should be in line with one another. They may have arrowheads or dots with the following rules:IMG_1678.jpg

With A3 Drawings, the lettering height for dimensions should be 2.5mm and a minimum of 7.5mm from the drawing.

For section views, the direction of the arrow on the label shows the angle of projection, so as seen below, the arrows for C-C are pointing to the right angle of view, so the section view will appear on the right side.

For detail view, the drawing can appear anywhere, but is best if close to the original. It can be any appropriate scale but must be labelled as such.

Auxiliary views should be drawn at 90 degrees to the angled face that it represents.

Section, detail and auxiliary views must be labelled only with letters, or View A / View B in the case of detail and aux drawings. All labels must be directly below the drawings.

Developable objects are objects that can be deconstructed into flat shapes. Cubes or cones can, but spheres cannot.


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