What is an engineering drawing?
A technical drawing that clearly defines and communicates a design to interested parties.
What are the standard A-series paper sizes and dimensions?
A5 (210 × 148 mm), A4 (297 × 210 mm), A3 (420 × 297 mm), A2 (594 × 420 mm), A1 (841 × 594 mm), and A0 (1189 × 841 mm).
What information does a drawing title block contain?
Project or part identification, description, scale and unit, projection type, drafter’s name, company information, and material for machined parts.
Which identification details can a drawing title block give for a project or part?
Its name or reference.
What is a nomenclature in a mechanism drawing?
A complete list of the elements that constitute a mechanism.
What defines orthographic projection geometrically?
It uses parallel projectors perpendicular to the projection plane.
Why are multiple views used to define an object?
A single projection cannot describe it completely without ambiguity.
Where is the left view placed in first-angle projection?
To the right of the front view.
Where is the left view placed in third-angle projection?
To the left of the front view.
What should be chosen first when projecting a part?
The most informative front view.
How are the other views projected when drawing a part?
Using straight 45° construction lines.
What do continuous thick lines show in drafting?
Visible edges and outlines, section outlines, and observation-direction arrows.
What do dashed thin lines represent in drafting?
Hidden edges and outlines, including hidden internal and external threads.
Which lines take precedence when drafting line types coincide?
Object lines take precedence over hidden lines and centrelines; hidden lines take precedence over centrelines; cutting-plane lines take precedence over centrelines in sectioning.
What does an auxiliary view show about an inclined surface?
Its true size and shape.
What does a sectional view show about an object?
Its interior construction as if a portion were removed by an imaginary cutting plane.
How are section hatching lines normally drawn?
Thin, equally spaced lines inclined at 45°.
When is 30° or 60° hatching used instead of 45°?
When 45° hatching would run parallel to an outline or axis.
What distinguishes a full section from a half section?
A full section cuts completely through an object; a half section is used for a symmetrical object.
What is a thread?
A helical groove formed on a cylinder’s inside or outside, used to hold parts, move them, or transmit power.
How does thread pitch differ from thread lead?
Pitch is the axial distance between adjacent corresponding points; lead is the distance moved per full revolution.
What happens when a nut on a right-hand thread turns clockwise?
It screws onto the bolt.
What must dimension lines avoid serving as or coinciding with?
Dimension features or other dimension lines.
Where should short dimensions be placed relative to long dimensions?
Short dimensions close to the model and long dimensions farther away.
What should be avoided when placing dimension lines?
Crossings, where possible.
Which lines should dimensions never reference?
Hidden or dashed lines.
How should dimensions for the same detail be organized?
They should be grouped together.
What overall dimensions must a part drawing always show?
The part’s total external dimensions.
From what feature should a hole’s position be dimensioned?
Its axis.
Which audiences receive designs communicated by technical drawings?
Colleagues, suppliers, and customers.
How do technical drawings support production work?
They support part manufacture and mechanism assembly.
What idea-related purpose do technical drawings serve?
They record new ideas.
Where is the title block located on a drawing sheet?
In the lower-right corner.
How are grid references arranged on a drawing sheet?
Letters run vertically downward, and numbers run horizontally from left to right, starting at the top left.
Where does a drawing’s grid-reference system start?
At the top left of the sheet.
What information does a nomenclature provide for each mechanism part?
Its index number, element number, description or name or reference, quantity, and sometimes supplier.
What optional source detail may a nomenclature list?
The supplier.
Which projection method is mainly used in the USA?
Third-angle projection.
Which views do planes P1, P2, and P3 produce, respectively?
The front, top, and right-hand views.
What do continuous thin lines represent in drafting?
Imaginary edges, hatching, dimensions, extensions, folded-up section outlines, visible thread bottoms, and local hand-drawn sections.
What do mixed thin lines represent in drafting?
Axes, symmetry planes, and primitive gear lines.
What do mixed lines with two dashes represent in drafting?
Nearby-part outlines and extreme positions of moving parts.
What marks the interruption in a partial view?
A break line.
How is the enlarged portion identified in an enlarged view?
It is enclosed by a sketch, such as a circle or another closed contour.
Which features does a local view show?
Only features from a main view that need clarification.
Which break-line styles represent short and long breaks?
Wavy lines represent short breaks; jagged lines represent long breaks.
What do phantom lines indicate in a drawing?
A part’s range of movement or repetitive detail.
How do imaginary tangent-edge lines end relative to part edges?
They stop before the part edges.
How is a section indicated on a drawing?
With thick lines, a thick cutting-plane line, direction arrows, and the same two-letter name on both views.
What does a local or broken-out section reveal?
A small area that clarifies an interior feature, exposed using a short break line.
Where is a revolved section placed in a drawing?
Turned into position and interposed on the same view.
Where is a removed section placed, and what does it show?
Clear of the main outline, showing only the cut surface.
Which types are common thread types?
V, square, Acme, buttress, and rolled threads.
What is the crest of a thread?
The outermost part of the thread.
How is an internal thread made?
A hole is drilled and then tapped with a machining tool.
Which standard defines metric threads?
ISO 965-1.
What angle do metric threads defined by ISO 965-1 have?
A 60° thread angle.
Where should the dimension number go for a small dimension?
Outside the extension lines.
Answer 19 questions on Mechanical Technical Drawing.
1. What is the purpose of an engineering drawing?
2. Which statements correctly describe standard A-series paper sizes?
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