7.5 Engineering Drawings Flashcards
How should you smoothe out food lines on drawings?
Smooth them DO NOT bend them backwards
What are the three most common standards used for drawings?
International organisation for standardisation (ISO)
American National Standards Institute (ANSI)
British standard (BS8888)
What are the three types of working drawings?
- detail drawings
- assembly drawings
- installation drawings
When is a detail drawing made?
- during aircraft design
What is included in a detail drawing?
- size and shape description
- material and heat treatment requirements
- protective finish instruction
- Machine finish if required
- part numbering and marking instructions
(Bscly everything required for fabrication)
What does an assembly drawing include? Where is this?
- reference individual parts’ by their part number
- specify type and number of fasteners needed to join them together
- found in the lower right hand
What dimensions are included in an assembly drawing?
Only those needed to assemble the parts included
What is an assembly?
- multi piece item that can be disassembled in to its components or units without being destroyed
- cannot perform a complete function independently
What’s the main purpose of an installation drawing?
- To show exactly where certain parts or assemblies are to be permanently fixed, pertaining to the aircraft
What does the bill of material on an installation drawing show?
Any instructions required for the installation
Any fasteners needed
Dimensions only given for those adjustments needed for the part to function
What is the difference between assembly and installation drawings in terms of locating?
Assembly drawings give parts locations in relation with each other.
Installation drawings give their position relative to the aircraft.
What word is in the title of all installation drawings?
“Installation”
When is a sectional drawing used?
To show a parts internal construction or shape
What are the four types of sectional drawings?
Revolved
Removed
Complete
Half section
Revolved section drawings: where is the cutting plane?
Cutting plane is perpendicular through the feature/ object
Revolved section drawings: how is the material cut with the cutting plane projected?
Rotated 90 degrees
Projected to the adjacent view on the adjacent view
When is a revolved drawing used and what does it show?
- used when only the shape of a part needs to be shown
- shows how a part is sectioned and revolved to illustrate it from a different view
What is a removed section drawing used for?
- to illustrate simple objects from another angle
If a drawing becomes too cluttered, where can removed drawing be displayed?
Section can be drawn adjacent to the view
What are complete sectional drawings used for?
To illustrate complex assemblies such as cable connectors
What does a half sectional drawing show?
Upper half of the drawing: assembly’s internal construction
Lower half: shows the entire assembly from the outside
Identify the drawing: All parts are in their relative positions but are extended outwards, so that each can be identified by their physical appearance or name
Exploded view drawings
What does a block diagram consist of?
Individual blocks that represent several components
Shows how they are all connected
What are block diagrams used for?
To aid troubleshooting of complex electrical and electronic systems
What do logic flowcharts show?
- shows specific logic gates and their relationship to other digital devices in a system using standardised symbols
- shows the inputs and outputs of individual components
What were logic flowcharts specifically developed for?
For analysing digitally controlled components and systems
What do schematic drawings show?
- the principle of the operation
- where objects are located only in relation to each other
- direction of fluid flow (if applicable)
Can the exact image of an object be seen in a schematic drawing?
No
What do electronic schematic diagrams show?
- show symbols for each component found in the circuit
- show function and flow
Do electronic schematic diagrams show the placement or scale of components?
No
What dimensional are pictorial diagrams?
Two dimensional drawings
What are schematic drawings mostly used for by engineers?
Fault diagnosis
See how components in complex systems interact
What do the types of projection refer to?
- orientation
- how it’s viewed on a flat plame
How is an orthographic projection drawing presented?
- Represents 3D object using several two dimensional views of the object
In an Orthographic projection, how many possible views are there from which an object can be drawn?
Six views:
Front
Rear
Top
Bottom
Left side
Right side
How does the first angle represent an object?
“Represent the side of the object that is remote from it in adjacent view”
The drawing is next to the part of the object it represents
How does the third angle present an object?
“Each view represents the side of the object that is nearest to it in the adjacent view”
The drawing is illustrated on the side opposite of the object
Which angle is European in origin?
The first angle
What is the first angle projection symbol?
Rectangle : target
What’s an isometric drawing?
Tilts an object forward so all three views can be seen in one view
Where are all the edges of the object on an isometric drawing?
The edges of the object all form a 30 degree angle to the drawing plane
What is an oblique drawing?
- An isometric drawing with one object face parallel to the drawing plane
- front if the object identical to the front view of an orthographic drawing
What is the depth axis of an oblique drawing?
- anything convenient
- most often 45*
What are perspective drawings?
- shows an object as it would appear to the observer
Are the actual angles and dimensions in a perspective drawing accurate? Why?
- not accurate
- lines aren’t parallel as it imitates how you’d see the object irl
In a drawing, if no inch mark is used what is the dimension given in?
Inches
What do centre lines look like?
Made up of alternate long and short dashes
— - — - — - —
What are dimension lines?
- an arrow with a vertical line on each side
How are the dimensions of circular parts given?
- In terms of the circles diameter
- Marked with the letter D or DIA
How are dimensions of an arc displayed?
- given in terms of radius
- marked w an R following the dimension
What do section lines show?
Indicate the exposed surfaces of an object in a sectional view
What do phantom lines indicate?
Alternate positions or layers or the object, or the relative position of a missing part
What do phantom lines look like? Is
One long and two short evenly spaced dashes
— - - — - -
What do break lines indicate? What do they look like?
- indicate a portion if the object is not shown
- short breaks are made by solid, freehand lines. Long breaks shown by solid rules lines w zigzags
What do leader lines indicate and how do they look?
- indicate a part or option that a note, number or other reference applies
- solid lines with one arrowhead
What are Biden lines also referred to as?
Dash lines
- - - -
What do cutting plane lines indicate?
Indicate the plane where a sectional view of the object is taken
What do viewing plane lines indicate?
Indicate the plane from where a surface is viewed
What’s the difference in the symbol of a solid metal rod and a hollow tube?
Solid metal is shaded
What are finish marks used for?
To indicate the surface has to be machine finished
Surface texture: is the number bigger or smaller if the surface finish is to be smoother?
Smaller
Smaller the number above the triangle- smoother the finish.
What does a circle above a triangle for surface finish mean?
No surface finish
When there’s a single number on the surface finish symbol, what does it mean?
That is the maximum degree of roughness acceptable
What a thick lined circle portrait?
Drilled holes
What do threaded holes have to show the thread crest and root?
Thread crest: thick circular line
Root: thin circular line
When the depth for a counterbored, countersunk or spotfaced hole aren’t given, what is the depth required?
The minimum depth required to achieve a flat seating
Whats the purpose of zones in an engineering drawing?
makes locating items easier
Where is the revision block?
upper right hand corner
What AN?
Army Navy
