Pattern Development Flashcards
NTS means
Not to scale
From your perspective
Has a vanishing point
Artistic and realistic
Perspective drawing
Shows front, top and right sides
Front surface is true size and shape of object
Uses foreshortening
Oblique drawings
Equal measure
Always at 30 degree angles
Isometric drawings
Used two of more views
Look directly at one side of the object
Orthographic projection
Arrowheads
3-4 mm long
Used to add notes or information
Leader lines
Less cluttered
Easy to read
Not all dimensions necessary
—-
Disadvantage
Cumulative error
Mistakes in math
Conventional dimensioning
Risk of cumulative error eliminated
Need for math eliminated
——-
Disadvantage
Takes up lots of space
Baseline dimensioning
Combines advantages of both baseline and conventional systems
Eliminates need for math
Running dimension
8 degrees 20’ 30”
8 degrees, 20 minutes, 30 seconds
Used to draw horizontal lines
T square
Draws small circles and arcs
Used in one direction only
Compass / divider
Parts of a circle
Chord
Diameter
Radius
Sector
Arc
Segment
Semi circle
Tangent line
Sector
Common center (circle)
Concentric
Different centres (circle)
Eccentric
Divide into two equal parts
Bisect
Drawing using only a ruler and compass
Angular construction
How many steps around the circumference with the radius does it take to complete a full circle
6
Common tool that is useful at finding the centre of a circle
Carpenter square
The space/gap used for an extension line
2 mm
4 dimensioning methods
Conventional
Baseline
Running
Number placement
Set square
Triangles
90-60-30 set square
30 degrees - 60 degrees
45 degree set square
90-45 set
A straight line not through the center touching the circumference with both ends
Chord
Any portion of the circumference
Arc
A portion of a circle bound by an arc and a chord
Segment
A portion of a circle bound by an arc and two radius lines
Sector
A line touching the circumference at one point only
Tangent line
Where the point bends
Where the two lines meet
Vertex
Triangle: equal on all sides
Equilateral
Triangle: two equal sides
Isosceles
Triangle: no equal sides
Scalene
AIT
T squares is a guide for drawing….
Horizontal lines
AIT
Tolerances control the level of accuracy acceptable deviations in measurements +_ / + / - …..
Can be above or below
Can be above only
Can be below only
AIT
What is this angle
60 degrees
AIT
How many times do you move the carpenter square when finding the centre
One time
AIT
How to make a blind flange (no hole in centre to stop connection)
- Lay horizontal and vertical lines
- Draw flange OD
- Draw bolt circle diameter
- Divide BCD into appropriate number of equal parts: depends on how many holes you need if you have eight bolt holes divide 360 by 8
- Add bolt holes
- Add a leader line to one bolt hole, giving bolt number and size
Two holing a flange
Straddle the center line of the flange
One hole
Is where it goes in center of hole typically is to attach a 45 degree to a normal pipe
Drawing. Real
————- = ————
Drawing. Real
Scale
Baseline dimensioning:
Common baseline locations are
The tangent line
The reference line
The datum line
The center line
Work points on structural drawings
A head Sean on vessels
Tangent line
(Baseline dimensioning)
The moment the curve starts (where the circle meets straight line)
Running dimensions
All tailed dimensions from this baseline
Disadvantage
Must watch for dimensions that are not tailed
Number placement
Unidirectional
Dimensioning from the bottom of the drawing
Number placement
Aligned
Number placement read horizontally from bottom and aligned vertically from the right side
Can you measure from hidden lines
No
C= pie D
Circumference
How many degrees in a triangle
180
Acute angle
Less than 90 degrees
Obtuse angle
More than 90 degrees
Hexagon
6 sides
Octagon
8 sides
Pentagon
5 sided
Trapezoid
A four sided figure with two parallel sides and two non parallel sides
Parallelogram
Four sided figure, opposite sides of which are parallel and equal
What type of pictorial drawing shows objects as they appear to the eye
Perspective
Which type of drawing used one orthographic view with parallel lines receding off
Oblique
Oblique drawings are generally used for objects that
Are small and simple
Isometric drawings show horizontal lines receding at
30 degrees
Drawings using oblique projection are foreshortened to
Make the drawing look more realistic
One disadvantage of isometric drawing is that
All of the faces are distorted
One disadvantage of perspective drawing is that
These drawings cannot be drawn to scale
Two true statements regarding orthographic drawings
The views are always two dimensional
The reader has to visualize the complete assembly
In order to have oblique drawings appear true to form the receding lines are drawn
Shorter than the actual length of the part
When dimensioning differs from conventional type it is called
Baseline dimensioning
The purpose of dimension are to
Indicate size and locations
Baseline dimensioning eliminates
Cumulative error
A hole dimension is expressed as a
Diameter
Wall thickness is measured in
Schedule
Millimeters
Standard
Extra strong
XXS
Little lines on tape measure are called
Graduations
Finding the arc on a rounded plate
Radius to focal point
