Standard

Convention

Lead Hardness

style of engineering lettering we will use

How tall should letters be in standard writing?

1/8 inches in height

How tall should numbers be?

1/8 inches tall

fractions?

normal letter height, but each numeral (numerator and denominator) should be shorter than 1/8” to allow space for the vinculum (horizontal line which separates the numerals).

Engineering Sketching

• black and white line drawings
• signed and dated to verify ownership
• form of COMMUNICATION
• technical drawings

First Step of any design?

Sketching

Which are Parallel Projections?

• Oblique
• Axonometric
• Orthographic

Which are pictorial sketches?

• Perspective
• Axonometric
• Oblique

Orthographic Projections

•  drawing views of an object by projecting them perpendicularly onto projection planes with parallel projectors
• Working or detailed drawings

How many view of an Orthographic Projection do you need?

the minimum views necessary to adequately represent the geometry.
–We need at least 2 views to accurately describe even the most simple objects.

What are the three principle projection planes?

How many principle dimmensions does each principle projection reflect?

 Two,

(choosing from Height, Width, and Depth)

What is the order of orthographic lines taking precedent over each other?

Center > Hidden > Center

Four Components of View Selection?

• obvious top
• Most descriptive view as front
• depth= smallest dimmension
• minimize hidden lines

Difference between orthographic and pictorials

Orthographic projections use two-dimensional views to represent the object, Pictorials show all three directions (axes) of space in one picture, much as they would be captured by a camera.

Parallel Projections

any lines that are parallel on the object will be parallel on the projected views

Perspective Projections

reproduce the effect that distant objects appear smaller than nearer objects. Lines which are parallel in nature appear to converge towards a single point.

Axonometric Isometric Projections

• Axes equally separated (120°)
• H, W, and D measurements are true size along isometric axes
• Angles must be located by coordinates
• Circles appear as ellipses on all surfaces

Preferred General Line

No hidden lines

but tangental edges

What wil circles in isometric resemble?

elipses

longest

Oblique Drawings

When and Why are Obliques great tools?

because of their simplicity they are good to quickly communicate ideas in early stages of the design process.

Cavalier Oblique Projections

Depth dimension=true size. (1.00)

Cabinet Obliqe

Depth dimension (receding axis) half size.

General Oblique

Depth dimension (receding axis) is between full and half size.

What angle ranges cause the most distortion in Oblique Pictorals?

Receding angles less than 30° and greater than 60° create severe distortion, especially in cavalier projections

Angles in Oblique must be...?

• drawn to true size (front view)
• located using coordinates
• (may be distorted)

Circles in Oblique Projections

Isometric vs Oblique

Curved Lines

If your object has many curved lines, isometrics look significantly better than obliques.

Perspective Projection

• the way eyes perceive the world.
• lines or angles with the same dimension on the object will have different dimensions on the drawing.

How to start and load a template

File

New

T: Drive

Layers

used to control the type of line that will be drawn.

What is the Arrowhead on a dimmension?

the head of the arrow that points to the extension line

What is the extension line?

The lines extended from the figure (by a gap) which marks the edges of the section being dimmensioned

Leader

Dimmension Line

The line between the arrowheads which can sometimes be broken by a dimmension #

[image]

Type of dimmensioning

Unidirectional

[image]

Type of dimmensioning

Conventional

[image]Dimmensioning style

Base line

Dimmension Spacings

Where should dimmensions go?

• Do not place dimensions inside any view
• Place dimensions between views

|1.00|  |1.00|

|----------3.00----------|

Do not cross dimension lines

Extension and visible lines can be crossed, but not dimension lines

Extension and visible lines can be crossed, but not dimension lines

What kind of features can you NOT dimmension to?

• hidden lines
• T-Joints

Can leaders go from the middle of the note?

How do you dimmension a circle?

With a leader pointing to the center of the cirle and the symbol [image] in front or DIA behind

In which view should you dimmension a hole?

The view they appear as circles

What view are cylinders dimmensioned in?

The view they appear as rectangles!

How are Arcs dimmensioned?

Dimmensioned in their round view with the prefex "R"

(Arcs greated that 180 degrees labeled with diameter)

[image]

No dimmension to center

Describe Bolt Circles

[image]

• Useful when the feature has repetitive holes in a circular pattern.
  –Draw a center line that passes through the center of each hole.( Not shown here)

How do you mark repetetive features?

Dimension repetitive features with a note in order to save space.

ie: .75 DIA- 4 HOLES

How do you dimmension chamfers?

What is a note and why is it used?

Used to reduce the number of dimensions or to provide specific information that is difficult to represent with regular dimensions.

ie: ALL FILLETS AND ROUNDS R.75

CHAM .5 x .5

How do you mark symmetry?

Can it stay like this the entire process?

–A center line can be used to indicate symmetry, which requires fewer dimensions.
–Not acceptable for late stage manufacturing drawings.

What is the formula for a leader in AutoCAD?

QLEADER

What is Tolerance?

• permissible level of error
• range of acceptable values

What is a general tolerance and where is it found?

•Apply to all dimensions on a drawing.
•Often found in the title block of all drawings intended for manufacturing or as a general note.

Why use a linear tolerance?

if a specific feature requires greater accuracy than the one expressed by the general tolerance a linear tolerance can over ride the general tolerance

What are the four main parameters of interest when looking at tolerances?

–Tolerance of the first mating part
–Tolerance of the second mating part
–Allowance
–Maximum Clearance

How do you find the hole tolerance?

–The difference between the diameters of the largest and smallest possible holes
–Determines the cost of manufacturing the hole
–Does not consider the Shaft at all

How do you find the shaft tolerance?

–The difference between the diameters of the largest and smallest possible shafts
–Determines the cost of the shaft
–Does not consider the Hole at all

How do you find the Allowance?

–The tightest fit between two mating parts
–Determines how the two parts will interact with one another
–Smallest dia. hole minus largest dia. shaft
–Does not affect the cost of the parts

How do you find the Max Clearance?

–The loosest fit between mating parts
–Determines how the two parts will interact with one another
–Largest dia. hole minus smallest dia. shaft
–Does not affect the cost of the parts

What is a clearance fit and what are the signs of the Max Clearance and Allowance?

• Shaft always smaller than hole
• Max Clearance= +
• Allowance= +

What is a line fit and what are the signs of the Max Clearance and Allowance?

• Shaft is less than or equal to the hole size
• Max Clearance- +
• Allowance- 0

What is a transition fit and what are the signs of the Max Clearance and Allowance?

•  (shaft) could be larger or smaller than the (hole). (depends on numbers)
• Max Clearance= depends
• Allowance=  depends

What is a force (interference) fit and what are the allowances and max clearances?

• the shaft will always be larger than the hole
• Max Clearance= -
• Allowance= -

How many fits are there in the English tolerance system?

If the number is increasing what does that mean?

5

the greater the tolerance is

How many types of fits are in the metric tolerance system?

As the numbers get smaller the fit gets...?

10

the fit gets tighter... H7u6 and U6h7= force fit

What units are values in English tolerance tables in?

thousanths of an inch

What are geometric tolerances?

controls the allowed level of error related to the geometry of features, not the size.

How round a pole must be, how parallel two lines should be... etc

How do you define geometric tolerances?

Geometric tolerances are indicated using symbols called feature control frames

What are Fastners and what are common non-permanent fastner?

process by which different components of a design are held or joined together is called fastening. A fastener is a mechanical device designed for this purpose.

bolts, nuts, screws, and pins

Common Heads and Drives

[image]         [image]

Hexagon              Slotted

Common Heads and Drives

[image]      [image]

Flat                             Phillips

Common Heads and Drives

[image]                 [image]

Oval                        Combined

Common Heads and Drives

[image]                          [image]

Round                           Square

Common Heads and Drives

[image]                [image]

Hex Washer                  Hex Socket

Common Heads and Drives

[image]           [image]

Truss                               Triple Square

Common Heads and Drives

[image][image]

Filister                       One Way

Common Heads and Drives

[image]                            [image]

Socket                                Spanner

What is the form of a screw?

What does the series indicate?

Whether it is a coarse thread or fine thread

What form is this?

Definition