Model Documentation

Working Drawing Documentation

Once a design has been researched and approved, the part is sent to be prototyped or manufactured. Appropriate documentation is needed to communicate the idea to everyone in the company. This is the most difficult, time consuming, yet the most important part of engineering communication. These documentation are called working drawings.

What are Working Drawings? Working drawings are a complete set of

documents that specify how an object will be manufactured and assembled. Each set should include: Part Drawings Assembly Drawings Parts List Any Special Specifications or Instructions.

Working Drawings Elements of Working Drawings

Drawing Layout Drawing Views Dimensioning Annotations Multiple Features

Drawing Layout Elements of Drawing Layout

Sheet Styles and Sizes Borders Title Block Scale Revision Block

Sheet Sizes

INCH DRAWING SIZESDRAWING SIZE BORDER SIZE OVERALL PAPER SIZE

A 8.00 X 10.50 8.5 X 11.00B 10.50 X 16.50 11.00 X 17.00C 16.25 X 21.25 17.00 X 22.00D 21.00 X 33.00 22.00 X 34.00E 33.00 X 43.00 34.00 X 44.00

American National Standards InstituteANSI

Title Block A box found in the lower right hand corner

of a drawing. It contains pertinent information on the part

Drawing Number Scale Material Title or Description Company Tolerances

Title BlocksANSI Large style title block. All title blocks should include the followinginformation.

Name of person who did the drawing.Company name. Many times companies willcreate their own borders and their logo will appear also.

Remember working drawings are made of manydifferent types of drawings and there are usually more than one sheet that goes with a design.

Scale of the part is important so the person being communicated to can get an idea of what the part looks like.

Title of the project. As opposed to a specific part.Specific part name in relationship to the

total design.

Zoning is used to find specific locations on thedrawing. Usually shown in numbers and letters.

Another person will check the drawing and approve the part for manufacture.

Documentation of how many times the drawinghas been changed.

Size of sheet. Very valuable when printing.Name of person who checked the drawing. Just like first drafts of papers written in English class, drawings go through many revisions.

General notes and information. Located here you will see information on, fillet and rounds, tolerances, and other general information thatwould take up too much space on the drawing ifrepeated on every feature.

Scale When objects can be drawn using the actual

dimensions, it is referred to as full scale or 1:1. Some objects are drawn larger than actual size, so one can clearly see details and dimensions these can be as large as 10:1.

Scale is represented as an equation. The left side is the drawing size and the right side represents the part.

Scale

Scale 5:1

The bolt is drawn five times larger than actual size

For clear and accurate dimensioning and specification of a part the drawing may need a variety of views.

The five basic views are: Orthographic Isometric Section Auxiliary Assembly

Drawing Views

Orthographic (Multiview Drawings)

Orthographic Projection is also known as a Multiview drawing. Orthographic projection is a way to project a view based on a line of sight that is perpendicular to that view. There are six views to any object as shown in the next slide.

Orthographic (Multiview Drawings)

The arrows represent the line of sight associated

with each view.

Orthographic Principal Views

Front, Top and Right views

are used most often. You can see how other views resemblethese three except they are not

as clear due to hidden lines.

Note how the viewsare oriented. Each view is

adjacent to the other asif they were unfolded

from a 3D shape.

Orthographic Angle of Projection

The example you have just seen is shown in the third angle of projection. This is the standard in the United States and Canada.

Orthographic 3rd Angle Projection

ISO Symbol

Views are projected onto planes that exist on the face of that view. Arrows show the direction of the

projection

Orthographic View Selection Steps in selecting the front view.

Most natural position or use. Shows best shape and characteristic contours. Longest dimensions. Fewest hidden lines. Most stable and natural position. Relationship of other views.

Most contours Longest side Least hidden lines Best natural position

Orthographic View Selection

Longest DimensionMost natural position.

No hidden lines.

Best shape description.

OrthographicView Selection Numbers A decision must be made in accordance to

how many views are needed on a drawing. Generally, three views are needed and, in some cases, only one or two.

Orthographic Example2 Orthographic viewsare used instead of three.

Orthographic Example3 View OrthographicDrawing

Dimensions to showsize and shape. Title Block gives

general informationabout the part.

Placing and Locating Orthographic Views

Which orthographic views you need are based on the same rules we had in the sketching unit.

Steps in selecting the front. Most natural position or use. Shows best shape and characteristic contours. Longest dimensions. Fewest hidden lines. Most stable and natural position. Relationship of other views

Most contours. Longest side. Least hidden lines. Best natural position.

Placing and Locating Orthographic Views

Parts are evenly spaced.Enough white space is left for dimensioning.

Third angle projection isused.

Isometric Views An isometric view is a pictorial view

inserted in an orthographic drawing. An Isometric, meaning equal measure,

is created by rotating the object at equal angles to the projection plane in order to appear inclined and to show three faces.

IsometricNote one pictorial view shows

height width and depth.Width and depth linesare drawn at 30 degrees from

the horizon line.

Isometric Views Isometric View

Section Views When a part has a lot of interior details,

hidden lines can make the part hard to understand and dimension. To see the interior of these parts, we cut some of the part away. This allows for details to be seen clearly, as well as, giving us alternative locations to properly dimension the part.

Sectional Views Types of Sectional Views

Half Full Offset Removed Revolved Broken-out Aligned

Half SectionNotice how the cutting plane line runs

through the center of the part and there is no arrow head.

In a half section, one quarter of the part is cut away. This is done with symmetrical parts where you would like to show the outside, as well as, the inside details.

Full Section A full section is a view that shows what

the object looks like if it were cut in half.

A cutting plane line is used to indicate how the frontview was cut. It is also labeled in case another section

is necessary. The arrows should point in the line of sight as you are looking straight on at the section.

Section lines called Hatch lines are used to show where the part is solid. This helps to see the detail that would be

normally blocked and only shown as hidden lines.

Offset SectionInterior features not in line with each other can be shown in an offset section view.Note how the cutting plane line changes and follows the center of each feature.

Revolved Sections Used when an object has a constant

shape throughout the length that cannot be illustrated in an external view.

The section is revolved 90 degrees. It may be represented one of two ways, either broken away or not.

Not Broken Away Revolved Section

Section is revolved 90 degrees

Broken Away Revolved SectionSection is revolved

90 degrees and brokenaway from part

Broken-out Section Views A small portion of an object may be

broken away to clarify an interior surface or feature. No cutting plane line is used.

Broken-out Section View

Section exposesthe interior surfaces

Auxiliary View To accurately view the true dimensions

of an inclined surface, one must create a view at 90 degrees from that inclined face. This is referred to as an Auxiliary View. This allows us to view the surface in its true size and shape.

Primary Auxiliary ViewMany times a feature on a part cannot

be seen in true size and shape. When thisis the case we use an auxiliary view.

In order to see a feature in it’s true size and shape,we must look at it straight on or perpendicularto the plane in which the feature exists. Note

that in this view (the auxiliary view) the slotted hole is true size and shape.

To obtain this view the auxiliary must be drawnfrom the view that allows the line of sight to be

perpendicular to the desired feature.

Line of sight.

Detail Views

A drawing of an individual part that contains all the information needed to manufacture the object is referred to as a Detail Drawing. These drawings contain all the specifications, dimensions and views needed for production.

A Detail View may be necessary to illustrate small features on a part. This is achieved via breaking out and enlarging the feature.

Detail ViewThe feature is broken out and enlarged for

clarity.

Assembly Drawings

Many products are composed of several different parts assembled into one. A drawing showing the working relationship of those parts is called an Assembly Drawing. This is achieved using views in the usual positions showing the layout out of the parts. A parts list is included on the drawing to identify the name, material and number of each piece.

Assembly Drawings General Exploded

Explosion factor Trails Tweaks

General Assembly Drawings

General Assembly Drawings are a set of drawings that include the detail drawings, assembly drawings and parts list needed in the production of an assembled object.

General Assembly Drawing

Includes all detail drawings of each

partIncludes theAssembly Drawing

Parts List

Exploded Assemblies

The explosion factor is the distancethe parts have been separated from

each other.

An Exploded Assemblyshows all the parts removed

from each other and aligned along axis lines

Identification numbers are generally placed inside balloons and point to the part with a leader line

Trials show the initial path the components moved along when

the view was exploded

A parts list is included on the

drawing to identify the name, material

and number of each piece.

Parts ListItem number on the drawing.How many parts are included

in the assembly.

Specific part number. All parts will have specific numbers

assigned to them. This makes computer data processing easier.

Description of part or the name.

Explosion Factor The explosion factor is the distance the

parts have been separated from each other.

Trails Trails show the initial path the

components moved along when the view was exploded

Tweaks Is adjusting the distance or location of

a part in an exploded assembly.

Before After

Dimensioning Views and dimensions provide a clear

description of the shape and size of parts and their features.

Parts are fun to design, but dimensioning the part to be manufactured can be difficult.

Dimensioning takes time and patience to get it right. Errors in a drawing will most likely be found in the dimensioning.

Decimal

The most common form of dimensioning uses the decimal system. Precision is set

by the number of decimal places.

Architectural

Arrow heads can be the same as decimal

dimensioning or can be displayed as architectural

ticks.

The Architectural Style of dimensioning is quite different from the decimal. Dimensions are shown in feet and inches.

Engineering

The engineering style of dimensions is shown here. The inch units are in decimal and feet and inches are displayed similar to the Architectural style of dimensioning.

Surveyor

A

B

Surveying dimensions are given in north and south directions. The example here is said to be North 46 degrees, 48 minutes,

39 seconds West. This indicates the line points in the northwest. Normally a distance is given.

DualDual dimensioning is a type that shows both metric and inch units

on the same drawing. There are two methods position andbracket.

Position method: Places the metric dimension over the inch dimension. Another acceptable practice is to place the metric dimension before the inch dimension with a slash after the

metric dimension.

Bracket method: The bracket method places the metric dimension in brackets. The metric dimension can be placed

above or to the right. Exactly what the units represent, needs to be noted on the drawing.

Dimensioning Standards Types of Dimensions Linear Dimensioning Arcs

and Circles Reference Dimensions Dimensioning Special

Features

Methods Rules and Practices Dimensioning Angles Dimensioning Curved

Features Coordinate

Dimensioning Tolerance

Standards

In order for the drawings to be dimensioned so that all people can understand them, we need to follow standards that every company in the world must follow. Standards are created by these organizations: ANSI -MIL ISO -DOD DIN -CEN JIS

Standards Institutions

ANSI - American National Standards Institute - This institute creates the engineering standards for North America.

ISO - International Organization for Standardization - This is a world wide organization that creates engineering standards with approximately 100 countries participating.

Standards Institutions DIN - Deutsches Institut für Normung - The

German Standards Institute created many standards used world wide such as the standards for camera film.

JIS - Japanese Industrial Standard - Created after WWII for Japanese standards.

CEN - European Standards Organization

Standards Institutions The United States military has two

organizations that develop standards. DOD - Department Of Defense MIL - Military Standard

Dimensioning Methods Dimensions are represented on a drawing using

one of two systems, unidirectional or aligned. The unidirectional method means all dimensions

are read in the same direction. The aligned method means the dimensions are

read in alignment with the dimension lines or side of the part, some read horizontally and others read vertically.

Aligned DimensionsDimensions are aligned

with the dimension lines

Unidirectional DimensionsAll dimensions and

notes are horizontal and readfrom the bottom

of the sheet

Types of Dimensions Their are two classifications of dimensions:

size and location. Size dimensions are placed in direct

relationship to a feature to identify to specific size.

Location dimensions are used to identify the relationship of a feature to another feature within an object.

Size and Location DimensionsSize dimensions

Location dimensions

Rules and Practices Accurate dimensioning is one of the

most demanding undertakings when designing parts.

Use the checklist to insure you have followed the basic dimensioning rules.

Dimensioning Checklist Each dimension should be written clearly with

only one way to be interpreted. A feature should be dimensioned only once. Dimension and extension lines should not cross. Dimension each feature. Dimension features or surfaces to a logical

reference point.

Dimension Checklist

Dimension circles with diameters and arcs with a radius.

A center line should be extended and used as an extension line.

Dimension features on a view that clearly shows it’s true shape.

Dimension with enough space to avoid crowding and misinterpretation.

Dimension Checklist Extension lines and object lines should

not overlap. Dimensions should be placed outside

the part. Center lines or marks should be used

on all circles and holes.

Linear Dimensioning The accuracy of the final product is

determined by the dimensions on the drawing. If all the dimensions originate from a common corner of the part, the object will be more accurate. This is referred to as Datum Dimensioning. Datum's insure the tolerance or errors in manufacturing do not accumulate.

Linear Dimensioning Dimensioning from feature to feature is

known as Chain Dimensioning. It is commonly used and easy to layout. It does have possible consequences in the manufacturing of a part. Tolerances can accumulate making the end product larger or smaller than expected.

Chain DimensioningThis step can be .490

To .510 wideThis step can be .490

To .510 wideThis step can be .490

To .510 wide This step can be .240To .260 tallThis step can be .240To .260 tallThis step can be .240To .260 tall

The chain dimensioning layout can have an

effect on the final length of the part ranging from

1.47 to 1.53

The chain dimensioning layout can have an

effect on the final height of the part ranging

from .72 to .78

Chain DimensioningPlacing an overall dimension will limit the chain effect of the

Tolerance build up

Placing an overall dimension will limit the chain effect of the

Tolerance build up

Datum DimensioningThe dimensions originate from a common edge

(DATUM) of the part

The dimensions originate from a common edge

(DATUM) of the part

This step can be .490To .510 wide

This distance can be .990 to 1.010 wide

This distance can be 1.49 to 1.510 wide

Dimensioning Angles Angled surface may be dimensioned

using coordinate method to specify the two location distances of the angle.

Angled surfaces may also be dimensioned using the angular method by specifying one location distance and the angle.

Dimensioning Angles

Coordinate Method Angular Method

Dimensioning Arcs and Circles Arcs and circles are dimensioned in views

that show the arc or circle. Arcs are dimensioned with a leader to

identify the radius in some cases a center mark is included.

Circles should have a center mark and are dimensioned with a leader to identify the diameter.

Dimensioning Curved Features and Arcs

Use a capital “R” for dimensioning arcs.

Large Arcs use centermarks.

Small arcs do not needcenter marks. Arrow can

be outside.

Or the arrow can be inside for small arcs.

DiametersA full circular object should be dimensionedusing it’s diameter. Holes should use hole

notes.Cylindrical parts may show their diameters in this

manner. Dimensioning on the right side viewwould be too crowded.

This specificationcalls for a hole with

a .5 diameterand 1.00 deep

Dimensioning Curved Features

Datum

Points are placed along the contourand are dimensioned from the datum

Reference DimensionsDesignates more than one of the same feature.

In this case it is identifying there are two identical holes

ChamfersExternal chamfer for 45 degree chamfers

only. There are two options.

External chamfer for angles other than45 degrees.

Internal chamfers.

Fillets and RoundsUse a capital “R” for dimensioning the arc.

Rounds

Fillets

Large arcs use centermarks.

Small arcs do not needcenter marks. Arrow can

be outside the arc.

Conical Tapers

Slot DimensioningThe two methods shown on the leftare the acceptable

methods for dimensioning slotted

holes.

Hole Location: Polar Coordinates

Polar dimensioning locatesfeatures by the use of angles

multiple holes are dimensioned from another

Rectangular Coordinates

Rectangular coordinates use linear dimensionsto dimension the hole locations

Rectangular Coordinates

Linear Coordinates are used to

locate hole dimensions

Shaft

Keyway

Hole

KeywaysKeyways

Tolerance Dimensioning Perfection is difficult to obtain. A

tolerance is associated with dimensions on a drawing to illustrate the permissible variation in size or location. A tolerance specifies how much the dimension may vary from the designated size on the drawing.

Tolerance Limits The largest size an object can be made to

is the upper limit. The smallest size an object can be made to is the lower limit.

Upper limit.126

Upper limitIs .380Lower limit

.125

Lower limitIs .373

Dimensioning Tolerances Limit Dimensioning shows the size of the

upper limit and the lowerlimit.

This dimension is unilateral becausethe size may only

deviate in one direction.

If your limits deviate above and below your basic size you have bilateral

dimensioning.

AllowancesSome parts fit together requiring an

allowance to be specified.It is the tightest possible fit

between two parts

If this part is made larger than .380 it will not fit together

properly

Alphabet of LinesObject Line: Thick lines about .6mm(.032in) that show the visible edges of an object.

Hidden Line: Lines used to show interior detail that is not visible

from the outside of the part. Center Line: Lines that define the center of arcs, circles or symmetrical parts.

They are half as thick as an object line.

Construction Line: Very lightly drawn lines used as guides to help draw

all other lines and shapes properly. Usually erased after being used.

Short Break Line: A freehanddrawn line that shows where a part is

broken to reveal detail behind the part or to shorten a long continuous part. (See

example of Long Break Lineon the next slide.)

Section Lines: Lines are used todefine where there is material

after a part of the object is cut away.

Alphabet of LinesCutting Plane Line: A line used to

designate where the part has been cut away to see detail. The arrows

point in the direction that you are looking.

Long Break Lines: Break lines are used To indicate we have shortened

the drawing to use our space more efficiently.

Dimension lines are used toshow distance. Arrows are drawn on the

ends to indicate where the dimension line starts and ends. The actual distance is placed in the middle of this

line. Dimension lines are used in conjunction with extension lines to properly

dimension objects.

Extension lines are used to show wherea dimension starts and stops on an object.

The line should begin about 1/16” away from thepart to prevent confusion with the object lines

Leader lines are used to show dimensions of arcs or circles. They are also used to

connect notes with features. The line with the arrowhead should be diagonal while the

Line connecting to the note is horizontal

How many lines from the previous slide can you identify

here?

Line Types and Specifications

Dimension lines are used to identify distances of features.It has arrow heads at the end to identify the extents. There

is a break in the middle to place the dimension. Dimension lines should be 10mm away from the object that is

being dimensioned.

Each succeeding dimension lineshould be 6mm from the previous one.

Extension lines are used to establish the extent of the dimension. Arrows from the dimension line should touch the extension line. Extension lines should have a small space between the endand the object that is being dimensioned. The extension line should also extend 3mm beyond the last dimension line noted.

Arrow heads point directly to the object that is being dimensioned or the extension lines at the end of the dimension. Arrow heads

are made 3 times as long as they are wide.

The dimensioning system used here is unidirectional. This is themost common. Another system you may see is aligned. If this drawing were using the aligned system the dimension, we are pointing to would be read horizontally from the right of the

drawing or turned counter clockwise 90 degrees.

AnnotationGeneral notes are information that pertains to the entire drawing,

unless specified in a local note. General notes are usually placed in the title block.

Local notes identify specific features that need a special operation.Hole notes are one such example. This note is placed with leaders

at the location of the feature it pertains to.

Hole Dimensioning

DiameterThroughDepthCounterbore orSpotface

Holes are specified with numbers and symbols.

Hole Dimensioning

Countersink

Finish Mark

Hole Dimensioning

Through hole is drilled completelythrough the material.

A blind hole is drilled to a specific depth.

A counter bored hole has a step sothe head of a bolt can sit

below the surface.

A spotface is a shallow cut used on castings to create a flat surface for

bolts.

Boss is a raised surface used in castings for reinforcement. Finished on top to create a flat surface for the bolt to seat.

A countersunk hole has an angular cut on the top

edge to allow flathead screws to sit below the surface

Thread Notes

Threads are dimensioned with the use of local notes. We willdiscuss two methods: the ISO

and the Unified National Threadmethod.

Major DiameterThreads per Inch

Identifies course or fine thread. In this case course.

F for fine.

Notes the threads are cut allthe way through the hole. Depth

can be specified here as well as LH forleft hand thread.

M for MetricNominal DiameterPitch of the threads.

This number can be 3,4,5,6,7,8,9. It is thegrade of tolerance in the threads from fine to course. The H is for allowance

G would be a tight allowance and H is no allowance.

Prior to THRU you may have an LHfor left hand thread. Finally THRU or a depth may

be specified.