Engineering Graphics Standard

8/4/2019 Engineering Graphics Standard

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E. R. Evans, Jr. - 1/2/01, Revised 1/7/02 Engineering Graphics Standard.doc - Page 1 of 16

Penn State Erie, The Behrend CollegeSchool of Engineering and Engineering Technology

Mechanical Engineering Technology

Engineering Graphics Standard

Approved: January, 2001

Introduction:The goal of this document is to promote consistency in engineering graphics practices taught and used atPenn State Erie, The Behrend College. Being approved by the engineering graphics faculty of the School ofEngineering and Engineering Technology, this document shall be the governing standard for all drawingsand sketches made in the graphics courses taught at the Behrend College. This standard is intended toclarify, not to replace, the national graphics standard ANSI/ASME Y14.

Sheet Layout:All orthographic sketching assignments shall be done on engineering calculation paper using the format

shown in Figure 1. The paper shall be oriented horizontally with the punched holes at the top. A title blockshall be sketched along the bottom border of the sheet. All required information is to be neatly printed in thetitleblock. Multiple sheets are to be stapled together, in order, with the staple in the upper left-hand corner ofthe sheet when the sheet is oriented vertically.

The following information must appear inthe titleblock of each sheet:

Course abbreviation and sectionnumber. (Ex: METBD 110.6)

Your name

The date the sketch is created

The block number of the partsketched.

All letters shall be 1/8 high single-strokegothic capital letters.

Figure 1: Orthographic Sketch Layout

Isometric sketches shall be made on specially printed grid paper supplied by the instructor. The orientationof the paper is as shown in Figure 1.

Drawings made with Pro/ENGINEER shall incorporate the standard drawing template prepared by thefaculty. The titleblock, having a horizontal format, will include the student name, the part name, the date,part material and a drawing number. The drawing number will be of the following format:

C11000301or

A11100203

Where the C = component, A = assembly, 110-003 and 111-002 are course numbers and sections, the lasttwo digits are consecutive drawing numbers. All component or part drawings will have drawing numbersbeginning with a C. All assembly drawings will have drawing numbers beginning with an A. See page 16 forstapling requirements for assignment submissions.

METBD 110.n YOUR NAME DATE BLOCK #

2 4 22

HAND SKETCHED BORDER

4 SIDES

.60

STAPLE HERE


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The information appearing in a titleblock for a drawing created using solid modeling software willautomatically be extracted from information contained in the solid model file. Students are not to alter thetitleblock information within the drawing file. All pertinent information will be changed in the solid model partfile.

View Arrangement:

All views of a part shown on a drawing or sketch shall properly aligned and oriented using third-angleprojection. The standard view orientation is shown in Figure 2. Unless otherwise assigned, only those viewsnecessary to completely describe the part shall appear on a drawing. The front view will be the view which

shows the most shape description with the fewest hidden lines. In general, the part will be oriented torequire a minimum of hidden lines. All views must be properly aligned vertically and horizontally. Deviationof this rule is considered to be a major error. Enough space must be provided between views fordimensions. The general rule of thumb is to be consistent in view spacing.

Auxiliary views of inclined planes must be properly aligned with the view it is projected from. Typically, wewill use partial auxiliary views showing only the inclined surface. The spacing to an auxiliary view will be

consistent with other view spacing when appropriate. Auxiliary views of oblique planes can be placed on asheet in a manner consistent with detail views.

Detail views are permitted to be placed in any convenient spot on a drawing. The detail location shall beshown within a detail circle, and the detail view will have a title to identify the view.

Where appropriate, drawings containing section views will show the cutting plane line in the correct view. Ingeneral, the cross-hatching symbol for cast iron will be used on section views. The pattern angle shallchange among adjacent parts in an assembly section. Shafts, fasteners and thin parts, such as washers andgaskets will not be sectioned in an assembly section view. Section views will be identified by title. The textfor titles shall be 3/16 high.

Line Weight:All lines on a drawing should be equally dark with the exception of construction lines which should be barelyvisible at arms length. Hidden and center lines have the same width. Object lines should be thicker.Dimension and witness lines should be thin lines. Cutting plane lines should be thick phantom lines. Cross-hatching lines should be thin and parallel. The spacing of cross-hatching lines should be consistent.

FRONTBACK

BOTTOM

RIGHTSIDE

LEFTSIDE

TOP

Figure 2: Standard View Orientation


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Hidden Line Conventions:Hidden lines are shown on drawing views to represent hidden edges or contours. They are made as a seriesof dashes, approximately 1/8 long, separated by gaps that are approximately 1/16 long. The followingrules should be followed when making hidden lines:

1. Hidden lines should neatly intersect with visible lines at the edge of an object.

2. Hidden lines should not appear to be a continuation of a collinear object line. This is also truewith curved hidden lines and curved object lines.

3. Hidden lines should meet when two or more come together at one point.

4. Hidden lines make T and L corners where they meet. Hidden lines should not form a cross (+) ifthe surfaces do not intersect.

5. Parallel hidden lines should be drawn with a staggered pattern similar to a brick pattern.

6. Hidden lines should appear to jump over object lines when possible.

CORRECT INCORRECT

SHOULDNT HAVE A GAP

CORRECT INCORRECT

HIDDEN LINESEEMS TO

EXTEND THE

OBJECT LINE

CORRECT INCORRECT

CORRECT INCORRECT

CORRECT INCORRECT

CORRECT

CORRECT INCORRECT

HIDDEN CORNERSSHOULD MEET


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7. Hidden line arcs should begin and end with a dash touching the tangent points with otherfeatures.

Center Line Conventions:

Centerlines are used to represent the axis of symmetry for symmetric parts or features. They also are usedto represent bolt circles and paths of motion. The centerline is characterized by a long line, a short dash,and another long line. The figure below shows the approximate sizes for a typical centerline.

Centerlines are used mainly for dimensioning and should be omitted from unimportant rounded or filletedcorners and other shapes that are self-locating.

1Center lines typically extend approximately 1/4 beyond a

round feature, except when used as an extension line in dimensioning. In this case, they are extended asnecessary. The following rules should be followed when making centerlines:

1. Use a single centerline in the longitudinal view of round features (holes or solid cylinders) andcrossing centerlines in the round view. The dashes should intersect at the center of the roundfeature. Note that centerlines extend approximately 1/4 beyond the feature.

2. For concentric features, the centerline extends approximately 1/4 beyond the largest feature.

LONG LINES ARE 3/4 TO1-1/2 LONG

DASHES ARE APPROX

.1/8 LONG

GAPS ARE 1/16 LONG

1Technical Drawin Giesecke et al 9

thEdition Pa e 186

CENTER LINEEXTENDS ~ 1/4BEYOND LARGEST

FEATURE

CORRECT INCORRECT

DASH SHOULD TOUCHTANGENT POINT

LONGITUDINAL VIEW

ROUNDVIEW

LONGITUDINAL VIEW

HOLE

SHAFT


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3. Omit centerlines on self-locating round corners and on fillets and rounds.

4. Join holes in a pattern with centerlines. Include a dash between holes following the rules for thecenter linetype if space permits.

5. Do not include dashes in round views of holes or solid cylinders less than 3/16 diameter.

6. Show centerlines on circular cut features.

7. Use centerlines to indicate a bolt circle. A bolt circle represents the location of a round patternof holes with respect to the center of the feature.

Precedence of Lines:Often times in engineering graphics, an object line, hidden line, and centerline must coincide on a drawing.At this point, the issue of which one to show becomes important. Object lines always have precedence orcover up hidden and centerlines. Hidden lines have precedence over centerlines. In a view havingcoincident cutting plane and centerlines, the cutting plane line has precedence. See Figure 3.

R.25THE CENTER OF THE ARCIS SELF-LOCATING - .25FROM THE TOP & RIGHTEDGES


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Dimensioning Conventions:Dimensions are used to convey the size information of the part. It is important to include all of the necessaryinformation in a neat and organized fashion so as to not confuse the reader. Size information should only begiven one time on a drawing.

The following figure shows the typical proportions for a dimension:

All drawings shall comply with the following dimensioning rules2:

1. On a drawing, include only those dimensions necessary to manufacture or inspectthe part. Dimensions should be placed on a drawing so that they are clearly understood and are not

ambiguous. A dimension should only appear on a drawing one time.

2. Dimensions should be no closer than 3/8 away from the view. Subsequent rows of dimensionsshould be no closer than 1/4 away from the previous row of dimensions. Longer dimensions shouldbe further away from the view than smaller dimensions. These spacing values may be increased ifspace is available on the drawing. In this case, the spacing should be consistent on the drawing, andsubsequent row spacing should be less than the first space.

3. Witness lines should extend from 1/16 away from the part to 1/16 beyond the last dimension line.

3.06

1.31

1/4 MIN

3/8 MIN

1/16

1/16

1/8

2Modern Graphics Communication, Giesecke, et al, 1998, Pages 304-305.

OBJECT LINE HAS PRECEDENCEOVER A CENTER LINE

CUTTING PLANE LINE HASPRECEDENCE OVER A CENTER LINE

OBJECT LINE HAS PRECEDENCEOVER A HIDDEN LINE

HIDDEN LINE HAS PRECEDENCEOVER A CENTER LINE

CENTER LINES SHOWN ASSHORT DASHES

SEPARATED FROM THE

OBJECT BY A SMALL GAP.

Figure 3: Precedence of Lines


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4. Arrows should be approximately 1/8 long and approximately 1/3 that width. They may be open orclosed or filled in.

5. Overall dimensions and other dimensions that relate to two adjacent views should be placed betweenthe views. Group dimensions together in one view when possible and appropriate.

6. Dimensions should be given clearly between surfaces and points having a functional relationship toeach other so that they can only be interpreted in one way.

7. Dimensions for a feature should be placed in the view that best represents the shape of the feature.This is called contour dimensioning.

8. Avoid dimensioning to hidden lines.

9. Neither extension lines nor centerlines should join views together.

10. Centerlines are used as extension lines when locating holes in a view. In this case, they maycontinue to be drawn using the centerline linetype or a witness line can be used.

11. Dimension lines should not cross. Extension lines should not cross dimension lines. Extension linesmay cross if necessary. In this instance, no gaps are shown in the extension lines.

12. No line of a drawing should be used as a dimension line or coincide with a dimension line. Adimension line should never be joined end to end with any line of the drawing.

H

H/3

H = 1/8

1.00

1.50

CORRECT INCORRECT

1.00

1.50

1.00

CORRECT INCORRECT

1.00

.50 .50

CORRECT CORRECT


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13. To avoid tolerance build-up, leave one dimension out of a string of dimensions.

14. Use two-place decimal dimensions unless more accuracy is required. See page 273 in the text forrules on rounding-off numbers.

15. Dimension lines for small features may require the arrows to be on the outside of the witness lines.The proper techniques are shown here.

16. Diameter dimension values must begin with the symbol f.

17. Holes are located by centerlines in their round view. Size dimensions for round hole features are alsogiven in the round view with a leader. If no depth is specified, the hole is assumed to go through thepart and is called a Thru Hole. If the hole is to not go through the part, it is called a Blind Hole andthe depth of the hole must be given using the depth symbol as shown below. H = the text height.

18. Leaders should extend from the beginning or the end of a note or dimension, not from the middle.Leaders must be drawn radially, so that the arrow points to the center of the circle.

f.50

f.75.25

f.50

f..25

CORRECT INCORRECT

f.50

f.75.25

INCORRECT

.75

1.25

f.50

.75

1.25

THRU HOLE BLIND HOLE

f.50.25

DEPTH SYMBOL

.50

.50

.50

.50

.50

.25.75.50.50

.25


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19. Multiple features having the same size can be dimensioned by a single note indicating the number offeatures followed by an X, followed by the feature size.

20. The diameter of holes can be shown in the rectangular view of the hole IF and only if the rectangularview is a section view.

21. Counterbores are located by dimensioning to centerlines in their round view. Sizes for counterboresare specified in the round view with a note attached to a leader touching the counterbore.

22. Countersinks are located by dimensioning to centerlines in their round view. Sizes for countersinksare specified in the round view with a note attached to a leader touching the countersink.

23. Slots should be dimensioned by specifying the width of the slot, the center-to-center distance to theends of the slot, and specifying an R at an end to indicate that they are round. No number is given in

association with the R.

3 X f.50OBSOLETE VERSIONS OF THIS NOTE

ARE:

f.50 TYP and f.50, 3 PLCS

f.50

f 1.00.25

MEANING

f 1.00 f .50

.25

ROUND VIEW W/ PROPERNOTE

f.50

f1.00 x 90

MEANING1.00

f .50

ROUND VIEW W/ PROPERNOTE

90

8

14 2 X R


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24. According to ANSI Y14.5M 1994, slots may alternately be dimensioned using the methods shownbelow.

25. Cylinders should be located by centerlines in their round view. The size information for solid cylindersis given in the rectangular view.

26. The letter R should always precede a radius dimension. The radial dimension line should only haveone arrow, and the leader line should point to or pass through the center point of the arc. The arrowshould touch the arc.

27. Chamfers should be dimensioned by a note attached to a leader. The note contains either the lengthof a side and an angle, or the length of both sides. The word CHAMFER need not appear in the note.

28. Dimension constant radius fillets and rounds for cast parts in a note such as:

ROUND VIEWRECTANGULAR VIEW

2.00

f.75

8

22 2 X R 8 X 22 2 X R

R .50

R .50 R .50

.06 X 45 .06 X .06

FILLETS AND ROUNDS ARE R.12.

45CHAMFERS

ONLY

.10

30


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29. Keyways should be dimensioned by giving the width of the key slot and the total height of the hole andkey slot. Keyseats in shafts are dimensioned by giving the width of the slot and the distance from thebottom of the keyseat to the opposite side of the shaft.

30. All lettering of notes and dimensions on a drawing should be horizontal. General notes should appearat the bottom left side of the drawing area. If more than one note is required, they should benumbered sequentially from the bottom of the page towards the top.

31. All drawings utilizing the metric system shall use the millimeter as the basic unit of measurement. Alldimensions shall be given as whole millimeters. Toleranced dimensions are expressed with a decimalportion. Metric drawings shall have the metric symbol, as shown below, on the right side of thedrawing just above the titleblock. The text should be centered in the box.

32. On metric drawings, values less than one millimeter begin with a zero preceding the decimal point.For drawings dimensioned in inches, zeroes are omitted from the dimension before the decimal point.

33. On casting drawings, finish marks are used to indicate surfaces to be machined. Finish marks should

be placed on the edge views of all finished surfaces, including hidden edges and the contour andcircular views of cylindrical surfaces. Finish marks may be omitted from holes or other features thatinclude notes indicating a machining operation. Finish marks should not be shown on parts madefrom rolled stock. Finish marks are not shown upside down.

1.392

.315 3.98

9.3

SHAFT

METRIC

A-SIZE: 8-1/2 X 11 B-SIZE: 11 X 17

LOCATION OF NOTES


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Tolerancing:As it is impossible to mass-produce parts which are exactly alike, every dimension on a drawing has anallowable variation in size. This variation is called a tolerance. Dimensions on a drawing may be specifiedor implied. Dimensions are not specifically toleranced have an implied tolerance value which is oftenindicated in the titleblock.

Features of size will be dimensioned using plus/minus tolerance dimensions. The tolerances may be given

as unilateral or bilateral tolerances as required.

In cases in which the part will be machined individually by hand, limit dimensions should be given. Limits arethe maximum and minimum dimensions of a feature. In limit dimensioning, solid features made by cuttingmaterial away will have the larger number above the smaller number. For holes and other features enlargedby cutting, the smaller number is given first.

The location of features should be controlled using a position tolerance specified in a feature control frame.Note that the dimensions associated with the tolerance are basic. Basic dimensions appear in a box, or canbe indicated by a general note. The tolerance of the profile of a part should be controlled with a profile of a

surface tolerance in a feature control frame. When using geometric tolerances, datums must be specifiedand shown on drawings.

.505

.500f f.500 - .505

.500

.505f

1.234+.000- .002

1.234.0021.232+.002- .001

UNILATERAL BILATERAL BILATERAL

38.49+0-0.05

28.810.0238.49+0.02- 0.01

UNILATERAL BILATERAL BILATERAL

I N C H S Y S T E M

M E T R I C S Y S T E M


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Section Views:Section views are used to show the interior features of complex parts. Drawings having a section view willshow the cutting plane line in the appropriate adjacent view:

These rules apply to the creation of section views.

1. Crosshatched areas are to be bounded by object lines.

2. Use the cross-hatching pattern for cast iron. All lines are thin and parallel. The spacing should beconsistent.

3. Cutting plane lines are to be thick phantom lines long lines separated by two 1/8 long dashes andthree 1/16 dashes. The cutting plane line should extend approximately 1/4 to 1/2 beyond the viewdepending on the situation.

4. Hidden lines are omitted from section views.

5. Visible edges and contours behind the cutting plane line should be shown.

6. Centerlines used for dimensioning can extend off of cutting plane lines passing through the center ofholes, etc.

Varies from ~ 1/4 to 1/2

~1/8

~3/16

CONTOURS BEHINDCUTTING PLANE LINE

ARE SHOWN

CROSS-HATCHING ISBOUNDED BY OBJECTLINES

NO HIDDEN LINESSHOWN

FULL SECTION FRONT VIEW FULL SECTION SIDE VIEWFULL SECTION TOP VIEW


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7. When a cutting plane passes longitudinally through a rib, the rib, by convention, is not crosshatchedin the section view. If the cutting plane line passes transversely through the rib, the rib iscrosshatched.

8. In aligned sections, features such as holes, ribs and spokes are rotated into the plane of thedrawing and shown true size and true shape in the section view.

Working Drawings:A set of working drawings contains an assembly drawing, a parts list, and detail drawings of each non-standard part. When possible, the parts list will appear on the assembly drawing. The parts in the assemblywill be keyed to the parts list by balloons, containing the part number, attached to the parts with leaders. Thedetail drawings will have a balloon containing the part number which corresponds to the parts list andassembly drawing.


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Threaded Features:The simplified method of thread representation shall be used on drawings. Thread notes for holes shallinclude the tap drill size and depth, the proper thread note and the depth of thread. Thread notes forthreaded rods shall include the thread note and the length of thread.

For threads created in a part, we will use the following table to find the minimum engagement to prevent pull-out of the steel fastener. D is the nominal diameter of the screw.

Part MaterialMinimum Thread

Engagement

Steel D

Cast IronBrass

Bronze1-1/2D

AluminumZinc

Plastic2D

LENGTH

3/4 10UNC 2A x 1.25

TYPICAL THREADED ROD

TYPICAL THREADED HOLE

f.656

1.313/4 10UNC-2B

.88

NOMINALTHREAD

DIAMETER

TAP DRILLDEPTH

THREADDEPTH

TAP DRILLDIAMETER

THREADS IN HOLES ARE USUALLYMADE 3P LONGER THAN THEREQUIRED EMBEDMENT OF THE

FASTENER. THE TAP DRILL DEPTHIS THEN 3P LONGER THAN THETHREAD DEPTH.

1P = THE THREAD PITCH= 1 / (# OF THREADS/INCH)


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Stapling Sheets Together:Multiple sheet submissions must be properly stapled together as shown in the f igure below:

Staple in this corner

TITL

EBLOCK

TITLEBL

OC

K

Typed or

Hand-Written

Pages

TITLEBLOCK

TITLEBLOCK

TITLEBLOCK

Staple in this corner

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Engineering Graphics Standard