ADVANCED MECHANICAL DRAFTING

LECTURE #5

PREPARING TO DRAW MANUALLY

• Purchase MECHANICAL vellum – size B, C, or D

• Use proper line types

• Use proper line weights– Object lines thick

– Hidden lines medium

– Center, phantom, & dimension lines thin

– Borders, cutting plane lines very thick

– Construction very thin and light

• Use proper text size– Notes, dimensions, labels 1/8”

– Drawing title and project 3/16”

• Use proper dimensioning techniques – review lecture #2 and DT-1000 student packet

PREPARING TO DRAW IN AUTOCAD

• Load drawing format – size B, C, or D• Move border and title block lines and

text to appropriate layers• Create layers and define line weights

and colors• Define dimension defaults• Define text font and size• Save format under a new name for later

drawings if necessary

LAYER DEFINITION

REQUIRED LAYERS:Border1 Cutting plane ObjectBorder 2 Dimension PhantomCenterline Hidden Text

Add other layers if desired

DO NOT DEFINE OR CHANGE THE COLOR, WEIGHT, OR TYPE OF ANY INDIVIDUAL ENTITY. DRAW EACH ON ITS APPROPRIATE LAYER

SETTING DIMENSION STYLES

MENU PICKS:

Dimension

Style . . .

Modify . . .

GEAR SHIFT HANDLE (GSH)GEAR SHIFT HANDLE (GSH)

OVERVIEW

• B-size drawing– Manual – vellum with mechanical title block

– CAD – format found in c:\title blocks\mech• One view required since “Ø” symbol will be

used on cylindrical parts• Longitudinal centerline required• Enlarged detail of retaining ring grooves

required• Design part in English units (inches), them

convert to metrics (millimeters) for detailing

TWO-SPEED TRANSMISSION

GEAR SHIFT HANDLE

1030FULL

ANDERSEN3-9-03DEM

3-9-03

100

Revision block to be discussed later

Project – always “TWO-SPEED TRANSMISSION”

Title – part name from layout

Drawing number – found with part name on layout

Scale – “FULL” for all drawings

Revision – begins at “0” and updates when drawing is revised

Drawn By – your last name

Date Drawn – date you finish the drawing

Layout – always “100” - found on design layout

Checked By and Date Checked are filled in by the checker (me) after the drawing is turned in. You place them on the drawing when you revise it.

Weber School District

Title Block Tolerances apply to all dimensions without specified limits or tolerances

STANDARD TITLE BLOCK DATA

Third Angle Projection symbol specifies the projection standard used on the drawing

Species that ANSI standards are applied to all parts of the drawing

Weber

GENERAL NOTESRULES

1. Must be clear, accurate, complete, and capable of only one interpretation

2. Use only commonly understood trade terms3. Must be simple, brief, and concise4. Use a condensed form, like a telegraph5. Use only commonly understood abbreviations6. Instructional notes should be in present tense7. When the same note is used on multiple drawings, its wording

should be identical on each one8. Should never repeat information found elsewhere on the drawing9. Should not refer to information on other drawings or documents,

but if the need arises, no reference should be made to data from more than one drawing or back

10. Should always be placed horizontally on the drawing11. Notes that apply to a specific feature on a detail drawing or to a

specific part on a layout should be placed adjacent to that item12. Should not be underlined (except section labels)

GENERAL NOTES

GENERAL NOTES:

1. REMOVE ALL BURRS AND BREAK ALL SHARP EDGES.

2. UNLESS OTHERWISE SPECIFIED, ALL DIMENSIONS ARE IN __________.

General notes shall be placed at the bottom of the drawing next to the title block and shall be placed

so as to allow empty space all around

Standard General Notes for Machined Parts:

GSSP, GSH, GSK, DG, DS

Other notes may be added later

INCHES or MILLIMETERS

ENGLISH TO METRIC CONVERSION(INCHES TO MILLIMETERS)

• Conversion factor 1” = 25.4 mm• Round off to one fewer decimal place than English• Zero precedes decimal point for dimensions < 1 mm• Angles specified in decimal degrees• Round upper limits down and lower limits up so as

not to exceed original envelope of tolerance• Round “MAX” dimensions down and “MIN” dimensions

up similar to limits• Remember to convert all dimensions on the drawing,

including those in notes, callouts, and title block

HANDLE DESIGNALL DIMENSIONS ON THE HANDLE (GSH)(GSH) MUST BE DESIGNED

IN ENGLISH AND DRAWN IN METRICSSTEPS:

1. Determine the proper English dimension (inches)

2. Multiply the English dimension by 25.4

3. Round the metric dimension to one decimal place less than the English

1. If dimension is a limit, round upper limit down and lower limit up

2. Round “MAX” dimensions down, round “MIN” dimensions up

4. Add leading zeros to any dimension < 1 millimeter

EXAMPLES:

.562 14.2748 14.27 3.38 85.852 85.9

.0047 .11938 .119 0.119 .001 .0254 .03 0.03

.005 MAX .127 .12 0.12 MAX .012 MIN .3048 .31 0.31 MIN

2.5612.554

65.049464.8716

65.0464.88

.0036

.00330.0910.084

.091

.084.09144.08382