Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 17P. 1Autumn Quarter Scaling and Dimensioning Lecture 17

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 17P. 2Autumn Quarter Topics For Today Review Dimensioning Discuss Scaling and How To Use Your Scale AutoCAD 2D Book – Lesson #6 Wednesday – Lab #6 –Gears, Sprockets and Chains Thursday – Quiz on Dimensioning!!!

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 17P. 3Autumn Quarter Review – Dimensioning Terminology

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 17P. 4Autumn Quarter Dimensioning The dimensions will be placed so that they all read from one direction Lettering will be 1/8” high (3 mm) Do Not Crowd – Use guidelines –1st Dimension at least 3/8” (10 mm) away from object –Additional Dimensions should be placed ¼” (6 mm) away from the previous dimension

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 17P. 5Autumn Quarter (.25 in) (.375 in) Review – Dimensioning Standards

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 17P. 6Autumn Quarter Dimensioning Guidelines Dimension positive cylinders on the non-circular view. Dimension negative cylinders (holes) on the circular view Precede the numerical value with a phi for all diameters

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 17P. 7Autumn Quarter Dimensioning Cylinders Positive cylinders Negative cylinders

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 17P. 8Autumn Quarter Dimensioning Cylinders - Standards Radii are used for half a cylinder or less Locations of cylindrical features are given from center line to center line –Do not dimension to the curved boundary of a cylinder

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 17P. 9Autumn Quarter Dimensioning – A Procedure Sketch Dimensions lightly on the first pass Dimension Positive Shapes Dimension negative shapes Locate features by –Finished surface to finished surface –Finished surface to center line –Center line to center line –Other locating dimensions

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 17P. 10Autumn Quarter Dimensioning – A procedure (cont.) Add notes Check dimensions for completeness – Are any of them crowded? Edit dimensioning Darken dimensions

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 17P. 11Autumn Quarter Dimensioning Basic Shapes – Assumptions Symmetry –Holes in the center of a cylindrical object are automatically located

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 17P. 12Autumn Quarter Scaling Drawings – Your Scale Full Size Inches – Increments of 50 ths Full Size Metric – Increments of millimeters Full Size Inches – Increments of 1/32 Half Size Inches – Increments of 1/16

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 17P. 13Autumn Quarter Notes on Scaling Drawings Always Dimension with the True Dimension… no matter what the scale. Be sure to include the scale used for the drawing in the title block. There are many more scales available with different multiplication factors.

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 17P. 14Autumn Quarter Dimensioning with AutoCAD Follow AC2D Lesson 6 closely to gain a working knowledge of the options for dimensioning with AutoCAD. Setting up the dimension properties to match the drawing is very important.

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 17P. 15Autumn Quarter AutoCAD Dimensioning Notes Linear Dimension vs. Aligned Dimension –A Linear Dimension is Horizontal or Vertical between any two points –An Aligned Dimension is created on the angle between the two points Ordinate Dimensions –Locate all features with X or Y values based from an origin point –Used commonly with CNC Machines

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 17P. 16Autumn Quarter Common AutoCAD Dimensioning Practices Do not adjust text size, arrow size, leader size, etc. in the Dimension Style Manager –Rather, adjust the Scale factor so all parts of the dimension are re-sized together. Lesson 6 instructs you to adjust specific values – follow the steps given for this drawing. Use Scale for most other drawings.

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 17P. 17Autumn Quarter PRACTICE PRACTICE PRACTICE!!! The best way to learn any technique/subject is to practice Try opening previous drawings and adding dimensions –Be careful to fully dimension the part without over-dimensioning –Ask the TA/Professor to check your work

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 17P. 18Autumn Quarter Assignments Dwg 33 – AutoCAD 2D – Lesson #6 –Basic Dimensioning and Notes –Follow lesson – Print with standard title block Dwg 34 – Scale 1-4, Scale 2-4, & Scale 3-4 –Practice with reading and creating dimensions on different scales. –Follow instructions on sheets