Pictorials in AutoCAD Class 8.2 : Using AutoCAD to Create Pictorial Drawings

R eadiness A ssessment T est n Individually take 3 minutes and respond to the following question: n What dimensions are contained on each of the principal projection planes?

Learning Objectives n Use AutoCAD to draw an oblique of an object given orthographic views of the object n Select the best orientation of an object in pictorial n Define what makes a drawing a: cavalier oblique, cabinet oblique, general oblique, isometric, axonometric, perspective, or orthographic views n Sketch pictorials of an object (either oblique or isometric) given orthographic views of the object n Use AutoCAD to generate Isometric Drawings of objects given the orthographic views of the object.

Types n Obliques – Cavalier – Cabinet n Axonometrics – Isometrics – Others n Perspectives

Cavalier Oblique n Front view true size n Receding Axis Angle (Normally 30°, 45° or 60°) is Variable n Depth dimension (receding axis) true size

Cabinet Oblique n Front view true size n Receding Axis Angle (Normally 30°, 45° or 60°) is Variable n Depth dimension (receding axis) half size

General Oblique n Front view true size n Receding Axis Angle (Normally 30°, 45° or 60°) is Variable n Depth dimension (receding axis) between half and full size

Angles in Oblique n Angles in front view are drawn true size n Other angles must be located using coordinates n Appearance of angles may be distorted

Obliques n Obliques are theoretical drawings. In reality, you can not actually view an object as an Oblique n Thin parts look very good as Obliques n Parts with angular features on multiple planes are difficult to draw as Obliques

Circles in Oblique n Drawn true size in front view n Drawn as ellipses on receding planes n Layout using a Rhombus

Today’s AutoCAD commands n Drawing setup – Drawing Aids n Display control – ZOOM n General Concepts – Keyboard Coordinates n Editing and inquiry – MOVE – COPY – TRIM n Object Snap – ENDPoint – TANgent – NEArest

Drawing Obliques in AutoCAD n Initially you should make a rough sketch of the object to get an idea of what your drawing should look like n Draw the front view as a flat orthographic view n Use the COPY command along with keyboard coordinates to place the front view along the receding axis to represent all frontal surfaces in the object n Connect the copies with lines representing the depth of the object. Remember to use OSNAP to assist in this process n Use ERASE and TRIM as appropriate to remove unwanted lines/arcs

Example

Construction of an oblique n Draw the front view using normal AutoCAD commands and techniques

Construction of an oblique n Use the COPY command to replicate the front view to depict the depth Command: COPY E Select objects: [ Other corner: [ 11 found Select objects: E /Multiple: m E Base point: [ Second point of E Second point of E Second point of displacement: E

Construction of an oblique n ERASE the portions of the depth profiles which will not be seen. Command: erase E Select objects: [ … Select objects: [ Select objects: E

Construction of an oblique n Add receding lines using OSNAP and the LINE command. Command: line E From Point: endp E of [ To Point: endp E of [ To Point: E …

Construction of an oblique n TRIM and ERASE the remaining lines which would not be visible. Command: TRIM E Select cutting edges: (Projmode = UCS, Edgemode = No extend) Select objects: [ 1 found Select objects: E /Project/Edge/Undo: [ /Project/Edge/Undo: E

Exercise 8.2.1

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

Drawing Isometrics in AutoCAD n Initially you should do a rough sketch of the object by hand to get an idea of what your drawing should look like n Switch the crosshairs to isometric mode n Draw the object using the LINE and ELLIPSE commands n Use F5 to toggle the current isometric plane n Use OTRHO and OSNAP to assist you in the drawing n TRIM or ERASE any portions which are not visible

Using isometric snap n If the crosshairs are not set in isometric mode, use the Drafting Settings dialog box. – Right click on snap button and choose settings

Drawing Ellipses n In isometrics, circular features which lie on the principal planes are shown as ellipses n These MUST be drawn using the ELLIPSE command with the Isocircle option Command: ellipse E Arc/Center/Isocircle/ : i E Center of circle: [ /Diameter: [

Pair Exercise n Draw an Isometric pictorial of the object shown on the next slide using AutoCAD. n The grid is a.2” grid n Use template E38c.dwt n Erase the “Robot Foot” n Include centerlines at the discretion of your instructor

Isometric Example

Think-Pair-Share n In the next 1 minute as an Individual n if I only answer one question... specifically what don’t you understand about pictorials [at least 3 things] n Now take 2 minutes n to merge your list with the person sitting next to you AND add 1 new item to the list n In the next 5 minutes n share the results with the other half of your team, delete questions that you can answer for each other, AND prioritize the remaining questions your list

Paired Homework