Chapter Thirteen. Sheet Metal Drawings

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Chapter Thirteen. Sheet Metal Drawings

Chapter Objectives

Learn how to create sheet metal drawings
Learn about sheet metal gauges
Understand sheet metal terminology

Introduction

This chapter explains how to create sheet metal drawings. Gauges for sheet metal are presented along with bend radii, flanges, tabs, reliefs, and flat patterns.

Sheet Metal Drawings

Figure 13-1 shows a 3D solid model of a sheet metal part and a dimensioned orthographic drawing of that part. The orthographic drawing was created from the 3D model. The following sections explain how to create the 3D sheet metal drawing.

A three-dimensional solid model and the orthographic views of a sheet metal part. — **Figure 13-1**

A solid model of the sheet metal part is presented. This object is L-shaped and the horizontal plate consists of 8 holes in two rows and four columns. It also consists of a hole in the shape of a rounded rectangle at the top end. In between the horizontal and vertical portions, a rectangular hole is present on the bend. The vertical section is attached to a U-shaped part, with a hole at the center. The orthographic views of this object are also presented. The object is rectangular of width 20 in the first figure. The diameter of the eight holes is 8 and the distance between the centers of the holes in two adjacent rows and the distance between the two columns is 8. The distance from the center of the hole in the right column to the right edge is 4. A hole in the shape of a rounded rectangle is of length 10, width 5, and the radius at the four corners is R2. The space to the right side of this hole is 5. The left edge of the rectangle is attached to a U-shaped section of radius 5. This section consists of a hole of diameter 5. The distance from the center of the hole to the left edge of the rectangle is 5 and to the bottom edge of the rectangle is 25. A rectangular hole of length 6.87 and width 5 is marked on the left edge of the rectangle at a distance of 3 from the bottom. In the next view, the object is rectangular of length 50 and width 20. Two vertical lines are drawn close to each other on this rectangle. The distance between the vertical lines is 0.5. On the left vertical line, a rectangle of length 9 and width 5 is drawn at a distance of 3 from the bottom.

Exercise 13-1 Creating a 3D Sheet Metal Drawing

Create a new drawing using the Sheet Metal (mm).ipt format.

See Figure 13-2. The Sketch panels will appear. See Figure 13-3. Sheet metal drawings are initiated as 2D sketches, then developed using a combination of Sketch and Sheet Metal panel tools.

A screenshot of the create new file dialog box illustrates the steps to create a 3D sheet metal drawing. — **Figure 13-2**

The create new file dialog box displays the file path at the top. The left pane consists of a drop-down menu for templates. On clicking this menu, the three options displayed are English, metric, and mold design. Here, the metric option is selected, which is step 1. The content pane shows three drop-down menus with a vertical and horizontal scroll bar at the end of the pane. The first section is part-create 2D and 3D objects. The sheet metal (mm).ipt option is selected in this section, which is step 2. At the bottom of the dialog box, the buttons for projects, create, and cancel are displayed. Here, the create button is selected, which is step 3.

A screenshot of the drawing screen illustrates the steps to create a 2D sketch. — **Figure 13-3**

A screenshot of the drawing screen on the AutoCAD is presented. The sketch tab at the top is selected. The left end of the ribbon consists of a drop-down menu to start a 2D sketch. The panels displayed are: create, modify, pattern, and constrain. Here, the dimension tool from the constrain panel is selected. The left pane shows a drop-down menu for the model. Here, the folded model menu is selected and the options listed are the view: master, origin, and end of folded option. On the 'part 2' drawing screen, a 2-dimensional sketch is created. A rectangle of length 50 and width 20 is drawn here.

Click the Start 2D Sketch tool, select the XY plane, and use the Two Point Rectangle tool and draw a 20 × 50 rectangle.

Move the cursor into the area of the ViewCube and click the icon that looks like a house (the Home tool).

See Figure 13-3.

Exercise 13-2 Adding Thickness

Right-click the mouse again and select the Finish 2D Sketch option.

The Sheet Metal panels will appear. See Figure 13-4. Not all tools will be active at this time, but they will become active as the drawing progresses.

A screenshot of the ribbon in the AutoCAD application is presented. The sheet metal tab at the top is selected. The panels displayed are: create, modify, work features, pattern, setup, and flat pattern. Here, the sheet metal defaults option from the setup panel is selected. — **Figure 13-4**

Select the Sheet Metal Defaults option located on the Setup panel under the Sheet Metal tab.

The Sheet Metal Defaults dialog box will appear. See Figure 13-5. The Sheet Metal Defaults dialog box is used to define the thickness, material, and bend characteristics of the part.

A screenshot of the sheet metal defaults dialog box illustrates the steps to define the thickness and other factors. — **Figure 13-5**

The sheet metal defaults dialog box consists of a drop-down menu for the sheet metal rule, which is set as default_mm. A checkbox to use thickness from rule' is presented below it. No checkmark is displayed on this box, and this indicates step 1. Secondly, the right end consists of a textbox to enter the thickness. Here, the thickness is set to 0.500 mm. Below these menus, a drop-down menu for the material is displayed. Click on the downward arrow to select from the available materials. Also, a drop-down menu to unfold rule is presented. The three buttons displayed at the bottom of the dialog box are ok, cancel, and apply, out of which the ok button is selected.

Inventor has many default values already in place. Figure 13-5 shows that the default thickness is 0.500 mm. Sheet metal is manufactured in standard thicknesses. Figure 13-6 is a partial listing of available standard sheet metal thicknesses in inches, and Figure 13-7 is a partial listing of sheet metal thicknesses in millimeters.

A table lists the thickness of the wire and sheet metal gauges in inches. — **Figure 13-6**

Tabulation of the gauge and thickness (in inches) are as follows: 000 000 and 0.5800; 00 000 and 0.5165; 0 000 and 0.4600; 000 and 0.4096; 00 and 0.3648; 0 and 0.3249; 1 and 0.2893; 2 and 0.2576; 3 and 0.2294; 4 and 0.2043; 5 and 0.1819; 6 and 0.1620; 7 and 0.1443; 8 and 0.1285; 9 and 0.1144; 10 and 0.1019; 11 and 0.0907; 12 and 0.0808; 13 and 0.0720; 14 and 0.0641; 15 and 0.0571; 16 and 0.0508; 17 and 0.0453; 18 and 0.0403; 19 and 0.0359; 20 and 0.0320; 21 and 0.0285; 22 and 0.0253; 23 and 0.0226; 24 and 0.0201; 25 and 0.0179; 26 and 0.0159; 27 and 0.0142; 28 and 0.0126; 29 and 0.0113; 30 and 0.0100; 31 and 0.0089; 32 and 0.0080; 33 and 0.0071; 34 and 0.0063; 35 and 0.0056; 36 and 0.0050; 37 and 0.0045; 38 and 0.0040; 39 and 0.0035; 40 and 0.0031.

The partial list of standard sheet metal thickness (in millimeters) presented in a table are as follows: 0.050, 0.060, 0.080, 0.10, 0.12, 0.16, 0.20, 0.25, 0.30, 0.40, 0.50, 0.60, 0.80, 1.0, 1.2, 1.6, 2.0, 2.5, 3.0, 3.5, 4.0, 5.0, 6.0, 8.0, and 10.0. — **Figure 13-7**

Figure 13-5 lists 0.500 mm as a standard thickness, so this default value will be used for this example. Click the checkmark in the Use Thickness from Rule box. There should be no checkmark in the box. Set the Material Style for Aluminum-6061.

Accept the 0.500 mm Thickness value, then click OK.

Select the Face tool from the Create panel located under the Sheet Metal tab.

Select the sketch, and click OK.

The 20 × 50 panel will now have a thickness of 0.50. See Figure 13-8.

A screenshot of the drawing sheet shows the face dialog box and the steps to add thickness. — **Figure 13-8**

In the screenshot of the drawing screen, the sheet metal tab is selected at the top. Then, the face tool is selected from the create panel. The face dialog box appears. This dialog box consists of three tabs namely shape, unfold options, and bend. Here, the shape tab is selected. This tab consists of the options to select the profile and solids and a section for the offset direction on the left. On the right, two sections are shown. The first section is the sheet metal rule. Here, the checkbox to follow defaults is selected and the drop-down menu is set to default_mm. The next section is the bend. Here, the bend radius option is selected. Out of the three buttons, ok, cancel, and apply, ok button is selected. On the drawing screen, the rectangular panel of thickness 0.50 is displayed.

Bend Radii

As sheet metal is bent, the inside surface is subjected to compression, and the outside surface to tension. These forces cause the material to stretch slightly.

To edit the bend radius for a sheet metal part:

Click the Sheet Metal Defaults tool listed under the Sheet Metaltab.

Click the pencil icon next to the Sheet Metal Rule box in the Sheet Metal Defaults dialog box. See Figure 13-9.

A screenshot of the sheet metal defaults dialog box and the style and standard editor dialog box. — **Figure 13-9**

In the sheet metal defaults dialog box, the drop-down menu for the sheet metal rule is set as default_mm. A pencil icon next to this drop-down menu is clicked. Then, the style and standard editor dialog box is displayed. On the left pane, the default_mm option is selected under the menu sheet metal rule. The three tabs displayed on this dialog box are sheet, bend, and corner. The sheet tab is selected. Here, the material of the sheet is set as generic and the thickness is set to 0.500 mm. The flat pattern bend angle is set to report bending angle (A) and a preview of the bend angle is displayed in this section. The flat pattern punch representation section consists of a drop-down menu, in which the formed punch feature is selected. Again, a preview is displayed in this section. The button at the bottom left corner is import and the bottom right corner is done. It is indicated to click the bend tab in this dialog box. The bend tab consists of a bend relief section. In this section, a drop-down menu for the relief shape is set to straight. A preview of the object is shown below this menu. On the right side, the relief width is set to thickness, relief depth is set to thickness times 0.5 ul, and the minimum remnant is set to thickness times 2.0 ul. The bend radius is set to thickness and bend transition is set to none. A note is shown to accept the default values.

The Style and Standard Editor dialog box will appear. See Figure 13-9.

Click the Bend tab. See the bottom dialog box in Figure 13-9.

The Relief Depth and Minimum Remnant values shown on the Style and Standard Editor dialog box are calculated based on the thickness value specified in the Sheet Metal Defaults dialog box. This defines the Relief Depth as 0.50 mm.

The default values for Bend Radius and Relief Shape will be accepted for this example.

Click the Done box. The Sheet Metal Defaults dialog box will appear.

Note

Reliefs are added to bends in sheet metal parts to prevent tearing as the bend is created.

Click the Cancel box. (No changes were made to the bend parameters.)

Flanges

A flange is a rim formed on the edge of sheet metal for strength.

flange

A rim formed on the edge of sheet metal for strength.

Right-click the mouse and select the Flange tool.

The Flange dialog box will appear. See Figure 13-10.

A snapshot of a pop-up menu is shown. — **Figure 13-10**

The options displayed at the top are as follows: go to flat pattern, measure, face, undo, cut, sheet metal defaults, flange, and new sketch. Here, the flange tool is selected. Some of the options displayed on the pop-up menu include repeat undo, dimension display, and home view. A note states: right-click the mouse and click the flange tool.

Set the length of the flange for 20 mm, accept the 90.0° Flange Angle, and select the lower rear edge of the sketch.

The lower edge was chosen because the flange total height is to be 20 mm. If the upper edge was chosen, the total height would be 20.5, the flange height plus the material thickness. Figure 13-11 shows the flange orientation resulting from edge selection.

A screenshot of the flange dialog box illustrates the steps to add flange. — **Figure 13-11**

The flange dialog box consists of four tabs, namely shape, unfold options, bend, and corner. The shape tab is selected. This tab displays the sections namely edges, height extents, height datum, and bend position. The first step is to enter a value for the flange length in the height extents section. On the drawing screen, the lower edge of the rectangular panel is selected, which is step two. The third step is to click the flip direction if needed. This button is found next to the height extents section. Out of the buttons ok, cancel, and apply at the bottom of the dialog box, the apply button is clicked, which is step 4.

Use the Flip Direction button to change the flange orientation if necessary.

Click Apply and then Cancel. Figure 13-12 shows the resulting flange.

An illustration of a flange added to sheet metal is presented. The sheet metal and the flange are rectangular and together resemble an L-shaped plate. — **Figure 13-12**

Tabs

Tabs are similar to flanges, but tabs do not run the entire length of the edge, as flanges do. Tabs are created using a new sketch plane, and the Two Point Rectangle tool located under the Sketch tab. See Figure 13-13.

tab

A feature similar to a flange but that does not run the entire length of the edge.

A figure presents the tabs added to an object. — **Figure 13-13**

A rectangular panel positioned vertically, is shown. A square with the length of sides equals 10 is marked on the top edge of the panel. The length of the panel on the sides of this square mark is 20 on each side. In the next figure, the L-shaped object is displayed with a square-shaped section attached to the flange at the center of the top edge. This square section denoted the tab. The cut-out portion of the flange, where the tab is attached denotes the relief.

Zoom the part so that the top-edge surface is identifiable; select the top-edge surface of the vertical flange, right-click the mouse, and select the New Sketch option.

Use the Two Point Rectangle tool located on the Draw panel under the Sketch tab to draw a rectangle from the back edge of the vertical flange as shown.

Use the Dimension tool to size and locate the tab in accordance with the dimensions given in Figure 13-13.

Right-click the mouse and select the Finish 2D Sketch option.

Select the Face tool, and define the tab as the Profile.

Select OK.

Figure 13-13 shows the resulting tab.

Reliefs

Reliefs are cut out in material to allow it to be bent. If the material were not relieved, it would tear uncontrollably as the bend was formed.

relief

An area cut out of material to allow it to be bent.

Inventor’s default relief value is equal to the thickness of the sheet metal material. Figure 13-13 shows the relief that was automatically created as the tab was formed.

Holes

Holes are added to sheet metal parts in the same manner as they are added to 3D models. See Figure 13-14.

Create a new sketch plane on the top surface of the tab.

Use the Point, Center Point tool to define a center point.

Use the Dimension tool to dimension the center point location.

Right-click the mouse, and select the Finish 2D Sketch option.

Use the Hole tool on the Modify panel under the 3D Model tab panel to create the hole.

In this example, a Ø5.00 hole was created located 5 from each edge of the tab.

Corners

Both internal and external corners are created using the Corner Round tool found on the Sheet Metal panel bar.

Click the Corner Round tool on the Modify panel under the Sheet Metal tab.

The Corner Round dialog box will appear. See Figure 13-15.

An illustration to create round corners in an object. — **Figure 13-15**

Three screenshots are shown. In the first screenshot, the corner round tool from the modify panel is selected, which is step 1. Then the corner round dialog box is displayed. This dialog box consists of options to set the corner and radius. The select mode section on the right consists of two radio buttons namely corner and feature, out of which the corner button is selected. The second step is to define the radius. Here, it is set to 5 mm. The third step is to click the selected corner. The buttons at the bottom are ok, cancel, and apply. Click apply and then the ok button, which is step 4. In the preview of the object, a curved line is drawn in one corner of the square-shaped tab. In the next screenshot, the second corner is selected. In the third screenshot, both the selected corners are changed into a rounded corner.

Set the Radius value for 5 mm and click the Selected option in the Corner Round box.

Select the two outside corners of the tab.

Click OK.

Figure 13-15 shows the resulting rounded tab.

Cuts

Cuts may be any shape, other than a hole, that passes through the sheet metal. In this example a rectangular shape is used. See Figure 13-16.

An illustration to add a rectangular cut to an object. — **Figure 13-16**

A new sketch plane is presented. The rectangular panel of an object is considered. A rectangle of length 10 and width 5 is marked near the left end, at a distance of 5 from the top edge and 3 from the left edge. In the second screenshot, the cut tool from the modify panel is selected, which is step 1. Then, step 2 is to identify the profile. That is, the rectangular region to be cut in the object is identified. The cut dialog box is displayed. The section on the left is 'shape' and the right is 'extents'. The options in shape are profile and solids. The checkboxes in this section are cut across bend and cut normal. The extents section consists of the options for distance and thickness. Out of the ok and cancel buttons at the bottom of the dialog box, the ok button is selected, which is step 3. In the next figure, the selected rectangular portion is cut from the object. In the next figure, the corner round tool is applied and the corners of the rectangular cut are rounded here.

Reorient the part, create a new sketch plane, and sketch a rectangle as shown. Use the Dimension tool to size and locate the rectangle.

Right-click the mouse and select the Finish 2D Sketch option.

The Sheet Metal panel bar will appear.

Select the Cut tool from the Modify panel.

The Cut dialog box will appear.

Select the rectangle as the Profile.

Ensure that the direction of the cut is correct, and click the OK box.

The rectangular area will be removed. The depth of the cut will automatically be set for the thickness value.

Select the Corner Round tool and set the Radius value for 2 mm.

Select the four inside corners of the rectangular cut.

Click the OK button on the Corner Round dialog box.

Cuts through Normal Surfaces

Normal surfaces are surfaces that are perpendicular to each other. Cuts in normal surfaces are made by making intersecting cuts in both surfaces. See Figure 13-17.

An illustration to add a cut through normal surfaces. — **Figure 13-17**

A set of four screenshots are presented to add a rectangular cut in an L-shaped object at the normal surface. In the first step, right-click the mouse and click the new sketch option. Some of the other options displayed here include look at, measure, face, undo, and cut. The rectangular panel of the object is selected. The tab is attached to one edge. On the opposite edge, a rectangular region is marked. This rectangle is of length 8 and width 5 and is at a distance of 3 from the right edge. Extend the rectangle beyond the edge of the part. In the next screenshot, the cut dialog box is shown. Ensure that the checkbox to cut across bend is selected. Then click the ok button. In the preview of the cut, an L-shaped object is shown with the selected rectangular portion marked near the normal surface of one panel. In the next figure, the rectangular portion is cut. Now, create and cut a second rectangular shape. This portion is of length 10, width 5 and at a distance of 3 from the right edge. This rectangle coincides with the previous cut. The object with the finished cut is displayed. That is a rectangular cut that extends from one rectangular panel to the other rectangular panel.

Create a new sketch plane on the vertical flange as shown, and sketch a rectangle.

Ensure that the rectangle extends beyond the rounded edge of the surface.

Use the Dimension tool to locate and size the rectangle.

Right-click the mouse and select the Finish 2D Sketch option.

Use the Cut tool to remove the rectangle.

Create another new sketch plane on the horizontal flange, and use the Dimension tool to size and locate the rectangle.

Right-click the mouse and select the Finish 2D Sketch option.

Click the Cut tool.

The Cut dialog box will appear.

Click the Cut Across Bend box, then click OK.

Hole Patterns

A hole pattern is created from an existing hole. See Figure 13-18.

A step-by-step illustration to create a hole pattern from an existing hole. — **Figure 13-18**

Five screenshots are presented. A rectangular panel with a tab attached to the center of the bottom edge is considered. A rectangular hole is shown at the bottom edge and a hole in the shape of a rounded rectangle is shown near the left edge. A point is located on this panel at a distance of 14 from the right edge and 4 from the top edge. The hole dialog box for sketch8 is presented in the next screenshot. The simple hole is selected under the type section. Through all termination is selected under the behavior section. A preview displays a hole of diameter 2 millimeters in this section. The ok button at the bottom is selected. A hole of diameter 2 appears on the horizontal panel of the L-shaped object. In the next screenshot, the hole is marked as the feature. The edge to the right of the hole is marked as direction 1 and below the hole is marked as direction 2. The rectangular pattern dialog box is displayed. Enter the values in this dialog box. The dialog box consists of two sections namely, direction 1 and direction 2. In the direction 1 section, the number of holes is set to 4 and the diameter is set to 8 millimeters. In the direction 2 section, the number of holes is set to 2 and the diameter is set to 8 millimeters. A drop-down menu in each of these sections is set to spacing. The two buttons at the bottom of the dialog box are ok and cancel. In the next figure, a rectangular hole pattern is displayed on the horizontal panel. Eight similar holes are arranged in two rows and four columns.

Create a new sketch plane on the horizontal flange.

Use the Point, Center Point tool and create a hole on the flange.

Use the Dimension tool to locate the center point.

Right-click the mouse and click the Finish 2D Sketch option.

Click the Hole tool on the Sheet Metal panel.

The Hole dialog box will appear.

Set the Termination for Through All and the hole’s diameter for 2.

Click OK.

The dimensions for the hole come from the dimensions given in Figure 13-1.

Click the Rectangular tool located on the Pattern panel under the Sheet Metal tab.

The Rectangular Pattern dialog box will appear.

Define the Ø2 hole as the Feature.

Click the arrow under the Direction 1 heading, then the top front edge of the part. Use the Flip Direction button to change direction if necessary.

Set the number of holes under Direction 1 for 4 and the spacing for 8 mm.

Click the arrow under the Direction 2 heading, and click the left front edge of the part to define the direction.

Set the number of holes for 2 and the distance for 8 mm.

Click OK.

Flat Patterns

Flat patterns of 3D sheet metal parts can be created using the Create Flat Pattern tool. See Figure 13-19.

An illustration to create a flat pattern of an object. — **Figure 13-19**

An L-shaped sheet metal part is considered. The create flat pattern tool from the flat patterns panel is selected. Then, the L-shaped object is displayed as a flat pattern. That is, the L-shaped sheet metal part is displayed as a rectangular object with the vertical section of the object at the top and the horizontal section of the object at the bottom.

Click the Create Flat Pattern tool.

A flat pattern will automatically be created.

Punch Tool

The Punch Tool is used to create various shapes in sheet metal parts. Because sheet metal parts are thin, many shapes are created by punching through the material. Sheet metal is placed in a press and a tool with the desired shape is inserted. The press then presses down quickly, piercing the sheet metal with the punch tool to create the desired shape.

To Use the Punch Tool

Draw a 4-in.× 6-in. rectangle using the Sheet Metal (in).ipt format. It is presented in an isometric orientation.

See Figure 13-20.

An isometric orientation of a rectangular object is drawn. The length and width of the object are 6 and 4, respectively. In this view, the rectangular object is tilted along the horizontal axis, such that the vertical axis shifts near the right edge. — **Figure 13-20**

Right-click the mouse and select the Finish 2D Sketch option.

Click the Sheet Metal Default tool; set the Thickness for 0.1019 (#10 gauge) and the Material Style for Steel, Mild. Click OK.

Click the Face tool.

There is only one shape on the screen, so the Face tool will automatically select the rectangle as the profile. See Figure 13-21.

A screenshot of the sheet metal defaults dialog box illustrates the steps to use the punch tool. — **Figure 13-21**

Four steps are indicated in the screenshot. The sheet metal defaults tool from the setup panel is selected. Then, the sheet metal defaults dialog box is displayed. The sheet metal defaults dialog box consists of a drop-down menu for the sheet metal rule, which is set as default. A checkbox to use thickness from rule' is presented below it. No checkmark is displayed on this box. The thickness is set to 0.1019 inches. Below these menus, a drop-down menu for the material is displayed. The material is set to steel, mild. The three buttons displayed at the bottom of the dialog box are ok, cancel, and apply, out of which the ok button is selected. The isometric view of a rectangular object is also displayed on the drawing screen.

Click OK.

Right-click the front surface of the rectangular part and create a new sketch plane.

Use the Point, Center Point tool and the Dimension tool and locate a center mark 1.25 from the left edge and 2.00 from the top edge.

Right-click the mouse and select the Finish 2D Sketch option.

See Figure 13-22.

A solid rectangular model is shown. A center point is marked at a distance of 2 from the top edge and 1.250 from the left edge. Note: Create a new sketch and create a part. — **Figure 13-22**

Click the Punch Tool on the Sheet Metal panel bar.

The PunchTool Directory dialog box will appear. See Figure 13-23.

A screenshot of the punch tool directory dialog box. — **Figure 13-23**

In the ribbon of the AutoCAD, the punch tool from the modify panel is selected. The punch tool directory dialog box is displayed. The dialog box consists of a drop-down menu to look in, which is set to punches. Then, the content pane displays a list of names and its date modified, type, and size. Some of the names are the curved slot, keyhole, and obround. Here, the obround option is selected. The left pane displays the preview of the obround punch. The open button at the bottom of the dialog box is selected.

Select the obround punch and click Open.

The PunchTool dialog box will appear. See Figure 13-24.

A screenshot of the preview tab in the punch tool dialog box. — **Figure 13-24**

The punch tool dialog box consists of three tabs at the top. The tabs are preview, geometry, and size, out of which the preview tab is selected. Here, the path address is displayed in the textbox for location. A section lists the punch names, where the obround.ide is selected. The preview is displayed to the left of this section. The 'across bend' and 'unfold in flat pattern' checkboxes are displayed below this section and these boxes are not selected. The default option is selected from the drop-down menu shown in the 'flat pattern punch representation' section. The two buttons at the bottom are, finish and cancel. Note: Click the geometry tab in the dialog box. Also, a preview of the obround punch is shown in the drawing screen. This hole is in the shape of a rounded rectangle of length 1.500 and width 0.500. The center of this hole is at a distance of 1.250 from the left edge of the rectangular object.

Click the Geometry tab and set the Angle value for 90°.

See Figure 13-25.

A screenshot of the geometry tab in the punch tool dialog box. — **Figure 13-25**

The punch tool dialog box consists of three tabs at the top. These tabs are preview, geometry, and size, out of which the geometry tab is selected. Here, enter a value of 90 for the angle. Note: Click the size tab in the dialog box. Also, a preview of the obround punch is shown in the isometric orientation of the object. The rectangular object is positioned vertically. The hole is in the shape of a rounded rectangle of length 1.500 and width 0.500. The center of this hole is at a distance of 1.250 from the left edge of the object.

Click the Size tab and set the length and width values for 1.25 and 0.75, respectively.

See Figure 13-26.

A screenshot of the size tab in the punch tool dialog box. — **Figure 13-26**

The punch tool dialog box consists of three tabs at the top. These tabs are preview, geometry, and size, out of which the size tab is selected. Here, the name and value of width and length are displayed in a section. A drop-down menu is displayed on the side of the textbox for length. Click this menu for a listing of the standard sizes. The width is set to 0.75 inches and length is set to 1.25 inches. The finish and cancel buttons are displayed at the bottom of the dialog box. The obround punch on the rectangular object is also displayed on the drawing screen.

Note

The length and width values must conform to the standard sizes listed under the arrowheads. Random values are not allowed.

Click Finish.

See Figure 13-27.

A solid rectangular model with an obround punch is shown. This hole is in the shape of a rounded rectangle. — **Figure 13-27**

Create another New Sketch plane on the front surface of the rectangular part and locate a center mark 3.00 from the left edge and 2.00 from the top edge.

Right-click the mouse and select the Finish 2D Sketch option.

See Figure 13-28.

A figure presents a finished obround punch in a solid rectangular model. A new point is created in the model. This point is at a distance of 2 from the top edge and 3 from the left edge. — **Figure 13-28**

Click the Punch Tool and select the keyhole option. Accept the default values and click Finish.

See Figure 13-29.

A screenshot of the punch tool directory and punch tool dialog box illustrates the steps to add a keyhole to an object. — **Figure 13-29**

In the punch tool directory dialog box, the content pane displays a list of names. Some of the names are the curved slot, keyhole, and obround. Here, the keyhole option is selected. The left pane displays the preview of the keyhole punch. The open button at the bottom of the dialog box is selected. In the punch tool dialog box, the preview tab is selected. A section lists the punch names, where the option keyhole.ide is selected. The preview is displayed to the left of this section. Out of the finish and cancel buttons at the bottom of the dialog box, the finish button is selected. A rectangular solid model is shown with a preview of the keyhole. The center of the keyhole is at a distance of 3 from the left edge. The circular portion of the hole is at a distance of 2 from the bottom edge. The total height of the hole is 0.875. The diameter of the circular portion is 0.562.

Create and locate a center mark 1.25 from the right edge and 2.00 from the top edge.

See Figure 13-30.

A rectangular solid model with an obround punch and keyhole is shown. A new point is located next to the keyhole. This point is at a distance of 2 from the top edge and 1.250 from the right edge. — **Figure 13-30**

Access the PunchTool Directory, select the Square Emboss option, and click Open.

The PunchTool dialog box will appear. See Figure 13-31.

A screenshot of the punch tool directory and punch tool dialog box illustrates the steps to add a square emboss to an object. — **Figure 13-31**

In the punch tool directory dialog box, the content pane displays a list of names. Some of the names are the curved slot, keyhole, obround, and square emboss. Here, the square emboss option is selected. The left pane displays the preview of the square emboss. In the punch tool dialog box, the size tab is selected. Here, the value of various parameters namely angle, width, length, and height are displayed. Enter the length value here. The length value is set to 1.500 inches. The finish and cancel buttons are displayed at the bottom of the dialog box, out of which the finish button is selected. A rectangular solid model is shown with a preview of the square emboss. The distance from the center of this emboss to the right edge is 1.250 and to the bottom edge is 2. The length of the sides is 1.

Change the Length value to 1.50.

Click Finish.

Figure 13-32 shows the finished rectangular part.

A finished rectangular solid model is shown. The rectangular part consists of an obround punch, keyhole, and a square emboss from left to right. — **Figure 13-32**

Chapter Summary

This chapter defined and illustrated how to create sheet metal drawings from 3D models and orthographic drawings. Features of sheet metal parts such as bend radii, flanges, tabs, and reliefs were presented, and flat patterns were created. The use of the Punch Tool was also illustrated.

Chapter Test Questions

Multiple Choice

Circle the correct answer.

1. How thick is a piece of #12 gauge sheet metal?

a. 0.4600 in.

b. 0.0808 in.

c. 0.0571 in.

d. 0.0050 in.

2. How thick is a piece of #30-gauge sheet metal?

a. 0.1443 in.

b. 1/8 in.

c. 0.0100 in.

d. 0.0031 in.

3. The thickness of a piece of sheet metal is defined using which tool?

a. Sheet Metal Defaults

b. Face

c. Fold

d. Hem

4. A small piece of bent material that does not run the entire length of an edge is called a

a. Flange

b. Tab

c. Relief

d. Contour

5. Which of the following materials is not available in the Material option of the Sheet Metal Defaults dialog box?

a. Steel, Mild

b. Aluminum-6061

c. Brass, Soft

d. Plexiglas

True or False

Circle the correct answer.

1. True or False: In the English unit system, the higher the sheet metal gauge number, the thinner the material.

2. True or False: A cut made next to a tab to allow for smooth bending is called a relief.

3. True or False: As sheet metal is bent, the inside surface is subjected to compression, and the outside surface to tension.

4. True or False: Normal surfaces are surfaces located 60° apart.

5. True or False: Punch tools can be used to create slots and keyholes.

Chapter Projects

Project 13-1

Redraw the sheet metal parts in Figures P13-1A through P13-1F using the given dimensions. Use the default values for all bend radii and reliefs.

Drawings present a sheet metal parts along with the specified dimensions. — **Figure P13-1A** MILLIMETERS

An object consists of a rectangular projection at the center. The horizontal plate on either side of this projection is rectangular with curved corners and two holes each. The top surface of the rectangular projection consists of an obround punch at the center. The flat pattern of the object is also presented. The object is in the shape of a rounded rectangle with four holes at the corners. The radius of the 4 corners is R4. The diameter is 4 times 4 through the 4 holes. The distance from the center of the holes to its nearest edges is 4. The centers of the holes that are one below the other are at a distance of 12 from each other. The obround punch of length 10 and width 5.63 is shown at the center. A vertical line is drawn on either side of this punch, at a distance of 2.25. This forms a rectangular section at the center. The distance from the obround punch to the bottom edge is 5 and the radius at the corners is R2. A vertical centerline is drawn for the object. Note that the object is symmetrical about the centerline. Also, the front view of the object is presented. The total length of the object is 30 and the length of the rectangular projection at the center is 10. The length of the object on either side of the projection is 10.

Figures present different views of an object along with the specified dimensions. — **Figure P13-1C** INCHES

An isometric view of an object is presented. The object consists of a rectangular plate with a hole in the shape of a rounded rectangle at the center. At the center of the front edge, a square-shaped tab is attached, which contains a hole at the center. The rear edge is attached to a tab at the corner. The tab is in the inverted L-shape, and the top surface consists of a hole at the center. The right edge is attached to a rectangular flange with four holes. In the top-view of the object shows a rectangular section of length 3 and width 1.94. The left corner of the top edge is attached to a square-shaped section. The sides of this section are of length 1 and consist of a hole at a distance of 0.50 from the right edge and 0.44 from the top edge. The rectangular section consists of a hole in the shape of a rounded rectangle. The hole is of length 1.50 and width 0.75 and is at a distance of 0.50 from the left edge and 0.63 from the bottom edge. Two small rectangular notches on the bottom edge denote the relief and a hidden line is drawn here, representing the tab. In the front view, a thin rectangular section is placed horizontally and extends vertically at the right end. This extension at the right end is of height 0.56. A square-shaped tab is attached to the top of the horizontal section at the left end. It is of height 0.69. A square tab is attached to the bottom of the horizontal section at a distance of 1 from the left end. This section consists of a hole, which is at a distance of 0.38 from the left edge and 0.25 from the bottom edge. In the side view, a horizontal rectangular section is connected to a thin vertical section at the bottom left side and connected to another horizontal section at the top-right side of the rectangular section. The rectangular section consists of four holes. The holes are of diameter 6 times 0.19. The distance between any two adjacent holes is 0.44 and the hole at the left end is at a distance of 0.31 from the left edge and 0.25 from the top edge. The width of the thin sections is 0.6 all around.

Figures present the different views of a sheet metal part along with the specified dimensions. — **Figure P13-1E** MILLIMETERS

An isometric view of an object is presented. The object consists of a rectangular plate with a bigger hole at the center and six small holes in a circular path around this hole. The front edge of this plate is attached to a rectangular tab, which contains a hole at the center. The left edge is attached to a tab, which is in the inverted L-shape, and the top surface consists of two holes at the corners. Also, a rectangular hole is present at the center of the normal surface. The right edge is attached to a rectangular flange with three holes. In the front view of the object, a horizontal section is connected to a vertical section of length 25 at the bottom right side and connected to an L-shaped section of length 15 at the bottom-left side. All these sections are of width 0.5. On top of the horizontal section, a rectangular extension of height 13.75 consists of a hole. This hole is of diameter 5 and is at a distance of 5 from the top and left edges. The top-view shows a rectangular object with two sections. The left section consists of rounded corners and the radius at these two corners is R6. Two holes of diameter 5 are present near these corners. A rectangular projection of height 10 is marked within this section on the right edge. The distance between this projection and the top-edge is 20. The section on the right is of length 49 and consists of a hole of diameter 20 at the center. The distance from the center of this hole to the right edge is 24.5 and the bottom edge is 25. Six holes of diameter 3 are evenly spaced along a circle, which encircles the center hole. This circle is of radius R15. Two small notches on the bottom edge of this section denote the relief and the tab is represented by a hidden line of length 10. These notches are at a distance of 14.5 from the left edge. The side-view shows a rectangle, which is positioned vertically. The length and width of this section are 50 and 25, respectively. Three holes of diameter 8 are present one below the other in this section. The distance between two adjacent holes is 15. A hidden rectangular line of length 7 is drawn on the center hole. The center of the bottom hole is at a distance of 10 from the bottom edge.

Project 13-2: Inches

Design and draw a box (similar to that shown in Figure P13-2) that has a capacity of

Diagrams present the exploded view of a box. — **Figure P13-2**

An exploded view of a box in the shape of a cube is shown. The front and rear faces of the cubic box are square-shaped and are attached to a thin rectangular flange at the right and left edges. The flanges are normal to the square surface. The left and right faces are square-shaped. The bottom face is square-shaped and four thin rectangular flanges are attached to the top of the four edges. In the next sketch, the front and rear face are square-shaped and are attached to a rectangular flange at the top and bottom edge. These faces are marked as 1. The top and bottom faces of the cubic box are square-shaped and are marked as 2. The right face is marked as 3.

100 cubic centimeters and is a cube.
4 fluid ounces.
100 cubic centimeters and is rectangular with the length of one side twice the length of the other.
125 cubic inches and is a cube.
125 cubic inches and is rectangular with the length of one side 1.5 times the length of the other.
8 fluid ounces.

Project 13-3: Inches

Draw the sheet metal part shown in Figure P13-3.

The part is made from #16 gauge mild steel.

Use the following values for the Punch Tool shapes.

The Round Emboss:

Height = 0.125

Diameter = 1.250

Angle = 30°

The Slot (obround):

Length = 1.50

Width = 0.50

The Curved Slot:

Outer radius = 0.625

Inner radius = 0.250

Angle = 180°

Diagrams present the different views of the sheet metal part. — **Figure P13-3**

An isometric view of an object is presented. A rectangular plate positioned vertically, consists of four round emboss. The top edge is attached to a rectangular flange, which contains two curved slots. The bottom edge is attached to a rectangular flange, which consists of an obround slot at the center. The top view shows the top flange. The two curved slots are at a distance of 2 from each other. The distance from the center of these slots to the top edge is 1.31 and the distance from the left slot to the left end is 1.50. Hidden lines are drawn denoting the bottom flange. In the front view, the rectangular plate of length 5 and width 4 is viewed. It consists of four round emboss near the four corners. The distance from the centers of these emboss to the nearest corners is 1. In the bottom view, the bottom flange with an obround slot is viewed. The center of the obround slot is at a distance of 0.75 from the bottom edge and 2.50 from the left edge. The flange at the top is of greater length and so slightly extends outward from this flange and can be viewed. The remaining portion of the top flange is marked with hidden lines. In the side view, the top end of a vertical section is connected to the right end of a horizontal section of length 2.50. The bottom end of the vertical section is also connected to the right end of a horizontal section of length 1.75.

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Table of Contents for Chapter Thirteen. Sheet Metal Drawings

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Chapter Thirteen. Sheet Metal Drawings

Introduction

Sheet Metal Drawings

Bend Radii

Flanges

Tabs

Reliefs

Holes

Corners

Cuts

Cuts through Normal Surfaces

Hole Patterns

Flat Patterns

Punch Tool

To Use the Punch Tool

Chapter Summary

Chapter Test Questions

Multiple Choice

True or False

Chapter Projects

Project 13-1

Project 13-2: Inches

Project 13-3: Inches

Table of Contents for
Chapter Thirteen. Sheet Metal Drawings