Bracket

Cad
Steel Bracket
AutoCAD 2002....
Creating Primitives....
1. Create a new file called Bracket. 2. Right -click the Snap button on the status bar. In the Drafting Settings dialog box, set the snap spacing to 0.5 and turn on the Grid and Snap modes. 3. Turn on the dynamic coordinate readout by pressing F6. You'll use the readout to help guide you in selecting points in the exercises that follow.....
Now start building the solid model.....
1. Click the Box tool on the Solids toolbar, or enter Box and press Enter. You can also choose Draw > Solids > Box. 2. At the Specify corner of box or [Center] <>: prompt, pick a point at coordinate 3, 2.5. 3. At the Specify corner or [Cube/Length]: prompt, enter @7, 4 and press Enter to create a box with a length of 7 and a width of 4. 4. The Specify height: prompt that appears next asks for the height of the box in the z-axis. Enter 1 and press Enter. 5. Open the Viewpoint Presets dialog box (choose View > 3D Views > Select) (or Viewpoint Presets instead of Select), and then enter 225 in the Form X Axis input box and 19.5 in the XY Plane input box.....
Turning a 2D Polyline into a 3D Solid....
1. Click the Polyline tool on the Draw toolbar. 2. At the From point: prompt, start the polyline from the coordinate .5, 2.5. 3. Continue the polyline around to create a rectangle that is 1 unit in the x-axis and 3 units in the y-axis. 4. Click the Extrude tool on the Solids toolbar, or type EXT and press Enter. 5. At the Select objects: prompt, pick the polyline and press Enter. 6. At the Specify height of extrusion or [Path]: prompt, type 1 and press Enter. 7. At the Specify angle of taper for extrusion <0> : prompt, press Enter to accept the default taper of 0(degree). The polyline now extrudes in the z-axis to form a bar. 8. Type R and press Enter to redraw the screen. The Extrude option converts polylines, circles, and traces into solids. (Regular lines, 3D lines, 3D Faces, and 3D polylines cannot be extruded.)....
Joining Primitives....
1. Start the Move command, pick the smaller of the two boxes, and then press Enter. 2. At the Base Point : prompt, use the Midpoint Osnap override and pick the middle of the black edge of the smaller box. 3. At the Second Point : prompt, pick the middle of the bottom edge of the larger box. 4. Choose Modify > Solids Editing > ..:namespace prefix = st1 ns = "urn:schemas-microsoft-com:office:smarttags" />..Union.., or type Uni and press Enter. You may also click ..Union.. on the Solids Editing toolbar. 5. At the Select objects: prompt, pick both boxes and press Enter.....
Now let's place some holes in the bracket. (....create negative forms to cut portions out of a solid.)....
1. Click the Cylinder tool on the Solids toolbar, or type Cylinder and press Enter. You can also choose Draw > Solids > Cylinder. 2. At the Specify center point for base of cylinder or [Elliptical] <0,>: prompt, pick a point at the coordinate 9,5.5. 3. At the Specify radius for base of cylinder or [Diameter] : prompt, enter .25. Note At with the Circle command, you can enter D to specify a diameter or enter a radius value directly. 4. At the Specify height of cylinder or [Center of other end] : prompt, enter 1.5 and press Enter. The cylinder is drawn. 5. Copy the cylinder two inches in the negative direction of the y-axis. You now have the cylinder primitive, but you still need to define its relationship to the composite solid you created from the two boxes. 1. Choose Modify > Solids Editing > Subtract, or type Su and press Enter. You may also click the Subtract tool on the Solids Editing toolbar. 2. At the Select solids and regions to subtract from...Select objects: prompt, pick the composite solid of the two boxes and press Enter. 3. At the Solids and regions to subtract...Select objects: prompt, pick two of the cylinders and press Enter. The cylinder has now been subtracted from the bracket. 4. To view the solid, choose View > Hide. You'll see a Hidden Line view of the solid.....
Tapering an Extrusion....
1. Draw a 3 X 3 closed polyline at the top of the current solid. Start at the back-left corner of the bracket at coordinate 3.5,3,1, and then draw the 3 X 3 closed polyline to fit in the top of the composite solid. Warning Remember to use the Close option to create the last side of the box. 2. Click the Fillet tool on the Modify toolbar. At the Select first object or [Poly6line/Radius/Trim] : prompt, type R and press Enter to set the radius of the fillet. 3. At the prompt for the fillet radius, type . 5 and press Enter. 4. At the Command prompt, (pres Enter to again issue the Fillet command, and then) type P and press Enter to tell the Fillet command that you want to chamfer a polyline.(4. or click 1-st line and 2-nd line). 5. Click the polyline. The corners become rounded. 6. Click the Extrude button on the Solids toolbar, or enter Ext at the Command prompt. 7. At the Select objects : prompt, pick the polyline you just drew and press Enter. (As the prompt indicates, you can pick polylines or circles.). 8. At the Specify height of extrusion or [Path] : prompt, enter 3. 9. At the Specify angle of taper for extrusion <0> : prompt, enter 4 for 4 (degree) of taper. 10. Join the part you just created with the original solid. Choose Modify > Boolean (Solids Editing) > ..Union.., and then select the extruded part and the rectangular solid just below it. Note In step 9, you can indicate a taper for the extrusion. Specify a taper in terms of degrees from the z-axis, or enter a negative value to taper thev extrusion outward. Press Enter to accept the default, 0 (degree), to extrude the polyline without a taper. ....
Extruding on a Curved Path ....
1. Choose View > Zoom > Extents and turn off the grid. 2. Choose View > Hide to help you view and select parts of your model in the following steps. 3. Place the User Coordinate System (UCS) on a vertical plane perpendicular to the back of the bracket. Choose Tools > Orthographic UCS > Left. 4. Start a polyline (at the point shown in the top image). Use the Midpoint Osnap to make sure you select the midpoint of the vertical corner edge. After you locate the first point, enter the following coordinates: @2<180;> New UCS > Y, and then enter 90. This command rotates the UCS 90 degrees around the y-axis so the UCS is perpendicular to the front face of the solid. 10. Draw a circle with a 0.35-unit radius. Tip The Hidden-Line view of the solid in Fig 12.18 shows a lot extra facets on the curved portion of the model. You can set up AutoCAD so these extra facets don't appear. Open the options dialog box and check the Show Silhouettes in Wireframe option on the Display tab....At this point , you've created the components needed to do the extrusion. ....
Next, you'll finish the extruded shape.....
1. Click the Extrude button ( or type Ext) on the Solids toolbar, click the circle, and then press Enter. (If Snap is ..ed) you can't select the circle (A.I.)). 2. At the Specify height of extrusion or [Path] : prompt, type P and press Enter to enter the Path option. 3. At the Select extrusion path : prompt, click the polyline curve. AutoCAD pauses a moment and then generates a solid tube that follows the path. The tube not look like a tube, because AutoCAD draws extruded solids such as this with a single line showing its profile. 4. Click the Subtract tool on the Solids Editing toolbar or choose Modify > Solids Editing > Subtract, and then select the rectangular solid. 5. Press Enter. At the Select objects : prompt, click the curved solid and press Enter. The curved solid is subtracted from the square solid. In this exercise, you used a curved polyline for the extrusion path, but you can use any type of 2D or 3D polyline, as well a lines and arcs, for an extrusion path.....
Revolving a Polyline....
1. Zoom in to the top of the tapered box. 2. Turn off Snap mode. 3. Return to the WCS by choosing Tools > New UCS > World. 4. Choose Tools > New UCS > Origin. 5. At the Origin : prompt, use the Midpoint Osnap override and pick the midpoint of the top surface. 6. Set the Snap distance to 0.25 and turn on Polar Tracking. 7. Draw a ployline using Polar Tracking with the following polar coordinates: Start at -0. 25, 0; @0.75<90;> 3D Operation > Rotate 3D. 2. At the Select Objects: prompt, select the revolved solid and press Enter. 3. At the prompt....
Axis by Entity/Last/View/Xaxis/Yaxis/Zaxis/<2point>....
use the Midpoint Osnap and click the right-side edge of the top surface. 4. At the 2nd point on axis : prompt, use the Midpoint Osnap again and click the opposite side of the top surface. 5. At the ../Reference: prompt, type 5 and press Enter. The solid rotates 5 degrees. 6. Click the Subtract tool on the Solids Editing toolbar or choose Modify > Solids Editing > Subtract, click the tapered box, and then press Enter.....
Editing Solids. Splitting a Solid into Two Pieces....
1. Zoom to the previous view and return to the World Coordinate System. 2. Click the Slice tool on the Solids toolbar, or type Slice and press Enter. Note In step 3, you could select more than one solid. The Slice command would then slice all the solids through the plane indicated in steps 4 and 5. 3. At the Select object: prompt, click the part you've been working on and press Enter. 4. At the prompt: ....
Specify first point on slicing plane by [Object/Zaxis/View/XY/YZ/ZX/3points] <3points>: type XY and press Enter. This command lets you indicate a slice plane parallel to the xy plane. 5. At the Point on XY plane <0,0,0>: prompt, type 0,0, . 5 and press Enter. This command places the slice plane at the z-coordinate of . 5 units. You can use the Midpoint Osnap and pick any vertical edge of the rectangular solid.(here don't press Enter (A.I.)). Note If you want to delete one side of the sliced solid, you can indicate the side you want to keep by clicking it in step 6, instead of entering B. 6. At the Specify a point on desired side of the plane or [keep Both sides]: prompt, type B and press Enter to keep both sides of the solid. AutoCAD will divide the solid horizontally, one-half inch above the base of the part. ....
Rounding Corners with the Fillet Tool....
1. Adjust your view of the model so it looks similar to the top image. 2. Click the Fillet tool on the modify toolbar. 3. At the Select first object or [Polyline/Radius/Trim]: prompt, pick the edge indicated in the top image of Fig. 12.26 4. At the Enter fillet radius: prompt, type . 2 and press Enter. 5. At the select an edge or [Chain/Radius]: prompt, type C and press Enter for the Chain option. Chain lets you select a series of solid edges to be filleted. 6. Select one of the other three edges at the base of the tapered form, and press Enter when you are done. 7. Choose Hide on the Render toolbar, or type Hide and press Enter, to bet a better look at your model, as shown in the bottom image of Fig 12.26. As you saw in step 5, Fillet acts a bit differently when you use it on solids. The Chain option lets you select a set of edges, instead of just two adjoining objects.....
Chamfering Corners with the Chamfer Tool....
To practice using Chamfer, you'll add a countersink to the cylindrical hole you created in the first solid.....
1. Type Regen and press Enter to return to a Wireframe view of your model. 2. Click the Chamfer tool ob the Modify toolbar, or type Cha. 3. At this prompt Select first line or [Polyline/Distance/Angle/Trim/Method]: pick the edge of the hole, a shown in Fig 12.27. Notice that the top surface of the solid is highlighted, and the prompt changes to Enter surface selection option [Next/OK (current)] ..:. The highlighting indicates the base surface, which will be used as a reference in step 5. (You could also type N and press Enter to choose the other adjoining surface, the inside of the hole, as the base surface.) 5. At the Specify base surface chamfer distance <0.>: prompt, type . 125 and press Enter. This command indicates that you want to chamfer to have a width of . 125 across the highlighted surface. 6. At the Specify other surface chamfer distance <0.>: prompt, type . 2 and press Enter. 7. At the Select an edge or [..Loop..]: prompt, click the edges of both holes and d then press Enter. When it is done, your drawing will look like Fig.12.28. 8. After reviewing the work you've done, save the Bracket . dwg file. ....
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Photo

Photo

Drawng a chair - Barcelon

Defining a UCS
1. Start AutoCAD and create a new file called Barcelon.
2. Set up your drawing as an architectural drawing with a scale
of 1”=1’-0” on an 81/2 x 11” sheet. Set the upper-right cor-
ner of the limits to 132x102. If you’re a metric user, you’ll
be drawing the chair at a scale of 1 to 10 on an A4 sheet.Your
Your work area should be 297 x 210, which is the equivalent of a
297cm by 210cm area.
TIP: If you are a metric user and you prefer to work in millimeters,
You can set the upper-right corner of the limits to 2970, 2100.Then,
when the book specifies a length or coordinate , multiply the specified
value by 10. For example, 50cm becomes 500mm. Coordinate 50,50
becomes 500,500. Your scale factor would also changed to 100.
3. Choose View>Zoom>All or type Z, press Enter, type A, and press
Enter again.
4. To draw the seat of the chair, click the Rectangle tool on the Draw toolbar.
Draw a rectangle (I draw a box) measuring 20” in the x-axis and 30” in the y-axis. Position the rectangle so the lower left corner is at the coordinate 2’-0”,2’-0”(see the top image of Figure 11.2) . Metric users should draw a rectangle that is 50cm by 76cm with its lower-left corner at coordinate 50,50.
5. To draw the back of the chair, draw another rectangle (I draw a box and I enter 3 at Specify height of the box) 17” in the x- axis,and 30” in the y-axis, just to the right of the previous rectangle (see the top image of Figure 11.2). Metric users should make this rectangle 43cm by 76cm.
6. Choose View> 3D Views>SW Isometric to see a 3D view from the lower left of the rectangles, as shown in the bottom image of Figure 11.2.
7. Select the two rectangles, and then click the Properties tool on the Standard
Toolbar. (I see Properties on: Right click; View>Toolbar>Properties;
Modify>Properties).
8. In the Properties dialog box, enter 3 in the Thickness setting and click OK. This
setting gives the seat and back a thickness of 3”. (I enter 3 at Specify height of the box) Metric users should make the thickness 7.6cm.
9. Close the Properties dialog box.
10. Zoom out a bit and give yourself some room to work.
Next you will define a UCS that is aligned with one side of the seat.

1. Right-click any toolbar, and at the pop-up menu, select UCS. The UCS toolbar apears.

2. Click the Display UCS Dialog tool in the UCS toolbar.

The UCS dialog box appears.

3. Select the Orthographic UCSs tab to view a se of preefined UCSs.

4. Select Front in the list box. Figure 11.3 shows the orientation of the front UCS.

5. Click the Set Current button to make the Front UCS the curren one.

6. Click OK to close the dialog box.

The Orthographic UCSs tab offers a set o predifined UCSs for each of the six standard orthographic projection planes.Figure 11.3 shows these UCSs in relation to the World Coordinate System. You can also accessthese orthographic UCSs from the Tools>Orthographic UCS cascading menu, or from the UCS dialog box.

Because a good part of 3D involves drawing in these orthographic planes, AutoCAD supplies these ready-made UCS orientations for quick access. But you aren't limited to these six orientations by any means. If you are familiar with mechanical drafting , you'll see that the orthographic UCSs correspond to the typical orthographic projections used in mechanical drafting.If you are an architect, the Front, Left, Back, and Right UCSs correspond to the south, west, north, and east elevationsof a building. Before you continue building the chair model, you'll want to move the UCS to the surfaceon which you wil be working. Right now, the UCS has its origin located in the same place as the WCS origin. You can move a UCS so that its origin is anywhere in the drawing where it's needed.

1. Click the Origin UCS tool in theUCS toolbar.

2. Use the Endpoint Osnap and click the bottom-front corner of the chair seat, as shown in

Figure 11.4. The UCS icon moves to indicate its new origin's location.

The operation you just performed created a new UCS based on the Front UCS you selected from the UCS dialog box. Now, as you move your cursor, you'll see that the origin of the UCS icon corresponds to a 0,0 coordinate. Although you have a new UCS, the WCS still exists, and you can always return to it when you need to.

Saving a UCS

Once you've gone through the work of creating a UCS, you may want to save it. Especially if you

think you'll wan to come back to it later on. Here's how to save a UCS.

1. Click Display UCS Dialog box n the UCS toolbar. You can also choose Tools>Named UCS. The UCS dialog box appears.
2. Make sure the Named UCSs tab is selected, and then highlight the Unnamed option in the Current UCS list box.

3. Right-click Unnamed, and then select Rename from the list box. Thae item change to allow editing.

4. Type 3DSW an press Enter for the name of your new UCS.

5. Click OK to exit the dialog box.

Working in a UCS

1. Click th seat back to expose his grips.

2. Click the bottom grip, as shown in the first image of Figure 11.5

3. Right-click the mouse to open the Grip Edit pop-up menu.

4. Select Rotate from the menu. Notice how the seat back now rotates with the movement of the cursor. Take a moment to play with this notation; it may take a while to grow accustomed to it. Because thi is an Isometric view, you can get an optical illusion effect.

5. Type 80 and press Enter to rotate the seat back 80 degree. Your view will look like the second image of Figure 11.5.

6. Click the bottom grip shown in the second image of Figure 11.5

7. Right-click the mouse again and select Move.

8. Using the Endpoint Osnap, click the top corner of the chair seat, as shown in the second image of Figure 11.5, to join the chair back to the seat.

9. Click both the chair seat an back; then, click the bottom corner grip of the seat, as shown in the third image of Figure 11.5.

10. Right-click the mouse; then, at the Grip Edit pop-up menu, click Rotate.

11. Enter -10 and press Enter to rotate both the seat and back minus 10 degrees. Pres the Esc key to clear the grips. Your chair will look like Figure 11.6.

The new UCS orientation enabled you to use the grips to adjust the chair seat an back.

Now, to finish th chair seat and back, add a 3D Face to their top and bottom surfaces.

1. To help you visualize what's going on a yo add the 3D Face, turn on the Hidden Shade mode by choosing View>Shade>Hidden. Or, if you have the Shade toolbar open, you can click the Hidden tool.

2. Click the 3D Face button on the Surfaces toolbar, or choose Draw>Surfaces>3D Face, to draw a surface over the top sides of the chair seat and back. Start the 3D Face in the left-most corner of the seat and work in a counterclockwise fasion.

NOTE

To dispaly the Surfaces toolbar, right-click any toolbar, and then choose Surfaces from the Toolbars dislog box.

3. Add the 3D Faces to the bottom of the chair seat and to the chair back, as shoiwn in Figure 11.7.

4. when you're finished adding the 3D Faces, turn off the Hidden Shade moder. Choose View>Shade>2D Wireframe.

Normally, when you are picking points for 3D Faces, it doesn't matter where you begin selectin points. But for the purpose of this chapter, you selected points for the seat's 3D Face starting at the left-most corner and working in a counterclockwise fashion. The way you create the chair seat will influence the acton for some UCS command options that you'll use later in this chapter.