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This example demonstrates 3D construction using only simple entities (points, lines, arcs, circles) to produce wireframes in modelspace. Descriptions of all lisp commands used in this example are available on this website. If you want to construct the example with Intellicad, you may wish to begin by setting these snaps : endpoint, center, node (point), intersection, and starting with the default UCS = WCS in plan view. Make sure the axes icon is visible somewhere on the screen. For 3D work, it is necessary to know the orientation of the UCS at all times.
To begin, BSE is used to produce the base; the rectangular surface with thickness using the values : X = 4, Y = 3, Z = .125 and accept the default position (0,0,0). Use V9 to see an oblique view of the frame as in figure 1A. All the CAD images in the example are in view 9.
Figure 1 ABC Figure 2 Figure 3
To produce a pattern of holes in the base, use PARALLEL (OFFSET) and draw four construction lines one unit away from from each bottom edge of the base. Then use 3DD (3D Diameter) to set four .375 round holes at the intersections of the four lines as in figure 1B. Delete the construction lines and prepare to add a flange with the ADF command. Specify the bend angle as 90 degrees, the radius as .125, the flange mode as zero (outside) and the flange length as 2.5 units.
Refer to figure 1C. To produce the flange in the up direction, pick the lower edge followed by the upper edge, which results in figure 2. Next, to produce a couple of rectangular slots in the new flange, first use LINE to draw a line between the points just generated by ADF. These points are in the plane of the lower surface of the base frame and also in the plane of the outside surface of the new flange. Using PARALLEL, select the line just drawn between the points and create a construction line .750 up. Then PARALLEL again, picking the left vertical line on the outside surface of the flange and creating a construction line .750 to the right. PARALLEL again, picking the construction line just drawn and create another at a distance of 1.000 . Then use 3DR (3D Rectangle) with the values : X = .25, Y = 1.0, and pick the intersections. The result is shown in figure 3. Delete the construction lines including the line between the points in the plane of the base frame. Now add another flange at the rear edge of the last flange (ADF remembers the last specified angle, radius and flange mode). Change the flange mode to 1 (inside), set the flange length at 2.0, and the result is figure 4.
Figure 4 Figure 5 Figure 6
Referring to figure 5, the arcs attached to the base frame need to be moved inward to produce a full bend relief. This is done simply using the MOVE command, selecting both arcs and relocating the free endpoint of one of the arcs to the endpoint of one of the vertical bendlines to the left of the newly constructed flange. Using LINE, connect the lower ends of the arcs to finish the corner as shown in figure 6.
Figure 7 Figure 8 Figure 9
Now add a flange to the leading edge of the last flange at an angle of 45 degrees (to the rear), changing the flange mode back to 0 (outside) with a length of 1 unit, resulting in figure 7. To close the gap between the lower edge of the previous flange and the nearest edge of the base frame, say, to provide a place to tack or fillet weld, move the two bottom edge lines of the flange with the MOVE command. Use the incremental option of the command: Displacement point: @-.124,0,0 (Enter). The .124 is used to prevent interference of the edges which could cause problems later with unfolding. Then with the LINE command, add lines to connect the moved edges with the flange and add thickness lines, resulting in figure 8.
To prepare to add a down flange from a section of the front edge of the base frame, it is necessary to break the edge lines at a specific distance from a known point. First use PARALLEL to get a new thickness line 2 units to the left of the front corner. Now using BK (a simplified BREAK command), break the edge lines at the intersections with the new thickness line. Use ADF to draw a new flange (changing the bend angle back to 90 from 45) 1.75 units long in the down direction. Figure 9 shows this flange.
Figure 10 Figure 11 Figure 12
Refer to figure 10. To construct a .090 wide relief notch, use PARALLEL to draw a thickness line parallel to the line connecting the endpoints at the top of the arcs. Use a distance of .090 . Another thickness line is needed, drawn perpendicular to the direction of the last parallel command and placed at the front edge of the base to connect the surrounding geometry and complete the notch. PARALLEL could be used, but that would require a rotation of the UCS. To avoid this, use COPY to place a line .250 from the last drawn thickness line in the desired direction. The displacement part of the command would look like this : Displacement point: @0,0,-.25 . Figure 10 shows the thickness lines in place. Now, using LINE, connect the endpoints of the thickness lines. Finally, use ELA (Entity Length Adjust), (or LLA for ICAD 2000) to extend the broken edge lines at the left to the new thickness line at the right. Figure 11 shows the completed notch.
Now, to prepare to draw a rectangular window in the last flange created, first draw a line between the points just outside the outer radii created by the last ADF command. These points are in the plane of the top surface of the base frame and also in the plane of the front surface of the new flange. Use PARALLEL to create a line at a distance of .600 down from the line just drawn between the points. Then use PARALLEL again to create a line .300 from the front left edge of the flange. Use 3DR with X = 1.4 and Y = .65, picking the intersection of the construction lines just drawn. Figure 12 shows the result.
Figure 13 Figure 14 Figure 15
Delete the construction lines. Then, using ADF, create a flange from the bottom edge of the window, with default values, .65 long, picking the inside line, then the outside to create a flange projecting out as shown in figure 13. The last step in this example is to create reliefs by moving the edges of the sides of the new flange by a fixed amount, say, .090 . Picking all the entities on a side's edge, use MOVE with .090 displacement in the appropriate direction. Do the same for the opposite side. The result is shown in figure 14. Finally, using 3DT, trim the projecting lines, then with ELA (or LLA), extend the window edges to the relief. The DAP (Delete All Points) tool is used to remove all the point entities in the model. Figure 15 shows the completed model.
To see a four-view dimensioned layout of this example, click here.
To see the flat (unfolded) pattern of this example, click here.
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