Note: Splines were significantly updated in AutoCAD 2011.

There are 2 methods for creating splines:

Sometimes you need to cut out part of one 3D object to fit another object. For example, in tongue & grove construction, you need to cut out the groove to fit the tongue. You can make this process easy with an option of the INTERFERE command.

Follow these steps:

1. Create an [...]]]>

Bill Walker sent me the following tip.

Sometimes you need to cut out part of one 3D object to fit another object. For example, in tongue & grove construction, you need to cut out the groove to fit the tongue. You can make this process easy with an option of the INTERFERE command.

Follow these steps:

1. Create an object with a tongue. For example, I drew a closed polyline and extruded it with the EXTRUDE command. (You could also create two boxes and use the UNION command to join them.)

2. Create an object that will receive the tongue. For this example, I’ve made a length of beaded face frame stock. It’s taller than the piece with the tongue, so the associated groove needs to stop at the end of the tongue. Again, you can draw a closed polyline and extrude it.

3. Position the two parts in the orientation that they will take when your model is complete. This is important, because we will be using the actual geometry of the two parts to create their final relationship. You can see that the tongue model interferes with the taller model that will have a groove (to accommodate the tongue).

4.  Switch to a layer whose color contrasts with the colors of the existing objects’ layers.

5. Start the INTERFERE command. At the Select first set of objects or [Nested selection/Settings]: prompt, select both object and press Enter when the prompt repeats.

6. At the Select second set of objects or [Nested selection/checK first set] <checK>: prompt, press Enter to check for interference and open the Interference Checking dialog box.

7.  In the dialog box, make sure to uncheck the  Delete Interference Objects Created on Close check box.  The result is that you create an interference object. You see it here in green.

8. Start the SUBTRACT command. At the Select solids, surfaces, and regions to subtract from .. Select objects: prompt, select the solid that will have the groove and press Enter to end selection. At the Select solids, surfaces, and regions to subtract ..Select objects: prompt, select the interference object you created and press Enter to end selection. You have just created the perfect groove for the tongue.

Here’s the same model and view with the Xray visual style.

Finally, I separated the objects and changed the viewpoint so you can see the groove more clearly.

Thanks to Bill Walker for submitting this tip! He is a 30+ yr. veteran of the Cabinet-Making Business who has focused on 3D modeling in AutoCAD for the last 10 years, ever since he realized that modeling in 3D let him solve problems the same way he would in the shop, but with less mess and noise. He’s a freelance AutoCAD modeler.

Create a new UCS with the 3 point option

Sometimes, you may want to return to [...]]]>

When you create a new User Coordinate System (UCS) in AutoCAD, by default, your viewpoint doesn’t change. Here I used the 3 (3 point) option of the UCS command to create a new UCS.

Create a new UCS with the 3 point option

Sometimes, you may want to return to plan view in that new UCS to get your bearings. You can do this with the UCSFOLLOW system variable. Type it on the command line and change its value to 1.

Then, when you create the new UCS, AutoCAD puts you in plan view for that new UCS.

AutoCAD plan view for the new UCS

Later (again, I’m not sure [...]]]>

AutoCAD’s surfaces have evolved over the years. First, you could add thickness to 2D objects. I’m not sure when that happened (let me know if you do), but it was in the mid-1980s, perhaps around Release 2.6. This is still the only type of 3D objects that AutoCAD LT can create.

Later (again, I’m not sure when), you could create polygon/polyface meshes. The commands were the 3D command, the 3DFACE command, the 3DMESH command, the PFACE command, and others.

Release 2010 introduced, a new type of  object, the smooth mesh. The REVSURF (revolved surface), TABSURF (tabulated surface), RULESURF (ruled surface), and EDGESURF (edge surface) commands now create the new mesh objects by default. (You can use the MESHTYPE system variable to create the older polygon mesh surface, if you want.) The new mesh objects offer much greater editing capabilities. For more information, see AutoCAD 2010 new features–scroll down to the “New mesh solids” heading and click the movie’s play button.

Because the older commands are pretty much outdated, I’ll be removing the exercises for them from the next edition of my book. But they’re still useful for people with older versions of AutoCAD and an excellent learning experience for those of you who are new to 3D drawing. So, I’ve decided to publish one of the exercises here.

In this exercise, you use the 3D command’s options to create a table and objects on the table. I assume a medium level of AutoCAD experience.

1. In AutoCAD, click New on the Quick Access toolbar or use the NEW command. Choose acad3D.dwt as the template and click Open.
2. Start the UNITS command. In the Drawing Units dialog box, set the Length unit from the Type drop-down list to Architectural. Click OK.
3. Turn on Object Snaps and set running object snaps for Endpoint and Midpoint. Switch to the 3D Modeling workspace, if your release has it.
4. Enter 3d on the command line and choose the Box option. Follow the prompts to make the tabletop:

Specify corner point of box: 1,1,30
Specify length of box: 4′
Specify width of box or [Cube]: 3′
Specify height of box: 1
Specify rotation angle of box about the Z axis or [Reference]: Press Enter.

If necessary, do a Zoom Extents to see the entire box. If you’re not in a 3D view, change the view to SE Isometric. (Use the VIEW command and choose SE Isometric from the Preset views.)

5.    Start the 3D command with the Box option again. Follow the prompts to make a leg:

Specify corner point of box: 1,1
Specify length of box: 1
Specify width of box or [Cube]: 1
Specify height of box: 30
Specify rotation angle of box about the Z axis or [Reference]: Press Enter.

6.    Mirror the leg, from one side of the table to the opposite side, using Midpoint object snaps for the mirror line. Then mirror the two legs in the other direction, so that you have four legs. Zoom out and pan as necessary to center the table in the drawing area. (If you have trouble finding the Midpoint object snaps, change the visual style to 2D Wireframe.)
7.    Start the 3D command with the Dish option. Follow the prompts to create a bowl on the table:

Specify center point of dish: 2′,2′,35-1/2
Specify radius of dish or [Diameter]: d
Specify diameter of dish: 9
Enter number of longitudinal segments for surface of dish <16>: Press Enter
Enter number of latitudinal segments for surface of dish <8>: Press Enter

The dish’s diameter is 9, so its height is half that, or 4-1/2. The center of the dish is at height 35@@bf1/2 because the tabletop is at 31 (31 + 4-1/2 = 35-1/2).

8.   Start the ELEV command on the command line. Change the elevation to 31. Leave the thickness at 0 (zero).
9.    Start the 3D command with the Cone option. Follow the prompts to create a salt shaker:

Specify center point for base of cone: 2′,1′
Specify radius for base of cone or [Diameter]: 1
Specify radius for top of cone or [Diameter] <0>: .5  (That’s 0.5.)
Specify height of cone: 4
Enter number of segments for surface of cone <16>: 8

10.    Start the 3D command with the Sphere option. Follow the prompts to draw an orange in the bowl:

Specify center point of sphere: 2′,2′,32-1/2
Specify radius of sphere or [Diameter]: d
Specify diameter of sphere: 3
Enter number of longitudinal segments for surface of sphere <16>: 8
Enter number of latitudinal segments for surface of sphere <16>: 8

11.    Start the 3D command with the Cone option again. Follow the prompts to make a plate.
(It may not seem logical to use a cone to make a flat plate. However, it works because you can create a truncated cone that is upside down and very shallow. It’s an unusual but interesting use for the CONE command.)

Specify center point for base of cone: 1′,1′
Specify radius for base of cone or [Diameter]: 2
Specify radius for top of cone or [Diameter] <0>: 5
Specify height of cone: 1/2
Enter number of segments for surface of cone <16>: Press Enter

12.    Start the 3D command with the Wedge option. Follow the prompts to make a wedge of cheese on the plate:

Specify corner point of wedge: 10,10
Specify length of wedge: 5
Specify width of wedge: 2
Specify height of wedge: 2
Specify rotation angle of wedge about the Z axis: 30

13.    Start the 3D command with the Pyramid option. Follow the prompts to draw a pyramidal pepper shaker:

Specify first corner point for base of pyramid: 2’6,2’6
Specify second corner point for base of pyramid: @1,0
Specify third corner point for base of pyramid: @0,1
Specify fourth corner point for base of pyramid or [Tetrahedron]: @-1,0
Specify apex point of pyramid or [Ridge/Top]: t
Specify first corner point for top of pyramid: @1/4,1/4,3
Specify second corner point for top of pyramid: @-1/4,1/4,3
Specify third corner point for top of pyramid: @-1/4,-1/4,3
Specify fourth corner point for top of pyramid: @1/4,-1/4,3

14.    Choose Home tab@@>View panel@@>Visual Styles drop-down list@@>Conceptual (the VSCURRENT command). Turn off the grid if it’s on. You can now visualize the drawing better.
15.    Save your drawing. It should look like the figure below.

The table with a plate, wedge of cheese, bowl, orange, and non-matching salt and pepper shakers.

3D objects in AutoCAD

The mouse wheel is the key to fast view changes:

When using the 3DORBIT command, the portion that you want to see may be hidden by another portion. In that case, before invoking the 3DORBIT command, select the object in which you are interested. Then 3DORBIT displays only the selected object. It’s cool! This [...]]]>

Tharakesh of HOPE Technologies Ltd. in Mumbai, India submitted the following tip.

When using the 3DORBIT command, the portion that you want to see may be hidden by another portion. In that case, before invoking the 3DORBIT command, select the object in which you are interested. Then 3DORBIT displays only the selected object. It’s cool! This also works for the 3DCORBIT command (3D Orbit with the Continuous orbit option).

Since 2007, however, you can use the dynamic UCS feature, which makes the process of [...]]]>

I rummaged around a box of miscellaneous junk and found this bolt. You can see that it’s about 3 inches long.

Follow [...]]]>

A common, but difficult task, is to create a threaded bolt. I recently got a request for more 3D tutorials, so here you go. This tutorial assumes an intermediate knowledge of AutoCAD.

I rummaged around a box of miscellaneous junk and found this bolt. You can see that it’s about 3 inches long.

Follow these steps:

1. Start a new drawing using acad3d.dwt as the template. Set the visual style to 3D Wireframe and the workspace to 3D Modeling.
2. Type plan to see the view from the top.
3. Create a new layer, object, and make it blue.
4. Start the POLYLINE command, specify a start point anywhere in the middle of the screen, and draw segments as follows:
   • 3<180
   • 3/16<90
   • .5<0
   • 1/4,-1/16 (this will be a diagonal line whose delta X = 1/4 and delta Y = 1/16
   • 2<0
   • Close

   Note: Close the polyline ensures that you’ll get a solid rather than a surface when you revolve. You’ll need the solid for later operations, such as UNION.

   

5. Start the REVOLVE command and select the polyline. Revolve it along the 3-unit line, for the default 360 degrees.
6. To get a fuller look, set the ISOLINES system variable to 8 and use the REGEN command.



7. Just to see the result, switch to the SW isometric viewpoint.
8. Then, switch to the Left viewpoint. You should be viewing the bolt from the top.
9. Start the UCS command and use the View option to create a new UCS. If you want, save it.
10. Return to the SW Isometric viewpoint again. You’re still in the new UCS. This will help you create the bolt’s head.
11. Start the CYLINDER command. The center should be the center of the revolved solid’s top. Use the Diameter option and set it to 9/16. The height is 0.25.
12. Create a polygon of 6 sides. The center is the bottom center of the cylinder, use the Circumscribe About Circle option. The radius = 9/32.
13. Use the EXTRUDE command to extrude the hexagon to the top of the cylinder.
14. To create the beveled top, draw a circle at the top of the cylinder, with the same 9/32 radius.
15. Extrude it, using the Taper Angle option. The taper angle = -45 degrees, the distance is -0.5, to extrude it downward.
16. Use the INTERSECT command and choose the extruded, tapered circle and the extruded hexagon, and you should see the familiar look of the head of a bolt. Here you see it in the Conceptual visual style.



17. To create the threads, start the HELIX command. The center is the center of the circle at the top of the thread area. The base radius is any quadrant of the same circle. Press Enter to set the top radius to the same as the base radius. Use the Turns option and set the turns to 14. For the axis endpoint, pick the center at the bottom of the rod, before it tapers to a point.
18. Switch to the World UCS and use the PLAN command. Turn the viewpoint so that the end of the helix is at the top or bottom. Below, you see it at the bottom. Use the UCS command with the View option.
19. To create the triangular shape of the thread, start the POLYGON command and set it to 3 sides. Set the center to the endpoint at the end of the rod. Use the Inscribed in Circle option. Set the radius to 1/16. If the endpoint of the heliix is at the bottom, as you see here, you need to rotate the triangle 180 degrees. It should look like the figure here. The point of the triangle needs to be facing outward from the rod of the bolt.



20. Start the SWEEP command and select the triangle. Use the Alignment option and set it to No. Then select the helix as the sweep path.
21. Use the UNION command to combine all the objects. Here’s the result in the 3D Hidden visual style.

Here’s the result with the Framing Steel material. I expected it to be silver but it came out coppery. It looked so good that I left it.

For an excellent set of 3D tutorials, go to JD Mather’s site.

Related tips:

* Tutorial: Draw a 3D threaded bolt-video tutorial (See a video of this tutorial!)
* 3D Tutorial: Draw a glass
* Carve a solid with a surface