The Power Pack_ISO
Based on an article by: Bill Fane



Build a simple rectangular frame using Power Pack tools.

As usual, there is more than one way to start a given command. For simplicity, we will walk through one procedure and then come back later to show alternate methods.

Start Mechanical DeskTop 4,5 or 6 Power Pack. If you are stuck with the Today window that comes up select CreateDrawings(tab)->Metric->0K (or Enter)>

1. Start a New assembly drawing (File->New). Make sure it is a New... file so the browser shows three tabs, rather than a two-tab New Part File.

2. Start the AMSTLSHAP3D command from command line or by selecting Content 3D > Steel Shapes... (if your menu bar shows Content 2D instead of 3D, select Content 2D > 3D to reset Content 3D to the top then select Content 3D > Steel Shapes...). The Select a Steel Shape dialog box is brought up (see Figure 1).


Figure 1: Select a Steel Shape dialog box.
(click image to enlarge)

3. Click the L-Shapes button. The Select a Steel Shape dialog box redisplays and looks something like Figure 2 with its array of L-Shapes and a tree directory that will display the Stadards were specified during the installation of MDT


Figure 2: Select a Steel Shape dialog box, with L-Shapes active.
(click image to enlarge)

4. Click ANSI L (Unequ... to select an ANSI standard steel angle with unequal leg lengths.

5. You are prompted to "Select first point [Concentric/cYlinder/two Edges]." Ignore the other options for now and just pick a suitable point towards the lower-left corner of the graphics screen.

6. You are now prompted to "Select second point ..." Make sure either the Polar or Ortho button in the status bar is on, and then pick a point to the right of the first one you selected. It does not matter how far to the right you pick because you are only specifying the direction and not the length for the steel angle. Ortho or Polar makes sure the steel will be horizontal.

7. A dialog box pops up with the imposing name ANSI L (Unequal angles)—Size Selection (see Figure 3). The scrollable window in this dialog box lists all the available ANSI standard steel angles with unequal legs, ranging from L 2.5 x 2 x 3/16 up to L 9 x 4 x 5/8. Select an L 5 x 3 x 5/16, and then click Finish.


Figure 3: The ANSI L (Unequal angles)—Size Selection dialog box.
(click image to enlarge)

8. You are now prompted to "Drag size [Dialog/Associate to/Equation assistant]." Enter a value of 20, and hey, presto, the steel angle of Figure 4 appears! Your color may vary.


Figure 4: A steel angle placed by the Power Pack.

You have created a new part within the assembly, and a Browser entry shows its instance (use the standard AutoCAD Copy command to create additional instances of this part). This regular Mechanical Desktop part has been generated from a dimensioned, constrained, extruded profile. It is fully parametric and can be edited using normal Mechanical Desktop editing tools.

Note: Although a generated steel shape is fully parametric, normally the only parameter you will want to edit is the extrusion length.

Now let's add a second steel shape to our frame.




Channel Two...
1. Start the AMSTLSHAP3D command again by selecting 3D Content > Steel Shapes... Because we have already used this command once, the Select a Steel Shape dialog box now resembles Figure 2.

2. On the right pane, click U-Shapes. The Buttons tab now displays a selection of available standards for U channel shapes.

3. Click the ANSI MC/C button.

As occurred for the steel angle, at this point you are prompted to "Select first point [Concentric/cYlinder/two Edges]."

Before doing anything else, let's study the options. As we have already seen, if we pick a point, we will be asked for a second point. These two points will determine the "length" direction of the steel piece. The Concentric and cYlinder options obviously allow us to orient the new piece of steel with a circular or cylindrical feature on an existing part in the assembly, while the two Edges option will allow us to align the new piece of steel with the edges of an existing part.

This is all correct as far as it goes, but two very significant conditions apply when you are placing steel shapes:

For these reasons, I usually find it faster, easier, and more effective to simply create the new piece at a random location and then to constrain it into the assembly. Let's do that next.

4. At the prompt "Select first point...", select a suitable point, and then a second point when prompted. The ANSI MC/C—Size Selection dialog box displays (see Figure 5).

5. From the scrollable window, which lists all available standard sizes of steel channels, select C 5 x 9, and then click Finish.


Figure 5: The ANSI MC/C—Size Selection dialog box.
(click image to enlarge)

6. Enter a value of 30 for the length when prompted "Drag size [Dialog/Associate to/Equation assistant], and a second piece of steel is added to the drawing (see Figure 6).


Figure 6: A channel has been added to the assembly.

7. Add three assembly constraints to mate the face of the channel to one leg of the angle, so that one end of the channel is flush with the other leg of the angle and the end of the angle is flush with the side of the channel (see Figure 7).


Figure 7: The channel is constrained to the angle.

8. Copy the channel, and constrain it to the other end of the angle as shown in Figure 8.


Figure 8: The channel has been copied and constrained.




Tee For Thee...
Given what you've already done, placing an AISC ST 3.5 x 10 tee shape into the assembly, with one slight difference, should be easy. When asked for the length, do not type in a value. Instead, enter an A for Associate to. When prompted to "Select a feature or dimension..." click the steel angle. All its underlying dimensions appear. Click the length dimension and then press the Enter key. Magic! The new piece of tee steel is exactly the same length as the angle!

Keep these three points in mind about Associate to.

To finish off our frame assembly, constrain the tee to the left channel with a mate and two flush constraints as shown in Figure 9.


Figure 9: The tee has been inserted and constrained.

And Now for Something Completely Related...
We saw that Associate to was a onetime measurement operation. What if we want to permanently link the length of a steel shape to some other part? For example, we might want to make the frame wider by increasing the length of the angle and have the tee follow suit.

No problem. Don't forget that all steel shapes are simply fully dimensioned and constrained extrusions.

1. Start the AMVARS command by selecting Part > Design variables or click on the P= button on the ..).

2. Create a Global variable called Width and give it a suitable value.

3. Edit the angle and the tee, and set their length dimensions equal to the variable called Width.

Now, when you edit Width, both shapes change length and the frame updates accordingly.

You Can't Get There from Here...
I mentioned earlier that there were several ways of sneaking up on the Power Pack commands:

1. The Content 3D menu leads you in by showing the general part categories: shapes, springs, fasteners, and so on. The dialog boxes under each selection show all available parts in all installed standards.

2. At the bottom of the Content 3D menu, the Parts Library pick shows you all installed standards. If you select a standard, ANSI for example, then subsequent selections such as shapes, fasteners, and so on will only offer ANSI standard parts even though others may be available.

3. There is a Content 3D toolbar (see Figure 10). A six-pack of beer contains six cans. The Power Pack toolbar has six buttons. Coincidence? Hmmm, I wonder...


Figure 10: The Content 3D toolbar.

And in Conclusion...
This brief introduction to the Autodesk Mechanical Desktop Power Pack has shown you a little bit of the power available in this product. You can insert virtually all of the stock components using the basic process we used with steel shapes:

1. Select a type of component (steel tee, steel channel, fastener, and so on).

2. Select its location.

3. Select a specific variant of the component (size of tee, diameter of fastener).

4. Specify the particular length required.

With about half a million parts, the Power Pack probably has what you need.


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