Graphics Programs Reference
In-Depth Information
you'll do this for nearly all the parts in this design. You'll become familiar with
me asking you to add Horizontal and Vertical constraints to sketch elements (and
I hope you won't become frustrated by how many times I ask you to do this).
The shape you presently have needs to become a square with a small gap in one
corner. It also needs to be much larger than it currently is. Going forward, I'll ask
you to approximate the correct part size when creating your sketch. Now, you'll
use some tools to correct this deliberate mistake and end up with what you need:
3. Select the Horizontal constraint icon in the Constrain panel.
4. Move to the double-ended arrow in the middle of the vertical line on
the left. As you near it, the midpoint of the line highlights. Select it
when it does.
5. Select the centerpoint of the sketch, in the middle of the Design
Depending on where you started your sketch and how long the segments
are, the sketch will shift to align the midpoint horizontally to the centerpoint.
Placing a Horizontal constraint limits vertical movement. It seems a little
strange at fi rst — the way to think about it is that the midpoint is limited to
moving horizontally.
On the right end of the status bar, Inventor now displays “7 dimensions needed”.
When you're working with parametrics, it's desirable but not mandatory that every
DOF be removed from the sketch. When this is done the sketch is fully constrained .
Another thing to be aware of is that you really don't need seven dimensions per se.
Adding a geometric constraint can eliminate one or more of the needed dimensions.
This is one of those things in life that you need to know but that you don't need to
think much about in most cases.
Now, let's limit center the bottom line using a Vertical constraint:
6. Press the Esc key to end the use of the Horizontal constraint tool.
7. Select the Vertical constraint from the Constrain panel, or press the
I key to start the tool.
8. This time, select the sketch centerpoint and the midpoint of the
bottom horizontal line. This line shifts into alignment as well.
OK. You've set the foundation, and you have something to build
on. I know it hasn't been too exciting yet, but now the changes will
start to be more apparent:
9. Select the Parallel constraint, and pick the top and bottom lines. The
curved arrow on the top line disappears because the top line is now
held parallel to the bottom line that is also constrained to be horizon-
tal. See Figure 2.12.
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