Still looking at 3D in AutoCAD



May 27, 2015

By: Bill Fane



Learning Curve Tutorial: Use the ViewProj and ViewSection commands to create 2D views of your models.

It was a hot and sweltering evening. Captain LearnCurve, his beautiful wife, their daughter and son-in-law, and their two grandsons had competed in a Rolls-Royce Owners’ Club fuel economy race. Children and grandchildren drove the ’89 Bentley Turbo R, but the captain and his wife were relegated to the Subaru due to a last minute issue with a bearing in the rear axle of their ’37 Rolls-Royce Phantom III.

The race ended on Saturday afternoon in the charming resort town of Tin Wiz, near Tofino, British Columbia, Canada. After the awards banquet, the others returned to their rooms, but the Captain stayed a few more minutes to discuss a technical issue with another member. As he made his way to his bedroom, he heard voices coming from the indoor hot tub. He stepped in to find six women in the hot tub. One of them asked if the captain wanted to join them and mentioned that they were about to take off their tops.

That’s it! The topic of this month’s learning curve!

Eh?

Topless – with pictures! This article will show you how to remove the top (or bottom, or side or end) of a 3D solid model to produce cross sections in a 2D working drawing.

The standard problem

Before we get into topless, let’s take a look at a few other things first. In my previous articlewe have seen how fast and easy it is to generate 2D working drawings from 3D solid models using the ViewBase command.

Yes, but the resulting designs do not meet our company’s standards!

That’s what I like about the standards; There are a lot of them. Let me guess: the problem is the room outlines and hidden lines are the wrong color.

Not if “white / black” is correct, but we are using red outlines and green hidden lines.

No problem, just change your template file.

Yes there is a problem – I tried but it didn’t work.

Aha, there is a trick. ViewBase needs things to be done in a particular order:

  1. Open the template file of your choice.
  2. Create a simple 3D Box object.
  3. Use ViewBase to create an isometric 2D view.
  4. The Layer command now shows that ViewBase has created two new layers called MD_Visible and MD_Hidden. Change their properties as desired (this would likely include colors and line weight).
  5. Delete the 2D drawing view and the 3D solid model.
  6. Save the template file.

That’s it! All new designs started from this template will have the desired layer specifications.

Now it’s pretty basic

In my previous article, we used the ViewBase command to create a set of 2D views in one go. So far, everything is fine, but what if we decided to add another view later?

No problem. The ViewProj command, found in the Create View panel of the Layout tab of the ribbon menu, allows us to create additional views that are projected from any existing view. (You must like the English language, where the same word, spelled the same but pronounced slightly differently, means something quite different. For example, I need project one more view to complete the designs for this project.)

Either way, its operation is quite intuitive. When invoked, it requests a parent view and then a location for the new view. It then continues to request locations for additional views, just like ViewBase does. (Actually, that’s not quite true. What actually happens is that ViewBase creates the parent view and then calls ViewProj. The only options are to undo the last view placement or exit the view. ordered.)

Here are now three interesting properties of the views created by ViewProj:

  1. All orthographic views created by it are locked on the parent. Moving the parent moves the projected ortho views, and ortho views can only be moved orthogonally.
  2. The parent view of projected views does not have to be the same as the original parent view. Any existing view can be selected as a parent and new views are locked to it.
  3. Deleting a parent view also deletes all of its children and grandchildren. I was discussing time travel with my 13-year-old twin grandsons and asking them the classic paradoxical question: If you were time traveling and killing your grandfather, what happened to you? Bryan responded that he would cease to exist, but then realized that if he didn’t exist, he couldn’t time travel, hence the paradox. Brodie said it would depend on whether or not her mother was born.

While we’re on the topic of parents, note that it’s also possible to have more than one parent view in a layout. For example, ViewBase allows us to select individual components in an assembly. We can create a single multi-part 3D assembly in model space, and then create 2D drawing views of the individual parts in a single paper space layout.

Look at the section on this part!

It is often desirable, or even necessary, to cut out a part to display the internal configuration in a 2D drawing view. Again, the ViewBase family of commands provides tools that are orders of magnitude better than the older features of AutoCAD. Let’s take a look at the simple part we used for previous articles on this topic.

We’ll start with a simple, generic section view. Since you have already created a ViewBase of the front view of the part, call the ViewSection command and select the front view.

Now select the start and end points of the section line and a location to the right of the front view for the section view. Presto! You instantly have a sectional view much like the figure below.

An “instant” section view created with the ViewSection command.

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