Still Looking at 3D in AutoCAD27 May, 2015 By: Bill Fane
Learning Curve tutorial: Use the ViewProj and ViewSection commands to create 2D views of your models.
It was a warm and sultry evening. Captain LearnCurve, his gorgeous wife, their daughter and son-in-law, and two grandsons had been competing in a Rolls-Royce Owners’ Club fuel economy run. The kids and grandkids drove the '89 Bentley Turbo R, but the Captain and his wife were relegated to the Subaru due to a last-minute problem with a bearing in the rear axle of their '37 Rolls-Royce Phantom III.
The run ended Saturday afternoon at the lovely seaside Tin Wiz Resort near Tofino, British Columbia, Canada. After the awards banquet, the others had gone back to their rooms, but the Captain stayed a few minutes longer to discuss a technical issue with another member. As he headed toward his room, he heard voices coming from the indoor hot tub. He stepped in to find six ladies in the hot tub. One of them asked if the Captain wanted to join them, and mentioned that they were just about to remove their tops.
That’s it! This month’s Learning Curve topic!
Topless — with pictures! This article will show you how to take the top (or bottom, or side, or end) off a 3D solid model in order to produce cross sections in a 2D working drawing.
The Standard Problem
Before we get into the topless bit, let’s look at a couple of other items first. In my previous article, we saw how fast and easy it is to generate 2D working drawings from 3D solid models using the ViewBase command.
Yes, but the resulting drawings don’t comply with our company standards!
That’s what I like about standards; there are so many of them. Let me guess: the problem is that the part outlines and hidden lines are the wrong color.
Not if “white/black” is correct, but we use red outlines and green hidden lines.
No problem, just change your template file.
Yes, there is a problem — I tried that but it didn’t work.
Aha, there’s a trick to it. ViewBase needs things done in a particular sequence:
- Open your desired template file.
- Create a simple Box 3D object.
- Use ViewBase to create an isometric 2D view.
- The Layer command now shows that ViewBase has created two new layers called MD_Visible and MD_Hidden. Edit their properties as desired (this would probably include colors and line weight).
- Delete the 2D drawing view and the 3D solid model.
- Save the template file.
That’s it! Any new drawings started from this template will have the desired layer specifications.
Now That’s Rather Basic
In my previous article, we used the ViewBase command to create a set of 2D views all in one hit. So far, so good, but what if we decide to add another view later?
No problem. The ViewProj command, found on 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've got to love the English language, where the same word, spelled the same way but pronounced slightly differently, means something else entirely. For example, I need to project one more view to complete the drawings for this project.)
Anyway, its operation is quite intuitive. Once invoked, it asks for a parent view, and then a location for the new view. It then goes on to keep asking for locations for additional views, just like ViewBase does. (Actually, that isn’t quite true. What really happens is that ViewBase creates the parent view and then invokes ViewProj. The only options are to Undo the last view placement or to eXit from the command.)
Now here are three interesting properties of views created by ViewProj:
- Any orthographic views created by it are locked to the parent. Moving the parent moves the ortho projected views, and ortho views can only be moved orthogonally.
- The parent view for projected views doesn’t have to be the same as the original parent view. Any existing view can be selected as the parent, and new views are locked to it.
- Deleting a parent view also deletes all its children and any grandchildren. I was discussing time travel with my twin 13-year-old grandsons and asked the classic paradox question: If you travelled back in time and killed your grandfather, what happens to you? Bryan replied that he would cease to exist, but then realized that if he didn’t exist then he couldn’t travel back in time, and hence the paradox. Brodie said that it would depend on whether or not his mother had been born yet.
While we’re on the subject of relatives, note that it’s also possible to have more than one parent view in a layout. For example, ViewBase lets us pick individual components out of an assembly. We can create a single multi-part 3D assembly in model space, then create 2D drawing views of the individual parts in a single paper-space layout.
Look at the Section on That Part!
It’s often desirable — or even necessary — to cut open a part to show the internal configuration in a 2D drawing view. Once again, the ViewBase family of commands provides tools that are orders of magnitude better than older AutoCAD functionality. Let’s take a look at the simple part that we’ve used for the previous articles on this topic.
We’ll start with a simple, generic section view. Given that you already have created a ViewBase of the front view of the part, invoke the ViewSection command and select the front view.
Now select start and end points for the section line, and a location to the right of the front view for the section view. Presto! You instantly have a section view somewhat like the figure below.