3D CAD

[bobgaggle]

I work in a scene shop and generate a lot of construction drawings in AutoCAD. Almost always 2d plans with ortho views. Sometimes on a complicated thing I'll do a quick and dirty 3d version so the fabricator can get a handle on what he's making.

Wanted to know the prevalence and usefulness of just switching over to 3d for everything. Example, I can save myself a lot of time if I draw this thing in 3d once, vs drawing 4 different views of the same thing in 2d. Making changes is exponentially easier too...

what are some other benefits of putting out drawings in 3d?

 

[Van]

As a TD I often cranked out 3d renderings as explanations just as you related. Once I got better at slicing and dicing my drawings I found that extrapolating my working, 2d drawings was pretty easy and it did increase workflow.

 

[kicknargel]

I do everything in 3D (using Vectorworks). Both for design and shop drawings. I can't really speak to comparative speeds of workflow, since I've always done it this way. For simple units I'm sure 2D is faster. But for more complex things, I suspect being able to model it once and take as many views as you want is faster.

Some advantages of 3D:

• Accuracy. For complex structures, taking the time to model it in 3D helps me to catch a lot of problems. I know all the parts will fit together, because I have a model.
• Communication. I think the ability to look at orthogonal views and mentally assemble them into 3D is a dying art. Being able to put nice 3D views right on the page helps folks on the floor quickly understand the big picture.
• Editing. All of my drawings are views of one model. So any change automatically propagates to all the drawings.

Over time, I've built a good template and workflow that speeds things up. Here are the basics (again, this is for Vectorworks. It would have to be interpolated for Auto CAD):

• I use classes for different components of each unit: frame, skins, trim, hardware, etc. That make it easy later to have drawing of just the frame, etc.
• I turn each unit that will have its own drawing into a symbol.
• I put all the unit symbols together on one layer so they all fit together and interact as in real life.
• When done, I make new layers, one for each unit, and put a symbol instance on the layer, oriented conveniently for the drawing.
• I have a sheet layer built with all the appropriate viewports pre-defined with top, side, front and 3D views, with different class visibilities. I select all the viewports and point them at one of the unit layers. Then all my views appear. Then I just arrange and add dimensions and notes. Repeat for each unit.
• I often draw a section detail in 2D manually. I draw it on top of a viewport view, then change the visibilities to see only my 2D. This allows me to communicate what I want without cluttering the drawing.
• I use hybrid symbols (that have a 2D plan view) to create a composite ground plan that's uncluttered.
• If I need more selective visibility, I either make symbols within my symbols, or use groups inside the symbol. I have some classes for group 1, group 2, etc, so I can turn them on and off in viewports.

I'll attach an example.

 

[RickR]

In modern CAD everything really is 3D, but you can set it be ignored. The real change is in how you think about drafting. If you are doing an electronic drafting table then, yes moving into 3D will be huge. The paradigm is to draw everything 3D and extract 2D as needed.

 

[rochem]

You hit the main ones on the head. Once you get used to drawing in 3D, everything just becomes easier. I work at a major scene shop in New York, and we do everything in 3D (I use Inventor primarily, but I bounce into 3D AutoCAD occasionally depending on the project). The biggest change for me was not having to think about things like drafting conventions until after I've figured the piece out. For a simple box or flat, that's not a big deal, but when designing a huge, forced-perspective, automated steel structure with hundreds of LEDs and an integrated automation track, being able to just worry about making the model work in 3D space is infinitely easier. Once I've figured out how to make it all happen, the software generally takes care of the drafting standards (such as hidden lines, hatches in sections, etc.) thus making it faster and easier for me to create shop drawings. And when something inevitably changes, I can update one model and know that the drawing and all the different views I have of it will update as well. Additionally, by working in Inventor, the software is smart enough to update related properties as well - so if I need to change a bolted connection from 1/4" hardware to 3/8" hardware, the corresponding bolt plates and such will update automatically throughout the model and the drawing. For flying scenery, modeling fully in 3D also makes finding your total weight and center of gravity very easy. I could go on and on, but from my experience, I don't know of any major scene shop in the area that still works in 2D. Even for a simple stock platform where the drawing just has orthographic views, modeling it in 3D and creating build drawings from there is infinitely faster than drawing the same thing 3 different times from different angles.

 

[bobgaggle]

Thanks for the input.

I spent the last 2 weeks on a self imposed trial by fire, modelling a double wall revolving thing for a new show. Fairly steep learning curve when you add the z axis. Took me forever to get the thing drawn, but was pretty smooth sailing afterwards when I was doing all my layouts.

 

[RickR]

Yup, a standard trade-off. Far more time in the initial work, far less time generating plans and revisions. The balance is key.

You are now likely very interested in learning 3D modeling tricks and tips. Like using smarter starting elements rather than building up a bazillion cubes, Importing anything that can be found, Knowing how it's to be built before/during modeling.