Join John Helfen for an in-depth discussion in this video Part feature introduction, part of Autodesk Inventor 2018 Essential Training.
- [Voiceover] We're now to a point in this course, where we can begin to talk about part features. These are the features that are used to create 3D models. We're gonna take a moment before we dig into that, to talk, at a high level, about how sketching and part modeling interact, and the different types of features we have. In Inventor, we have the ability to create sketched features and placed features, and I'm gonna go ahead and create a basic model and you don't need to follow along, you can just watch so that you understand the concept, so we'll dig into each of these as we move along in the course.
I'm gonna start by creating a new part file, and starting a new sketch, and I'm gonna select a face to sketch on. Now the first feature, that you're gonna create in Inventor, for every single part, is a sketched feature. What that means, is that you have to draw a 2D shape, that will define the 3D model, that is created from that shape. In the browser, you can see now, we have Sketch 1, and I'm gonna go ahead and right click and select two point rectangle, and I'm gonna select the center point of the sketch, and just draw a rectangle.
I'm not gonna put on dimensions or anything like that. I just wanna show the process, and explain the difference between sketched and placed features. I'm gonna go ahead and finish this sketch, and I'm gonna right click and select extrude. By default, Inventor will select the closed profile that we sketched, and add a depth to it. Now I'm gonna go ahead and cancel this, just so that I can show very briefly, that, that same shape could create other 3D shapes. If, when we right click, rather than selecting extrude, we selected revolve.
Inventor will automatically select the single profile, but in this case, this 3D modeling feature has an additional input, and that's an axis. If we select a line within this sketch, you can see that Inventor revolves around that axis point, and we get a cylinder instead. That's really important, so that you understand that each 2D shape, could become a number of different 3D model shapes. I'm gonna go ahead and right click, and select extrude, and accept that change, and start with a cube, so that we can see the difference between sketched and placed features.
In the browser, you can see our first sketched feature. This is called out base feature, Extrusion 1. If we click the plus next to it, you can see the sketch that drives it. You can always go back and double-click on this sketch to edit it. You can make it taller, you can add dimensions, you can make changes to it, but once you finish the sketch, the model updates. Next, we're gonna go ahead and repeat that process. Once you have a base model, you're going to repeate the sketching and extrude, or sketch and model process, to add and remove material from this model, to sculpt the final shape.
I'm gonna go ahead and select on this top face, and I'm gonna use the heads up display, and I'm gonna click the create sketch button on the far right. This will create a new sketch, on the top of that model, and we could go ahead and right click, and select center point circle, to draw a circle on the top of this shape. The size doesn't really matter here. I'm gonna go ahead and just draw the shape and finish this sketch. You can now see, in the browser, we have Sketch 2. If we were to right click, and select extrude. We can use that shape to generate geometry.
I'm gonna go ahead and shrink that down just a little bit, and click the green check mark to select OK, and create that extrusion. Now in the browser, we have two extrusions. We can always double-click on this sketch to go back and change the size or position of the circle, but we're gonna continue on and look at placed features now. Placed features are features that don't require a sketch, but instead, require some piece of geometry from a solid model. The ones that are most commonly used are Fillet and Chamfer.
Sometimes Hole is included there, but it's unique in that you can create a hole using a sketch or a placed feature. It kinda runs the boundary between both. To create a Fillet, or round an edge, all you have to do is either launch the command from the ribbon bar under the modify panel, and select an edge, or if you select an edge in the model, Inventor's heads up display automatically presents Fillet, and Chamfer, so that you can round or slice off this edge. I'm gonna go ahead and click the Fillet command, and you can use the heads up display to adjust the size of this Fillet.
Once you've got that created, you can click the green check mark to select OK, and create that Fillet. The other option we had, when we selected an edge, was Chamfer. Chamfer is very similar to Fillet, except instead of rounding the edge, it simply slices the edge off, and it does it by default at an equal distance to each side, in this case an 1/8 of an inch. There's other options here as well, and we'll get into those as we get further into the course, but if we click the green check mark, we now have a series of features in our browser, that are both sketched and placed.
The first two are sketched, since they are driven by these sketches that are consumed underneath them, and the last two are placed. They don't have a plus symbol next to them, because they're not generated or controlled by a sketch itself. Just like the sketches, you can always double-click on these, to return to that process, and edit that feature. We could for example, make this slightly deeper, or slightly bigger, and click the green check mark, and it updates. Let me go ahead and do that one more time.
I'm gonna double-click on that Fillet one more time, because there is something else that happens here, that's important in relation to part modeling, and that's the fact that this Chamfer is missing from the graphics window, and it's grayed out in the browser. The way Inventor works, is it's a history based modeler. At the point in time when we created this Fillet, the Chamfer didn't exist, so essentially, when we double-clicked on this Fillet, we've gone back in time in this model, so that we can make a change to this feature, and then when we click OK. Inventor traverses through the remaining features that may be below it, and updates them according to this change.
This is the power of a 3D parametric history based modeler. Is there's a lot of logic and a lot of power, in how you create this, and you can always go back in time, to make modifications to what you've done already.
- Reviewing interface changes
- Projecting and importing geometry
- Working with Autodesk AnyCAD
- Understanding part modeling
- Building parts with placed features
- Working with partial chamfers