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We can now continue looking at the Loft command, but this time we're going to add a additional intelligence by creating rails. In the previous video, we simply lofted through three shapes, and then we used some of the options within the dialogue box, for the loft to control the overall shape. And how the 3D model transitioned through the profiles that we selected. We can get more accurate control by creating rails. To do this, we're going to take the model we created in the previous video.
And we'll hover over the loft in the browser, and right-click on it and select Delete. What we'll see is a dialog box that allows us to select what we're going to delete. By default, it'll delete everything if we click OK. If we uncheck this consumed sketches and features option, it will delete the feature but leave behind all of the sketches and work planes that were created to generate the original loft. Now that we have those in place, we save ourselves some time without having to recreate each of those profiles. To create the rails, we're going to create a new sketch, and we're going to go to the Origin geometry and look for the x,y plane, which is the plane that runs up through the center of the part.
I'm going to go back to our home view, because the next thing we want to do, and this is really critical when you're creating rails. As we want to create rails that intersect each profile exactly. And the way we can do that, is through the Project Geometry function. In the draw panel, there's a Project Geometry option, and, when we select that we can then select each of these profiles. And, it takes the ellipse or the circle and projects it to the flat plane we're currently in.
By doing that, we have the end points of these lines, touching the outside edge of the ellipse and the outside edge of the circle at their tangent points. I'm going to leave these as solid reference lines, and this is going to cause us a problem in a little bit, but I want you to see it, just so you can remember it, and I can show you how to resolve it. But, now that we have this projected, we can look at it from the front view, and we can use the endpoints of that line, to control the spline that will be the rails.
If we go to the Spline drop down and select Spline Interpolation. This is the type of spline that I prefer to use when I am creating loft. Because I think it gives me incredible control over the angle and curvature of the line that I'm using as the rail. I'm going to start the line by hovering over the end point of the projected line in the bottom sketch. I'm going to create a control point in between the first two work planes. I'm going to create a point at the intersection of the midplane. I'm going to create an additional point in between the next two work plains, and a final point at the endpoint of the top circle.
I can then click the green check box, to create this Spline. And if I zoom in on this a little bit, you can see that I have the ability to click and drag on each of these points. And you'll also notice the little gray dots running around near this. These are curvature handles, which by default I try not to use unless I really need that very precise control. But if I do, I can simply click and drag on one of these, and, it will allow me to define more accurately how that line transitions through this specific point.
I'm not going to get into all the detail of customizing that completely, because I actually prefer a little bit smoother of a transition. And, if you get into changing these handles a little too much, sometimes you can make the line look a little less smooth. Now that we have the basic spline shape, we can right-click in the graphics window and select Create Line. To generate a center line that we can mirror this spline around, because you're going to need a rail on each side. And when we create the Loft, you'll see why. Now that we have this line, I'm going to right-click on it, and select Center Line, just so that I have it identified as a center line.
To mirror this spline, I can go to the Pattern panel and select the Mirror option. And by default, I'm entered into the selection mode. I can simply select the line I want to mirror. I can go to the dialog box and select the mirror line selection tool, and, select the line we just created as the mirror. By clicking Apply and then Done, I've created an exact mirror of this spline. And, if I left-click and drag on any of these points. You can see I have symmetry created, that allows me to control the exact shape of the rail on both sides.
Now you'll notice, because I moved this handle, this line has enabled the handle. I'm going to right-click on that and deselect activate handle. What this will do is allow a little bit more of a smooth transition through those points. Now that I have my rails complete, I'm going to finish the sketch. And if we orbit, you can see that essentially what we've done is create to create a wire frame shell around this shape. And it'll allow the Loft command to actually control the exact shape of the loft as it runs through the profiles.
I'm going to go ahead and click the Loft command from the create panel, and. we're ready to continue creating our loft. And we'll start out by adding sections, just like we did in the previous movie. We're going to select each of the profiles that we created. And if we look at it from the front view, you'll notice that it looks exactly like the shape we had previously. If we rotate to the side, you'll see the same is true. And the reason for that is, up to this point we haven't done anything different. We've selected these and last time we just hit Okay, and created that basic shape.
What we want to do now, is add the rails. If you remember when we projected that geometry, I mentioned we were going to to run into a problem and that's fine. What I'm going to do, is I'm going to select my first rail. And, because I'm not getting a preview, there's an indication that something's wrong. So what I want to do, if for example I were to click Create here, I'll get an error. And what the error says, is that I'm attempting to create a loft where the rail, intersects the profile multiple times. And the reason for this, is the geometry we've projected is reference geometry not construction geometry.
So what's happening, is when I click this rail it's running all the way up from the bottom to the top, it's connecting to this projected line, and working its way back down to the other side essentially creating one large loop. To fix this, we can go back to the sketch, sketch four. We'll go back to our home view and if we zoom in, we can right click on each of these pieces of geometry and convert them to construction. By doing this, Inventor will ignore them as part of the loop creation process and allow us to create this loft.
So, we'll go ahead and enter the loft command again. We'll select the profiles that we started with. And we're back to that shape, and now, we'll go ahead and click the Rail option and we'll add our first rail. And you'll look at this from the front, and you can see what's happening. Now the loft is following this exact rail, but what's happening, as it pulls on this side, it's also pulling this side. Because currently, this side is not controlled by a rail. What we can do, is simply add this additional rail, and you'll see the precise location of the shape follows that rail.
And we can click Okay to create our feature. The important item here, is because this is a parametric model, we can always go back to this loft, and modify any of the loft shapes that are created, but we can also change the rails as well. By double-clicking on sketch four, you can see we're back to editing the rails. And if I wanted to make this neck just a hair longer, I could simply click and drag down towards the other profile. Or, if I wanted to, I could make this bottle curve inward.
And have a completely different shape, and by clicking the Finish Sketch, the model is updated to reflect the changes to the rails. This should provide you enough foundation, to create complex shapes in Inventor using the Loft command.
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