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Have you ever tried to control the shape of a curved form in the Family Editor? If so, you know that flexing them sometimes throws you a curve ball. In this course, Paul F. Aubin explores several techniques to tame your unruly parametric curves. This includes examples of circles, arcs, arches, splines, and even complex curves like cyma moldings. The real power comes in with formulas, profile families, and proportions, which allow you to mathematically control your curves. At the end of this course, we can't guarantee you'll never have misbehaving curves, but we'll give you several useful tools to help tame them.
Let's continue with our gothic arch. In the previous movie we took our seed family and reconfigured it to make the framework that we needed for the gothic arch. And the essential framework here is this triangular form that is created from two reference lines, that have been locked and constrained to the corresponding reference planes. Now we're going to use each of these reference lines as the spring line for basically two angled, segmental arches. And I'll do that all inside of a single sweep object.
So I'm going to go to the Create Panel, click on the Sweep button, and sketch my path. I'll use the start end radius arc. And I'm going to snap right to the endpoint of this reference line. And then the opposite endpoint over here. And then I'm just going to pull that arch out just a little bit, like so. I'm going to cancel out of the command. Now the reason I want to cancel out of the command is, I want the arch on both sides to be exactly the same. So the easiest way to do that is to just select the one that I have here, and mirror it to the other side.
So particularly since I eyeballed it, I don't really know wat distance that is. But now I know that these two are exactly the same. And, of course, I get this flurry of automatic sketched dimensions here, which makes everything very distracting. So let's take care of, the stuff that is easy to constrain and that is all of these end points and that's just align and lock. Now, there's going to be several of them so you gotta be patient. So we go to the align command and I'll just start here at the top using this reference plane here and the endpoint and lock.
Then I'll go to this one here, and inpoint, and lock. Now there's actually two inpoints touching each other. So I'm going to repeat that again just to make sure and if I get an error like this, then that's fine, then I know it's taken care of. Otherwise. It's better to just lock it again. You see there in that direction it let me lock it again. So that ensures that both endpoints of the two touching arcs are locked, not just one of them. So that's why I say if you get that error message that's fine just cancel but otherwise you want to go ahead and align and lock it.
So I'm just doing this in each direction. And each direction. Okay, so that gets all the end points locked. Now the next thing I want to do is establish this height right here. Now you're seeing these two automatic sketch dimensions. Revit is assuming that we want to lock down the center point. So, if you're wondering where is that dimension going to, you could actually turn on your center mark over here and then it should become a little bit more clear. If I look at this arc, its center point is way over, which explains why this 0.113.
Now we don't really care about where the center point is for this example, but I just wanted to point out to you why you're getting that seemingly odd automatic sketch dimension. So what we're going to do is add a dimension,in a line dimension, and this time we're going to dimension from the reference line. Now it's really important that you click the reference line first, because that establishes sort of the parallel direction that we're looking for. And then you highlight the sketch line, and then I'll just sort of pull that dimension out over here somewhere.
Notice that that makes that automatic sketch dimension disappear. If we do it again in this dimension, reference line first, sketch line, pull that dimension out over here somewhere. Actually, let me pull it over here where I have more room. That makes this one disappear. I'm going to take both of these, and label them, with a new parameter. So I'm going to do add parameter, and I'll just call this arch height. And I'll click OK.
That's labeled on both sides. Now, if we want we can flex that before we continue. So, let's try 0.2, click Apply. You'll see both of those will flatten out a little bit. Let's try 0.3 or let's try 0.4 to make it more extreme, and you see they bulge out. So I think 0.2 looks pretty good. That's kind of a nice gothic shape. If you flex the height. Let's try 1.5. Click Apply. See how everything kind of shortens out? Maybe 1.75 might give me a nice configuration here.
So really, this is just you're trying different numbers until you like the proportions you see. So I'm going to go ahead and click OK. Let's finish that. And then of course go to the 3D view, and like we've done in other examples, I'm just going to sort of sketch in a rectangle right now. So I'm going to do edit profile, draw a rectangle, like so, modify, click finish, finish again, and there's my. Gothic arch form. Now let's do one more thing that we haven't done in some of the previous movies.
Let's load this into a project and test it out. Because, remember, at the beginning of this chapter we talked about face-based families and we're working in a face-based family right now. So there's this, sort of, extrusion back here that represents some surface in your project. So let's see the way that behaves. So I'm going to do Save As. I'll make it a family and put it on my desktop and just call this gothic. Now I've provided in the exercise folder a sandbox file, my sandbox file is literally just an empty Rivet project with a single wall in it. So you can either create a new project and draw a wall.
Or you can open up the sand box file either will work fine. Make sure it's open. So you can see here in the background I have the file called sandbox already open. If it is open, and you click this load into project button, it will go right to that project. If it's not open, it will tell you you don't have any open projects. Notice that when I do that, it runs the component command, and then over here under placement, I can either place it on a work plane or a face, and it defaults to face. So you see how at the moment it's not giving me Any place to place it, but as soon as I move my mouse around the surface of this wall.
It will recognize the face of that wall and in fact it doesn't care which face, you see you can put it on the top face or the side face. Of course those don't make a whole lot of sense, so I think this one make a little bit more sense and I can click to place it on the screen there. Now, it's a little shallow right now so let me just select that, edit the type and let's change the height here to 1.75 and click OK. And you see how they get a little bit taller. So, it's working, it's flexing the way that we expect and it is associating itself with the face of this wall.
If you select either these another feature of the face base family is they have an elevation parameter. So over here I could actually type in a number, like maybe 6, and that 6 is measured from the floor. So, if you were to look at this head on from say a south elevation, and you were to measure the distance, from the floor to right there it's exactly 6. So this thing is exactly 6 units off of the floor. So that's another feature that you get with a face based family.
That 'ill only work if you put it on a vertical face. So if we placed it on the floor, or on the surface of a roof, or something like that, then that elevation parameter would become invalid. So to kind of summarize what we've done here. Basically, all the gothic arch is really just two segmental arches standing up at an angle and touching one another at that point. But the basic process to build them is exactly the same. So once you kind of have an idea that all that's really required to make a curve flex is three controlled pieces of that geometry, then it opens up the possibilities to create all different kinds of forms.
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