Using void forms
Video: Using void formsEach of the five solid forms that we've explored so far in this chapter can also be created as voids. Void forms carve away from the solid forms to which they are joined. If you create a void form in the same physical location as a solid, Revit will automatically join the two forms for you. As an alternative, you can create the void freestanding and then move it into place and join it to the solids later. The choice is up to you. What I have on screen is a file that brings together a sample of all the forms we've been talking about so far. Some of this I'm going to leave as a practice exercise for you to explore further.
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In this course, Paul F. Aubin creates standardized content such as furniture, doors, and many other architectural components using The Family Editor in Revit. The course starts with the basic concepts: family hierarchy, libraries, resources, reference planes, and constraints. The course also takes a deeper look at the smart data beyond the geometry, such as material and visibility parameters, as well as creating nested families and arrays, controlling rotation in work planes, and working with advanced formulas.
- Understanding family concepts
- Creating an annotation vs. a model family
- Adding geometry
- Working with reference planes and constraints
- Creating extrusions, blends, and sweeps
- Creating parametric relationships
- Editing element visibility
- Building complex families
- Adding conditional formulas
- Creating towers and arches
Using void forms
Each of the five solid forms that we've explored so far in this chapter can also be created as voids. Void forms carve away from the solid forms to which they are joined. If you create a void form in the same physical location as a solid, Revit will automatically join the two forms for you. As an alternative, you can create the void freestanding and then move it into place and join it to the solids later. The choice is up to you. What I have on screen is a file that brings together a sample of all the forms we've been talking about so far. Some of this I'm going to leave as a practice exercise for you to explore further.
What I'm going to focus on is the void forms in this file. So I'm going to start here at the top of this wrought iron bracket with this form right here. This is a Blend that just goes from a simple square shape at the bottom, to a long thin square shape at the top. I'd really like to kind of round off that top edge. Now you wouldn't be able to achieve a form like that directly with any one of the other solid forms. So it really requires the combination of two forms. So in this case, we're going to start with the overall solid, and then we're going to carve away from it with a void.
Now I've provided some lines here to get us started and to make it a little bit easier to create this form, but feel free to experiment on your own and create a different shape if you like. We create voids in much the same way that we create the solid forms. If we look here on the Home Tab of the Ribbon, we've got our five solid forms here, and a Void Form tool next to it that lists out the same five forms. So you can create any one of the five shapes that we've previously explored as a void form. In this case, we'll just do a simple Void Extrusion.
Now like we did with other forms, we want to pay attention to our work plane. So if we look at the other views of this project, what we see here is there's a Reference Plane along the back edge of this bracket: Center (Front/Back). If we look at the back view, we're looking right at that Reference Plane. Now, if you want to be sure that Revit is choosing that correct Reference Plane, we can click the Set tool as we've done in previous movies, we can open up the list, and we can choose the Center (Front/Back) Reference Plane.
Now, this will be confirmed for us here in the 3D View. You'll see that we're now using the plane in the back of that steel bracket as our work plane, and I'm going to go ahead and click OK. Then we're going to zoom in a little bit on this top edge here, and create an extruded void form here at the top. Now, if I go to Void Forms and I choose Void Extrusion, I could trace over these shapes, or I can just use the Pick Lines and actually pick them directly. So that's what I'm going to do.
What I'm mainly interested in is this curve right here. The shape of this stuff out here is not terribly important. It just needs to be big enough to cover over the part of the form we want to carve away. So in other words, it needs to be big enough to capture these little corners that we want to carve off. So if I do the form that I have sketched here, it's more than big enough to achieve that result. If I click Finish and create the form, we're going to see something a little strange here. Now first of all, the Depth of the form is defaulting in this file to 12.
So it looks like it's doing something different than what we've seen previously. Well, if we go to the Manage Tab and we look at Units, I've just simply taken the units in this file and changed them to Decimal inches. So it's still the default 1-foot depth that we were seeing in other files. It's just now expressed in inches. So you can feel free to change the units in any of your Family files that you like. Secondly, if you recall from our discussion at the beginning of this chapter about work planes that there is a positive and a negative direction of each work plane. So in this case, the Extrusion is actually going in the wrong direction.
Now, we have a few ways we can deal with that. We could of course reverse the work plane, but if you recall, I recommended that you not do that late in the design process. In other words, if I came over here and tried to reverse this work plane now, it would probably have a detrimental effect on some other geometry in the file. So that's really not a good choice. Instead, all I have to do is just deal with this one void that's going in the wrong direction, and I can do that here with the numbers, or I can just simply do it here with the grips. It's really up to you.
It depends whether you want to have some more rational numbers here or whether or not the more random numbers are acceptable to you. Either way, it's not terribly important because what we're going to see is when the void is done, the void actually becomes invisible, and we see the result of the void interacting with the solid that it's joined to. So I like rational numbers, so I'm going to go ahead and change these to 2 and -2 and click Apply. That will reduce the size of this overall void down, and you see that it does intersect now the 3D form.
When I deselect it, it will immediately apply itself to the underlying form. I can come in here, select these model lines, and just simply delete them; they're no longer necessary, and you can see the end result. I have this nice little curve here at the top of the finial and a more finished-looking result. So we have a similar condition down toward the bottom. So let me just pan this down into this location here. Here, I already have a void form that was previously created.
This void form is created in exactly the same way as the one we had up above. The difference is this void is already here, and so when we come in and create the new solid form underneath it, it won't automatically apply itself. So we'll get to see that different workflow in that situation. Now, what I want to build here is a swept blend. So I'm going to use this curve that I've provided in the file as the path, and then I'll create my two shapes to finish off this curve down at the bottom. I'm going to go to the Home tab, and I want to make sure that my work plane is set before I get started.
So I'm going to go to Set. If I know the work plane that's passing through this bracket, I could use the center work plane, there is one here, Center (Left/Right), but I want to show you another option here. There's actually this Pick a line, and use the work plane that was sketched in. I just want point that out to you as an alternative option that you can use in your own work. So since I have a line right there, I can click on that, and you'll see there is a work plane right there; six of one, a half-dozen of the other in this case. So I've got that work plane.
I'm going to choose my Swept Blend, and I'm going to sketch my path. I'm going to choose the Pick Lines option, and I'll click on this curve that we've created. That gives me my path. So I'll finish that. Here, what I'm going to do is something that I alluded to in the Swept Blend movie and in the Sweep movie. We're going to do it sort of in pieces and parts throughout the training series. So I've already provided some Profile Families here in this file. We mentioned in those previous movies that you can create a Swept Blend or a Sweep using Profile Families instead of sketches.
So it defaults to By Sketch. But if you open up this list, you see there are actually some items here on the list. These are nested Profile Families. Now, in a future chapter, we're going to actually create the Profile Families ourselves from scratch. So we will learn how to do that. Here to focus more on the void forms, I've just provided the Profile Families for us to use, so we can just choose them off the list. So for our Profile 1, I have this one called Bracket Finial Profile1.
If we just take a quick look at that, it's just a pre-drawn shape, it's a 2D shape. The insertion point was planned carefully, so that it ended up right on the curve and it has the subtle little concave curve here to give a little bit more interesting finish to our form. I'm going to go to Select Profile 2, open up the list, choose my Profile2, and that one is just a simple rectangle, so that it matches up with the existing form. So it'll look like it's smoothly going from the arc curve into the Swept Blend.
So I've got my two shapes, it's going to blend from this one to this one. I'm going to finish that. If we spin around, you can kind of see the result. Now by itself, that's an interesting form and we could leave it like that. But using the void, you can kind of see the way they intersect. We can actually cut off those hard edge corners there and make it a little smoother, a little bit less sharp edge, maybe a little more interesting. So we can use the void to do that. Because the void already exists, it doesn't automatically apply.
So what we do is we use the Cut Geometry tool for this purpose. This just simply allows us to come in and apply the void to the form after the fact. So we click Cut Geometry, we select the geometry that we want to cut, and then we select the void. When you do, the void will disappear and the effect will get applied to that form. So if I escape out of that command, notice that there is the Swept Blend. If you move your mouse around here somewhere, there's the void form.
So you can always get back to the original forms, select them, and edit them in any way necessary. But when they're deselected, you get the final result. So we're going to leave this file at this stage and I'm going to leave these shapes over here for you to further experiment with this. Over here, you can add a sweep to finish off this end of the bracket. Here's the path of the sweep and you can sketch the shape. And then if you look at these little collars over here, these are just Revolves. I've given you the starting point of one of those collars right here; here's the form and there's a path buried in there somewhere; there it is right there, that you can use as the axis.
So feel free to practice with this file and using these forms, feel free to modify any of the forms that I've provided here and practice any of the forms that we've looked at in the previous movies and even add some more voids if you like. So while the focus of this movie has been on the void forms, the larger purpose of the file that we're working in here is to give you an opportunity to experiment with all the forms that we've been discussing throughout this chapter. So I do encourage you to spend some time and practice in here each of the features that we've looked at over the last several movies.
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