An Easier Way to Build Chair Legs in Revit 2016
marcteer@blackspectacles.com

Marc Teer

July 20, 2016

An Easier Way to Build Chair Legs in Revit 2016

A free tutorial from the Black Spectacles Course Custom Families and Parameters in Revit 2016.

In this Black Spectacles FREE tutorial, you will learn an easier and more efficient way to build chair legs in Revit 2016 using nested families. This tutorial is part of the Black Spectacles course on Custom Families and Parameters in Revit 2016 in which you will learn how to utilize the different types of families and parameters to quickly and efficiently create complex and customized designs in your projects.

View the entire course here:
Custom Families and Parameters in Revit 2016

Building Chair Legs and a Nested Family Tutorial

Step 1: Create a reference plane for the arm width

In order to build the legs for this chair, you first need to go back to the floor plan view. With the design of this chair, the legs are going to land right in the middle of the arms. So there are a few extra reference planes that you need in order to build the legs of this chair. So you need to locate the center line of the arms and the center line of the back and then an imaginary center in the front.

Let’s start with the front.

You need another reference plane that’s going to stand in for the arm width, so that it’s equal on all four sides. Then you need another reference plane that's going to represent the center of that sort of imaginary arm.

Go ahead and create a dimension string, make it equal, and then put an overall. This is arm width. Even though there is no arm there, that's the dimension you need. That's the parameter that you need. So it doesn't matter, because it's not actually going to any geometry. This is just in order to locate where the legs are supposed to go.

Repeat this process to add three more reference planes. One going down the middle of each arm, and one going down the middle of the back. Then draw dimensions in there that equalize those, so that that middle reference plane is always going down the middle of the arms.

So now you have the center point, which is basically the intersection of those two reference planes you see in this image. That's the center point of the leg, on the bottom of the chair. Now you are ready to build one of the legs.

Step 2: Create a circle and make it a parameter

The leg is not just going to be a simple extrusion. This is going to start with a circle at the bottom and then it's going to flair out and become a rectangle at the top. It's very common in furniture designs; it's very common leg type.

Go to “create” and instead of “extrusion,” click on “blend.” When you're doing a blend, you're defining the shape at the bottom and defining a shape at the top.

Now you’re going to start with a circle and use the intersection of these two reference planes as the center of the circle. This is way too big of a circle, but you're going to parameterize it. But before you can put a parameter on it, make sure that that circle sticks to that intersection. To do this, click on the circle and then the circle itself has properties. Turn on the check box for “center mark visible” in the circle properties and this little tick shows up. Then you simply use the align tool, and align that vertically and horizontally, and that locks the circle into that position.

Now you can click on that circle and a dimension appears. Click on the dimension and you can make this a parameter now. Click on that and name it “leg radius” and check the option to make it a “type” parameter.

Now this is inside of the sketch, which is very important. Because once we get outside of the sketch, this dimension will actually disappear.

Step 4: Create the Leg Width parameter

Now edit the top. The top is going to be a rectangle. So I’m going to draw a random rectangle in that general area. This time we are going to put the dimensions directly into this sketch.

So go to “Start Dimension,” then go from one sketch line to the middle reference plane, then to the other sketch line. Then say “equal.” Repeat this process going horizontal, then give it an “overall” from sketch line to sketch line going both ways

Select both of those dimensions, say “add parameter” and this is going to be named “Leg width.” Also a “type” parameter.

Step 5: Finish the sketch

The last thing you have to do is finish the sketch.

Go to “Modify | Create Blend Top Boundary” in the menu options and click the green check mark under “Mode” to save your changes and finish edit mode. Then open up the Family Types properties menu and change the numbers here.

Make leg radius 0.75 inches and make the leg width 2 inches.

No go to the front view to see what you’ve created. First, you should notice immediately that you made a mistake. You made the work plane, the wrong work plane. To fix that, click on “edit work plane,” and select “Level: Ref. Level.”

That drops it down, but you can see that the leg is too tall as well. So use the align tool to align it, and then padlock that.

The leg also looks too chunky. So let's change the dimensions again. This time, make the Leg Radius 3/8” and the Leg Width 1.5” and you get a nicer-looking leg.

Step 6: Create 4 legs by a nested component

The problem with doing things this way is that there’s 4 chair legs. You’ve only just built one of them. Revit doesn’t like to have things copied. If you were to copy and paste that leg 3 times, all of the reference planes and everything that leg is tied to are lost. So go ahead and delete the leg you just created.

A more efficient way of getting legs into this project, is to actually have a nested component. On the desktop is a file in called “Leg.” So what we're going to do is go to “Insert” then to “Load family,” and go to that “Leg” file. This file is set up exactly the way you just built that leg, but it was done in a completely separate file.

Once you open that file, the only thing you have to do is go down into “Families” in your project browser and find the leg file. Click on it and drop it into all 4 locations where you want that leg.

Then simply select all four of these legs and then assign those parameters. So “leg height,” “leg radius,” and “leg width” are all in what is called a “nested family.” They're all “instance” parameters within that nested family. So now you can just click on “Leg Height” and in the “Associate Family Parameter” box, assign that to “Leg Height,” and repeat the process for the other two dimensions. You can see all the legs adjusted.

Go to the 3D view and there is the finished chair.

Watch the video here:

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