Create a parametric profile by sketching (open profile example)

Question:
How can I create a parametric profile with openings using the Sketch Editor?

Answer:
The following support article will take you through step by step instructions for creating an open parametric profile using the Sketch Editor. In this example a parametric rectangular hollow section will be created using the Sketch Editor. The finished profile is shown below. The overall height, overall width, height of top flange, height of bottom flange and web thickness can be varied for this example profile.

See also: Create parametric profiles by sketching
 

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Example

1. Open Sketch Editor

Tip: It can be easy to make mistakes when using the sketch editor for the first time so it is a good idea to regularly save the sketch as you are creating it by clicking the Save sketch button 

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For this example we will not need to use the grid so you can hide the grid or zoom in close enough to not see the grid lines.

1. Click on one of the grid lines to select it, then right-click and select Hide
2. Click the Sketch polyline button
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3. Sketch the shape of the polyline as shown below, placing the middle line parallel to the vertical axis. Place each point by clicking the left mouse button and click the middle mouse button to finish

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The reason for this is that when you add in a horizontal or vertical line the sketch editor automatically attaches a horizontal or vertical restraint to that line. We want the middle line to always remain vertical so we want a constraint on this line but the other two legs should not be constrained as these need to move according to the angle variable. It does not matter where the polyline is drawn in the sketch editor or the length of the line segments. The lengths will be adjusted by variables that will be added later.

The positioning of the profile is determined by the Part positioning planes. These planes define the vertical and horizontal extremes of the part. In this example we are using the default part positioning planes. 

The positioning of connections relative to the profile is determined by the Connection positioning planes.

Add angle dimensions

1. Click the Sketch angle dimension button  
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2. Click line 2 and then line 1, as marked below

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This will create an angle dimension between line 3 and line 2 on the right side of the profile. The angle is measured anti-clockwise from the first selected line to the second, so if the lines are selected in the opposite order we would have created an obtuse angle on the left side of the profile.

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3. Create another angle between line 3 and line 2
4. Click the Display variables button 
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    to open the Variables dialog box
5. Change the Value of the angle for each of the Angle variables slightly and you should see the angle change in the Sketch Editor

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Add free dimensions

In this step we will add dimensions to legs 1,2 and 3.

1. To add a dimension click the Sketch free dimension button 
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2. Click the start of the line you want to add the dimension to
3. Click the end of the line
4. Finally, click somewhere to the side of the line to determine the position of the dimension line

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5. Click the Display variables button 
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    if the Variables dialog box is not open
6. Try altering the Values of the variables to change the lengths of the profile lines

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Create a thickness variable

1. Click the Add button in the Variables dialog to add a new variable
2. Click in the Name cell of this variable and type t
3. Click in the Formula cell and type in a value for the thickness

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4. Expand the selection tree so that you can see the sketch Extrusion Type and Thickness

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5. Right click on Thickness and select Add Equation
6. Type the name of the thickness variable after the equals sign

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The thickness will now be displayed in the Sketch Browser.

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Change extrusion type

This is not quite right because we want the length variables to define the outside edges of the profile and what we can see in the Sketch Editor is that the length variables are defining the center-line of the profile. We can correct this by changing the Extrusion Type.

There are three extrusion types, with possible values 0,1 or 2:

• 0 - The sketch is extruded symmetrically to the outside and inside of the polyline. (Default)
• 1 - The sketch is extruded to the outside of the polyline
• 2 - The sketch is extruded to the inside of the polyline

1. Right click Extrusion Type and select Add Equation
2. Type 2 after the equals sign

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Define how variables will appear in the profile catalog

1. Change the Visibility of all the variables to Show. This will make it possible for the user to change the value of the variable in the Profile catalog
2. Add the name you want to give to the variables in the Label in dialog box column. In this example we will make the labels match the FP_N profile variable names

The values that are entered in the Formula row when the sketch is saved will be the default values when the sketch is used so you should enter appropriate values before saving.
 

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Use the profile

1. Click the Save sketch button 
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    when the profile is complete

The sketched profile will be saved into the Profile catalog in the Tekla Structures model that is currently open. The name you used when you saved the sketch should appear in the list of profiles.

See also: Use sketched profiles in a model
 

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Add an image of the profile to the catalog

1. Create an image of the profile and save it as a .bmp file in the Bitmaps folder of the installation folder

For example, if you have installed version 2018 to C:\TeklaStructures, it needs to be saved in C:\TeklaStructures\2018\Bitmaps.

See also

Create a parametric profile by sketching (closed profile example)
Create parametric profiles by sketching