Example parametric assembly: Roof ladder without cage
The following example describes creating a roof ladder as a parametric assembly in Tekla EPM. The example can be helpful when you are learning to create parametric assemblies yourself.
1. Create a description for the parametric assembly
-
Click New and create an item with the following properties:
- Shape: CO
- Description: Roof ladder (no cage)
- Click Add.
2. Create variables for calculating the ladder length and the number of rungs and collection clips
- Click the Parametric Assembly ribbon tab.
- On the menu, select Parametric Assembly Variables.
-
Create the following variables without adding default values:
- Overall length of the ladder
-
Variable Name and Variable Description: Ladder Length
-
Variable Type: Length – Feet, Inches, Fractions – Meters
-
- Overall width of the ladder
-
Variable Name and Variable Description: Ladder Width
-
Variable Type: Length – Feet, Inches, Fractions – Meters
-
- Overall length of the ladder
- To close the Parametric Assembly Variables dialog box, click the Close button (X) in the upper-right corner.
3. Create side rails
-
Click New and create an item with the following properties:
- Quantity: 2
- Shape: FB
- Dimensions: ½ x 3
- To create a formula for calculating the length, click Formula next to Length.
-
In the Formula dialog box, do the following:
- Clear the existing text in the box at the top of the dialog box.
- In the Additional Variables list, select Ladder Length.
- Click Add Variable.
-
To have the ladder project beyond the landing elevation, type
+ and the length in feet and inches
without a space between.
The formula should now read approximately: [Ladder Length]+3'6.
-
Click
OK to save the length formula and return to the Parametric Assembly dialog box.
Note that whenever a property is calculated with a formula, it is marked with (F) in the Parametric Assembly dialog box.
- Click Add.
4. Create the rungs
- Click New.
-
To create a formula for calculating the number of rungs, click Formula next to Quantity.
We want to calculate the number of rungs determined by the ladder length, starting 6 inches above the landing. The result should then be divided by 1'-0.
-
In the Formula dialog box, do the following:
- Clear the existing text in the box at the top of the dialog box.
- In the Parametric Assembly Variables list, select Ladder Length.
- Click Add Variable.
- Type +6".
- Add parentheses () around [Ladder Length]+6".
- Type /12" directly after the right parenthesis.
- Click OK to save the length formula and return to the Parametric Assembly dialog box.
-
Set the shape and dimension properties of the rungs as follows:
- Shape: RD (round bar)
- Dimensions: ¾"
- To create a formula for calculating the length of the rungs, click Formula next to Length.
-
In the Formula dialog box, do the following:
- Clear the existing text in the box at the top of the dialog box.
- In the Parametric Assembly Variables list, select Ladder Width.
- Click Add Variable.
- Click OK to save the length formula and return to the Parametric Assembly dialog box.
- Click Add.
5. Create the connection clips
- Click New.
-
To create a formula for calculating the number of clips , click Formula next to Quantity.
We want to calculate the number of clips based on the length of the ladder.
-
In the Formula dialog box, do the following:
- Clear the existing text in the box at the top of the dialog box.
- Type CEILING.
- Type the left parenthesis (.
- In the Parametric Assembly Variables list, select Ladder Length.
- Click Add Variable.
- After the variable, type /6').
- To calculate enough clips for both sides, type *2.
-
To include the first
and last clips for both rails, type +2.
The calculation should read CEILING([Ladder Length]/6’)*2+2. This means that Tekla EPM calculates the total ladder length divided by 6’-0, rounds it to the nearest foot, multiplies the result by 2, and then adds 2 more connection clips.
- Click OK to save the length formula and return to the Parametric Assembly dialog box.
-
Set the shape and dimension properties as follows:
- Shape: FB
- Dimensions: 3/8 x 4
- Click Add.
6. View the result
You can now view the result and test the parametric assembly.
For more information on testing a parametric assembly, see Create a parametric assembly.