The Instance to Vary option in the Linear and Circular Pattern Property Managers allows you to vary the dimensions and locations of instances in a feature pattern. You can vary the dimensions of a series of instances, so that each instance is larger or smaller than the previous one. You can also change the dimensions of a single instance in a pattern and change the position of that instance relative to the seed feature of the pattern.
For linear patterns, you can change the spacing between the columns and rows in the pattern. For circular patterns, you can arrange the instances to become closer together or farther apart.
Below is a part with the slot cut into it. We will pattern that slot 5 times (total) and will vary the distance between them by 7mm and also change few dimensions.
As shown below open the Linear Pattern from your Features Toolbar or Insert > Pattern/Mirror > Linear Pattern. Now in the Property Manager for Direction 1, we select the linear edge as shown below and type in a distance of 30mm for a total of 5 instances. In Features to Pattern we select the Cut Extrude feature (slot) and as shown below we get a preview.
Now the new function in SolidWorks 2013 is that you can select the Instances to Vary dialog box as shown below and make changes. Here in Direction 1 Increments we will type a value of 7mm and as shown below it will vary the dimension 30, 30+7 (37mm), 37+7 (44mm), 44+7 (51mm) respectively.
Now in the dialog box where it says Choose Feature dimensions to vary in Direction 1 we will select the dimensions we want to vary. In our case we will select the dimensions 80mm and 15mm directly from the graphics area and they will appear in the form of a row as shown below. In the Increment column we will specify the value as 50mm increment for 80mm dimension and 4mm increment for the 15mm dimension. Also as shown below the preview is updated and if it does not then make sure Full preview option is selected.
From the above preview we can see that the last instance is too big and its going outside the part. So here we can click on the Magenta color dot and say Modify Instance as shown below.
The Modify Instance opens up a dialog box in the graphics area and here we will change the value (Slot length to 150mm) as shown below.
Below is the final part and as seen the Linear Pattern has given us the slot with varying different parameters.