SolidWorks Tips & Tricks sponsored by SolidWorks for the Sheet Metal Guy

Control the Corner Gap of a Four-Sided Box
A common part is the four-sided box. This part has numerous variations, with open corners, closed corners, and overlapping corners. Some variations have additional flanges and tabs. But they all start with a basic box. There is one question that arises very often with this very common part. How do you control the gap in the corners of a common four-sided box to ensure that the flat pattern is squared up for punching? The answer lies in a simple equation using math formulas.

First of all, create a simple 50mm by 100mm Base Flange on the Top Plane with a Thickness of ‘1.50mm’, as shown in Figure 1. In the FeatureManager design tree, right click on Sheet-Metal1 and pick Edit Feature. In the Sheet-Metal1 PropertyManager, set the default Bend Radius to ‘1.75mm’ and click the OK button.

Figure 1

Pick the Edge Flange button in the CommandManager, or pull down the “Insert” menu and pick Sheet Metal – Edge Flange. Pick the four edges of the base flange to create your four-sided box. In the Edge-Flange PropertyManager, set the Flange Length to a Blind Length of ‘25mm’. Make sure that the Outer Virtual Sharp button is depressed. Set the Flange Position to Material Inside and click the OK button to accept the settings and create the flanges, as shown in Figure 2.

Figure 2

Looking at the top of the part, as shown in Figure 3, you can see that the ends of the side flanges are not in line with the edges of the base flange. SolidWorks uses a Gap distance to control the corner relief. The gap distance is measured diagonally, similar to an isosceles right triangle. You can easily create an equation using math formulas to make sure that the corner relief is properly drawn. In this case, the gap distance equals the bend radius times the square root of 2.

Figure 3

In the FeatureManager design tree, right click on Annotations and pick Show Feature Dimensions. Double click on the 1.80 dimension, the gap distance. In the Modify dialog box, pick Add Equation from the pull down menu. In the graphics area, select the R1.75 dimension, the Bend Radius dimension. Then, select the multiplication (*) button. Finally, select the square root (sqr) button followed by the 2 button. Once the equation is complete, as shown in Figure 4, pick the OK button.

Figure 4

Pick the OK button in the Equations dialog box. The Gap distance dimension is updated. To get the part to update with the new gap distance, press Ctrl+B or pull down the "Edit" menu and pick Rebuild. Now, if the Bend Radius of the part is ever changed, the equation ensures that the Gap distance will always be updated to the correct dimension to ensure that the flat pattern is squared up for punching, shown in Figure 5 and Figure 6.

Figure 5

Figure 6

To learn more about sheet metal part creation, click here.

SolidWorks for the Sheet Metal Guy Course 1: Part Creation

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