Mirror Mirror

Just like with traditional parts, you can take advantage of symmetry with sheet metal parts by using the mirror feature. Using patterns, like mirroring, can be helpful in your design, by keeping your performance up and making modifications easier. Depending on how the mirror is being applied, there will be special requirements for the selections of the mirror feature to accommodate the sheet metal functionality.

I am going to be applying the sheet metal functionality along with the mirror feature to create a cardboard castle for my niece’s American Girl doll. I want to design the castle out of cardboard so that I can build it with her out of old boxes. Many people forget that SOLIDWORKS sheet metal functionality is not explicitly for sheet metal. It can be applied to any model which is thin walled, has “bends” at the corners, and can be flattened. I did a little research and found that a standard shipping box uses a single walled board with a C-Flute thickness of approximately 4 mm. Cardboard will not stretch in the corners where it is bent so the neutral plane will be the same length in the bent state as the flat state. I will use a K-Factor of 0.5 for the bend allowance to capture this behavior.

Mirror a Feature

There are several sheet metal features which can be mirrored, including the Edge Flange, Miter Flange, Hem, Base Flange/Tab, and Closed Corner features. When mirroring a feature there are a couple things to keep in mind.

The first will be the mirroring face/plane. When mirroring a feature, the plane/face must be centered between the faces of the base/boss. Clever placement of your origin will allow you to use the default planes for this. If a default plane is not available, creating a plane using the “mid plane” option is quick and easy.

The second will be to consider the sheet metal parameters. The mirror function will need to use the same exact conditions. If the geometry of the new location does not allow this, the mirror will fail.

In my cardboard castle design, I mirrored a feature to create the detailing along the top of the turret walls. Using the sheet metal tab feature, I made the detail along the top of one of the walls. I then mirrored the tab feature to create a matching detail on the opposite wall. I repeated the whole process for the detailing for the other pair of wall on my turret.

Turret walls

Mirror a Body

Sheet metal bodies can also be mirrored. If the body will be mirrored and merged, then the selected mirroring face/plane must be a face located on the body. This will result in a single sheet metal body. If the body will be mirrored but not merged, any plane/face can be used. This will result in multiple sheet metal bodies in the same part file, also known as a multibody design. The new body created from the mirror feature will be linked to the original body’s sheet metal feature.

In my cardboard castle design, I used the mirror body command in both ways. I used the mirror body with merge turned on when creating my front wall with the gate. I modeled half the wall, and then mirrored it to make the opposite side match. I used the mirror body with the merge option unchecked to create an opposite hand version of the turret. I couldn’t just copy and rotate the original because the door and windows needed to be on specific sides.

Doors and Windows

Mirror a Part

Sheet metal bodies can also be mirrored to create opposite hand versions and saved as separate files. To create a separate file, you will need to start by selecting the plane/face you wish to mirror across. Once the plane is selected, the option to “Mirror a Part” will become available under Insert on the Menu Bar. You will be shown a list of properties to include in the new files, which include a sheet metal option. You will also have an option to link the new file to the original.

Mirror Part

My cardboard castle is now complete. Taking advantage of the sheet metal and mirror functionality in SOLIDWORKS offers me several advantages for this engineering project with my niece. I now have a flat pattern to work with, which we can get all the needed measurements from, or even print out patterns to trace on the cardboard. It will also be easy to make modifications, in case she thinks the princess’ tower needs to be taller, the turrets should have spiked walls, or a secret door needs to be added. My niece and I are now ready for a weekend of fun!

Happy modeling!


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