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For this week about computer controlled cutting I will work in two directions. (1) Exploring different joining shapes between perpendicular pieces of cardboard. In a rectangular shaped box with a lid I tried as many different joining shapes as possible and (2) Using the Sheet Metal function from Solidworks in this case for 3 mm cardboard. Instead of joining two or more pieces perpendicular bending the corner has great benefits.

Way of work in the joining shapes: For modelling the box with joining shapes I like to work in Solidworks in one part. There I can make multiple bodies. This way it is possible to design all the pieces you need just in one part quickly. You have to know the concept of how to merge or not to merge when creating new features in Solidworks. When the part is complete (all bodies needed) it is possible to convert each body into a new part. After saving all parts can be assembled in the main assembly. It is recommended to assemble the first design part with all the original bodies as well. This way you will not lose the original information. When assembling the parts use the origin to align each part. All parts are on the right place automatically. For laser cutting make a new drawing and assemble all the views from the parts on a page. Save as a dxf file and it is ready for cutting.

Way of work in the Solidworks Sheet Cardboard module: The Sheet Metal module from Solidworks lets the designer work in two ways. (1) start from scratch in Sheet Metal, this way you design from thinking in sheet material. Personally I prefer (2) design the shape that you need, cut the shape open so it can be unfolded and start the Sheet Metal function at the end of a part. Both methods work, I just prefer the second method. The important difference between steel and cardboard in this case is the strain allowed in the material before it breaks. Ordinary steel can have much strain before it breaks. Cardboard unfortunately will break much easier with a little strain. Also the thickness of the cardboard is much bigger compared to the most used sheet metal (3 - 1 mm). The bigger thickness also results in a larger strain when bending. The Sheet Metal module in Solidworks automatically calculates the compensation from each bend (great function). But in Cardboard this is not necessary. The solution I use here is reducing the bending radius to 0.1 mm. The centre line of each bend will be shown on the unfolded parts for cutting. The bend lines can be cut with a dotted line right through the cardboard. After laser cutting the outer corner can be cutted open with a knife. Be careful not to cut too deep. To explain this method more in detail in Solidworks please check this tutorial
(in Dutch :( with many) pictures). Conclusions on the two different directions: (1) Many possibilities for joiningshapes. A few of them are good for clif hanging, others are too week. The behaviour of cardboard is much defferent compared to solid materials, but the basic principles can be tested like this. (2) Using the SheetCardboard module in Solidworks is very efficient.

The work will be explained in the following subjects.
Result Cardboard models
Joining Box Solidworks
Proto Cardboard Box
Beehive drawer Cardboard
Proto Behive drawer Cardboard
Using the machines
Download project files