[Maker’s Note] 3D-printing Application in Woodworking Joints: KAWAI TSUGITE (3-way joint)

by Yun-Han Lin

Preface

Tenoning is a very sophisticated technique in woodworking, and Kawai Tsugite actually gives me a great starting point on tenoning!

Challenges in 3D-printing

Those who have been using 3D-printing would know the most important part to a printed object is the support material and its strength. Too much support material is only a waste and can make it hard to disassemble the model. The strength of printed parts also varies based on the printing direction. Yet, it is hard to take care of these two variations at the same time. Sometimes, when two forces are applied to an object at different points, it is hard to print the piece in only one direction. For this reason, there needs to be two parts, which is when tenoning comes into play.

Advantages of using mortise and tenon joints

Models with special patterns and shapes are easily printed:

Compared with woodworking, it is easier to build models in specific shapes using a software for printing. Kawai Tsugite, our model this time, would take hours to be completed, even for experienced carpenters in joinery. It requires measurement and planning with precision and takes about only half an hour to complete modeling using a software, before the printer takes care of the rest.

Control tolerance: The good thing about using digital technology is that the tolerance for each printed model does not vary too much.

Disadvantages of using tenon joints

No elasticity for interference fit:

Acrylonitrile Butadiene Styrene (ABS) and Polylactic Acid (PLA) plastics are inelastic. Therefore, when it comes to assembly, unlike wood pieces that can be deformed through hammering to create interference fit that puts the pieces together, too much forces applied on PLA plastics would only break the parts into pieces. This problem can be solved using draft angles or trapezoid tenons.

Long printing hour:

For the time of building tenon joints using 3D-printing and wood pieces, the two is pretty much the same, but 3D-printing is faster sometimes. Yet, if you are only making a 2x2x10cm piece, it takes at least 3 hours to be 3D-printed, while wood pieces take only a few cuts and voila!

Recommendations for future projects

I think using tenoning in 3D-printing projects has a lot of potential. Take Kawai Tsugite we tried this time as an example. A mortise or tenon joint that is compatible for parts in different directions can make various changes to a model. However, if you want to build a model that can be disassembled and assembled repeatedly, you might not want to use Kawai Tsugite. The reason is that the parts can slide off when they are not glued when forces such as shearing forces or normal forces are applied at the same time. For this reason, we may start looking into some 3-piece mortises or those that feature a reinforced structure using wood jointers. Screws and nuts can also be used, which I think can be quite helpful.

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