3D Printed Coat Hook and Key Holder That Hangs From a Door Handle, Made Using Generative Design

A coat hook and key holder that hangs from a door handle

Fusion, 3D printer

My first attempt did not go well. After taking some measurements of the door handle i made some drawings that informed the design, but didn't actually account for dimensions or shape of handle.

Once in fusion, I did not define the objects to keep nor the obstacles well...The solution found a way to squeeze between and fuse where I did not want.

This design also would not have worked anyways. I hadn't yet really thought about where the forces would be and how the object would rest against the door.

I thought that 40N applied to one of the faces of each hook and the underside of the loop would suffice. From the spindly arms, I assumed this was incorrect.

I made a second design with a larger coat hook and from it, a smaller key hook. The shape of the hook was made by extruding point splines and manipulating their handles. The tray is made from simple rectangles. And the top loop was made with straight lines from the corners of the tray intersecting a circle that is the diameter of my door handle. Filet was applied to all of these shapes.

For obstacle geometry I started with a point spline on the zy plane that wrapped between the hooks and the tray as well as between the top loop and the tray. Next I placed the rectangular cube inside the tray and the part beneath the loop. At this point I tried the previewer and the model was connecting the top loop with the front of the tray. So I added the big vertical block in front of the loop and intersecting with the first obstacle. I also wanted the top loop to connect towards the back of the tray. So I made sketches on the flat part of the obstacle beneath the loop, extruded up and then pulled towards the central line of the object. This left a small gap at the bottom for the generative design to connect. This worked pretty well.

Looking at the previewer again, it was clear the two hooks needed separation. Also, even though my design was asymmetrical, defining a symmetry plane forced the generated geometry to have a hook on the other side. So I added another obstacle on the other side of the center hook.

I added forces and made sure to add forces to all of the faces on the side of the hook. This did seem to make the hook connections much more sturdy. I didn't do this for the top loop, though I should have.

There were two types of results. The first picture shows the first general type which was super overwrought and bulky. The second type general type had thinner, well-placed connections that looked like they would support weight well. The top loop's connection to the tray did not seem sturdy enough. So I selected a couple small faces at the joint between my set geometry and the generative geometry and used the automated modeling option in fusion to connect to the side of the tray. This worked great and I choose a more bulky option since it didn't interfere with the functionality and would ensure it was a solid connection. I particularly liked that it matched the style and added material all along the edge of the tray.

I had to removed the extra symmetrical hook and also used automated modeling to heal up a face left behind. This also added an extra layer around the base of the hooks connection with the tray, which seemed like a plus.

It was printed in a Bamboo Lab X-1 Carbon. The design was turned on its side to ensure continuous beads of material orthogonal to the direction of the main direction of force on the object. The top loop may suffer because of this, but a lot of the force is on the back plate, so I hope it will last. Should be easy to repair if needed.

It came out with quite a lot of support material. Took a long while to remove, but the piece beneath felt solid and I never felt like I might break the piece. Some of the support material was fused on and there are a lot of scars left behind.

The design fit perfectly on the handle, providing clearance for the door to operate, coat and keys to hang, and my car key in the little tray.

The purple looks great!