When I was younger, I was fascinated by the apple peeler-corer-slicer we had in our kitchen. It replaced three distinct steps with a single motion — plus the shapes involved (the spiral on the shaft, the three-pronged spear for the core) were complex and beautiful. When my Mechanical Synthesis class (MAE 2250) assigned the task of replicating a kitchen object in Fusion 360, I knew this contraption would be perfect.

However, two problems presented themselves: the shapes involved were complex, and we had gotten rid of our peeler-corer-slicer years ago. Fortunately, I was able to find a nice image of a similar model online, including some rough dimensions:

The dimensioned peeler-corer-slicer image I found by searching online.

Unfortunately, there was no way around the complexity of the geometry. But its beauty and my love of CAD got me through the process, and the result was a near-identical copy of the picture. I was particularly happy that I figured out how to insert the image as a properly scaled canvas in the 3D workspace — that helped me a lot with proper scaling as I focused on smaller details.

I made all the joints movable in the CAD model (part names in bold correspond to the figure below):

• The shaft rotated and slid left to right, and its range of motion was properly constrained to keep it from phasing through the frame.

• The locking lever rotated to unlock the shaft, and it sprung back into place when released with the mouse. Its tension spring didn’t stretch, because shape changing is not implementable with joints.

• The peeler arm tilted toward and away from the shaft, and it sprung back as if acted on by its torsion spring. I managed to get the torsion spring to seem to twist: I modeled it in two halves, one anchored to the frame and the other anchored to the peeler arm. Then I applied a cylindrical joint between the two halves, and linked the rotation to the sliding motion, thereby keeping the spiral wire coils perfectly overlapped with each other.

• The peeler blade could be adjusted on the peeler arm (in real life, this adjustment lets you choose the depth of the peeler cuts)

• The suction lever moved the suction cup up and down when rotated.

Sadly, I didn’t get a chance to record these motion capabilities or other screenshots before my access to the Fusion file was revoked at the end of the semester. Lesson learned: always keep a backup copy.

The final render of the peeler-corer-slicer model, with relevant parts labeled.