Fondant Cutting Machine

As part of our first senior design capstone class, our professor gave us the open-ended prompt of prototyping a food carving device that can cut designs in food from a digital input. The machine needed to be safe, easy to use by a home cook, and stay within a $250 budget. I was in a team of four other mechanical engineering seniors who created a device that that can cut shapes out of fondant, solving a customer need for cake decorators who might want to cut repeated or custom geometries from this flat, playdoh-like icing.

We started by doing a customer needs analysis, identifying what our end users considered to be most important. We researched online and conducted several interviews of our own with people ranging from the average adult to professional food artists. We repeatedly heard that a device of of the kind we were looking to make should make the food carving process easier; hold the food in place; and be easy to clean, maintain and assemble.

Next we identified the major subsystems that would be involved in our device, and came up with ideas for how each of them might be implemented. We found that we needed a cutting apparatus, a system for the cutting tool's XYZ movement, a way to send digital inputs to the machine, some sort of status indicator, and safety mechanisms. As we began developing our prototype, some ideas worked well and others did not, but we ultimately used the following approaches in our final product.

Since we were cutting into fondant, which is not very thick, our cutting mechanism was a swivel blade, which passively rotates as it is dragged along a surface. This blade was mounted on a gantry that traversed the bed of the machine. The fondant itself was rolled out onto a removable cutting board that had a textured surface. This not only helped to hold our food in place, but also made cleanup easier, since the cutting board could easily be taken out of the machine.

The XY motion of our machine used a CoreXY system, where we had a system of timing belts and pulleys connected to two stepper motors that remained stationary at the back of the machine. (Read more about how CoreXY works here!) This minimized the volume and weight of moving parts, using the machine's power more efficiently. The z-axis was controlled by a lead screw that permitted the swivel blade to move up and down on the gantry.

Instructions for the gantry's movement were prescribed via Gcode. A user needed to draw their desired shape(s) in Inkscape, and then use an extension available in Inkscape to generate a Gcode file. This file was streamed via Universal Gcode Sender to the machine, which had an Arduino with GRBL loaded on it that can translate Gcode into instructions for how our motors should move to generate the desired cutting path of the user's image.

Along the way, we used several techniques from the design process. Among other things, we:

• Created low-resolution prototypes to visualize our ideas and get customer feedback before developing the actual prototype

• Experimented with different blade types and quantified their effectiveness at cutting through fondant to choose the best one for our device

• Ran thermal simulations of our motors in SOLIDWORKS to explore whether or not overheating would be a concern

• Developed a failure modes and effects analysis to understand weak points in our design

• Used Otto and Wood's principles of design for manufacturing and assembly as well as sustainability considerations to make our device easy to assemble and disassemble

Ultimately, our device cost about $240, was 20" x 18" x 8", and successfully cut several shapes in fondant on the day of our demonstration. It also met several of the customer needs that we had identified at the beginning; the main area for improvement was probably safety, but given our budgetary constraints we designed our machine to minimize risk to the user as best as we could. Overall, our professor was thoroughly impressed by our performance as well as the accompanying report and presentation.