Hot Wire Tool
initial molded prototype
final product
The task at hand for this project was to design a hand tool that uses heat dissipated across a nichrome wire to produce an electrical current. The learning objectives from this assignment were to 1) use molding and casting techniques to create parts for physical prototypes, 2) design a device that requires the combined use of materials with different functional characteristics, and 3) determine the shape and dimensions of mechanical components based on ergonomic principles.
The specific exercise at hand was to create the hand tool using molded, 3-D printed, or machined components. One specification included was to implement a power button to control the electrical input. The thoughts behind the design revolved around functionality, maintenance, usability and appeal. From here, ideas were sketched out. The idea that my group felt would best suit this assignment was chosen to be developed. From there a CAD model was produced to be 3-D printed for a final prototype.
power drill concept
screwdriver concept with lateral and medial grips
handsaw concept
screwdriver concepts with bottom positioned grip
The design process that went into the tool revolved heavily around ergonomics. Due to the nature of the hand tool, it was necessary to research the average hand size in order to accommodate for the majority of the population. It was determined that the optimal diameter of the hand tool needed to be around 1.5 inches and the minimum length of the handle needed to be 4 inches.
Our thought process behind the design came down to how we wanted the tool to be used. Since the intention of the tool is to be able to cut foam, we thought about how it would be utilized. Our group decided on a tool that would use a power grip. The power grip allows for the tool to be used at multiple angles, maximum force to cut off as much material as possible, and the ability to keep the hand as straight as possible for the best accuracy.
Ultimately, the design we decided on came down to appeal, usability and ease of manufacturing. We found that the power drill shaped model fit our requirements best out of all the ideas. For the handsaw model, we liked the appeal and usability but found that the ease of manufacturing and assembling would be too difficult. For the screwdriver models we decided that the simplicity of the tool would not be as appealing.
CAD model
interior cutout of CAD model
3-D printing initialized
3-D printing progress
Results & Evaluations
In the end, our group successfully manufactured our hot wire tool. However there were challenges along the way. The biggest issue occurred during the 3-D printing process. Since the tool covered a large area to print, it was difficult to keep the piece flat down on the board. Our first printing trial resulted in a curvature on the bottom face of the printed tool. In order to combat this issue from happening again, we added more support structures to the print to keep the piece flat as possible. After a second print, we ended up with a handle we were satisfied with. Once we had the handle printed, assembling the parts together was not too difficult. The nichrome wire and clay mold were glued to the barrel of the tool. The button was fitted into its cutout and the wires were led out the holes created at the bottom of the handle. The two printed parts were then fastened together with screws to secure the hand tool together. We tested the tool shortly afterwards and it performed as expected. The tool operated at a rating of 4.2 amps and only cut foam while the button was pushed down. We achieved what we set out to do for our assignment.
powered on demonstration
powered off demonstration