The University of North Carolina at Chapel Hill

Designers: Jordan Hutchinson and Justin Fender

INTRODUCTION

Our client is a carpenter who has functional use of just one arm due to a brain tumor. He is unable to do finishing carpentry, such as nail setting and chiseling. Both of these tasks require the use of two hands – one to hold the hammer, and the other to hold the nail set or chisel. When setting nails, the user strikes the nail set, which then punches the nail head below the wood surface. Chiseling requires similar actions. These tasks pose a challenge to individuals like our client, due to his disability.

Our goal was to create devices for nail setting and chiseling that can be operated with just one hand. The client needed devices that were easy to use, comfortable, practical, and portable. We developed these devices by modifying commercial PowerShot® staple guns with custom tips to perform the desired functions (see figures 1-2). The nail set tip has a “V” shape, so that the tip hits the nail only and not the surrounding material (i.e. wood). The chisel has a long beveled tip so that it can chisel into wood.

Figure 1. The completed device, where the custom nailset tip is at the bottom right.

Figure 2. The interior mechanism of the chisel’s staple gun in which only one piece was removed and modified other than the casing.

SUMMARY OF IMPACT

This design allows our client to be less dependent on help from others, and to perform his work independently with just one hand. The client remarked that the device, “allows me to have the ability to set nails without having someone do it for me. This gives me more independence especially since I don’t have to hire an extra carpenter needed for the job, saving $15 an hour.”

These devices are safe, lightweight, portable and simple to use. It is easy to activate the staple gun lever that does the mechanical work of driving the nail into wood or chiseling wood. The device includes a safety latch to prevent undesired activation of the device.

TECHNICAL DESCRIPTION

Figure 1. Custom tips for chisel (foreground) and nail set (background). The chisel tip is approximately 2” long

Due to the requirements of functionality, size, weight, reach, and cost of the device, a commercial staple gun was used (see figure 2). The device is small with dimensions 16.50 inches x 1.50 inches x 9.25 inches; it is easily portable and weighs 3.17 pounds. Due to its small size and weight, the device can be used in a wide array of positions and is not limited to one which provides the most torque and leverage. As long as the handle can be depressed, the device will do its job. The custom tips were the most expensive components. The device is easily made and fixed if broken because we have only replaced one component of the commercial product (see figure 3). Our client was initially the only intended user of the device, but the universal design aspect of the device allows it to be used by anyone intending to increase their productivity, efficiency, and ease. Since our client is now adjusting to using his non-dominant hand, our device is made so that it can easily be used with minimal coordination. The device effectively drives the heads of nails below the surface of all types of woods tested.

The cost of the project is $40.