Guitar Strummer

Designers: Jason Bennett and George LaVerde
Client Coordinators: Jane Stavely, Kaaren Jewell
Supervising Professor: Dr. Larry N. Bohs

The client, who is now eleven, had a stroke on the left side of his brain when he was three. Consequently, he does not have the physical coordination in his right arm and hand to strum a guitar. The Guitar Strummer gives the client the opportunity to learn how to play the guitar, despite his physical constraints. The design is simple, lightweight, and portable, and the client can assemble and use it without assistance. The client uses his left leg to control the rhythm of strumming.

A foot pedal actuates a pivoted striking rod that hits all of the strings at once. When the pedal is tapped, a cable pulls up on the short end of the rod, causing the long end of the rod to swing down and strike all the guitar strings simultaneously, creating a sound similar to strumming. The striking rod housing unit is removable for easy transportation and storage.

How this project helped
Because the client has minimal control over his right arm and leg, he does not have the capability to play the guitar. This device provides the client with that capability.

The Guitar Strummer (Figure 1) uses a foot pedal to pull a bike cable that is attached to a polycarbonate striking rod. The rod’s starting position is slightly above the strings. When the client taps the foot pedal, the mechanism on the pedal pulls the bike cable, which thereby pulls the short end of the rod so that the opposite end swings down and strikes the strings. A rubber band, which attaches to a hook on the striking rod, holds the striking rod in the resting position. The rubber band rests       in a groove on the back of the striking rod housing unit. The striking rod is slightly loose on the cable so that when it hits the strings the rod has some mechanical freedom from the cable mechanism and can thereby bounce to prevent damping. Instead, when the rod strikes the strings, the rubber band pulls the rod back up and allows the strings to resonate.

The foot pedal mechanism is modified from a bass drum foot pedal. The bike cable housing is attached to an aluminum L-shaped plate. The cable passes through a hole in the plate. The end of the cable is held by a rotating disk that is fastened to the original mallet rod. When the pedal is pressed, the end of this mallet rod is rotated along a circular arc away from the aluminum plate, thereby pulling the cable. The cable and cable housing extend up to the guitar where they attach to the striking rod housing unit.

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