Dilip Nagarkar, Swetha Sundar, Chao Yin, Cristina Wong-Nomura (Duke University)
ABSTRACT
The goal of this project is to make modifications to an existing drum kit so that our client, a young boy whose TAR syndrome causes him to have short arms with limited strength and reach, can pursue his love of music by learning to play the drums. Various components of a standard drum kit were modified to make his playing experience more comfortable; the drumsticks are customized for his hands, a cymbal damper rests on the ride cymbal stand, the seat is contoured and padded for stability, the tom drums are extended and the toms’ weight is balanced by the additional leg on the bass drum. These changes allow the client to use all the components of the drum kit and play without causing himself any pain or discomfort, while maintaining his independence.
BACKGROUND
Our client is a twelve year old boy who loves music and wants to learn to play the drums. He has Thrombocytopenia-Absent Radius (TAR) syndrome, a genetic disorder that causes congenital bone deformities and reduces blood platelet count [1]. The radius bone is absent in the forearm, the ulnae is often shortened or deformed and occasionally, the long bones are absent in the arm [2]. Patients have thumbs of relatively normal size and shape, but their function is typically impaired [3].
Playing a standard drum kit poses several difficulties for the client, particularly relating to his comfort and range of motion. Due to his limited reach, he tires more rapidly and has difficulty stopping the cymbals once they are crashed. He leans down when striking the snare drum and the floor tom, which causes back pain over time. The position and elevation of the toms and the cymbal require him to bend over and stand slightly to adequately reach these components. The client has to put in additional energy to hold the drumsticks due to their smoothness and lack of grip.
PROBLEM STATEMENT
The goal of this project is to modify a drum kit so our client can play the drums comfortably.
DESIGN AND DEVELOPMENT
We initially met with our client and his family to better understand his physical limitations and what he wanted in the drum kit. Previously, he had to lean forward and strain his body to be able to reach various components of the drum kit. We wanted to make playing the drums ergonomic so he would be comfortable. We purchased a used drum kit through Craigslist and drumsticks from Guitar Center. Each component of the drum kit will be discussed separately below:
Drumsticks – We wanted to extend the drumsticks so the client could better reach the drum kit. Our first prototype was constructed by cutting a drumstick in half, tapping holes in both halves and inserting a long bolt to connect the two pieces (Photo 11). The lack of volume in the center of the drumstick made it feel bouncy. The client noted that the bolt in the center made this drumstick heavier. An alternative we considered was making drumsticks from scratch using the lathe. However, we concluded that getting the shape to mimic a standard drumstick may be difficult with an unfamiliar machine. Our goal with the second prototype was to keep the material uniform to improve sound quality and keep it light. Both of these objectives were satisfied by using a portion of a second drumstick and inserting it into a sawed drumstick using dowels (Photo 12). We added athletic tape to give our client a better grip. Alternatively, we considered purchasing StickGripps, a commercially available custom drumstick grip, but determined athletic tape to be a cheaper, yet equal quality alternative.
- Photo 11: First Customized Drumstick Prototype
Photo 12: Dowels in Second Drumstick Prototype
During our next client testing, we noticed that the prototype worked well for the client’s right hand, but his left hand had more trouble holding the stick in an upward direction, despite the athletic tape grip. In our next prototype for the left hand drumstick, we used a bouncy ball (recommended and provided by the client’s mother) as a grip (Photo 14). The client also found the diameter too large to fit between his fingers on his left hand, so a portion of the drumstick was reduced in radius using the lathe. This notch gave the client something to “latch onto”. After testing with our completed tom extensions, the client did not need the left hand drumstick to be extended, so we kept the original length.
Photo 14: Grip Enhanced Drumstick
The final design of the drumstick incorporated the second prototype, the extended drumstick with athletic tape, for his right hand and the third prototype, the enhanced bouncy ball grip, for his left hand.
Seat – The drum kit we purchased came with a seat, but our client found it small and unstable. The client liked a saddle shaped and padded chair at Guitar Center. Purchasing this seat was out of our budget so we decided to build the seat. The seat base is removable from the stand by unscrewing a mount on the underside. We built our own seat base and attached it to the stand using the manufacturer’s mount. Our first prototype used a saddle-shaped piece of scrap wood (Photo 15) that was upholstered using a mattress pad. This chair was too small and the contours were hidden by the thick cushioning. Our final seat design was larger and had exaggerated contours. In addition to the foam and mattress pad material (Photo 16), we upholstered this with velvet material and attached it all to the stand using the mount (Photo 17).
Photo 15: Saddle Shaped Seat Base
Photo 16: Foam Layered On Seat Base
Photo 17: Final Ergonomic Chair Design
Cymbal Damper – Usually, drummers dampen the cymbal with their fingers, but as this posed a challenge to our client, we designed a cymbal damper that operated as a lever. One alternative we considered was adding a “damping branch” to the drumstick, but we decided that would make drumming more difficult. A first prototype was assembled using materials found in the lab (Photo 18). We used the perforated metal bars so we could adjust the length and angle of the lever arm. For the next prototype, we used aluminum for the center block rather than wood and plastic covered with foam for the strike pad. The crook of the lever arm was formed by bolting two pieces of aluminum together (Photo 19) and after testing, we discovered that this loosened after some use. For the final design, we welded the angle in the lever arm so it would be a more effective damper (Photo 20).
Photo 18: First Cymbal Damper Prototype
Photo 19: Second Cymbal Damper Prototype
Photo 20: Final Cymbal Damper Design
Heel Activated Foot Pedal – Projects designed for our client in the past customized left pedals to be heel-activated. We therefore decided to switch the toe-activated bass drum pedal to a heel activated pedal (Photo 1). We decided to reverse the pedal chain so when the heel pushed down on the pedal, the mallet hit forward (Photo 2). We lathed metallic extension piece to the central rotating rod of the pedal so the mallet could be attached on to the side and away from the foot (Photo 3). During testing, our client reported discomfort with the pedal. So we ran several pedal orientation tests and concluded that the original toe activated pedal was more comfortable for the client.
Photo 1: Regular Bass Drum Pedal Configuration
Photo 2: Heel -Activated Bass Pedal Configuration
Photo 3: Central Rod Extension for Heel- Activated Pedal
Tom Extensions – We wanted to bring the toms close to the client. We did not have a metallic piece that both fit over the original tom connector from the bass drum and also fit inside the attachment to the tom drum, so we designed a telescoping tom extension mechanism where a crutch tube which is lined with holes drilled through the tube, was placed over and bolted to the original tom connector on the bass drum. A PVC pipe which fit into both the crutch tube and the tom attachment was then placed inside and bolted to the crutch tube and attached to the tom on the other side (Photo 4). Since the PVC pipe, crutch tube and tom connector did not fit together perfectly; the telescoping tubes would move and rotate, reducing the stability of the tom extensions. This was overcome when we found tube connectors at the hardware store that fit snugly over and connected the tom connector from the bass drum with aluminum tubes we bought to fit in the toms. This connection was bolted together for further stability (Photo 5). Since the toms now extended out with a larger moment arm, we added support bars under the toms extensions so that all the load did not go on the bass drum-tom connector joint (Photo 6).
Photo 4: Tom Extension Prototype Using Crutch Tubes
Photo 5: Tom Extensions Using Tube Connectors
Photo 6: Finished Tom Extension Mechanism
Third Bass Drum Leg – Adding the tom extensions increased the torque of the system, so a third bass drum leg was created to prevent the drum from tipping. Our prototype secured a metal strip under the bass drum support screws at the bottom of the drum. We bolted a metal rod or leg to a hinge and then bolted this metal hinge to the strip secured under the bass drum (Photo 7). This leg worked well, but it was not adjustable. We then designed an adjustable stopper that screws into the bottom portion of the leg (Photo 8). We also added a Velcro strap that allows the leg to be stowed against the drum and out of the way when not needed (Photo 9). The leg works effectively as an added support (Photo 10).
Photo 7: Third Bass Drum Leg Prototype
Photo 8: Adjustable Length Screw Leg
Photo 9: Leg Stowing Mechanism
Photo 10: Activated Third Leg
EVALUATION
The ergonomics of our design were crucial to its success. Therefore, client testing was imperative, as the feedback was essential. In addition to component tests, we left the drum kit at the client’s home for over a week as a test run. We have also evaluated our design based on theory, using basic principles of mechanics. Please see “Quantitative Analysis” for further details.
DISCUSSION AND CONCLUSIONS
The modified drum kit features ergonomic design and provides a comfortable drum playing experience for the client. The distance between the client and components of drum set is minimized by the presence of the tom extensions. The cymbal damper’s lever mechanism allows the user to control components further away from a distance so he can avoid leaning his body forwards. The drumsticks provide optimum grip and take advantage of the client’s varying hand strengths.
The primary limitation of this device is also its main advantage, which is its heavy customization. All the components of the drum kit are modified with a single client in mind. If these parts are used with a different client, the same sort of ergonomic advantage will not be seen. The marketability of this device remains low because a customized device cannot be mass produced. Patients with TAR syndrome have varying physical capabilities and limitations so designing a universal drum kit is not plausible.
VIDEO
REFERENCES
- 1. Bonsi et al. 2009
- 2. Hall et al. 1969
- 3. Goldfarb et all, 2007
ACKNOWLEDGMENTS
This project is supported by the National Science Foundation under Grant No. BES-0610534. We would like to thank our professor, Dr. Larry Bohs, for his assistance and support, Steve Earp for his help in machining, Veronica Rotemberg for assistance in design and our clients for providing us with terrific feedback and for providing us support throughout this semester long design process.