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With a design in mind, I created a rough build plan and purchased wood.

Wooden Life-Size Wind-Up Car Rough Build Plan

Upon purchasing wood, I analyzed the dimensions to ensure I could get all my desired pieces out of it and then created a cut plan.

Life-Size Wind-Up Car Wood Template

Life-Size Wind-Up Wooden Car Cut Plan

I then began cutting.

Life-Size Wind-Up Wooden Car Pieces 01

Life-Size Wind-Up Wooden Car Pieces 02

Life-Size Wind-Up Wooden Car Pieces 03

Life-Size Wind-Up Wooden Car Pieces 04

From here, after speaking with Peter Brue and some peers, I plan on cutting finger joints to connect the box from of the car. Pete recommended I do so on a band saw and said I could further reinforce the hold by drilling down through the joints and driving a dowel into the hole. As you can see in my build plan, I was planning on attaching the wheels to the axle by cutting a plus shape into each. However, after discussing, I think I will drill a hole though the wheel and axle and drive a dowel all the way through (this is an idea I pondered earlier after speaking with the Landscape Architect, as mentioned in an earlier post) and/or locking the wheel in place by drilling holes on either side of the wheel and driving a dowel pin through, locking the wheel in place. My hesitation with the latter idea is I fear if the wheel is not locked onto the axle, it will spin freely and not propel the vehicle forward.

Sketches by Erdem

Sketches by Erdem Selek

Erdem, my professor, quickly identified my design was getting too complex. Scanning through my sketches and looking at my model, he said the design of the vehicle was distracting and overshadowing the rubber band element of the toy. Thus, Erdem recommended I stick with a simple form, such as the box of my original, cardboard model or a simple cylinder shape. He conveyed he preferred the proportions and feel of my first, cardboard model and that the wooden model was getting too big and complex. He demonstrated the effectiveness of a simpler design through the sketches pictured above, showing that the design put a greater emphasis on the rubber band and its imperative role (whereas the user might look at one of the more complex designs and question, for example, “why use a rubber band?”). With the more basic design, though, Erdem stressed there still must be a sense of direction in the vehicle, that the user should comprehend which side is the front. If done well, a simple vehicle design with relatively nonexistent or hidden mechanics has the potential to spark more interest within the user. That being said, he pointed out I could reveal or hint at the rubber band through a slit on either the top or side of the car. Erdem pointed out these could also function as handles. With a simple vehicle design, as he explained, the vehicle could sit in a room, decoratively, but also serve a functional purpose and, ideally, the user will look at and question the product. What is that box? What does it do? Is it just a box with wheels? What’s inside the hole? Why is there a rubber band? Upon interacting with the box, the user will discover that it is in fact a large wind-up toy.

Based on my model, I’m not sure if I can accomplish my goal of being able to ride on the wind-up vehicle, at least within the product time frame. This is disappointing and unfortunate but, as Erdem expressed, even if the vehicle could not bear a child’s weight, the idea of a large wind-up toy still holds potential for fun. Furthermore, my final product for this project could be the first version, the first prototype, of an eventual model that can transport an adult.

After receiving input from a variety of peers, I set out to revise my wooden life-size wind-up car model.

Revised Wooden Life-Size Wind-Up Car Model 01

I extended the axle around which the rubber band would wind up and cut an in-wheel hook. I tried securing the wheel to the axle by cramming rubber bands under and immediately next to the wheel on both sides.

Revised Wooden Life-Size Wind-Up Car Model 02

Revised Wooden Life-Size Wind-Up Car Model 03

I lined the wheels with rubber bands to increase traction and, like the axle, secured the wheels with rubber bands.

Revised Wooden Life-Size Wind-Up Car Model 05

Revised Wooden Life-Size Wind-Up Car Model 08

When I tested the vehicle, I discovered the rear crosspiece, despite the hole, hindered the band. Thus, I decided to remove the piece for at least testing purposes.

Revised Wooden Life-Size Wind-Up Car Model 09

Revised Wooden Life-Size Wind-Up Car Model 10

Despite the new axle and rubber bands securing the wheels on the sides, the car did not work and, instead, spun in place. The issue was, in part, due to the fact that the band did not wrap around the larger axle piece. and instead, after hooked, wrapped around the dowel. In an attempt to resolve this, I added a grove around the axle wheel. I also added the rubber bands around the wheels as did I with the first attempted wooden model.

Revised Wooden Life-Size Wind-Up Car Model 11

Still, though, the vehicle did not work.

After my wooden life-size wind-up car did not propel forward when bearing my weight, I reached out for help from a few peers including a Landscape Architect, Software Engineer, Mechanical Engineer, and Construction Engineer (and, as discussed in a previous post, fellow Industrial Designers). I asked for their input on both how to adjust the vehicle so it could transport an adult and how to improve the vehicle overall. Through my consultations, I plan to investigate the following adjustments.

Life-Size Wind-Up Car Consultation 01

Larger Wind-Up Axle: Not broadening the entire axle but the part about which the rubber band wraps up. I don’t remember the exact physics reasoning behind this, but I think it will aid torque.

Life-Size Wind-Up Car Consultation 02

Rubber-Lined Wheels: Wrapping rubber bands around the circumference of the wheels to improve traction.

Life-Size Wind-Up Car Consultation 04

In-Wheel Axel Hook: Connecting the rubber band to the axle via a hook within the axle (opposed to an extended dowel) should ease winding up the vehicle (the user will not need to guide the rubber band and prevent it from catching the end of the dowel). Furthermore, removing the dowel removes the potential risk of it falling out.

Life-Size Wind-Up Car Consultation 07

Rubber Band Catch: Preventing the user from having to feed the band through the hole every time it is freed from the axle after wound up.

Life-Size Wind-Up Car Consultation 08

Peg-Held Wheels: The Landscape Architect recommended I take a long drill bit and drive a hole completely down both sides of the wheel, through the axle, and then secure the wheel to the axle via a dowel on each side, held in place by the rubber bands extended about the circumference of the wheels. I’m not sure if this is the most effective or efficient way to secure the wheel, but I think it does hold potential.

Life-Size Wind-Up Car Consultation 05

Altering the Contact Size of the Body: While one argued that I should increase the connection board, therefore increasing the surface area and more evenly dispersing the weight on the axles, another posited that this would be detrimental as it would increase friction.

Life-Size Wind-Up Car Consultation 09

Altering the Size of the Wheels: There was discussion on making the wheels bigger (especially the rear wheels, which power the vehicle), with the argument that speed racing cars have large back wheels, the Mechanical Engineer argued that while it may make a difference, the wheels are probably alright in terms of size.

I entered the shop with a rough build plan. However, I approached the design flexibly and altered details as I crafted. Fortunately, I had the help of Peter Brue to navigate the various tools and relatively foreign environment.

Life Size Wooden Wind Up Car Model 01

Life Size Wooden Wind Up Car Model 02

Life Size Wooden Wind Up Car Model 03

Life Size Wooden Wind Up Car Model 05

Life Size Wooden Wind Up Car Model 06

Life Size Wooden Wind Up Car Model 08

After cutting out all the pieces, I assembled the vehicle.

Life Size Wooden Wind Up Car Model 09

I then attached a large rubber band (C9 Round Resistance Band) to the rear crosspiece and wound it up about the axle.

Life Size Wooden Wind Up Car Model 11

Life Size Wooden Wind Up Car Model 13

Life Size Wooden Wind Up Car Model 14

The car did not propel forward (at least as far) as I had hoped, so I modified the design so that the band would stretch farther. I did this by switching the cross pieces, cutting a hole in the second piece, and extending the rubber band back, though the hole, and then around the axle.

Life Size Wooden Wind Up Car Model 15

Life Size Wooden Wind Up Car Model 16

Again the car did not propel forward as far I had hoped. Instead, the axle and wheels simply spun pretty much in place. I recognized two factors that likely produced this result: poor craftsmanship and lack of traction. The wheels were loosely attached to the axle, which was unevenly sanded and not itself securely in place relative to the body. Also, the relatively frictionless surface of the concrete floor freed the wooden wheels to spin in place (instead of moving forward). In an attempt to resolve both issues (craftsmanship and traction), I added rubber bands around the wheels which held them in place and added bands of traction around the surface.

Life Size Wooden Wind Up Car Model 17

The life-size wind-up car then propelled forward! However, it did not yet do so when bearing my weight.

Life Size Wooden Wind Up Car Model 18

Moving forward, I hope to figure out how to alter the vehicle so that it may move forward when a person is sitting on it. One suggestion from my peers was to use larger wheels, therefore increasing the surface area. I plan on reaching out to others with engineering and physics insight for additional input. I would also like to ease the setup. I decided to not attach the band to the axle so that, once relieved, it would not halt the vehicle nor wind up the other direction. Alternatively, by allowing the band to snap off the axle, the vehicle is able to continue propelling forward. However, currently it is difficult to feed the band through the hole and then wind it about the axle. A peer recommended I place a hook or even simple rod stopper across the rear hole so that the band would free from axle but not completely retract and thus simply require the user to stretch it the short distance from the back piece to the axle. I would also like the user to simply pedal backwards to wind it up and not have to guide the band around the axle and keep it from catching on the dowel.