We began our mechanical model with a drawing of our concept. Both of us went to universities for undergrad that had a huge football scene. So we thought it would be fun to create a model of a football field with players that moved up and down on the field.

 

 

 

 

 

We used the Noun Project to find .ai files for icons that matched our theme (American football players, field goal posts, and a field design to etch on the wood). We also created a 2D drawing generated by en.makercase.com, in order to create a tight-fit box that could be easily assembled. The setting we chose was to use a finger size of approximately 1 and a kerf of 0.008.

We looked at existing mechanical models from previous years to determine how big we wanted our entire model to be, and also we created many hand drawn sketches in order to determine internal measurements for our model as well as distances between different parts and features.

We used these measurements to create our first, low fidelity cardboard model, and made small adjustments where necessary (to minimize material use wherever possible). 

Our cardboard model helped us notice that there was a lot of slop and movement/twisting of the cam-followers, that made the motion get stuck occasionally. This led us to create a second layer, underneath our top surface to keep the cam followers vertically aligned the whole time.

With the addition of our second layer, our cam followers we had made were not as ‘tall’ as we would have liked them to be, so we laser-cut different size options to test what we would like best.

After creating and learning from our low-fidelity cardboard model as much as possible, we moved on to laser cutting our pieces out of wood. We cut the outer box with an etched top field, players, field goal posts, as well as the cam followers and circles (toothless gears) that would be tight-fit and glued to the dowel.

Here are some of our wood pieces being cut by the laser cutter:

Then we started assembling our model, to ensure everything fit together well.

We are really proud of how we maximized space when laser cutting the wood!

When selecting our post-processing methods, we chose staining the wood to make our model a darker color so it was easier to see the etching on the field. We chose a dark brown colored water stain and applied a coat. We let it dry for at least 24 hours and then applied a layer of oil finish.

While the stain was drying, we sanded the gears and cam followers down, this ensured the cam followers would move smoothly as the dowel and gears spin.

We assembled the model again, this time using wood glue to secure the toothless gears to the dowel and then tested the function of the gears inside the box and confirmed that the play was removed. 

To be able to see the gears working inside the box, we laser cut a piece of acrylic to be used as a viewing window. We attached the acrylic to the front piece of the box with velcro. 

To support the mechanical model, we laser cut some more pieces to add. The dowels needed a stopper to prevent them from slipping out of place. We cut a donut-shaped piece with the inner diameter matching that of the dowel so it could be tight-fit and secured around the dowel, but flush against the box to serve as a stopper. To support the goal posts, we cut small rectangles to place around the bottom of the posts to keep them upright on top of the box model. We also cut out football shaped handles to turn the dowels. Additionally, we cut a nameplate to place on the back of the model.

Once all of the final pieces were cut out, we assembled the box and started applying wood glue. We glued the players to the cam followers and the field goal posts to their supports on the box. We also glued down the top piece of the box with the field to ensure longevity of our mechanical model.

For the vinyl piece, we wanted to add the common phrases used to cheer on the football teams at our undergrad universities. We used VinylMaster Cut software to create the file and print the phrases on black vinyl. Then, we weeded out the excess, added on the transfer paper, and applied it to the sides of the box.

Overall, we are very happy with the outcome of our mechanical model! The players and cam followers smoothly move up and down as the dowel spins the gears. The stain gave the wood a nice finish and made the field etching really stand out. We are both obsessed with it, and plan to fight over it later.

Cost Analysis:

Cost Type	Item	Cost	Source	Quantity	Total
Material	Cardboard	$5.29	Walmart	1/8in x 2ft x 4 ft	$5.29
	Wood	$5.48	Home Depot	1/4in x 2ft x 4ft	$5.48
	Varathane Wood Stain	$12.98	Home Depot	1 quart	$12.98
	Gorilla Wood Glue	$3.97	Home Depot	1 bottle	$3.97
	Gloss Black Vinyl	$7.99	Amazon	1 roll	$7.99
Labor	Laser Cutter Operator	$19.90/hr	ZipRecruiter.com	12 hours	$238.8
	Prototyping Engineer	Custom ($20/hr)	Team	21 hours	$420
Total Cost					$694.51

Clean Workspace Photos: