P5: Human-powered vehicle #

Your mission is, as a team of 4, to build and test a human-powered vehicle that can traverse the course depicted in the diagram below. You start at the green line and end at the green star.

The vehicle should have the following qualities:

  1. It is piloted and powered entirely by 1 or more of your team members.
  2. It can carry a passenger (one of your team members) to the destination without damaging them.
  3. It makes traversing the course easier than dragging the passenger or carrying them like a backpack.
  4. While traveling, nobody onboard the vehicle should touch the ground.
  5. The vehicle should not require unusual balance or skill to pilot (no unicycles, pogo sticks, unstable monstrosities).

The challenge course

As usual, you should develop 1-3 learning goals for the project, in the usual format on Canvas. My goal is to give you the opportunity to work on an engineering challenge that is physically larger and likely involves higher forces than the smaller, desktop projects we’ve done so far.

Resources #

  1. Your team must spend at least $100 of Tufts’ money. To order stuff, post a message in the #designforfab channel in the Nolop Slack workspace. Brandon will order whatever you ask for. The upper limit is $150ish. You are welcome to buy more stuff if you want.
  2. 2x3 lumber will be available in the Nolop store for around $5/8 ft. Also, some plywood, 1/4", $10 per 2x4 ft panel. We also have lots of aluminum framing.

Trials / due date #

  • Tuesday, April 19, 10:30 AM: show the class a drawing of your vehicle.
  • Thursday, April 28, 10:30 AM: preliminary trials on the course. This is mandatory.
  • May 9, 3:30 PM: final trials on the course. We will invite a crowd.

P4: Gravity-powered record player #

With a partner, build a gravity-powered record player. It should be able to play a 7" diameter record for 4.5 minutes at 45 RPM. If you decide you need a horn to amplify the sound, do not 3D print one. Instead, use folded sheet metal, cardboard, or the like. You might make a trigger mechanism that would start the record playing.

You will be given: #

  • 1 vinyl record
  • 4 or 5 steel needles
  • As many bricks as you request, within reason

Please set your learning goals for the project on Canvas as soon as you have time.

A few pieces of advice #

As you think about your learning goals, it would be pretty safe to assume that all of you will be able to make a record spin. Sure, you might have a last-minute failure where some pulley comes loose on a shaft, but generally, you’ll get it.

You will probably also find that the sound of the needle is surprisingly audible, even with a hastily constructed paper horn for amplification.

For most of you, the major challenge of the project will be figuring out how to control the speed of the record so that it spins at a constant rate. If you have no method of speed control, your record player will start slow, then spin really fast for a few seconds, and then tail off dreadfully. Having a low-friction system is also pretty important– it’s difficult to control speed if the thing is really difficult to spin in the first place. Actually playing for 4.5 minutes is a pretty ambitious goal, but can be done with a low-friction system.

P4 proto: Thursday, March 31, at the start of class. The record should spin under gravity power by this date.

P4 final: Tuesday, April 12, at the start of class. (Was previously April 7.)

P3: Make a puzzle ball #

In a team of 3, design and fabricate a spherical puzzle similar to the Perplexus. Your puzzle should contain a total of at least 15 puzzle stages. Each team member should fabricate at least 5 stages; each person’s stages don’t have to be contiguous.

You will be given:

  • 2 steel balls, 9 mm in diameter: McMaster 1598K31
  • 1 transparent plastic ball, approximate inner diameter 195 mm


  • Do not alter the big plastic balls. Do not drill holes in them or glue things to them. (This is for two reasons: I want to reuse them next year, but also, if you glue stuff in, you will very, very likely regret it. You need to be able to assemble, test, and then iterate. Adhesives do not iterate.)

Prototype due: Tuesday, March 1, at the start of class.

Project due: Tuesday, March 8, at the start of class.

P2: Build a wind-powered car #

Build a small vehicle (less than 40 cm long) that can drive upwind without any source of energy other than the wind. We will use a fan for testing.

A few guidelines to help your learning:

  • On the final vehicle, Lego gears are prohibited. You can use other Legos (wheels or whatever) if you want, but no Lego gears. This is to encourage you to learn how to design a gear, if you want to use gears. For prototyping, anything goes.
  • If your design uses a propeller, do not 3D print a propeller, unless it is entirely of your own design. This is to encourage you to learn how to design a propeller.
  • Your vehicle does NOT have to be a car. Wheels are cool, but other methods could also work, depending on your goals.

P2 due dates #

P2 learning goals: Tuesday, February 8, 11:59 PM on Canvas.

P2 proto: Thursday, February 10, at the start of class.

P2 final: Tuesday, February 15, at the start of class. You can submit documentation up until late Tuesday night, but we will be testing vehicles in class.

P1: Build a trigger mechanism #

Make a trigger mechanism that can reliably hold and release a 9.8 N force (the weight of a 1 kg mass on Earth).

The goal here is not to make a missile weapon, but to control a large force from a rubber band with a small force from your finger.

You will be given: #

  • 1 ball bearing, 22 mm OD, 8 mm ID, 7 mm width, part number 608RS
  • 1 socket head cap screw, M8 x 1.25 mm, 30 mm length (McMaster 91290A434)
  • 1 M8 x 1.25 mm nut (McMaster 91828A410)
  • 2 M8 washers (McMaster 98689A116)
  • 1 rubber band, size 64
  • 1 plastic ball, 12 mm in diameter
  • Various bolts and washers, available in the gray drawers in Nolop
  • Various brass heat-set inserts, available in the orange cabinet in Nolop
  • Various washers, available in the gray drawers in Nolop

You will need to obtain: #

  • Probably some cardboard for prototyping
  • Probably some acrylic or plywood from the Nolop store for laser cutting