Projects

P5: Gravity-powered record player #

Build a gravity-powered record player. You can do this on your own or with a partner, if you feel like you’ll learn more working in a team. 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 paper, folded sheet metal, 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 when the weight bottoms out. 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. We’ll talk about modeling this in class.

P5 proto-design: Wednesday, March 12, at the start of class. The record should spin under gravity power by this date.

P5 final: Wednesday, March 31, at the start of class.

P4: Build a sheet metal lamp #

Build a lamp out of sheet metal. The target here is two-fold: experience with sheet metal and experience with aesthetic design.

You will be given: #

  • A sheet of 5052-H32 aluminum, 0.032 in thick, roughly 12 inches square
  • A sheet of A1008 steel, 0.030 in thick, roughly 12 inches square
  • An LED light bulb
  • A light socket with a cord and switch

A few guidelines to help your learning:

  • Aluminum is a lot more forgiving than steel. With aluminum, if you get a bend slightly off, you can probably still rebend it or tweak it a bit to make it fit. With steel, not so much.
  • We have pop rivet tool in Nolop.
  • We have two hand punches in Nolop.
  • If you want to waterjet an intricate pattern, don’t. It will take forever and use a huge amount of garnet. Instead, search for “perforated metal” or “cloverleaf sheet.” You could split a sheet with a friend if it’s expensive. Home Depot has big sheets; Amazon has smaller stuff. You can also lasercut other materials as panel inserts.

P4 due dates #

P4 learning goals: Wednesday, February 19, 11:59 PM on Canvas.

P4 final: Wednesday, February 26, at the start of class. You can submit documentation up until late Wednesday night, but please bring your lamp to class.

P3: Build a wind-powered vehicle #

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.

You will be given: #

  • 1 hardened steel shaft, 4 mm diameter, 300 mm long (cut only with hacksaw, NOT bandsaw or shear!)
  • 4 ball bearings, ID 4 mm, OD either 9 or 12 mm
  • More ball bearings, if you need them

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.
  • Think carefully about tip speed ratio: https://mmpa.org/wp-content/uploads/2015/09/Tip-Speed-Ratio-Provided-by-Kid-Wind-PDF.pdf
  • More technical info about wind turbine blade design from Erich Hau’s 2005 book, Wind Turbines. I would start by looking carefully at figure 5.10, and then going back to look at optimal tip speed ratio in figure 5.7.
  • You might also be interested in this Javascript airfoil simulator. You could mess around with it to create an airfoil profile that maximizes lift/drag ratio, and then click the “geometry” button to get the XY coordinates of the profile, which you could then pull into Onshape.

P3 due dates #

P3 learning goals: Monday, February 3, 11:59 PM on Canvas.

P3 final: Wednesday, February 12, at the start of class. You can submit documentation up until late Wednesday night, but we will be testing vehicles in class.

P2: Build a sturdy wooden chair #

Build a chair out of wood.

You will be given: #

  • 1 square of plywood, 15.5 inches on a side
  • 2 2x4’s, each 8 feet long
  • 1 1x3, 8 feet long

You can use any other wood you can find or buy, but don’t go buy a bunch of fancy wood. The idea here is not to make an heirloom, but to make a structurally sound chair with basic materials.

A few guidelines to help your learning:

  • If you feel compelled to stain or paint your chair, please wait until after the due date and don’t do it in Nolop. (You should probably do it outside, but it’s probably too cold for that, which is why I’m trying to convince you not to do it.)
  • Think about the loads that your chair will experience when you lean back in it or tip in any direction. Try to reinforce the legs and back so that they won’t break.
  • Glue joint strength is proportional to surface area.
  • In general, fasteners shouldn’t take load directly– they should hold load-bearing parts in place.
  • If you feel the need to cut a 2x4 the long way, just use a 2x2 instead. We have a pile of those.

P2 due dates #

P2 learning goals: Monday, January 27, 11:59 PM on Canvas.

P2 due: Monday, February 3, at the start of class.

P2 learning results: Monday, February 3, 11:59 PM on Canvas.

P1: Build a mechanical car launcher #

Design, prototype, and refine a mechanism that can reliably hold and release a 9.8 N force (the weight of a 1 kg mass on Earth) to launch a toy car off a jump.

The goal here is threefold:

  1. control a large force from a rubber band with a small force from your finger
  2. learn how to build a smooth mechanism
  3. actually launch toy cars off a jump

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 90591A161)
  • 2 M8 washers (McMaster 98689A116)
  • 1 rubber band, size 64
  • 1 toy car for propulsion
  • 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