MechanismsandThingsThatMove

Attendance

Speaker: Dan Formosa - Smart Design

Final Projects - Requirements:

• It doesn't have to have a motor, but it must move
• You may have up to 1 partner if you choose, no group projects
• If you are stuck for ideas, think of our original themes of "the line between art and engineering lies only in our minds" and the concept of abundance and constraints
• 1pg Proposal due next week

SPRING DEMOS! Did anyone do the math? Show and tell.

Machine Shop Tour:
Location: 544 Park Ave. @ Nostrand, Brooklyn
Time: 10:30am
Date: Friday, April 10th

Combining Simple Machines

All complicated machines, mechanisms, and robots, are made up of combinations of simple machines. They also help us convert rotary motion - the most common input motion - into linear, up and down, or intermittent output motion.

Cranks

Cabaret Mechanical Movement pg 41
A crank is a basically a lever attached to a rotating shaft

• Ex: bucket in well, Mechanical Wooden Face

Cabaret Mechanical Theatre

Ratchet & Pawl

Cabaret Mechanical Movement pg 77
Gives a motion that is not continuous (stepped, intermittent)
Ratchet: basically a wheel with notches cut into it
Pawl: pushes against the notches and drives the wheel around in steps. A second pawl (detent) can stop the wheel from slipping backwards.
A ratchet/pawl system can also be used as a clutch
Ex: ratcheting screwdriver

Linkages

Cabaret Mechanical Movement pg 67
A linkage is a connection that transfers motion from one mechanical component to another. Sometimes a linkage is a lever, but the vocabulary isn't important

• Eric's heart linkage

Why use a linkage?:

1. Change direction, altering the motion
2. Alter speed and/or acceleration
3. Change timing of moving parts
4. Apply a mechanical advantage
5. Elegant and efficient motion - KMODDL

Four bar linkages are the simplest closed loop kinematic linkage
Consist of 4 segments:

1. Crank
2. Ground/Frame
3. Follower
4. Lever/Coupler

linkage examples
examples of different configurations
Designing a 4 bar linkage
Grashof's law:
The sum of the shortest and longest link of a planar four bar linkage cannot be greater than the sum of remaining two links if there is to be continuous relative motion between the links

Interactive 4-bar

Real life linkage art:Kal Spelletich's small machines, Eric & Scott's RoBat midterm

Uses

• machine components and tools
• automotive suspensions and
• bolt cutters
• internal combustion engine's piston/rod/crank
• front loader
• windshield wiper
• umbrella