Compound Machine Design
Introduction
Reuben Garret Lucius Goldberg was born in 1883 in San Francisco, CA. Goldgerg’s father who happened to
be a police and fire commissioner insisted on him becoming an engineer. Rube graduated from the University
of California, Berkeley with a degree in Mining. He then worked for San Francisco’s Water and Sewer
Department for 6 months before he quit and started working as a cartoonist. He worked on a number of
famous cartoons of the time but what made him famous was his crazy engineering of complex contraptions to
perform simple tasks- now known as Rube Goldberg.
Challenge
Your group is tasked to build a Rube Goldberg machine that will lift a weight at
least 8” from its starting position. When achieving this goal, keep in mind that you
want the greatest mechanical advantage!
Design Constraints
 The applied effort force may only be provided by a single human input.
 The compound machine must lift the weight at least 8” from the starting
position.
 The final design must include a minimum of 4 different mechanisms. These
mechanisms must include the 6 simple machines and/or the 3 power train
elements discussed in class.
o 2 of the same types of simple machines do not count as 2 different
mechanisms.
o 2 of the same type of gear trains do not count as different mechanisms.
 The compound machine must have a mechanical advantage greater than 3.
 The compound machine must easily fit in the storage space designated.
(Limited to one metal base. The 2nd base may be used as a structural support
system to the side of your 1st base.)
Procedure
1) Define the Problem – carefully read all constraints and objectives
2) Generate Concepts – In a new section in your EN called Rube Goldberg:
a. Evidence of brainstorming (sketch and annotations) – One per group member.
b. As a group, decide on the best concept. A decision matrix must be used for this. It is your group’s
choice.
3) Develop a Solution –
a. Create a concept sketch** of your chosen design idea. Your concept sketch should use both pictorials
and words to easily and clearly convey your complete design idea without any verbal input. One per
group.
**YOU MUST GET MY SIGNATURE ON YOUR CONCEPT SKETCH BEFORE MOVING ON TO THE NEXT STEP**
4) Construct and Test the Prototype
a. If there are any modifications made to your design during the prototype phase, be sure to note the
changes that were made and why they were made. Then, create a modified concept sketch. This
modified concept sketch should be a sketch that is separate from (and in addition to) the original concept
sketch.
b. Take photos of
i. Your overall compound machine
ii. Each separate mechanism
c. Calculations –
i. Calculate the Individual IMA of each simple machine
ii. Calculate the Total IMA of the Machine
iii. Calculate the Total AMA of the Machine (best you can)
iv. Calculate the Efficiency of the Machine (best you can)
5) Evaluate your Solution. This is a written portion (completed by each group member) that verifies all criteria and
constraints were met and discusses the calculations. Could you have gotten better IMA, AMA or efficiency
results? What would you do differently next time? This will be submitted through turnitin.com.
6) Present Results – The group will create a presentation with our PLTW template that highlights the ideas, solution,
calculations and evaluation. To save the PLTW template, download it from the LMS and Save As in your student
home folder under POE. We will use this template throughout the year.
Grading Criteria
Working Prototype
40%
PLTW Template Document
25%
Written Portion- Reflection Paper
20%
Group Member/Teacher Evaluation
15%
Extra Credit – the group with the highest IMA will each earn +5% extra credit