This Mechanism Teaching Board uses a common A3 sized Pegboard as a backing to connect all the Mechanism Models to. The Mechanism Models provide a useful teaching resource to help students understand how mechanisms work, and how particular ones convert or reduce/increase various types of motion.
The board, once assembled, includes models of 4 different types of Cam, the 3 classes of Lever, two different Pulley setups, a simple Gear system, and a compound Gear system.
In my classes (Engineering, ages 14-16) students learn about mechanisms and how they work, and are then asked to design and construct a toy which uses at least one mechanism. Mechanism in this context is explored as something that converts one type of motion to another (linear, rotary, osculating, reciprocating, etc). Most students design models of their mechanical toys in various CAD programs to get a visual understanding of what they need to build.
Designed using Solidworks and Autodesk Inventor
The mechanisms are built individually and assembled in Solidworks.
The print in place pivot point on all mechanisms sits flush with the front face, so they can be printed face down requiring no support. My printer looks much nicer on the top side than the bottom side, so I printed them face up with supports to hold up the entire cam/gear/pulley/lever while the pegboard pin stood underneath.
Gaps used in the print in place parts are set to 0.25mm, keep this in mind when choosing your layer height.
Students are expected to learn about:
- the nature and purpose of mechanisms
- the components that make up mechanisms
- the function and operation of mechanisms such as levers, pulleys, gears and cams
- friction and its significance to the operation of mechanisms
- mechanical Advantage, velocity ratio and efficiency in mechanisms
- methods of driving mechanisms
Students are expected to learn to:
- dismantle and assemble mechanisms to understand how they work
- design and construct mechanisms for specific purposes
- carry out experiments to demonstrate engineering principles
This project is suitable for students aged 13-16 who are studying a course related to mechanisms, science, engineering, maths, technology, design, woodwork, etc.
Prior knowledge required includes understanding and calculating ratios and understanding different types of motion.
The project outlined here would consist of either 3D Modelling/Printing or woodwork/plastics construction.
In this case it would require, respectively:
- Computer, CAD Software of your choosing, 3D Printer, ample filament, etc
- Timber for construction, relevant hand tools or machinery for working timber, perspex or other plastics for construction, relevent hand tools or machinery for working plastic.
This project can be quite simple or quite detailed depending on how you'd like to run it.
A suggested workflow:
1) Confirm prior knowledge of ratios and calculation
2) Confirm prior knowledge of motion principles
3) Use above Mechanism Teaching Board to teach about mechanisms and how they work
4) Design various design solutions and coming up with toy ideas
5) Create hand drawings of ideas, detailing the mechanisms that will be used. Identify input motion point and type, and output motion point and type
6) Develop a materials list and/or steps of construction
7) Create CAD Model/3D Print and/or begin workshop construction
8) Assemble toy
9) Testing and Project Evaluation
At the end of the project students would have designed and constructed and mechanical toy out of either 3D Printed plastic or construciton using wood/plastic based on knowledge they have developed regarding motion and mechanisms.
Suggestion for grading and assessment of the function of the toy:
Tell the students you will conduct the required "input motion" 10 times, and award 1 mark for each successful "output motion". For example, a toy wherein you turn a handle in rotary motion (input) to move a figurine up and down on top of the toy (output) you would turn that handle 10 times, and for each succesful up and down motion of the figurine, they are awarded 1 mark.