The document discusses different types of gears that could be used to build a gearbox, including spur gears, helical gears, worm gears, and bevel gears. It analyzes the advantages and disadvantages of each type of gear and their feasibility for a semester-long student project to build a gearbox out of acrylic. The document concludes that spur gears would be the most suitable choice for the project due to their simplicity, ease of manufacturing from acrylic sheets using a laser cutter, and efficiency despite being louder and wearing more easily than other gear types.

1. Making a Gearbox
Gear We Are
Rowan Duffield, Jake Bellman, Shanaka Sirinanda, Jacquie Filardo

2. How do we go about it?
To start our creative process on the gearbox,
we knew we would have to be as open minded
as possible, and remember to include all
options. We also knew we would have to think
about many things other than just the setup of
the gears. There is the extra challenge of this
being a very long and involved group project.
http://www.teamten.com/lawrence/projects/acrylic-
pendulum-clock/binding.jpg

3. In this
presentation
➔ Brainstorming
How we mapped out all our ideas and
what we would have to consider
➔ Research
We gained an understanding of
different types of gears
➔ Plan for upcoming weeks
We needed to make sure we had a
schedule, and were able to quickly
identify when we were falling behind

4. SPUR GEARS
● Simplest
● Easiest to manufacture
● Very efficient (94%-99%)
● Teeth project parallel to the
axis of rotation
● Loud and wear easily
(compared to helical)
● Used in rack and pinion
systems, mechanical watches,
rolling doors
Parts of Spur Gears
We use this terminology as standard. Not shown
in this diagram is the thickness. The module is the
teeth per mm of pitch diameter.
http://www.anaheimautomation.com/manuals/forms/images/Gear%20Diagram.png

5. MATING
SPUR GEARS
● The larger of two mated gears
will spin slower
● It will also have more torque
● Will change direction
(clockwise to anti-clockwise)
● Idler gear is used to allow the
driven gear to spin the same
way
○ Gear ratio
determines
properties of
mated gears
http://s.hswstatic.com/gif/gear-spur.jpg
http://www.overunity.com/14767/ultimate-proof-of-magnetic-vortex-free-book-
and-videos/dlattach/attach/141725/image//

6. Helical Gear
● Run smoothly and quitely
● Durable
● Can take high load applications
● Less wear then other gears
● Less efficient
● Power loss due to axial load
thrust http://36.media.tumblr.com/916cd1d2d22c8d61f3819f4d3a418509/tumbl
r_inline_nm66mgkFBD1qhy5k6_1280.jpg

7. http://www-
mdp.eng.cam.ac.uk/web/library/enginfo/textbooks_dvd_only/DAN/gears/in
tro/gearboxBIG.jpg
You would find helical gears mainly in the automotive
industry. Although many real world applications that
deal with high load can be applied as well.

8. Gearbox
Gears
Material String
Assembly
HousingShafts
Connection
/Fastners
MountManufacturing Cantilever
Bolted
Bracket
Chain
Rope
Fishing
Line
Reduce Axis
Length
Lightweight
Torsion
Connection
Stiffness
Rectangular
Cylindrical
Length
Wood
Plastics
Metals
SizeNumber SystemsType

9. Worm Gears
A worm gear in its simplest form is a
Helically threaded worm screw and
wheel
Used to significantly reduce speed
An increase in torque
Simple design
Increased friction
Locking feature
Typical worm ration 5:1 to 75:1

10. Feasibility of a worm Gear for the project
You’d find worm gears in musical instruments cars
from the early 20th century. These worm gears
are metal.
The majority of uses are limited to the type of
material.
Dealing with acrylic it wouldn’t be feasible due to
friction forces.
Efficiency can be increased providing the correct
material was used as well as lubrication.
upload.wikimedia.org/wikipedia/commons/6/6d/AX_Music_Man_Bongo_
5_Head_Rear.jpg

12. Bevel Gears
Photo courtesy Emerson Power Transmission Corp.
• Mainly used for changing the
direction of rotation by 90 degrees.
• They can be used for different
types of machinery including
locomotives, automobiles, printing
presses, marine applications,
electrical equipment and railway
tracks among others.
• Ex : Differential drives, hand drills

13. Advantages
• Possible to change the operating angle.
Disadvantages
• Must be precisely mounted
• Shafts' bearings will be exposed to significant forces
• Limited gear ratio

14. Conclusion
Helical –
o Efficiency loss due to power transfer.
o Not allowed bearings so the thrust component we can not fix.
o Manufacturing requires precise equipment which we do not have
access to.
Bevel –
o Must be mounted precisely and hard to cut from an acrylic sheet.
o Shafts' bearings will be exposed to significant forces

15. Worm –
o Large amounts of friction heat due to the worm screw and the
worm wheel sliding against each other.
o With acrylic having a low melting point damages to the worm
gearbox would be critical.
Spur –
o These will be the gears used for our semester long project,
o mostly because of the ease of manufacturing.
o We are cutting out gears from an acrylic sheet using a laser
cutter, so an extruded shape is required.