Title: The South Florida Industry Partners Education Mousetrap Car Design Seminar
1The South Florida Industry Partners
EducationMousetrap Car Design Seminar
- Presented by Glenn N. Cunningham, P.E.Senior
AssociateHazen and Sawyer, P.C.
2Objectives of the Design Seminar
To define and explore concepts of the SECME
Mousetrap car enabling our students to
- Know the elements of the design required
- The Technical Report
- The Technical Drawing
- The Competition
- To exchange ideas in a common forum - industry,
college, coordinators, parents and students
- Develop critical thinking skills, a solid science
and math foundation with practical application
and competitive excitement - Design and build a mousetrap car that satisfies
the rules - Know the rules and scoring formulas
3What is a mousetrap car?
- Opportunity to learn elements of a good design
while experiencing the thrill of competition - Car with the body of a mousetrap propelled by the
force of a spring - Not a mice catcher
- Economical way to complete a design for a few
dollars/unit - Your ticket to Nationalsas a winner
4What are the components of a mousetrap car?
- Victor mousetrap
- Three or four wheels
- Gears (driver and follower gears)
- Bail and bail string
- Washers and plastic tubing ends
- Creativity and practice
5What does the mousetrap car look like?
- Mousetrap on wheels?
- NASA moon buggy?
- Anything your imagination wants it to look like
- Your creativity will make the difference
6An approved mousetrap car does not look like
these
- Mousetrap base cannot be altered in any way
- No batteries or external power is permitted
- The VICTOR plastic model mousetrap is not allowed
- Refer to the Survival Guide
7How does the mousetrap car work?
- The spring on the mousetrap car is tensioned
(energized) by winding the bail-string unto the
drive-shaft of the driver mechanism - When released, the tensioned spring causes
angular rotation on the drive-shaft, thus turning
the rear wheels and producing linear motion on
the mousetrap car
8What are gears?
- Toothed wheels simple machines
- Most common are spur gears (commonly used on
mousetrap cars) - Used to transfer force, increase or reduce linear
distance traveled, increase or reduce speed, and
change direction of rotary motion
9Why do we need gears? Consider a mousetrap car
without gears
- The energy stored in the spring is released into
the wheels in an instant, producing a big bang,
and spinning wheels trying to move the car at a
high speed - The result is usually a fast start and not much
distance covered
10Why do we need gears? Consider a mousetrap car
with gears
- The energy stored in the spring is released in a
steady controlled way - The result is usually a constant speed and more
distance covered
11How do gears work? - Consider a design using
two gears
The large gear is the driver gear and is mounted
on a drive-shaft
The small gear is the follower gear and is
mounted on the drive wheel axle
12How do gears work? - Consider a design using
two gears
- The driver gear is a 40 tooth spur gear and the
follower gear is a 8 tooth spur gear - The gear ratio is.408 or 51
- A gear ratio of 51 means that every-time the
bail-string turns the drive-shaft, the gears
produce five revolutions on the wheels - Therefore, the car has the potential to travel
five times the distance of a car designed
without gears
13How does gear ratio relate to distance traveled?
- Consider same design using two gears
- Driver gear 40 tooth follower gear 8 tooth
- Total gear ratio 51
- Diameter of drive wheel 2.5-inch
- Linear distance traveled / revolution (2.5 x
3.14) 7.85 inch/rev - Converting, 7.85 inches X (2.54 cm/inch) 19.94
cm/rev - Target distance 25 meters 2500 cm
- Required drive axle rotation 2500 cm / (19.94
cm/rev x 5) 25.0 rev
14Can we calculate how our mousetrap car is
likely to perform?
- Yes..We can calculate the expected performance
of our car because - We can design the length of our bail-string, gear
ratio, wheel sizes, and calculate the expected
distance traveled - We know the length and weight of our car
- We can do the calculation !!
15What about the technical drawing and report?
- The Technical Drawing and Report are required as
part of the submittal package without either
the entry will be disqualified - A good Technical Drawing and Report can earn 50
points each (refer to Survival Guide) - An entry could win the actual race, but lose the
overall competition because of mediocre or poor
performance in the Technical Drawing and Report - Follow the rules in the Survival Guide - Every
point earned may make the difference between
first and second place
16What about the layout of the technical drawing?
17Constructing a mousetrap car
- We are confident that everyone here can build a
mousetrap car - To demonstrate our confidence
- We are asking you , everyone, to go back to your
respective schools and help your students build a
mousetrap car. Here is HOW!!
18Building a mousetrap car materials required
- Mousetrap (wood victor)
- Balsa wood strips (1/4-inch sq.)
- Wood glue (super glue)
- Wood dowels (1/8-inch dia.)
- Leggo gears (40 tooth and 8 tooth)
- Wheels (2-inch and 1-inch dia.)
- Washers (type No 6)
- Tubing (1/8-inch inner dia.)
- Grease
19Building a mousetrap car tools required
- Tool box
- Hammer
- Small hand-saws
- Rulers
- Scissors
- Exacto knives (utility knives)
- Screw-drivers (flathead and phillips)
- Drill and drill-bits
- Drummels
- Pliers (needle-nose and standard)
- Soldering iron and solder
- Hot glue gun and glue sticks
- Tape measure
- Misc. attachments
20Building a mousetrap car a basic design
- A basic design, using gears, is presented to
provide hands-on instructions on building a
mouse-trap car. - A basic design, not using gears, can also be
completed by deleting Step No 5, Fourth Mark,
and also noting that the Third Mark would
become the location of the driver wheel axle
21Building a mousetrap car preparing the
mousetrap
- Hold mousetrap firmly on hard surface
- Remove all accessories not required(bait-hook,
locking lever and fasteners) - Use needle-nose pliers to open gap onloop at end
of bail arm. Straighten bail carefully (bail
will break at weakened 90-degreebends)
22Building a mousetrap car prepare wood-frames
axles, gears
- Cut 3 pieces for axles from the 1/8-inch
dowel(two 9 cm long and one 10 cm long) - Cut 4 pieces for car frames from the 1/4-inch
balsa(four 21 cm long) - Glue 2 pieces for the car frame together. Repeat
this for the other 2 pieces, to form two
1/2-inch x 1/4-inch pieces - Label each car frames as shown T Top, B
Bottom (on the 1/4-inch faces) and I Inside,
O Outside (on the 1/2-inch faces)
23Building a mousetrap car mark wood-frames
axles, gears
- Holding one side of the car frame, (with O -
Outside marking facing up),insert 4 markings in
the following places - First mark 1 cm from end of car frame Use an
axle to make an impression into the frame, 2 mm
below the center-line of the frame. (This is
the location of the front wheel axle) - Second mark 12 cm from same end of car frame
(This is the location of the rear-end of
mousetrap) Note that the red V is located at
the rear-end of mouse-trap
24Building a mousetrap car mark wood-frames
axles, gears
- Continued..
- Third mark 15 cm from same end of car frame Use
an axle to make an impression into the frame,
2 mm above the center-line of the frame. (This
is the location of the driver gear axle) - Fourth mark To complete this, place the large
gear over the 15 cm mark. With the large gear
held in place, engage the small gear. Use an
axle to make an impression into the frame, 2 mm
below the center- line of the frame. (This is the
location of the follower gear mounted on the
rear wheel axle)
25Building a mousetrap car tape wood-frames
together
- Tape both frame pieces together, (making sure
that the tape does not cover any of the
impressions marked in No. 5) - Both frames should be lined up with the
markings,T - are together, B - are together, I -
are inside, and O - are outside.
26Building a mousetrap car Putting the pieces
together
- Drill holes at centers of the three impressions
(front wheel axle, driver gear axle and follower
gear drive wheel axle), marked in No 5. Before
removing tape, examine to make sure that holes
are properly aligned - Glue inside of first frame (glue on inside) to
side of mousetrap - Install gears, axles and second frame (hand-held
in place) to verify proper alignment. (Note that
axles should be at right angles to frames) - Glue inside of second frame (glue on inside) to
other side of mousetrap
27Building a mousetrap car Putting the pieces
together
- Align gears, test gear rotation and glue center
of gear to axle. (Carefully apply 1 drop of glue
only) - Complete installation of wheels, washers and
tubing ends. Test wheel rotation. - Attach bail-string to bail and bail-string
attachment to the driver axle. First,
attach bail-string to closed loop at end of bail
and cut bail-string to proper length, depending
on the option selected for bail-string attachment
to the driver axle Option 1 String
over-lapping rap method. Holding end of string,
wrap string around the driver axle,(by rotating
the driver axle by hand), making sure that the
succeeding wraps overlap the previous
onesOption 2 - Loop and fixed attachment
method. Form loop at end of string. Glue ¼-inch
long dowel attachment to driver gear axle. Place
string-loop over fixed dowel attachment and wrap
string around axle,(by rotating the driver axle
by hand)
28Building a mousetrap car Putting the pieces
together
- Check and verify proper alignment of components
- Test mousetrap car and make adjustments as
necessary - Great job and see you at the competition!!!
29The finished product
30Store materials and tools in a safe area upon
completion
31The South Florida Industry Partners
EducationMousetrap Car Design Seminar
- CONGRATULATIONS and THANK YOU.
- You are absolutely the very best.
- http//www.youtube.com/watch?featureplayer_detail
pagev83b3zgqTzz4t45s
32Lets make it happen We support S.E.C.M.E.