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By
William Baltazar and David Milison
He was a low-average student when he entered my manufacturing
technology class in 1995," Technology Education teacher William
Baltazar recalls. "But he got turned on when we did the automated
CO2 car curriculum. It released a flood of latent
creativity." Baltazar reports that, after this marginal student's
car took first place in the Florida and national Technology Student
Association (TSA) competitions he went on to use the program for
other creative projects while studying and working harder.
"He was in danger of not graduating but, now know ing he could
succeed in one area," says Baltazar with pride,
"he was motivated to pull up his
grades all around, and graduated in 1996."
Baltazar has taught the combined CAD/CAM/CNC classroom activity unit
for six years, first in Florida middle schools, then at Miami Senior
High School, and now at the new Dr. Michael M. Krop High School in
Miami Beach.
The project became feasible with
the synergistic combination of school-owned Mastercam CAD/CAM
software and Techno's DaVinci CNC machine, complete with special CO2
car fixtures and cumculum software licensed from IMS
Technologies. These
different softwares integrate seamlessly, providing
starting-point templates for first-time machinists, and the template
parameters conform to the ISA official CO2 car
competition specifications.
Setting young minds free.
"But," says Jim Kayle, Curriculum Specialist for Technology
Education for Broward County in Florida, "I was convinced, even
then, that a design-based curriculum was the direction we should be
going in. If the learning process is enhanced by using an advanced
technological application, that,s terrific." Kayle's district, the
fifth largest in the nation, began purchasing the Techno CO2
system soon after its development.
"A program like the car," he says "allows kids to succeed in a very
complex field. CNC isn't simple, so this is an opportunity for them
to gain relevant experience in a very technical area.
The
300,000+ student Miami-Dade school district-the country's third
largest-includes William Baltazar''s school.
Miami Dade County's students have
won numerous awards in TSA competitions at the regioinal, state and
nationals levels, and continue to be excited about using the mill.
Kayle's counterpan in the Miami-Dade school district, Clare Warren,
says that her teachers are also excited about the mill and
continually explore new applications.
"We consistently conduct training sessions to keep our faculty up to
speed," she says, and will even offer a graduate-level course for
her teachers through a local university next semester. She will
also send an instructor to Mastercam's educational headquarters in
Gig Harbor, WA, to train in Mastercam Level II so that he, along
with William Baltazar, can serve as a resource for teachers
throughout the county.
Step-by-step through the process...
Baltazar found some colleagues at teacher workshops daunted by a
perceived complexity of the CO2 unit.
He recalls having one of his
students, Carlos Vasquez, design a car before their very eyes at a
workshop in conjunction with the TSA national convention in
Louisville in 1995. The bottom line: anyone can do it.
Here's how it works.
PC-based Mastercam already embodies the processes a student
would need to design a 3D shape. The resident CO2 car
template file puts students through a 10-day self-teaching matrix
during which they walk through the steps from initial geometry to
toolpathing. The program allows them to make cross-section-based
design modifications of their own before creating the NC toolpath
and machining their invention.
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The
template file gives students an isometric overview of the
inch-by-inch cross sections of the left half of an already-designed
12"-long car. They can access single cross-sectional slices
through the CO2 car blank every inch by turning off all
levels and turning back on just the slice of car they warn to
describe. The template shows where to start and stop the spline,
which describes the car body, and which sections to avoid when
cutting. To alter the shape, students simply chart new points on
the template section with the mouse. The software then creates a
spline through these points. The students then change level and
depth, blank the old template, and make the new one visable. They
move easily, step by step, through the process and, with
imagination, can describe a complex car body worthy of Ferrari.
After
all the cross-sections are drawn, the halves are then mirrored to
complete the design, the splines surfaced and then rendered. The
rendered image allows students to examine their designs for TSA
compliance and can be sent to a printer. Seeing the real thing on
the screen assures students of having successfully transformed their
own aesthetic concepts into a working file. The design is then
rotated to assume the same position as the CO2 car blank
that will be mounted in the fixture.
Next,
students put a window around the cross-section again, and the
toolpath for the right side of the car is automatically generated.
Students then use the solid model toolpath verification to ensure a
gouge-free machining performance. The IMS fixture is set up to cut
the cars from the side-first the right, then the left-to eliminate
any possible tool burial problems of the 1" deep cutter in the
2-1/2" stock. A properly set up fixture with positive stop indexing
makes for a virtually seamless two-pass finished product.
When
the stock is mounted, the shaft on the back of the fixture engages
the pre-drilled CO2 canister hole in the blank and is
pushed forward until the front of the blank fits into a holder at
the front of the fixture A few taps of a softblow hammer secures the
blank for right-side cutting. After the right side is cut, the
fixture is unlocked and indexed 180º to cut the left side.
...
and beyond. For advanced high school and secondary students,
designing CO2 cars can be very challenging. They can go
beyond defining their cars with simple cross-sectional slices and
take advantage of the software's full surface modeling. The fixture
can also index the car into position so that those students who
envision alternative designs have the machining means to bring them
to life. All four sides can incorporate finer detail and different
shapes.
One student, motivated to experiment with the CAD possibilities,
designed a shell car, basically a hollowed-out version of the
template car. He found that the empty cavity was catching air and
slowing the car. Undaunted he countered the flaw by modifying the
design to include vents to allow the air to pass through. With
re-engineering time allowed by the DaVinci's machine's speed, he
succeeded on the third attempt, the vents finally worked as he had
hoped.
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In another creative burst, the student designed a flexible
suspension that he hoped would absorb the shock from bumps, reducing
bounce and increasing speed Unfortunately, the original suspension
was so soft that the rear of the car rubbed the surface The
redesigned, stiffer suspension produced a workable combination of
flexibility and stiffness-again the advantage of CAD/CAM speed and
rapid machining turnaround.
An optional
special fixture attachment makes wheels that are much truer than
hobby shop parts and that can vary in weight to bring the cars to
the exact minimum weight specification. The system's flexibility
allows students to experiment even further, designing planes,
airfoils, boats and rockets, for example.
The DaVinci
machine has ball screws on all three axes, just like industrial
machines, improving its power and accuracy. Its 24000 RPM spindle
allows an 80 IPM feed rate, turning out each side of the car in 8-10
minutes, while beautifully machining the wood. At that speed, an
entire class can cycle through the car curriculum in a workable time
frame.
Training
winners.
Baltazar takes
his whole class through the complete process in nine weeks. He
begins with a three-day demonstration, then turns the students loose
on the technology. Excitement over the project is so high that
students often come after the school class day to fine-tune their
cars, as do TSA members who are not taking the course but want to
enter cars in competition.
It's no secret that the
ability to give the end product a personalized, concept-car look
helps make the program attractive. What's more, the showing at such
regional and state events as the Dade County Youth Fair. CO2
car race reflects positively on the schools represented.
Baltazar is no
stranger to pride in his students' ability to win. His first
students to compete in the national TSA event hailed from Thomas
Jefferson Middle School in Miami. After coming in first through
14th out of the 16 front runners at the Youth Fair in 1996, they
placed first and second in the state and national races. In 1997,
his students from Miami Beach Senior High School placed second in
the state. They were bracketed in first and third places by Miami
students at Barbara Coleman Senior High School.
An amazing
race.
"Winning a race
certainly isn't everything," says Baltazar. He recalls another kind
of victory for a student with whom he worked for two years.
"He was hyper-just not able
to concentrate." He might have been labeled as an ADD student. He
developed an interest in the CO2 car competition and came
regularly to after-school sessions to learn the system. His Youth
Fair entry didn't place, but he had, by then, developed an abiding
interest in technology. "He's finishing his second year at
Miami-Dade Community College," Baltazar almost gleefully reports,
"and is planning to follow that with another two years' work on an
engineering degree. The step-by-step entry into CAD/CAM/CNC
resulted in a tremendously positive change in this student's life."
William Baltazar
is a Technology Educa non teacher at Dr Michael M Krop High School,
Miami, FL David Millson is editorial consultant for CNC Software/MasterCam
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