Accurate digital car model with Geomagic Studio

Mega Bloks uses major carmakers' methods to design toy that replicates European rally car

Mega Bloks, one of North America's top 10 toy brands, faced a dilemma: The company wanted to create a curvy rally car toy, but its trademarked building system is based on geometric blocks.

Mega Bloks solved the problem with digital tools and processes commonly used by major automakers, including 3D scanning services from Creaform, Geomagic Studio reverse-engineering technology, and traditional CAD/CAM software.

With the rally car project, Mega Bloks wanted to achieve a die-cast level of realism.

The company's design team started with a series of sketches in the archetype of existing European rally cars.

The sketches provided the basis for creating a clay model.

"We needed the car to be recognisable to the people who love rally cars, without stepping into the legalities of licensing," says Mega Bloks design coordinator Yanick Tremblay.

"We see so many cars each day that we have developed a keen eye for knowing if a car looks good or not".

"Going from a sketch to a clay model was a good way to approach styling." To save time and clay, the designers modeled only half the car, sculpting the clay on top of the company's signature building blocks and then using a mirror to achieve the symmetry effect.

They not only wanted to ensure that the style and shape of the car respected the limitations of the company's construction system, but that "blocks wouldn't be poking out of the fender," says Tremblay.

"We needed a good understanding of our dimensions." The model also enabled the designers to get approval quickly for the shape of the car.

"We could change the shape of the car in hours rather than days".

"If we were creating a CAD model, we would have spent maybe a month generating the shape".

"Not until it was completed would we learn if it was good enough." Mega Bloks turned to Creaform to have the final clay model scanned and a Class-A surface created from the data.

The system, a Zephyr laser scanner with an integrated Faro arm, was first positioned by a coordinate measurement machine.

It then projected a laser line on the clay model and, with a camera, measured 600 points 60 times per second, for a total measurement of 36,000 points per second.

The process is akin to painting: The laser line swept across the clay model, obtaining the required measurements in less than 10 minutes, according to Charles Mony, president of Creaform.

"You don't have any contact with the part, which is a benefit," says Mony.

"You don't deform the clay." The scanner produced a model with about 500,000 points - very small compared to a scan of a full-size automobile, which might contain upwards of 10 million points.

The resolution was 10 microns.

"Resolution is very important because you need to capture the styling lines and detail that the designer intended," says Mony.

The STL file from the scanner was imported into Geomagic Studio, Raindrop Geomagic's reverse-engineering software used by major automakers to create accurate digital models for engineering analysis.

Geomagic Studio automatically generated a polygon model, and then supplied the interactive editing tools needed to produce a better fit and finish.

Creating the CAD model in Geomagic Studio took only one day, compared to the two or more weeks it would have taken Mega Bloks to create a comparable model using traditional CAD software.

Geomagic Studio also enabled Creaform to prepare the car's body for the next step in the process.

"The interactive process we used with Geomagic Studio optimized the car's shell, filtering and smoothing it and doing the symmetry," says Mony.

"The resulting file, in IGES format, enabled Mega Bloks to start the engineering work on the model very early in the process while we worked on the Class-A surface." The Mega Bloks design team imported the IGES file from Geomagic Studio into SolidWorks, the software the company traditionally uses to design its block-style building systems.

Designers used SolidWorks to split the car into aesthetically pleasing parts that would be easy for a child to build with.

The software was also used to optimise the parts for the very high tolerances required for injection molding of the toy's interlocking pieces.

"The gaps between all the parts needed to be as seamless as possible," says Tremblay.

"Through the process of integrating this rather high-definition shape with our very basic blocks, we needed to make sure that everything fell into place and snapped together and was sturdy but also safe for the child." Concurrently with this process, Creaform used CATIA software to produce the car's Class-A surface.

After about a week, the initial surface was ready to show to the design group.

"It was an iterative process between us and Mega Bloks," says Mony.

"Creating the surface is manual with CATIA, but there is a styling tool that can be used to smooth the surface and check the molding and the molding process." The final surface was delivered to Mega Bloks in about two weeks, shortening the company's typical design time by two to four weeks.

"No other process would afford us such a degree of liberty in the styling of the car and still meet the very precise dimensioning of our block-building system," says Tremblay.

"It also enabled us to refine the car's aesthetics to the level of professional car styling." A Ford GT created in the same realistic fashion has since joined the Rally Car in Mega Bloks' Pro-Builder line of toys for children ages 5 years and up.

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