Andrew Tool and Machining of Plymouth made precision-machined gear boxes for the robot arm on the Mars Rover that NASA plans to land on Mars Aug. 5. Jim Breth Project Engineer and Bruce Hanson President, held duplicate parts that were made for the rover. They were standing on a stairway on the main floor of Andrew Tool & Machining on Thursday morning May 3,2012 (Dml - Star Tribune/The Minnesota Star Tribune)

When it comes to long-distance shipping, Andrew Tool & Machining of Plymouth probably holds the state record.

Its precision-machined gear boxes are currently en route to Mars, as the moveable joints in a robotic arm on the new Mars Rover, called Curiosity.

Scheduled to land on Mars Aug. 5, the nuclear-powered, MiniCooper-sized rover will use its robot arm to sample and analyze Martian soil and rocks for signs of life. The rover is expected to function for two Earth years, or one Martian year.

That will cap what may be Andrew Tool's most arduous and unusual precision machining project. Over 18 months, the firm built about 20 different rover parts to an accuracy of two ten-thousandths of an inch, under the watchful eyes of NASA's on-site technical people.

"The parts Andrew Tool was machining are some of the most complex parts on the rover," said Richard Rainen, manager of the rover's mechanical team at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "There are just a few machine shops in the country that have the ability to do that."

The parts underwent a detailed NASA review of 190 different features on a single 4-pound gear assembly called an "actuator." The rover has three of the actuators to move the different joints in its arm. (For a NASA video of Curiosity's robot arm, see tinyurl.com/7yghj82.) Andrew Tool also made six actuators that drive the rover's wheels and four that steer it.

"Being able to hold those tolerances was the real challenge," said Bruce Hanson, Andrew Tool's president.

The equipment that Andrew Tool used to make the parts seems like something out of a science-fiction movie. There's "electrical discharge machining," in which an underwater electrical charge bores out the inside of finger-length metal pipes, and "five-axis machining" in which a part can be moved up and down, sideways and back and forth while at the same time being spun and tilted. Hanson said it is a combination of machines, human care and elaborate testing that allowed the firm to make the finely detailed rover parts.

The microscopic accuracy of the actuators will be important when the rover receives radio instructions from Earth to move its robotic arm, said Jimmy Breth, Andrew's project engineer. The actuators will prevent the arm from under-shooting or over-shooting the desired amount of motion, he said.

But making the parts wasn't the end of it. A year into the project, in late 2008, NASA decided that the titanium gears it had ordered Andrew Tool to build were too malleable a material to last through Curiosity's anticipated exploration lifetime. They ordered Andrew to rebuild the parts out of what Breth calls a "nickel-based super-alloy" that weighed four times as much.

Hanson said the rover project generated about $500,000 in revenue for Andrew Tool, making it one of the firm's larger projects. But Breth said it was the firm's biggest project ever based on the number of hours it took.

The company finished the rover project in advance of a planned NASA launch date of late 2009, but the complexity of the rover's design delayed NASA's plans, Rainen said. The launch was rescheduled for last November, when the relative positions of Mars and Earth were again favorable for the rover's flight.

The Curiosity rover now faces its first ruggedness test. It will parachute through the thin Martian atmosphere, then use rocket braking to slow its speed further before it lands, supposedly wheels down and ready for a drive on the planet's surface. After the landing, Curiosity will replace NASA's smaller Spirit rover that's currently stuck in the Martian sand after surviving on Mars much longer than expected. But Curiosity is unlikely to get stuck because the rover's arm is strong enough to pull the craft free of the sand, Breth said.

Andrew also does precision metal work for the computer chip and aerospace industries.

"I use Andrew Tool because they do good work and I can depend on them," said Curt Major, the model shop manager for AeroSystems of Plymouth, which tests jet engine prototypes in a wind tunnel for companies such as Pratt & Whitney and Rolls-Royce. "I've tried other precision shops, and found that I'd rather deal with Andrew."

Rudolph Technologies of Bloomington uses Andrew Tool to make the camera focusing gears for its computer chip inspection equipment.

"We've tried other machine shops in town," said Jeff Nelson, Rudolph's operations vice president. "But when we really need high-tolerance work we go to Andrew, even though they're not always the cheapest."

Steve Alexander • 612-673-4553