His touch is lost, the one that built parts for Galileo's flight to Jupiter, the one that knows instantly when a spacecraft rod is off by a thousandth of an inch--one-third the thickness of a piece of paper.
Until recently, machinist Antonio M. Fonseca worked in the Jet Propulsion Laboratory's "back shop" by feel, with what he calls a craftsman's touch. But today he picks up a spacecraft beam and his instinct escapes him. He can't think in inches anymore. His whole thought process has been thrown off kilter. Engineers are shipping him blueprints in the strange new world of millimeters, a measurement that he cannot picture in his head.
"I don't trust that (metric) system," grouses Fonseca, 54, a Burbank man with 30 years' experience in machine shops. "I trust what I know."
In La Canada Flintridge, Fonseca and 45 other JPL machinists are building the Mars Pathfinder, NASA's first attempt at an all-metric spacecraft. With few exceptions, all Pathfinder's parts are metric sized, from its nuts and bolts to its 10-kilogram (22-pound) robotic rover, which will scurry across the bumpy Mars terrain to study soil and rocks.
What is happening to the machinists will slowly happen to many Americans as the metric system inexorably creeps into new areas of life. The change is sluggish because the United States remains the only industrialized nation in the world yet to adopt the system; the government's push in the 1970s for a national conversion fizzled long ago. Still, metric conversion is spreading into sectors of the economy that depend on international standards--and, as a result, uncertainty is spreading into work that experienced professionals such as Fonseca once did without pause.
Consider the dilemma of Werner Schwarz, 36, a 15-year JPL machinist.
Before Pathfinder, Schwarz, a big man from Saugus with a ponytail, didn't hesitate when he had to punch a row of holes in an aluminum plate, each an inch apart. He put the plate on the worktable of a milling machine and turned a crank to move the drill bit to the next hole. He didn't have to watch the digital readout that tells how far the drill bit moves; he knew in his head how far an inch is.
He demonstrates how he used to do it, spinning the crank without looking. Bam. Crank to the next hole. Bam, bam, bam.
Afterward, he checks the digital readout to see how accurately he had moved from hole to hole. He is off by six thousandths of an inch, the thickness of a strand of hair sliced four times.
Metric holes throw him off. For metric jobs, when he turns the crank, he has no idea how far he's going unless he checks the digital readout, which switches to metric with a push of a button. That slows him down, strips away his sense of mastery.
"If you give me a metric dimension, I'll sit here for about 15 seconds (and watch the readout), and I'll get it right, but that's 15 seconds vs. nothing," Schwarz said.
He's going to have to get used to it. After Pathfinder is launched next year, every JPL-built spacecraft will be made with metric parts. Officials at JPL, NASA's leading center for solar system exploration, say the switch is necessary to keep up with international space agencies.
The machinists who are building Pathfinder get no share of the media spotlight that shines on the space agency's gravity-defying astronauts and sober mission control room. Their windowless warehouse reeks of oil and shakes from monstrous machines, hissing, clanging, whirring. In steel-toed boots, dozens of men--no women--work on their feet all day in a room so loud that it is impossible to talk without shouting. Their step is cushioned by a soft, scruffy linoleum floor littered with shaved aluminum bits and gravel to sop up spilled oil.
JPL scientists and engineers are weaned on the metric system. But it's the boys in the back shop who have to retool 20 years or more of gut feeling in the English system of inches. Most of them have no more than a high school education, and make an annual salary of about $40,000 to $50,000. Yet they are the elite in their field, able to etch the fine grooves on a part, work that can save a spacecraft from stress fracture.
The work is punishing. Their hands are disfigured by scratches and scars, their fingerprints nearly rubbed out. But they find time to play darts during breaks and rib each other with nicknames.
For these men the switch to metrics is not simply about numbers. They are used to complex trigonometry formulas in their work; they can understand that a millimeter is about the thickness of a dime. This, they explain, is about a loss of control, of having to operate in a new language with the awkwardness and imprecision of translation.
"A lot of the work that gets done isn't so scientific," said Richard E. Fleischner, a design engineer for Mars Pathfinder. "It's (instinctive judgments made by) these guys with tons of experience--in English (inch) units."
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