Titan Gilroy's first act began on the run. His mother fled to Hawaii to escape an abusive husband. And despite a few years of homelessness, she managed to keep her children in school. The move was a difficult adjustment for Mr. Gilroy and his sister, who were picked on for being outsiders.

Mr. Gilroy took up boxing as a way to defend himself. He eventually earned a reputation for being a tough fighter, but that gift got him expelled from several public schools. He was finally admitted to a private Catholic high school, working part time to help pay the tuition. After graduating in 1988, Mr. Gilroy was discovered by a local boxing trainer, who sent him to train with Dick Saddler, former trainer for George Foreman and Muhammad Ali.

Once a blossoming boxer, Titan Gilroy quit and turned to machining. Titan Gilroy

A blossoming boxer, Mr. Gilroy fought as a sponsored amateur, winning 35 of 38 amateur bouts, including a number of amateur Golden Gloves tournaments. In 1991, he moved to Las Vegas to train with Olympic coaches at Top Rank Boxing, one of the biggest fight promoters in the U.S. One of his trainers, Mitch Hamp, says Mr. Gilroy was a good fighter with potential to do well. "That's saying something since it's a tough sport. I have very few success stories here," he says. But before Mr. Gilroy could make his professional debut, he got into a fight at a nightclub and seriously injured two men. He was charged with assault and served three years prison.

After being released on parole in 1995, Mr. Gilroy half-heartedly returned to boxing at Top Rank, uncertain of what he wanted to do with his future. A few months later he got into a fight with a neighbor. He wasn't charged, but being in handcuffs reminded him of how easily he could lose his freedom -- and his wife and son, with whom he'd only recently reunited. Mr. Gilroy quit boxing the next day. "I told my manager 'I can't do this anymore,' " he says.

The following year Mr. Gilroy moved his family to Northern California and took an entry-level job at Zinola Manufacturing, a small machine shop in Sunnyvale with nine employees. He didn't know it at the time, but Mr. Gilroy had launched his second act. He had no previous machining experience, so he volunteered to work overtime to learn. He also took evening courses for machining at the National Tooling and Machining Association. He quickly realized he had an aptitude for using the computer numerical controlled (CNC) machines, which cut parts out of metal. Within a year, Mr. Gilroy was head programmer and shop foreman.

Titan Gilroy went from boxing and then prison to become a successful business owner. Jeremy McCain

Over the next five years, Mr. Gilroy worked his way up through several companies and eventually became a manager at Nagy Precision, in Cedar Ridge, Calif., where he worked for four years. When the owner sold the shop in 2005, Mr. Gilroy and coworker Jeff Weaver decided to start their own CNC shop. They were helped by a former vendor, William Selway, owner of Selway Machine Tool, who guaranteed a loan for $300,000 and sold them several CNC machines. "I could tell he was going to make it work," says Mr. Selway. "He had a clear vision of what he wanted, his enthusiasm really impressed me and he was not afraid of working very, very hard."

Titan Engineering began with four CNC machines, which Mr. Gilroy worked day and night. He slept on a sofa bed at the shop so he could meet deadlines. And he took every metals job he could, producing tattoo gun parts, paintball gun receivers and surveying equipment. "I'd sleep for an hour, the alarm would go off and I'd change parts," he says. "I was working around the clock." He was also the company's salesman, cold calling and following up on referrals.

The hard work paid off. Mr. Gilroy was profitable his first year in business, with $1 million in revenue. He now manages 53 employees and recently moved into a 35,000-square-foot facility. The company now has 20 CNC machines and specializes in producing highly intricate parts for aerospace companies and Schilling Robotics -- a manufacturer of robotic submersibles. Mr. Gilroy, now 39, estimates the company will top $6 million in revenue in 2008.

He says he's done far better as a businessman than a boxer. And he isn't worried about the rough economy slowing the company down, since his shop creates parts that few other companies can. "It's all about working hard and staying focused on your goals," says Mr. Gilroy of his second career. "Every day I like to prove that manufacturing is not a dead art in America. That's what keeps me going."

Write to Dennis Nishi at cjeditor@dowjones.com