But then, he took an informal poll: Would they be willing to move it across the street to an old Parking Authority building and keep trying for a few more weeks?
The students answered with whoops and applause, though at least one was heard to express concern about studying for exams.
The attempt to break the record was the opening event for the fourth annual citywide science festival, which runs through Saturday, May 3, with dozens more scheduled at schools, museums, restaurants and more.
A Rube Goldberg machine takes its name from the 20th-century engineer turned cartoonist, known for his drawings of wacky, complex machines. Purdue University is the current holder of the Guinness record for the largest such device, with a 2012 creation consisting of 300 "events" in which energy was transferred. A row of dominoes counts as one event, for example.
The Drexel students pulled lots of late nights in recent weeks in building a machine with more than 315 events. Some of the students were more accustomed to solving problems on paper than with their hands. For them, it was a new experience.
"Designing is hard," said Laura Bennett, a team member from Maryland. "A lot of trial and error."
The students conducted a final test run at about 11 a.m., and determined that numerous small adjustments would be needed.
Then at noon, Franklin Institute president Dennis Wint hit a giant blue button to start the first official attempt. That turned on an LED, activating a light sensor, which in turn was rigged to send a toy car shooting down a track to trigger a mousetrap.
But there were snags almost immediately.
Sometimes a pendulum, pulley, or other device would get stuck, and a student had to nudge things along by hand - a no-no if the attempt were to count for the record.
The device was divided into 14 modules of two dozen events apiece, with a team of students assigned to design and build each one. Many of the teams designed their modules to evoke the identity of their sponsoring partners.
A module sponsored by the Wistar Institute, known for its cancer research, featured a life-size Darth Vader figure to warn against the "dark side" of smoking. A module sponsored by the Philadelphia Zoo included a blue plastic elephant.
The trio of Siddhanathan Shanmugam, Habeeb Olawin, and Stanley Burke finished work on their module at 8:30 Thursday night.
"We got the whole thing to run 20 times through," said Burke, of Pottsville, Pa.
But on Friday, they, like most other teams, had some minor glitches.
Chris Lester, a graduate teaching fellow, moved from team to team, lending a hand where he could. It was not enough.
"We had a great experience," Fontecchio said. "The students learned a lot. We did not break the world record - yet."