The stainless steel machine, housed in a lab outside of Washington, D.C., is used to measure force. And in this case, a lot of force: it is rated at 4.45 million newtons.

Work on the project began last year, when crews began carefully disassembling the machine’s three-story stack of stainless discs, each weighing approximately 22,700 kilograms.

The discs were then cleaned and machined, and the instrument was reassembled and recalibrated.

“This was an extremely complicated, time-consuming, labor-intensive operation with major risks and decisions at every turn,” said the institute’s mass and force group leader Zeina Kubarych. “From planning to teamwork and coordination, to risk mitigation and execution, this was a remarkable achievement and a success to be proud of.”

According to the institute, the machine’s lifting frame is made of various grades of steel. The force-generating parts consist of AISI 410 and 416 series stainless, it said.

NPR has more on the story here. And you can see a video of the machine being taken apart here.