A circular iced steel sleeve spends time in a cooler filled with dry ice measured at about -120 degrees Fahrenheit (F). After a couple of hours, machinist shop foreperson Stuart DeHaro said the metal part, a cylinder about 8 inches in diameter and 2 inches tall, will shrink by a few 1000ths of an inch, just enough to allow it to slip into place on a large steel motor endcap.
DeHaro and his team of machinists are used to dealing with minuscule measurements – they routinely make parts to within 1/10,000th of an inch (0.0025mm).
F&S machinists work with steel, brass, stainless, aluminum, copper, and a wide array of plastics. They perform both by-hand machining, while other projects benefit from mills that are run by computer and can generate specific or hard-to-accomplish shapes.
Jose Mendoza, a fourth-year machinist apprentice, manually milled this now-frosty ring over the course of the previous two days: it’s exactly .100 inches wide.
The Roger Adams Laboratory supplied DeHaro with the dry ice; he originally intended to use liquid nitrogen, which would achieve temperatures around -320 F. However, because of the much more dangerous nature of the liquid, it needs a special container with valves to ensure the correct pressure as a room-temperature item is put into it and capped. The overall life safety concerns shifted DeHaro’s thinking to the much more readily available, and still effective, dry ice.
Mendoza donned the gloves to put the piece into place. He knew just how cold dry ice is (“you can’t touch it on your skin,”), but had never frozen an object before installing it. Mendoza did a couple of “test runs” practicing where his hands and arms should go moving the sleeve over, needing to work quickly as the frozen-O hits warmer air.
So: take it out of the cooler, turn, quickly slip into place, use mallet if necessary.
Mendoza did just that. After a few bangs with a soft mallet, the sleeve is in place; a steel cold success!
As a few seconds go by, the coloration of the cylinder seems to shimmer slightly and give off wisps of evaporation, signs of how the super cold metal slowly comes back to room temperature, expanding it into a tight fit with the endcap.
Inside of this goes a large roller bearing, which attaches to the shaft of the motor.
“Machinists serve a vital role in replacing or replicating parts that otherwise might be impossible to find, particularly on old building systems,” said DeHaro. “Other parts are very expensive and so the detail of our work is important in lengthening the life of those other parts.”
The Beckman Motor
“This motor serves one of the 4 big supply fans that make up the primary air-handling unit (AHU). This AHU serves most of the building and is critical to our operation here at Beckman,” explained Josh Whitson, director of facilities at the building. “This AHU needs to be functional to provide the appropriate number of air changes, maintain proper pressurization, maintain space temperature, and provide the appropriate amount of outside air. This supply fan is critical for that operation and it provides redundancy in certain seasons depending on the outdoor air conditions.”
Whitson knows about working with F&S, as he worked there from 2004 to 2022. Most of his time was as an Engineer Specialist from 2009 to 2022 managing the Energy Performance Contracting program.
“As always, working with F&S is great,” Whitson said. “There are so many great people at F&S that are truly experts in their field. We rely heavily on those individuals to continually improve Beckman. Transitioning to Beckman has been great and I really enjoy building upon the relationship I have with F&S in my role.”