The Distinctive Tesker 840
Tucked away in a corner behind Keystone’s tooling die library is a filing cabinet stuffed with decades of history. Among the dozens of folders that house the purchase and maintenance records for numerous machines, there is a 4-inch file on the Tesker 840—one of only four or five of the world’s largest thread rollers ever built. More than just a collection of detailed documentation, when you leaf through its contents, there is evidence not only of the late second-generation owner Jim Krejci’s early vision for the 840 but also how it has evolved over time to become a fixture on our shop floor where it still runs jobs today. The folder is also filled with pictures, invoices, and correspondence that document the decades of upkeep, maintenance, and pride that have modernized and kept the 840 operational.
A Historical Timeline
Inside that folder, several documents form a timeline, most notably, an article in a protective sleeve that very well may have been Mr. Krejci’s a-ha moment:
March 20, 1972
Pages now yellowed with age from Metalworking News announced that General Motors had a “giant” new thread roller on the floor. Referred to as “the largest thread roller in the world,” the article explains that GM would now be able to provide thread ball screws and rolled ACME thread screws up to 12 and 15 inches, respectively, for dam gates, large machine tools, steel rolling mills, and more, thereby opening a whole new market for the company.
August 7, 1973
About a year and a half later, a handwritten document by Mr. Krejci shares that Keystone had recently purchased the Tesker 840. It is attached to a typed page from Tesker that lists several companies that have purchased the smaller 630. An excerpt:
“The purpose of this letter is to ask whether you have run into rolling jobs which were too large for your 630 Tesker. As you probably know, the 840 has a rolling pressure of 600,000 pounds and can handle parts to 15” in diameter.”
March 5, 1974
Correspondence with Tesker including dimensions for a support block fixture:
Dear Dean,
Per phone conversation, enclosed are drawings of support block required for rolling large diameters on the 840. I’ve put in most of the dimensions for you [sic] can juggle them around if necessary. Use your own judgement. We would appreciate it if this fixture can be shipped with a set of 3 pitch rolls that Richy is making for us. One is no good without the other.”
Jim Krejci.
The Tesker 840: Here to Stay
Allan Young, who joined Keystone in October 1973 and is still here today, said the Tesker 840 was brand new to the company when he started. One of the first jobs he remembers was for HPM, a plastics and die-casting equipment operation in Mount Vernon, Ohio, that closed in 2010. “I was a young rookie, but… that’s what I remember as the first job. They made these big tie bars for plastic injection molding.” That was a 14.5-inch diameter, 22-foot bolt weighing in at 16,000 pounds.
Since then, Keystone has roll threaded bars on the 840 for dozens of customers. Although the big jobs are few and far between, the 840 has a continued role in the industry and at Keystone. “Dams, for example—if they’re repairing a dam or building a new one. In any year, you could do a few pretty cool projects, then you might not get any for five years. It just depends.”
Fun Fact: Today, a new 840 would cost over a million dollars.
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