They are "The right tool for some jobs". But I've never worked where we needed that job done. Closest thing was cutting a 2 inch wide by 1 inch deep keyway into a 2000 to 5000+ pound alloy steel casting. THE BOSS found a "key-seater", forget the brand, similar to those shapers but pulled the cutter vertically, cutting on the down stroke. As the size of our machines increased size and weight of the parts increased. We made automobile scrap metal shredding rotors, replacement rotors for both Hammermill brand and Newell, and we made a rotor for Proler Corp, scrap metal processing company on an "as needed" basis. We built one and shipped it to their Terminal Island, CA scrap yard. Their New Jersey yard just happened to be right across the Hudson River from the World Trade Center and got all the ferrous scrap from that. The rotor for Terminal Island weighed around 85,000#, 4 axle semi-tractor and 5 axle trailer and all kinds of special permits. The Hammermill & Newell rotors weighed 40,000 to 48,000#. We designed and built a 104"x98" Super-Duty Newell rotor for Auto-Shred of Detroit, to grind up a mountain of Detroit Diesel city bus engines from scrapped busses. Took a year for the mountain to disappear.
We had a tool&die shop make parts for us on DeVlig Jig Mills, generally they did good work but occasionally they would screw up. I kept a constant stream of work going down the street a mile to Williams & White Co. They had done a bit of work for us years before I started at this company, but I had crazy high demand for machined parts and they were slow on their own work so I loaded them up! I was told we needed a "Rotor a Week" to make our shipping Dollar commitments. I've got a picture of 4, FOUR rotors loaded and shipped on ONE DAY. An 85,000# Pooler rotor, a 40,000# Newell, and two 45,000# Newell, and there was 3-4 truckloads of shredder mill wear parts shipped that day too.
The alloy steel sand casting foundry we were a division of is still in business, but the scrap shredder rotor & shredder mill business is gone. In fact, the Moline, Ill end of the new Interstate 74 Mississippi River bridge is built right where our building was located.
Last machine operation on a 16" diameter and 15 feet long rotor shaft was cutting a 2.000" keyway most of the length of the shaft. A 20" diameter shaft got a 3.000" keyway. And Yes, we reconditioned used rotors too. I swear they took on some jobs to try to monopolize my time doing 5 to 10% of my work and I'd drive the 4-5 miles down to work Sunday afternoon after the NASCAR race.