"Seeking a power plant for their airplane, the Wrights contacted many of the dozens of firms that by then were manufacturing gasoline engines. Ten responded, but none could meet power and weight requirements the Wrights specified, or could do so at a reasonable price. Undeterred, the brothers decided to build their own.
The Wrights contracted a local Dayton foundry, the Buckeye Iron and Brass Works, to cast the aluminum crankcase. Buckeye acquired their raw aluminum from the nearby Pittsburgh Reduction Company, renamed Alcoa in 1907, the world’s leading producer of aluminum."
Here is a drop forge in action. https://www.youtube.com/watch?v=qOatvBsDRYM The force of the drop forge is usually expressed in tons. It basically smashes the red hot steel into whatever shape the die below is. Crankshafts are just one thing that are often forged. Aluminum material is also forged. I think the aluminum control arms found on many cars today are probably forged. Cast aluminum would probably not withstand the pounding a suspension takes.
Allow me to suggest that only a YOUNG machinist could complete the job. An old machinist would never live to see th completed crank!
An old machinist would probably realize before starting that it would be faster to rough out the shape using his drill press and band saw before starting the machining phase.
The young machinist might realize that after struggling for some time or perhaps when the peanut gallery of friends drinking his beer while watching surmised “hey joe, wouldn’t that go faster if you…”
Billet cranks are being manufactured today but they are not cheap. I think a bare 4 cylinder crank runs 2-3 grand. CNC machine tools can wade through it a lot faster…
Some years ago I had a chance to tour the Logisitics Center at Tinker AFB where overhauls are done on AF tankers, AWACS, B-52s, etc and the sheer size of the place along with the machine tool capability is almost beyond belief.
They’ve even got a climate controlled booth where during a demonstration a double-edged razor blade was broken in half and then robotically welded back together. This left a great looking weld bead that is difficult for the naked eye to even see.
I never stopped at Tinker, but that would definitely be fun to see.
It’s interesting to hear that “box beam” description. I’ve never worked on anything smaller than a B-52, so the concept of a single-piece center structure is foreign to me.
Besides forged, cast, and billet cranks, some engines had assembled crankshaft and piston rods with no removable lower caps. I don’t know what held them together though, bolts I would guess.
Lots of motorcycles use(d) the pressed-together cranks. Instead of plain bearings they usually have roller bearings. Here’s a company that specializes in rebuilding them. http://crankworks.com/index.php/crank-services
