““There are very interesting reasons why forged is better than cast, and they’re not obvious. But then, I’m old, and an engineer.”” I was just being sarcastic, I thot the OP wanted to build a crankshaft in his garage. …
No, not expecting to construct my own crankshaft any time soon … lol. Just curious about how it is done. Thanks to all for good, informative comments.
hmmm … well, I think a person could build one in their garage if they absolutely had to. It might not be very durable, might vibrate a bit. But in a pinch I think it could be done. I recently read a book (Hornet Flight by Ken Follet) about WWII, and how in Denmark during that time the Danish citizens had no access to gasoline, it was all confiscated for war use, but that didn’t stop folks from driving their cars and motorcyles and using their farm tractors. Not the most inventive among them anyway. They’d use wood for fuel instead of gasoline, and burn the fumes of a smoldering charcoal fire, piped into their engines. I recall a discussion about this idea on a prior CarTalk episode (or maybe it was here). People are pretty inventive when they have to be.
And thanks Oldtimer for the movie suggestion, I just put in my request for “The Worlds Fastest Indian” to my DVD provider, and will pick up the DVD tomorrow. (According to the movie description, Burt was from New Zealand rather than Australia.)
It’s a great movie. You’ll enjoy it. They also did the wood burning bit for public buses in Japan toward the end of WW2 when gasoline for public use was a mere fantasy.
According to the movie, Burt used iron sewer pipes for his cylinders, with homemade cooling fins. He said the metal was well “seasoned.”
I could put together the burner, tank, and piping needed to generate fumes from wood chips. I could no way no how make a workable crankshaft for a car.
@texases … I think if you could do the first, you could do the second. It would just be harder and take longer is all. But if it was say your only escape for an otherwise certain demise, and you had plenty of time to do it, well, making your own crankshaft would be the better option.
You’d make a mold out of sand of the appx shape – sand being an easily obtained substance that won’t melt too much from the molten steel – then you heat up some scrap steel in a ceramic bucket (finding this might prove the most difficult part of the job, you might have to make this yourself if you are on a desert island or something, from native clay) 'til it melts using a furnace you construct of fireclay bricks; you heat the furnace so it is superheated enough to melt the steel using a home-made bellows, then you pour the molten steel into the mold, let it cool a bit, then drench it with water. Next you file it to the proper size for all the bearings (like I say, this will take some time), then you build a charcoal fire on top of it to case harden the surface. Voila, a crankshaft. Well, you might have to repeat the process seferal dozen times 'till you get it right. Like I say, may take some time.
Sure I could cast a hunk of metal, but grinding the journals with the needed precision requires more than my toolbox can offer.
ok, ok … I think we’ve kicked this dead horse enough … lol …
GSJ, this is what the “gas-generator” looked like in Denmark on cars, busses, motorcykles etc. during the war.
Chevy used steel cranks on the early small blocks 283’s(dont know about the 265’s) dont know if they were forged or not,how did the Wright brothers make a crank for thier airplane engine?-Kevin
They didn’t. They bought the engine from an engine manufacturer. The engine manufacturer bought the crank from a machine shop with specialized setups. The machine shop bout the “blank” from a casting house. The casting house bought the raw material from a smelter. And so on.
That’s exactly how it happens today, except that the major manufacturers provide the design to the engine manufacturing division of their company. Limited volume manufacturers like Lotus often buy engines from major manufacturers and modify them. The Elise had a 1.8L Toyota I4 engine.
A good machinist could whittle one out of a block of steel that would work fine if time were not an issue.
It’s easy to think of machinists back in the early part of the 20th century as being yardstick hacks in overalls but they were a lot more precise than given credit for.
That’s true. In which case it would be a billet crankshaft.
wow. Imagine the number of passes that would take for the machinist to hog out that much material. Allow me to suggest that only a YOUNG machinist could complete the job. An old machinist would never live to see th completed crank!
Well, GeorgeSanJose, Just how much would charge me to build me a small V8, about 4 liters, for my '09 Dodge caravan? It has the 4-speed automatic.
January 28
TSMB - I saw a video a while back about how they machined the center portion of an F-111 out of a single block of aluminum - 90% or more of the metal was removed. I was surprised this was the best way to do it, but it avoids all issues with molds, casting, and forging.
True enough mountainbike. Cutting the metal would be time consuming in itself but the setup time for doing those cuts would be mind boggling.
The numbers would probably start to blur after a month or so…
The center portion of what F-111 part? the turbine shaft?
The center portion of the ENTIRE PLANE! This single part included both wing pivots. IIRC, of course…
I’d love to see that process.
So the information was wrong about the Wrights making thier own engine with sufficient power to weight to power the “flyer”?-Thanks,Kevin