Pressed-together crankshafts

Just how strong are built-up crankshafts? They're common in very small engines, some of which seem rather highly stressed. They seem less common in
larger engines, but those I'm familiar with are high-production types where tooling costs matter less than per-part costs.
For example, if somebody wanted to build a small, one-off diesel engine, say a 200cc v-twin, would a built-up crank have a chance? At the other end of the spectrum, are the cranks in very large marine diesels (think Emma Maersk) built up or monolithic?
Thanks for reading,
bob prohaska
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On Sun, 27 Jun 2021 02:31:53 -0000 (UTC), bob prohaska

Isn't a Harley Davidson crankshaft "built up" and simply pressed together?
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John B.
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wrote:

Not sure about Harley but MANY Motorcycle cranks are and many 2 stroke cranks. They work pretty good in applications where there is not much chance of impact / shock loads which have a tendancy to twist built-up cranks out of true. They are also used in applications where comnpactmess is required and there is no room for bolted split-cap rods
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wrote:

From memory I believe that some single row radial aircraft engines also had built up cranks although I don't remember how they were assembled.
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"John B." wrote in message
From memory I believe that some single row radial aircraft engines also had built up cranks although I don't remember how they were assembled.
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John B.
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wrote:

Another application where there was no room for bolted split cap rods.
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On 6/27/2021 12:11 AM, Clare Snyder wrote:

The newer Harley motors are using a pressed together crankshaft , the older ones used a bolted assembly with tapered joints located with keys . The newer ones have evidenced a tendency to twist at low RPM/heavy throttle . I know my 1990 has a bolted crank assembly , not sure about the 2009 Sporty but I think it was before the bean counters "improved the profit margin" .
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Snag
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On Sun, 27 Jun 2021 02:31:53 -0000 (UTC)

You can make one piece with big-ass power hammer and hot steel ;-)

https://youtu.be/8bT6txm4RpA?tp3

https://youtu.be/8bT6txm4RpA?tp3

Cool old video, the whole thing is interesting if you haven't already seen it...
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Leon Fisk
Grand Rapids MI
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"bob prohaska" wrote in message
Just how strong are built-up crankshafts? They're common in very small engines, some of which seem rather highly stressed. They seem less common in larger engines, but those I'm familiar with are high-production types where tooling costs matter less than per-part costs.
For example, if somebody wanted to build a small, one-off diesel engine, say a 200cc v-twin, would a built-up crank have a chance? At the other end of the spectrum, are the cranks in very large marine diesels (think Emma Maersk) built up or monolithic?
Thanks for reading,
bob prohaska
--------------------------- https://www.dieselarmy.com/engine-tech/engine/dynamic-diesels-inside-the-worlds-largest-engine/
".. it exceeds 50% thermal efficiency in its maximum economy mode."
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"bob prohaska" wrote in message
For example, if somebody wanted to build a small, one-off diesel engine, say a 200cc v-twin, would a built-up crank have a chance?
-------------------------------
https://www.homemodelenginemachinist.com/threads/making-a-builtup-crankshaft.10838/
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Very impressive photos. Thanks for posting!
bob prohaska
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On 01/07/2021 22:40, Jim Wilkins wrote:

I couldn't find any information on whether the Wartsila engine was a built up crank but the Doxford ship engine was, some info here http://www.dieselduck.info/historical/01%20diesel%20engine/Doxford/works.htm and repairing the damage due to not doing the correct engine starting procedure resulting in slippage of the shrink fit crank http://www.waghornswood.net.nz/Manuals_01_18/Interesting/The_realignment_afloat_of_a_ships_main_engine_crankshaft.pdf . I mentioned that incident to a neighbour's friend who had worked for BOC and he said he had been involved in a similar fix in the docks at Bristol UK.
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Fascinating articles! Thanks for posting!
bob prohaska
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Yes, thanks, very interesting.
For a more technical view, this explains submarine Diesels to new recruits fresh off the farm. https://archive.hnsa.org/doc/fleetsub/diesel/index.htm
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On 7/2/2021 6:04 PM, David Billington wrote: ...

...
Clever ... I wonder if this sort of repair had been used prior or if the author was the first. If first, I have to admire his willingness to jump in the deep end, so to speak.
I got a chuckle out his titles: "RJF Hudson PhD., BAppSc., DMS., CEng., Extra First Class M.O.T FIMarEST., FIMechE., MCMI."
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"Bob Engelhardt" wrote in message
On 7/2/2021 6:04 PM, David Billington wrote: ...

...
Clever ... I wonder if this sort of repair had been used prior or if the author was the first. If first, I have to admire his willingness to jump in the deep end, so to speak.
I got a chuckle out his titles: "RJF Hudson PhD., BAppSc., DMS., CEng., Extra First Class M.O.T FIMarEST., FIMechE., MCMI."
------ I suspect that every possible sort of failure had occurred soon after a design was introduced. Prior to WW2 engineering was cut-and-try, strengthen whatever broke.
https://www.enginehistory.org/members/articles/CrankDesignEvol.shtml "Eventually, in the late 1930s, experimental stress analysis began to be incorporated into the design process."
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What's an example of a bosch badged appliance made by say whirlpool that has impossible to get parts?

They had a parts department and you got the parts. Try that with a LG anything. It's not super uncommon for an entire assembly to be cheaper or more avialable than a single part in it. It's silly, but nothing too new.
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On Fri, 15 Oct 2021 18:41:18 -0000 (UTC), Cydrome Leader

Not what I said. Check where your Bosch dishwasher is made -- it aint der fatherland!!!

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Pakistan? China? I'd never make the mistake of buying a bosch appliance.
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On Fri, 5 Nov 2021 20:01:55 -0000 (UTC), Cydrome Leader

It's the only brand of dishwasher available in the USA that is BUILT IN THE USA. (at least that was true a year and ahalf ago)
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