Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work.

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Default Crankshaft construction

How were crankshafts made before the development of specialized
machine tools? I've looked around on the Web and found no
description that doesn't rely on purpose-built machinery.

I did find http://modelengines.info/goldeng/const/crankshaft.html
but I can't figure out how the author located the offset center
holes in the blank.

Thanks for reading,

bob prohaska


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Default Crankshaft construction

On 6/26/2017 8:36 PM, bob prohaska wrote:
How were crankshafts made before the development of specialized
machine tools? I've looked around on the Web and found no
description that doesn't rely on purpose-built machinery.

I did find http://modelengines.info/goldeng/const/crankshaft.html
but I can't figure out how the author located the offset center
holes in the blank.

Thanks for reading,

bob prohaska


Harley cranks are built up of a pair of flywheels , a crankpin (con
rods are fitted and mounted before assembly) , a pinion shaft to drive
the cam and auxiliary items (oil pump, timing ignition , etc) and a
sprocket shaft for power output .By inference , since this motor is a
direct take off of radial aircraft engines , they would be made the same
way . The crankpin location in that example was located by simply
measuring the offset - carefully ...

--

Snag

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Default Crankshaft construction

On Tue, 27 Jun 2017 01:36:44 -0000 (UTC), bob prohaska
wrote:

How were crankshafts made before the development of specialized
machine tools? I've looked around on the Web and found no
description that doesn't rely on purpose-built machinery.

I did find http://modelengines.info/goldeng/const/crankshaft.html
but I can't figure out how the author located the offset center
holes in the blank.

Thanks for reading,

bob prohaska


General-purpose engine lathes. That's the way engine rebuilders do it
today.

Faceplate fixtures (or special, dedicated fixtures) on the spindle
clamp the ends of the crank in an offset position so that the crank
throws are centered.

Without special fixtures, it's very tedious.

--
Ed Huntress
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Default Crankshaft construction

"bob prohaska" wrote in message
news
How were crankshafts made before the development of specialized
machine tools? I've looked around on the Web and found no
description that doesn't rely on purpose-built machinery.

I did find http://modelengines.info/goldeng/const/crankshaft.html
but I can't figure out how the author located the offset center
holes in the blank.

Thanks for reading,

bob prohaska


The holes in the ends can be identically spaced with a simple drill
jig. They don't have to be parallel to the blank as long as it will
clean up. If you want the throw exact you can turn two disks to the
diameter equal to the throw which you can measure and adjust to
micrometer accuracy, put drill bushings in their center and press them
together to make the spacing jig.

I found it easier to locate and drill the first hole, hold its disk in
position with a dowel pin, put the second disk on a chucked dowel pin
and move the table until the disks touch.

A multicylinder engine might need temporary spacers in the throws to
stiffen them.

http://www.wright-brothers.org/Infor...903_Engine.htm
"The crankshaft was made out of a block of machine steel 6 by 31
inches and 1-5/8 inch thick. I traced the outline on the slab, then
drilled through with the drill press until I could knock out the
surplus pieces with a hammer and chisel. Then I put it in the lathe
and turned it down to size and smoothness."

-jsw



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"Jim Wilkins" wrote in message
news
.....
I found it easier to locate and drill the first hole, hold its disk
in position with a dowel pin, put the second disk on a chucked dowel
pin and move the table until the disks touch.


These are stiffer and don't damage a drill jig hole in mild steel as
quickly as longer-fluted bits:
http://www.travers.com/spotting-drills/c/297807/




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Default Crankshaft construction

bob prohaska wrote:
How were crankshafts made before the development of specialized
machine tools? I've looked around on the Web and found no
description that doesn't rely on purpose-built machinery.

I did find http://modelengines.info/goldeng/const/crankshaft.html
but I can't figure out how the author located the offset center
holes in the blank.

Thanks for reading,

bob prohaska



You can make a crankshaft using nothing more than 2 center points a
scale, a pair of calipers, a hacksaw and file if you want to do it manually.


--
Steve W.
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Default Crankshaft construction

On Monday, June 26, 2017 at 6:40:30 PM UTC-7, bob prohaska wrote:
How were crankshafts made before the development of specialized
machine tools?


I did find http://modelengines.info/goldeng/const/crankshaft.html
but I can't figure out how the author located the offset center
holes in the blank.


That model was turned on centers, with two center-drilled pivot
positions at each end. Then, the ends were cut off so the finished
item doesn't show where the centers were.

Probably forged or cast rough items were similarly turned on centers.
After you finish the ends, the evidence is gone.
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"whit3rd" wrote in message
...
On Monday, June 26, 2017 at 6:40:30 PM UTC-7, bob prohaska wrote:
How were crankshafts made before the development of specialized
machine tools?


I did find http://modelengines.info/goldeng/const/crankshaft.html
but I can't figure out how the author located the offset center
holes in the blank.


That model was turned on centers, with two center-drilled pivot
positions at each end. Then, the ends were cut off so the finished
item doesn't show where the centers were.

Probably forged or cast rough items were similarly turned on
centers.
After you finish the ends, the evidence is gone.


https://books.google.com/books?id=Kc...xtures&f=false



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Default Crankshaft construction

On Tue, 27 Jun 2017 17:12:10 -0400, "Jim Wilkins"
wrote:

"whit3rd" wrote in message
...
On Monday, June 26, 2017 at 6:40:30 PM UTC-7, bob prohaska wrote:
How were crankshafts made before the development of specialized
machine tools?


I did find http://modelengines.info/goldeng/const/crankshaft.html
but I can't figure out how the author located the offset center
holes in the blank.


That model was turned on centers, with two center-drilled pivot
positions at each end. Then, the ends were cut off so the finished
item doesn't show where the centers were.

Probably forged or cast rough items were similarly turned on
centers.
After you finish the ends, the evidence is gone.


https://books.google.com/books?id=Kc...xtures&f=false



This is the kind of fixture they used in the early days of car and
aircraft manufacturing. Start at about 3:30 and you'll see what it's
about in a few seconds.

https://www.youtube.com/watch?v=WnP_STFjtK4

You see the fixture are work again starting at 4:11; this time, for
grinding.

This not for models; I think Bob's original question was about real
crankshafts.

--
Ed Huntress
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Default Crankshaft construction

On Tue, 27 Jun 2017 17:42:27 -0400, Ed Huntress
wrote:

On Tue, 27 Jun 2017 17:12:10 -0400, "Jim Wilkins"
wrote:

"whit3rd" wrote in message
...
On Monday, June 26, 2017 at 6:40:30 PM UTC-7, bob prohaska wrote:
How were crankshafts made before the development of specialized
machine tools?

I did find http://modelengines.info/goldeng/const/crankshaft.html
but I can't figure out how the author located the offset center
holes in the blank.

That model was turned on centers, with two center-drilled pivot
positions at each end. Then, the ends were cut off so the finished
item doesn't show where the centers were.

Probably forged or cast rough items were similarly turned on
centers.
After you finish the ends, the evidence is gone.


https://books.google.com/books?id=Kc...xtures&f=false



This is the kind of fixture they used in the early days of car and
aircraft manufacturing. Start at about 3:30 and you'll see what it's
about in a few seconds.

https://www.youtube.com/watch?v=WnP_STFjtK4

You see the fixture are work again starting at 4:11; this time, for
grinding.

This not for models; I think Bob's original question was about real
crankshafts.

Greetings Ed,
I have seen a picture, years ago, of a large single throw crank
shaft being turned and using, I believe, oak fixture plates on the
faceplate. In fact, the faceplate itself may have been wood too. Maybe
wood bolted to a cast iron hub. Nevertheless, some sort of hardwood
was being used to fixture the offset. Not only that, wood was used as
a support between the faceplate and the throw and another piece of
wood fixturing was used at the center, so that the throw was centered
just as it was at the faceplate. The fixturing at the center end of
things was a disc with a female center in it and with a wood support
between the disc and the throw, similar to the faceplate setup. The
picture wasn't great but it looked like there was some sort of
shimming between the wood and the throw.
I turned the throw on a 3.5 hp Clinton engine some years ago to
clean it up after I ran the engine too low on oil. This was a small
crank. I used a 4 jaw chuck and I seem to remember there being a
center already drilled into the throw that I was able to use. Since I
didn't balance the setup I had to run the job real slow. But the old
picture I saw had stuff attached to the faceplate that I assume was
for balancing. Since the picture was so old they probably didn't have
tooling that could be run very fast anyway so maybe balance wasn't
that big of a concern. On the other hand though the men making that
kind of stuff back then were certainly craftsmen for the most part so
the balance was probably very good. Especially considering that many
of the machines they were using weren't that rigid.
Eric


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On Tue, 27 Jun 2017 17:24:47 -0700, wrote:

On Tue, 27 Jun 2017 17:42:27 -0400, Ed Huntress
wrote:

On Tue, 27 Jun 2017 17:12:10 -0400, "Jim Wilkins"
wrote:

"whit3rd" wrote in message
...
On Monday, June 26, 2017 at 6:40:30 PM UTC-7, bob prohaska wrote:
How were crankshafts made before the development of specialized
machine tools?

I did find
http://modelengines.info/goldeng/const/crankshaft.html
but I can't figure out how the author located the offset center
holes in the blank.

That model was turned on centers, with two center-drilled pivot
positions at each end. Then, the ends were cut off so the finished
item doesn't show where the centers were.

Probably forged or cast rough items were similarly turned on
centers.
After you finish the ends, the evidence is gone.

https://books.google.com/books?id=Kc...xtures&f=false



This is the kind of fixture they used in the early days of car and
aircraft manufacturing. Start at about 3:30 and you'll see what it's
about in a few seconds.

https://www.youtube.com/watch?v=WnP_STFjtK4

You see the fixture are work again starting at 4:11; this time, for
grinding.

This not for models; I think Bob's original question was about real
crankshafts.

Greetings Ed,
I have seen a picture, years ago, of a large single throw crank
shaft being turned and using, I believe, oak fixture plates on the
faceplate. In fact, the faceplate itself may have been wood too. Maybe
wood bolted to a cast iron hub. Nevertheless, some sort of hardwood
was being used to fixture the offset. Not only that, wood was used as
a support between the faceplate and the throw and another piece of
wood fixturing was used at the center, so that the throw was centered
just as it was at the faceplate. The fixturing at the center end of
things was a disc with a female center in it and with a wood support
between the disc and the throw, similar to the faceplate setup. The
picture wasn't great but it looked like there was some sort of
shimming between the wood and the throw.
I turned the throw on a 3.5 hp Clinton engine some years ago to
clean it up after I ran the engine too low on oil. This was a small
crank. I used a 4 jaw chuck and I seem to remember there being a
center already drilled into the throw that I was able to use. Since I
didn't balance the setup I had to run the job real slow. But the old
picture I saw had stuff attached to the faceplate that I assume was
for balancing. Since the picture was so old they probably didn't have
tooling that could be run very fast anyway so maybe balance wasn't
that big of a concern. On the other hand though the men making that
kind of stuff back then were certainly craftsmen for the most part so
the balance was probably very good. Especially considering that many
of the machines they were using weren't that rigid.
Eric


That's fascinating stuff, Eric. I remember seeing photos and drawings
like that in the old machining books we had in the McGraw-Hill library
(going back to 1877, the year of _American Machinist's_ founding). I
spent many lunch hours pouring through them.

They used wood in a lot of places where we wouldn't think of it today.
Also, speaking of crankshafts, they often used threaded steel spacers,
where necessary, to keep the cranks spread open then they were under
end-to-end pressure between centers.

Modern high-speed steels were developed roughly between 1910 and 1930.
Before that, with rare exceptions, most machining was done with plain
high-carbon cutting tools. They were hard, but they couldn't take any
heat. So drilling, turning and milling were done slowly -- very
slowly.

--
Ed Huntress
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Default Crankshaft construction

My original notion was of a large billet with center holes on the main
axis and every crank throw axis, the question being directed at how the
throw axis centers were found. Clearly, that's not how it was done.

Thanks to all who replied, I was thinking in the wrong way!

bob prohaska

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"bob prohaska" wrote in message
news
My original notion was of a large billet with center holes on the
main
axis and every crank throw axis, the question being directed at how
the
throw axis centers were found. Clearly, that's not how it was done.

Thanks to all who replied, I was thinking in the wrong way!

bob prohaska


Clever inventors amd mechanics have been making crankshafts for a very
long time:
https://en.wikipedia.org/wiki/Hierapolis_sawmill
"With the crank and connecting rod system, all elements for
constructing a steam engine (invented in 1712) - Hero's aeolipile
(generating steam power), the cylinder and piston (in metal force
pumps), non-return valves (in water pumps), gearing (in water mills
and clocks) - were known in Roman times."

https://commons.wikimedia.org/wiki/F...nd._Pic_01.jpg

-jsw


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Default Crankshaft construction

On Wed, 28 Jun 2017 06:53:15 -0400, "Jim Wilkins"
wrote:

"bob prohaska" wrote in message
news
My original notion was of a large billet with center holes on the
main
axis and every crank throw axis, the question being directed at how
the
throw axis centers were found. Clearly, that's not how it was done.

Thanks to all who replied, I was thinking in the wrong way!

bob prohaska


Clever inventors amd mechanics have been making crankshafts for a very
long time:
https://en.wikipedia.org/wiki/Hierapolis_sawmill
"With the crank and connecting rod system, all elements for
constructing a steam engine (invented in 1712) - Hero's aeolipile
(generating steam power), the cylinder and piston (in metal force
pumps), non-return valves (in water pumps), gearing (in water mills
and clocks) - were known in Roman times."


Amazing. The Romans had much of what we do today.


https://commons.wikimedia.org/wiki/F...nd._Pic_01.jpg


Yummy! Now we can have roast pig.

--
The Federal budget is a complex document. However, working
for a President committed to keeping his promises means my
job is as simple as translating his words into numbers.
Mick Mulvaney, Director OMB on Trump
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"Larry Jaques" wrote in message
...
On Wed, 28 Jun 2017 06:53:15 -0400, "Jim Wilkins"
wrote:

"bob prohaska" wrote in message
...........
Clever inventors amd mechanics have been making crankshafts for a
very
long time:
https://en.wikipedia.org/wiki/Hierapolis_sawmill
"With the crank and connecting rod system, all elements for
constructing a steam engine (invented in 1712) - Hero's aeolipile
(generating steam power), the cylinder and piston (in metal force
pumps), non-return valves (in water pumps), gearing (in water mills
and clocks) - were known in Roman times."


Amazing. The Romans had much of what we do today.


The Renaissance was a return to Rome's level. Europe didn't advance
beyond them in most ways until about 1800. One century later we had
cars and airplanes.
https://www.amazon.com/Ancient-Engin.../dp/0345482875

-jsw




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Default Crankshaft construction

Jim Wilkins wrote:

The Renaissance was a return to Rome's level. Europe didn't advance
beyond them in most ways until about 1800. One century later we had
cars and airplanes.
https://www.amazon.com/Ancient-Engin.../dp/0345482875


That century covered a lot of ground 8-)

Some of the ploughwork is chronicled in
https://books.google.com/books/about...d=X-EJAAAAIAAJ

It's available as a very good free E-book and quite fascinating to wade
through. It'll be old news to most following this thread, but if not the
book is well worth a look. One of the more striking parallels is between
toolmaking of the 1800's and electronics of the 1900's.

Thanks for reading,

bob prohaska

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