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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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#1
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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 |
#2
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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 |
#3
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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 |
#4
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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 |
#5
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Crankshaft construction
"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/ |
#6
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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. |
#7
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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. |
#8
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Crankshaft construction
"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 |
#9
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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 |
#10
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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 |
#12
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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 |
#13
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Crankshaft construction
"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 |
#14
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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 |
#15
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Crankshaft construction
"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 |
#16
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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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