Ved's Dancer's End Engine

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vederstein

Must do dumb things....
Joined
Feb 26, 2011
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In 2013 my wife and I vacationed in England. One of our stops was a the London Museum of Water and Steam. All the engines there are either part of the original water works the place used to be or engines brought in from other locations that were used for pumping water. One of the "imported" engines was the James Kay Dancer's End engine.

I thought it would be a good start for the my next project.

I would say that my design is inspired by original engine but is in no way a model of it. Interestingly, if you watch the video of the actual engine (below) the beams are timed 180° apart. If you think about that it means that this engine could've been supplanted with a single cylinder engine with twice the cylinder area and get the same performance. In my design, I'm clocking the beams 90° apart making is a self starting steam engine.

The design isn't yet complete, but thus far I'm liking the way it's coming together.

Dancer Engine.JPG




And the original engine:

 
I believe I've finished the design of the engine:

Assembly - Dancers Engine.png


I'm debating if to do a build log on this one or not.

Either way, as usual, when I finish the engine and get the bugs out, I'll post on this forum all relevant files and documents so you too can build this engine.

...Ved.
 
That is such a majestic beast running at that Kew museum.... mesmerizing in its movements. I will be watching along on this ride and looking forward to your renderings...

BC1
Jim
 
I'm curious about the design of the valve eccentrics used on both original and model engines. The James Kay Dancers Beam engine uses extremely large diameter eccentrics and correspondingly large "big ends" to drive the valves. This would seem to incur higher surface speeds increasing wear, but distributed over larger surfaces, decreasing wear. The design shown in Ved's model uses the simpler "pin at the proper position and radius", also seen on original engines. There's not much surface area but not much surface speed or mechanical load, either.

Can anyone offer any opinions or facts regarding the two designs?

Thanks,
Larry in New Jersey
 
Sorry, didn't recognize the valve drive shaft and bevel gearing. :)
But any OTHER engine with "pin at the proper position and radius" .

Thanks,
Larry
 
Larry:

I don't put that much thought into my engines. It's not like these actually have any purpose. They're toys.

I've had good luck with eccentric cam/tappet designs lately. Reference my recent "Four Square" and "Swashplate" engines. The tappet runs a spool valve for admission and exhaust. The valve is then sprung from the opposite side holding it against the cam.

My last rendering doesn't show the spring and/or spring housing, but it's a larger version of what I have on the Four Square.

 
Larry G. Can't help exactly, but in the drive to reduce exhaust emissions from cars, there is a drive to reduce friction. (well, has been since Newcomen!). Simply put, comparing main and big-end bearing sizes over the decades (and when I worked in Engine Design in the 1980s) bearings were made smaller diameter - to reduce the running friction. (actually, the amount of oil in shear between the pin and bearing). So to make a cast iron crank "lower friction", the bearings were made 1mm smaller in diameter, retaining the width. - Later, the width was reduced by a mm. The loss of stiffness of crank was compensated by adding a ladder frame to the bottom of the block... so the design isn't just a case of any one part becoming larger or smaller, but the whole design has to compliment every element. UK designs were for much stiffer cranks, than Japanese designs with slimmer (more flexible) cranks, and much stiffer main bearing supports, clever flywheels, more expensive cast iron processing, etc. etc. to cope with the slimmer crank flexing more. Even the oil pump had to achieve higher flow to cool the bearings. The FEA of the crankshaft increased some corner radii from 2mm to 3mm, to reduce the stress concentration, etc.
But on models, many things are changed "to look better".... Aesthetic Design, as taught in Art School, or simply "make easier", without a thought to "proper Engineering" design. (Actually this is structural design). And most of the "model engineering" I see is simply a scaled or roughly scaled version of something someone remembers... bad/wrong memories, accidental changes, mods to suit available materials or processes, warts and all!
So any resemblance to an original design is purely coincidental in most cases... Not that "original designs" were ever fixed or without evolution and changes (usually to reduce cost!). Especially in the ages of "single production" - as in the Newcomen, to Trevithick era. George Stephenson was possibly the first to "Mass produce" engine designs and parts, as he supplied many castings to others, e.g. the cylinders on his Rocket and Timothy Hackworth's Sans Pareil were all made by George Stephenson. (Possibly the same batch of more than 20?). Although Boulton and Watt supplied many engines, I understand these were all "individually" made, and without interchangeable parts. They didn't have the quality of machines we take for granted, so everything was "fitted" - uniquely. And designs could change from one to the next as suited "latest thinking" - or "customer's Whim"!
(Please teach me where I am inaccurate?).
Cheers!
K2
 
Hi Vederstein, Well done on your "four square" engine - I class it as an "experimental" engine. = Made to find out what is needed to make a functioning engine with these various elements. (pistons, cams springs, etc.). I like it, and it seems to perform as well as any other design with that size of bore, stroke, rpm, etc... which is what you really expected.
Well done on the entertainment you have provided as well, by this thread.
I look forward to any further refinements, or your next design.
K2
 
Larry:

I don't put that much thought into my engines. It's not like these actually have any purpose. They're toys.

I've had good luck with eccentric cam/tappet designs lately. Reference my recent "Four Square" and "Swashplate" engines. The tappet runs a spool valve for admission and exhaust. The valve is then sprung from the opposite side holding it against the cam.

My last rendering doesn't show the spring and/or spring housing, but it's a larger version of what I have on the Four Square.



Hello Vederstein, (name?)

I greatly appreciate the effort that you put into developing, documenting, and sharing your thoughts and designs on the board. Not to mention the skill in producing them and bringing them to "life". Whether they are useful tools or toys doesn't diminish their value.

My question simply pertains to the use of the very large eccentrics seen on many historic engines, such as the James Kay Dancer's End. These early and obviously successful engines had numerous features to compensate for wear in the power transmission path, such as the wedges behind the brasses. Friction losses and efficiency may not have been given serious thought at the time, although progress was certainly made, as seen in the Corliss and UniFlow designs.

Thanks,
Larry
 
Larry G. Can't help exactly, but in the drive to reduce exhaust emissions from cars, there is a drive to reduce friction. (well, has been since Newcomen!).
... George Stephenson was possibly the first to "Mass produce" engine designs and parts, as he supplied many castings to others, e.g. the cylinders on his Rocket and Timothy Hackworth's Sans Pareil were all made by George Stephenson.
...
(Please teach me where I am inaccurate?).
Cheers!
K2
Stephenson was an important figure in engine design, but much more, as well;
~~~~~~~~~~~~~~~
www.history.co.uk
The 'Father of Railways', George Stephenson, built the first commercial locomotive and railways, setting a standard adopted worldwide. He also grew straight cucumbers competitively, married three times and may be why we call people from Newcastle, 'Geordies'.
~~~~~~~~~~~~~~~
Thanks :)

Larry
 
Thanks Larry. I have read much of his history (forgotten more than remembered!). But the point I was making was that his Locomotive Works mass produced items that had previously not been mass produced for steam engines. With a few exceptions as always. Simply because mass production was entering heavy engineering by that point in history as the industrial revolution took off. With the advent of railways, many more identical parts were needed than for the stationary engines that had previously made the industry, so parts were made to be interchangeable - within tolerance - rather than "fitted"... Hence the supply of 20 cylinders to Timothy Hackworth for him to select the appropriate cylinders for the Ranhill trial loco. I suspect these were slightly varying (within some tolerance) in size, but essentially mass produced - rather than "one-off" manufactured parts. Actually, even today, in modern cars, etc., the pistons and crank bearings are selected "to size" as the manufacturing process is not so precise as the design demands. Hence Cylinders, crank journals, con-rods, gudgeon (piston) pins, etc. are graded by end-of-line gauging, then parts marked. These parts are then identified in the assembly plant and appropriate graded parts are matched together to give a much better reliability and durability of engine than just the machining tolerances will allow. - Just like Timothy Hackworth selecting cylinders and pistons that matched for Sans Pareil.
BUT Not what most modellers do!
Ken
 
Ved... "I'd like to be younger..", but we just have to do what we can do with what we have (in mind and body). We are but temporary curators of our genes, models and friendships. I have as many models that have out-lived their makers as I have models I have made - the pretty ones all made by others! We can only trust the legacy we leave to others is not wasted, but something of that is shared. I believe that what we leave of use to following generations is all we are worth. "The Great" (Euclid, Maxwell, Trevethick, Boyle, Einstein, Tesla, etc.) leave us knowledge and records. Our models are some of that legacy. (Also a bit of FUN!).
(Flippin eck! That was a bit deep for Good Friday! - Please excuse my odd mood.).
K2
 
K2
On the contrary, you have made a great comment.
On several occasions , I have been asked to repair models that resided in Museums or personal collections
and I am amazed that these models made 100 or 150 years ago do not have the modelers name
or date on them.
Not all these models were works of art such as Bill Huxhold made, but that is not the point.
Have you noticed that famous painters signed their works even before they became famous. So too should model builders do that. It's somewhat ironic that we would like to have a marked gravestone when we die saying our name and dates , but our models go unidentified. oft to the future as blank remnants without any identification. The model does not have to be an exact scale or size, it may only represent a concept or design , and that is as important as well. The Smithsonian had a display years ago of some models made before 1900 and the exhibit was awesome , but most had no ID of the builder.
So do it--- yours may be the remembered as made by " My great-great grandfather "
Rich
 
After sorting out the possesions of a few relatives of mine who have passed, and on contemplation on my own and my wife's future "downsizing," I can add to the discussion...

Not only should models and projects be identified, but notes should be left with "items to save" with what they are and why they should be kept.

It's too easy to make decisions to be regretted later when under pressure to get things settled quickly.

--ShopShoe
 
It's easy to conceal documents within a base. I usually sign mine if I can keep my signature out of sight. Often this is inside cylinder cleading. I have nameplates for all my engines when they were shown (University open days, when I worked there) with a second plate showing the technicians involved.

This was to give the impression that everyone in the workshop had contributed. I had no interest in self-aggrandisement. Even if all the engines were only my work!
 
Oh how I wish I had the skills and patience to make models of that beauty.

...Ved.

I think you're doing just fine Ved, you have some very good skills that only get better as we go.

Congratulations to "Grasshopper" & yourself for the build of the "Swashplate" engine. Posted here: https://www.homemodelenginemachinist.com/threads/vedersteins-swashplate-engine-finished.34094/
It's pretty awesome to see someone else have enough interest in your design to set off & build it, especially a "New" design.

Keep the new designs & drawings coming Ved, you can see it's appreciated.

John
 
I think you're doing just fine Ved, you have some very good skills that only get better as we go.

Congratulations to "Grasshopper" & yourself for the build of the "Swashplate" engine. Posted here: https://www.homemodelenginemachinist.com/threads/vedersteins-swashplate-engine-finished.34094/
It's pretty awesome to see someone else have enough interest in your design to set off & build it, especially a "New" design.

Keep the new designs & drawings coming Ved, you can see it's appreciated.

John

It helps that David and I live only six miles apart.

Thank you for your encourgement.

...Ved.
 
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