# Designing steam engines



## chucketn (Jun 14, 2018)

At the risk of being shushed, and drummed out of the forum, I would beg to ask the question "How to design a steam(or air) engine. "?
I have built a few very simple engines, and followed many builds here and on other forums. I've collected plans for all sorts of 'steam' or 'air' engines from all over the web. Recently I was fascinated by Brian Rupnow's Double Acting Double Cylinder Oscillating Engine build. Fascinated to the point I read his threads on all the forums it was posted on, made notes and downloaded most of his pictures. I decided I wanted to build this 'simple' engine. But, being totally retired and on a meager pension, instead of buying Brian's plans, I set out to design it myself using Fusion 360. I got as far as my interpretation of a cylinder(which I'm 3d printing at the moment). I intend to use 3d printing to prototype my engine, and then build it in metal, possibly even casting some of the parts in aluminum.
I began to realize there has to be a method to my madness, and you guessed it, I don't have a method.
So, I would ask the revered denizens here, how do you go about designing your engines? I mean those you design without a plan to go by, like Brian did... Do you start with the cylinder and go from there, or the crank throw and work back to the cylinder? How do you decide on the crank throw, the stroke, the bore, the size of the flywheel, the length of the piston rod, etc.?
Is there a book I can buy/download, or a thread in a forum that explains the why and how of steam engine design?
If you haven't guessed, I have no 'engineering' experience other than designing simple stuff that I can make on my lathe and mill, or print on my 3d printer.


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## chucketn (Jun 14, 2018)

Writing the above seems to have influenced my 'Google foo'. I just found this web page and am studying it now...
This is the kind of info I'm looking for...
http://www.panyo.com/oscillators/

Plus that web page gives me more search terms to use... LOL, found the edit...


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## gbritnell (Jun 14, 2018)

First decide on a style of engine, horizontal,vertical, simple, double acting or oscillator. Next figure what bore and stroke you want then work from there. It's hard to give exact dimensions for everything otherwise we would be designing the engine. If you have a lot of reference material just use what someone else has already created.
gbritnell


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## Mechanicboy (Jun 14, 2018)

chucketn said:


> At the risk of being shushed, and drummed out of the forum, I would beg to ask the question "How to design a steam(or air) engine. "?



Steam engine and air engine is difference in timing..

Steam engine --> timing with expansion for less consumption of steam.

Air engine --> Timing without expansion. Also full pressure of air from TDC to BDC and exhaust from BDC to TDC. No economical consumption if you are using air pressure tank instead air compressor. Except CO2 engine who can be created to get less consumption of CO2 from pressure tank with CO2 gas (The CO2 engine has ball valve in cylinder head who are opened by the tap on top of the piston a bit before TDC and has a equal period after TDC to the ball valve is closed, then the CO2 gas is expanding until exhaust port is opened. ).


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## chucketn (Jun 14, 2018)

I was under the impression that a 'steam' engine will run on compressed air. Is that not so?
I guess what I'm after is an explanation of  the mathematical relation ship of the intake and exhaust ports, the stroke and the length of the crank arm. I know these are all inter-related, I just can't get my head around it. I have built wobblers before from plans. I want to be able to build without a specific plan.
I have just been looking at a site from Cornell University, http://kmoddl.library.cornell.edu/resources.php?id=113 that has mechanical models and explains them with math equations that are way over my head.
Brian, if you're reading this, how did you determine where to put the trunion port holes, and how long to make the crank arm? I understand the trunion port holes will be on an arc with the radius equal to the distance from the trunion pivot to the block port, and the length of the arc has a relationship to the length of the crank arm. But how do I figure that out?


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## Mechanicboy (Jun 14, 2018)

chucketn said:


> I was under the impression that a 'steam' engine will run on compressed air. Is that not so?


The steam engine can run at compressed air, but less effective than if the steam engine ran at steam due timing with expansion ( with air = no expansion in a closed cylinder).


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## chucketn (Jun 14, 2018)

Well, I've figured out how to find one dimension, the location of the trunion ports. I drew a mockup of the cylinder pivot point, the arc inscribed by the cylinder port, and a circle representing the crank arm travel. I drew lines from the 90 and 180 points on the crank arm circle through the center of the cylinder pivot and on through the trunion port arc. Am I on the right track?


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## chucketn (Jun 14, 2018)

Mechanicboy said:


> The steam engine can run at compressed air, but less effective than if the steam engine ran at steam due timing with expansion ( with air = no expansion in a closed cylinder).


Well, I've not progressed to building boilers yet, so my engines will run on compressed air only.


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## chucketn (Jun 14, 2018)

Is the crank arm length the same as the stroke of the piston?


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## Mechanicboy (Jun 14, 2018)

chucketn said:


> Is the crank arm length the same as the stroke of the piston?



Crank arm is 1/2 of the stroke.


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## fcheslop (Jun 14, 2018)

This book may help answer a few questions on design
https://redirect.viglink.com/?forma...www.fastonline.org/CD3WD_40/JF/424/19-423.pdf


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## chucketn (Jun 14, 2018)

fcheslop said:


> This book may help answer a few questions on design
> https://redirect.viglink.com/?format=go&jsonp=vglnk_152901297241915&key=5e5e6e04e939b9674c384ca8b03117f4&libId=jif2suvu010248ul000DA3nx7ldk0&loc=https://www.rcgroups.com/forums/showthread.php?1226384-Books&v=1&out=http://www.fastonline.org/CD3WD_40/JF/424/19-423.pdf&ref=https://www.google.co.uk/&title=Books - RC Groups&txt=http://www.fastonline.org/CD3WD_40/JF/424/19-423.pdf


LOL, thanks fcheslop. Laughing because I downloaded that book a few moments before you posted... Thanks!


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## fcheslop (Jun 15, 2018)

At least youve got a copy
This one although a little out of date is still a handy reference
https://redirect.viglink.com/?forma...www.fastonline.org/CD3WD_40/JF/424/19-422.pdf


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## Pthunberg (Jun 15, 2018)

A 3D drafting program like Rhino 3D can be very helpful in working out the geometry of all the moving parts. Bit of an expense and it requires learning how to use the software.


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## chucketn (Jun 15, 2018)

Pthunberg said:


> A 3D drafting program like Rhino 3D can be very helpful in working out the geometry of all the moving parts. Bit of an expense and it requires learning how to use the software.



I have and am learning Fusion 360. In fact, I used it just yesterday to draw a diagram of a oscillating engine cylinder and crank of different diameters, to plot the port openings in the trunion.


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## bouch (Jun 15, 2018)

I suggest you download Charlie Dockstater's valve gear programs.  These will let you verify what you design for cylinder ports/valves/valve gear will actually run.

http://www.billp.org/Dockstader/ValveGear.html

Different programs for different valve gear.  If you're going to build a non-reversing engine, then you should use the slip eccentric and just assume one direction of running.


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## Anatol (Jun 15, 2018)

chucketn said:


> At the risk of being shushed, and drummed out of the forum, I would beg to ask the question "How to design a steam(or air) engine. "?



"How to design a steam(or air) engine. "

I think this is a GREAT question. Fundamental. There are those in this community who just want to build, and are happy to reproduce, scale etc, existing plans. (No criticism intended). Others want to understand the design principles. I'm in the latter camp. 

What I struggle with is having a gut sense of relative proportions. I do not yet have enough experience to know, ie - what cross section of stem pipe or steam passage is 'in the ballpark' for steam at x temp, with cylinder volume y, running at speed z? similar equation apply to valve openings, etc.


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## Anatol (Jun 15, 2018)

fcheslop said:


> At least youve got a copy
> This one although a little out of date is still a handy reference
> /QUOTE]
> 
> I second that, I found the Harris book very informative, and its got an introduction by Westbury, who is quickly becoming god to me


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## Anatol (Jun 15, 2018)

oops, somehow I included my text as if it was part of Frazer's quote. I tried to fix it but it didn't fix.
(Admin - I tried twice to remove the extra "quote" at the end of the doc, but it didn't change the displayed message.)


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## Anatol (Jun 15, 2018)

Mechanicboy said:


> Crank arm is 1/2 of the stroke.



as I  understand it, the longer the connecting rod, the more efficient the engine. (within reason ,


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## Anatol (Jun 15, 2018)

chucketn said:


> .
> This is the kind of info I'm looking for...
> http://www.panyo.com/oscillators/
> .



I found this page a while ago, seems useful, I wrote to the author but communication petered out.


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## Anatol (Jun 15, 2018)

chucketn said:


> I have just been looking at a site from Cornell University, http://kmoddl.library.cornell.edu/resources.php?id=113 that has mechanical models and explains them with math equations that are way over my head.



This is a wonderful resource - Cornell has one of two existing sets of Reuleaux's late C19th encyclopedic set of mechanism models. The other is in Germany I think.   http://kmoddl.library.cornell.edu/rx_collection.php
I'd love to see it.  
They also have CAD models and STL files of many mechanisms.


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## chucketn (Jun 15, 2018)

I've found a few tidbits of info. Like relative size of piston  in relation to bore and stroke. Mostly from old engineering books describing real engines. On the other hand, a lot of the old texts on steam engine design discuss the history, or a brief description of improvements. I've not found much that describes the relationships of stroke to port angle or crank diameter...
Brian, how did you do it?


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## fcheslop (Jun 15, 2018)

With simple wobblers in a lot of cases they are simply designed to run with little thought 
A few designers the likes of K N Harris, James Senfit and Harry Wedge have developed the engine 
The stroke and the crank to cylinder pivot have an effect on the porting as you need to fit 3 diameters as in two in the upright and one central in the cylinder within the swing of the cylinder. I tend to sketch it up with a rule and pencil just to see what will fit in . I try to keep the dead area to a min and have tried a little overlap on the exhaust and find they run a bit better
I use the simple wobbler for most of my steam launches on steam and only bed in on air
Another factor often forgotten is the forces acting on the cylinders pivot especially with some of the rather hefty offerings about 
Steam tables may also be useful


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## chucketn (Jun 15, 2018)

Thanks again, fcheslop.  The names you mention are familiar. As I mentioned before, I figured out  a simple drawing to find the trunion ports. Not sure I understand what you mean  by dead area, or overlap.


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## Anatol (Jun 16, 2018)

fcheslop said:


> . I try to keep the dead area to a min and have tried a little overlap on the exhaust and find they run a bit better



Do you mean that there is a short period when the cylinder port  is open to both inlet and outlet?  -  that for that time, steam supply goes directly to exhaust?  This seems counterintuitive.  Do you have an idea why this is advantageous? 

I love the simplicity of the wobbler, but surely the symmetry of valve timing (inlet and exhaust being open for same amount of time (number of degrees of crankshaft rotation) is not optimal. Theres no way - as far as I can see -  to have inlet open for a short time after TDC and exhaust open all the time between BDC and TDC.


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## Peter_A_Lawrence (Jun 16, 2018)

All,
      I've looked into the theory that steam engines won't run on air, or won't run well on air. The main difference is that steam is hot and air is cold, so from thermodynamics, at the same pressure, hot gas has more energy than cold gas, so you get more power out of the hot steam than you get out of the cold air, but if you didn't let the air cool while compressing it, it would have about the same energy as steam at the same temperature.  As far as the notion that air won't supply power to the engine during expansion phase, that doesn't compute, the only thing we know is that it won't supply as much power as hot gas, but to say that it won't supply any power is simply incorrect.

Peter Lawrence.


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## Mechanicboy (Jun 16, 2018)

The timing of the steam engine.


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## Cogsy (Jun 16, 2018)

Interesting, I've never seen such a diagram for a steam engine (I'm not a steam guy). What's the reason for the compression region? Isn't it just wasted engine power and efficiency? I would have thought exhaust til almost TDC would work better.


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## Mechanicboy (Jun 16, 2018)

Cogsy said:


> What's the reason for the compression region?



The purpose of compression in addition to the steam pressure emitted into the cylinder a bit earlier before TDC, we utilize the steam as much as possible when the steam expands in a closed cylinder. The purpose is reduced steam consumption and better power out of steam engine. 

The wobbling steam engine is a poor economy in steam consumption and difficult to get more power out of wobbling steam engine due limited by spring who are holding the cylinder to valve plate.


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## goldstar31 (Jun 16, 2018)

Apologies
Wrong topic

Norm


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## Cogsy (Jun 16, 2018)

Mechanicboy said:


> The purpose of compression in addition to the steam pressure emitted into the cylinder a bit earlier before TDC, we utilize the steam as much as possible when the steam expands in a closed cylinder. The purpose is reduced steam consumption and better power out of steam engine.
> 
> The wobbling steam engine is a poor economy in steam consumption and difficult to get more power out of wobbling steam engine due limited by spring who are holding the cylinder to valve plate.



I'm afraid I still don't understand the compression purpose - it uses engine power (from steam of last stroke) to compress air before the inlet opens. Once the inlet opens, the amount of steam admitted depends on difference between steam pressure and cylinder pressure, so having increased pressure from compression reduces the amount of steam admitted to the cylinder. So in my mind it uses power, then restricts available power as well. It seems very inefficient to me.


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## Mechanicboy (Jun 16, 2018)

Cogsy said:


> Once the inlet opens, the amount of steam admitted depends on difference between steam pressure and cylinder pressure, so having increased pressure from compression reduces the amount of steam admitted to the cylinder.



In fact steam pressure is higher than pressure of compression. The advantage of compression in the cylinder: Less loss time to create cylinder pressure when the vapor pressure is admitted into cylinder. Then the cylinder has got more pressure to transfer power to the crankshaft just after TDC has been achieved and the steam can continue to expand after the slider valve is closed.


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## Mechanicboy (Jun 16, 2018)

See at the indicator diagram for steam engine..


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## fcheslop (Jun 16, 2018)

Dead space the angular movement before the port starts to open
On some of the better toy engines made in the 1920s the exhaust port is drilled slightly larger dia then the inlet allowing it to open to exhaust sooner
Circular ports although easily machined are not the most effective does it have a lot to offer making them as per K N Harris design I simply dont know or should say can prove other than the engine performs better on the water
Anyone can build a wobbler that will run it takes a bit more care to make one that runs well
In his books either 1 or 2 Building Simple Steam Engines the  author Tubal Cain(not the guy on utube) actually suggests allowing a slight overlap of inlet and exhaust ports allowing slight bypass and again from experience it seems to help and once the engine is running how much steam do you really loose giving the time it takes the wee cylinder moves fully left to right probably a lot less than from an ill made engine
All the above is simply from experience building wee wobblers for the last 40+ years and sailing them in my toy boats
The reason some slide /piston valve have  also later exhaust to de accelerate the mass before going over centre another is to  use the desaxe principal as found in petrol engines.
Just my two bobs worth from a rough [email protected] model maker
Oscillating engines have been used in full size practice powering ships and factories and are still available today for steam launches Reeves sell castings .These engines have little resemblance other than the principle of operation to the rather nasty tinny things made for children to set fire to carpets or lino with or that maybe my ill spent youth
cheers
frazer


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## pp2076 (Jun 16, 2018)

Cogsy said:


> I'm afraid I still don't understand the compression purpose - it uses engine power (from steam of last stroke) to compress air before the inlet opens. Once the inlet opens, the amount of steam admitted depends on difference between steam pressure and cylinder pressure, so having increased pressure from compression reduces the amount of steam admitted to the cylinder. So in my mind it uses power, then restricts available power as well. It seems very inefficient to me.


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## Cogsy (Jun 16, 2018)

Thanks pp2076 - that makes sense, I knew it couldn't be about power.

Jens - I realise the steam pressure is higher than compression but the total pressure can only be as high as steam pressure. So by raising the cylinder pressure before admitting steam, the amount of steam admitted is reduced, and available power is thus reduced, for a given cylinder pressure. The energy of the compressed air is generated by the engine so costs more energy than it produces, which is why I was confused. It is thermodynamically impossible for the compression to create more power.


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## Donrecardo (Jun 17, 2018)

You may find this usefull for what you want to do , I did

Don


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## chucketn (Jun 17, 2018)

Donrecardo said:


> You may find this usefull for what you want to do , I did
> 
> Don



Thank you, thank you, thank you...


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## Donrecardo (Jun 17, 2018)

Glad to be of help. If you just change one number at a time you will soon see how it works

Don


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## chucketn (Jun 19, 2018)

I've been playing with the simulator Donrecardo posted. I managed to scale up the Full Double Oscillator model to near where I want to build it. It brought up a question. The default model shows the piston covering half the ports at TDC and BDC. What effect would this have on a running engine? Should I modify my design to not cover the ports? To cover them less, more?
What affect would this have on a running engine? If this was covered in the posts previous to this, I missed it.
Bear in mind, I have no experience running my engines on steam. I might build a boiler some day, but for now I will run them on compressed air. So explanations should be primarily for air, with maybe a contrast if run on steam.


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## Anatol (Jun 19, 2018)

Don, that's a wonderful little app. Thanks for sharing. It only simulates oscillator, correct?


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## Donrecardo (Jun 19, 2018)

Hi Anatol, 
yes single and double acting oscillators


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## gbritnell (Jun 19, 2018)

Steam engines used for motive power, locomotives and traction engines generally had something called cut-off. Being as steam is an expansive gas cut-off was used to make the engine more efficient. When the engine wasn't required to work hard the valve could be adjusted through linkage to cut the steam supply to the cylinder anywhere from 30% to 60% of the piston travel. Most stationery engines used a simple valve connection because once started they ran at a governed speed to provide power for industry. 
The reason I state this is because if you're going to design an engine it's better to create it with valve timing used for steam as opposed to using air. An engine that runs on steam will also run on air. I don't know the exact cut-off numbers of say a Stuart #10 but I would guess somewhere around 60% of piston travel. Using air will provide enough pressure on the piston for this period of time to allow the engine to go past center where it will then receive another shot of air to push the piston in the opposite direction (on a double acting engine)
gbritnell


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## goldstar31 (Jun 19, 2018)

I tend to be somewhat jaundiced about steam because of 'family experierinces' . The great uncle working the Royals out of Carlisle and the buckled back from ever open fireboxes and  and a father under a dropped fire tube in a locomotive boiler. I could go on but suggest that you might want access my very good friend- Don Ashton's website on steam locomotion.  Last time information that Don was building a full size steam locomotive.

Don's CV is quite impressive, he wasn't just a steam boffin.

Regards

Norman


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## Charles Lamont (Jun 19, 2018)

Cogsy said:


> Jens - I realise the steam pressure is higher than compression but the total pressure can only be as high as steam pressure. So by raising the cylinder pressure before admitting steam, the amount of steam admitted is reduced, and available power is thus reduced, for a given cylinder pressure. The energy of the compressed air is generated by the engine so costs more energy than it produces, which is why I was confused. It is thermodynamically impossible for the compression to create more power.



It is not about power, it is about efficiency. A sudden inrush of steam into a (relatively) cold cylinder would be wasteful - it is always best if things happen smoothly in terms of both flow velocity and temperature change. The fact that with compression less steam is admitted is a good thing. If you are concerned about there being less power, your cylinder was too small in the first place. Make the cylinder bigger to compensate. For the *same steam consuption *a larger cylinder with the right amount of compression will give more power than the smaller cylinder without, because the steam is used more efficiently.

In a steam engine running on steam, what is being compressed is steam, not air.


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## fcheslop (Jun 19, 2018)

Thinner piston they only need to be a little thicker than the seal or look at the drawings in the link
http://jpduval.free.fr/Moteurs_vapeur_simples/MV deo 10x20.pdf


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## TimTaylor (Jun 21, 2018)

A couple of other interesting references:

Model Stem Engine Design by R.M. de Vignier 1936

Steam Engines - Engine Governors  I.C.S. staff 1926-1929 (published by International Textbook Company)

The first is accessible online from the university of Chicago Library, don't have  a source for the second....


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## chucketn (Jun 22, 2018)

I found the Vignier book at the U of C library, but it is not available for download by the general public.

I cannot find Steam Engines - Engine Governors I.C.S. staff 1926-1929 (published by International Textbook Company) at all.


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## TimTaylor (Jun 23, 2018)

Yeah, U of C requires a membership to download also.

The following is a link to a list of books on steam engine theory and design that are in the public domain - some interesting reading - 
http://www.vapeuretmodelesavapeur.com/telechargements/livres-vapeur-sans-copyright.pdf

This is a ink to the ICS Blue  Book archive - the governor book is not on the restored list, but there are several other interesting titles there -
http://icsarchive.org/icsarchive-org/bb/


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## chucketn (Jun 23, 2018)

fcheslop said:


> Thinner piston they only need to be a little thicker than the seal or look at the drawings in the link
> http://jpduval.free.fr/Moteurs_vapeur_simples/MV deo 10x20.pdf


Thank you.


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## chucketn (Jun 23, 2018)

https://books.google.com/books?id=gDwxAQAAMAAJ&pg=PR1&lpg=PR1&dq=r.m.+de+vignier&source=bl&ots=OTZfG6sis8&sig=5_aFBwlKb6yWsfBCBjlMYlmqN4c&hl=en&sa=X&ved=0ahUKEwja4rvFkerbAhUJjq0KHaweAhkQ6AEIOjAF#v=onepage&q=r.m. de vignier&f=false

Found the *R. M. de Vignier book at the above address, link there to .pdf download.* Found by searching on Google for R.M. deVignier.
I have read the copy I downloaded, and my head is swimming from all the info I found. Thanks Tim for posting the link that got me looking for that reference.
I will re-read this book several times and refer to it often.
I found a comment on the Google Books page for this book that the copy ended at page 81 while the index says there is another chapter starting on page 87, and indeed it does end at page 81!
Tim, or anyone else that may have a copy of this book, does your copy have the missing pages? May I get a copy of them from you?
The information presented in the book is fantastic, but brings further questions. Are the timing, power, and other calculations described for vertical and horizontal slide valve and piston valve engines pertain equally to oscillating engines? The missing chapter has info pertaining to ports, patterns and such. I would very much like to get the missing pages.
I will invariably be asking more questions, as I think this book has given me enough information to at least know what questions to ask.


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## chucketn (Jun 25, 2018)

I have made the drawing above based on what I've learned from this forum and others, and the various books I have been referred to. I'm still trying to define relationships that could be added to this drawing, not as a steadfast rule but as a guideline. One question that has not yet been answered to my understanding is : should the piston cover the ports at the top/bottom of the stroke, half cover, or not cover them at all? What is the benefit of yes, no or half covered?
Bogstandard, are you looking?
Where I have the lable "Total length of piston and piston rod", there are supposed to be dimension leaders pointing to the center of the left most circle and the 9:00 o'clock point on the middle circle on the right.


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## chucketn (Jun 25, 2018)

I tried to improve the drawing...


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## bouch (Jun 28, 2018)

chucketn said:


> View attachment 102401
> 
> One question that has not yet been answered to my understanding is : should the piston cover the ports at the top/bottom of the stroke, half cover, or not cover them at all? What is the benefit of yes, no or half covered?



If you cover the ports at the top/bottom of the stroke, you're preventing any steam from getting into the cylinder.  I wouldn't want that for any steam engine.  The only thing that should prevent steam/air from getting into the cylinder is the valving, not the piston blocking the port.  If the piston blocks the port while the valve is admitting steam, you've pretty much made the valve timing useless.  (and for the purpose of an oscillator, the valving is the rocking of the cylinder)

It even more important with an oscillator.  That'll cause the steam/air pressure in the port to push the piston away from the body, which will cause leakage.


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## Anatol (Jun 28, 2018)

bouch said:


> ...  If the piston blocks the port while the valve is admitting steam, you've pretty much made the valve timing useless.  (and for the purpose of an oscillator, the valving is the rocking of the cylinder)
> .



Good point. But with an oscillator the ports cannot be in the top of the cylinder, unless you make a manifold  internal to the cylinder head. You can squeeze the ports into the top corner. So what size gap between piston and end of cylinder is deemed to be too much? Is some gap  desirable for any (other) reason? (Some argue for it in unaflow engines.)


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## Charles Lamont (Jun 28, 2018)

In a simple oscillating engine:

1) the clearance between piston and cover can be minimal - a few thou to prevent mechanical contact due to inaccuracies and wear;

2) the piston should not completely block the port, but remember that at dead centre the piston is not actually moving in the bore; 

3) putting the ports at as large a radius from the pivot allows them to be as big as possible for free steam flow;

4) minimising the distance between the crankshaft and pivot bearing maximises the angle of swing, again allowing large ports;
assuming the engine is double-acting, this can involve clever design like hiding part of the gland in a recess in the rod side of the piston.

5) A trunk guide for the crosshead takes the lateral thrust off the gland, piston rod, and piston (a very bad thing for them anyway) allowing the bearing area 
of the gland to be minimised, helping with (4).

6) In small engines the gas flow velocities and dimensions are small (and therefore so is the Reynolds number) meaning that none of this matters much unless
high speed and power output are required: mostly they will breathe just fine.


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## Anatol (Jun 29, 2018)

"1) the clearance between piston and cover can be minimal

2) the piston should not completely block the port, 

3) putting the ports at as large a radius from the pivot allows them to be as big as possible for free steam flow;"

these points seem mutually antagonistic. Presumably, a compromise is best - ports are as large as possible and as close to cover as possible,  and cylinder only covers half the port at TDC?


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## TimTaylor (Jul 4, 2018)

Chuck,

I got a copy of the de Vignier book from a friend that is broken into three pdf files - only issue is that the page orientation is rotated 90 deg so I wound up just printing it out - the one you found is much easier to read.

I checked and the pdf copy I have does have the missing information from pages 82 through 94. Since it is now in the public domain (original copyright 1907 and books copyrighted in the US before 1923 are expired and legal to copy), there should be no problem letting you have it.

Tim


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## TimTaylor (Jul 4, 2018)

Here's a link to another good reference. While it's about full size steam engines and not model engines per se, the same principles apply.....

http://books.google.com/books?id=ms...r&dq=Steam+engine+principles+and+practice&lr=

Tim


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## chucketn (Jul 4, 2018)

Thank you, Tim. Much appreciated. PM sent.


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## chucketn (Jul 5, 2018)

I've drawn up and printed enough parts for a mock-up of one cylinder, piston, , crank disk,  and flywheel to prove the design concept. I also machined a short version of the axle, one cylinder pivot pin, one piston rod, and one crank pin. I laid out the crank and trunion axle locations on a scrap of aluminum and drilled the holes to mount the Cylinder and axle.


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## Richard Hed (Aug 9, 2020)

gbritnell said:


> First decide on a style of engine, horizontal,vertical, simple, double acting or oscillator. Next figure what bore and stroke you want then work from there. It's hard to give exact dimensions for everything otherwise we would be designing the engine. If you have a lot of reference material just use what someone else has already created.
> gbritnell


I would have said "decide what power you want" which of course dictates the volume of the cylinder X the pressure X CPM (cycles per min.), and then said what you said.


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## Richard Hed (Aug 10, 2020)

fcheslop said:


> At least youve got a copy
> This one although a little out of date is still a handy reference
> https://redirect.viglink.com/?format=go&jsonp=vglnk_152907415999615&key=5e5e6e04e939b9674c384ca8b03117f4&libId=jig38qyd010248ul000DAk9e7gdym&loc=https://www.rcgroups.com/forums/showthread.php?1226384-Books&v=1&out=http://www.fastonline.org/CD3WD_40/JF/424/19-422.pdf&ref=https://www.rcgroups.com/steam-boats-656/&title=Books - RC Groups&txt=http://www.fastonline.org/CD3WD_40/JF/424/19-422.pdf


What are you two talking about?  When I go to that site, it is a foreign language that I have never seen before.  PDF?


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## goldstar31 (Aug 11, 2020)

Richard Hed said:


> What are you two talking about?  When I go to that site, it is a foreign language that I have never seen before.  PDF?



I didn't have  any problem with Frazer's post. There was a perfectly good set of working drawings for me- if I was so inclined


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## Donrecardo (Aug 11, 2020)

chucketn said:


> https://books.google.com/books?id=gDwxAQAAMAAJ&pg=PR1&lpg=PR1&dq=r.m.+de+vignier&source=bl&ots=OTZfG6sis8&sig=5_aFBwlKb6yWsfBCBjlMYlmqN4c&hl=en&sa=X&ved=0ahUKEwja4rvFkerbAhUJjq0KHaweAhkQ6AEIOjAF#v=onepage&q=r.m. de vignier&f=false
> 
> Found the *R. M. de Vignier book at the above address, link there to .pdf download.* Found by searching on Google for R.M. deVignier.
> I have read the copy I downloaded, and my head is swimming from all the info I found. Thanks Tim for posting the link that got me looking for that reference.
> ...



When I go there I cant see any pdf link , infact it states that no ebook is available


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## JCSteam (Aug 11, 2020)

After a bit of link manipulation i can find the link for the PDF, however there is a re-direct on the link. It goes to the page i believe Richard, Don, and myself have seen.
This is the links page Here but even from there its on a redirect. 

Jon


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## JCSteam (Aug 11, 2020)

Some interesting reference from that thread.
Little Boys Book of Engine building
Model Engine Making Or Model Engine Making
Model Engineer's Handy Book
Model Steam Engine Design

Jon


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## Busted Bricks (Aug 11, 2020)

I made a parametric drawing in Freecad of an oscillating steam engine. If I change a dimension, all the others follow suit accordingly.


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## sarel (Aug 12, 2020)

JCSteam said:


> After a bit of link manipulation i can find the link for the PDF, however there is a re-direct on the link. It goes to the page i believe Richard, Don, and myself have seen.
> This is the links page Here but even from there its on a redirect.
> 
> Jon


I have had no sucess getting to book of RM de Vignier with the link


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## Donrecardo (Aug 13, 2020)

sarel said:


> I have had no sucess getting to book of RM de Vignier with the link


No , I still dont have it either . Could someone who has it be good enough to upload it to the files section so we can all find it ?


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## Anatol (Aug 15, 2020)

Donrecardo said:


> No , I still dont have it either . Could someone who has it be good enough to upload it to the files section so we can all find it ?



ditto, that would be much appreciated
BTW, I found a free version of Stumpfs 1922 edition at 
http://www.survivorlibrary.com/library/the_una-flow_steam-engine_1922.pdf


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