Corliss Engine Model

[Captain Jerry]

My subconscious keeps whispering the word "Corliss Engine".  These were the giants that made steam engines more efficient and kicked the industrial revolution into high gear.  They are easily recognized by the complicated linkage that controlled the four separate intake and exhaust valves on each cylinder using a wrist plate on the side of the cylinder.

Has anyone designed or built a Corliss Engine model with cylinder dimensions of 3/4" bore x 1" stroke or smaller?  Or can anyone point me toward plans for a slightly larger engine that could be scalled down?

Jerry

[sbwhart]

Jerry

I've had an ankering to do a Corless about that size, but keep getting put off at the small size the valve trips would have to be the only way I can think of getting round the problem is the have the valve trips over scale.

Good luck with your quest.

I have some full size info if that would be of help.

Stew

[Jasonb]

Anthony mount has a new corelis design which will be in EIM, not sure of teh bore but possibly a bit larger at 1" to 1.25" though most of his engines can be scaled up or down and its vertually all fabricated. Bruce Eng will have the plans

http://modelengineeringwebsite.com/Guildford_2012.html#2

[Jo]

Hi Jerry, 

I am currently building a Cross Compound version of Arnold Throp's Corliss engine:
 


It is a big model and very heavy (there is also a four cylinder version of this engine on the plans ). This is the progress to date on my engine:

.

Her HP cylinder is 1 1/8" bore, 3 7/8" long. Arnold when he wrote up this engine, justified why he had built this engine so large by saying that the problems of making a smaller one and getting to to work can be severe, for instance the steam ports on my engine are only 1/32" wide!!!! The same argument was given to me a couple of weeks ago when I discussed the size of Anthony Mount's new engine with him.

Coles also do a set of castings for a Corliss that was documented in Live Steam.



I am not sure of the cylinder size for her, I would have to look it up at home.

Jo

[ausdier]

Here is one I have nearly finished drawing.
It has a 1-3/8" bore and a 3" stroke.
It comes from a series by Charles Heckel in the 1938 "The Model Craftsman"

[Captain Jerry]

Ausdier, Jo and Jason,

Thanks for the responses and the links.  Those beautiful models and the obvious skills of the makers make it clear that this kind of model could be a lifetime project for a much younger man than me. 

Stew

Scale...That is the problem, not to mention the number of fiddly pieces at any scale. Neither my equipment nor my shop are large enough to build an engine with fully functional valve gear at a size that I can see.  I have been modeling the mechanics of this in Alibre' and it is clear that even if I could produce the pieces at the microscopic sizes necessary, they would not have the strength to perform. 

I am thinking that the closest that I could come to a working engine at this size is to ignore some of the finer points of the design and produce a simulated version with lots of compromises, sort of an Elmer Verburg approach.  I would have to design a trip mechanism or ignore it completely and just do an engine with four rotary valves and no trips.  That might be enough of a challenge for me.

I'll keep thinking about this so I would appreciate any suggestions or advice.

Jerry

[arnoldb]

Cap, I've also been harboring some ideas about this one... for quite a while.

Like you, I've also come to the conclusion that for a small one, some of the details will have to be dropped, and an Elmer-like design will work well with barstock.

The porting through the cylinder block could be tricky to figure out.
One option would be to make it from two pieces of brass - so that the steam passages can be milled on top and a block soldered over to cover them again.
Alternatively, one could drill them all and use plugs like Elmer did frequently to seal up the unnecessary holes.  Then the block could be made from a single block of just about any material.

I don't think making the rotary valves will be too much of a problem.

Simplifying the valve gear itself and getting that to work might be the most difficult part; and I'd have to agree that it might be feasible to completely ignore the trips (or just fit optional dummy ones) for a small scale version.

Kind regards, Arnold

[sbwhart]

Jo

That looks a wonderful engine.

Ausdier

They look very nice designs well drawn up I'll just have to get to grips with 3D one day trouble is I'd rather spend the in the shop cutting emtel than learning how to 3D

Same as you guys I came to the conclusion that the best way for a small size corless would be to fudge it, with a simplified version, but that kind of takes the magic away from the system.

I saw a model by Neil Carney of a Corless pumping engine at an exhibition that looked like it had a working Coreless next time I meet Neil I'll ask him how he made the valve gear.

Stew

[Jo]

Just got home and dug out the Cole's design:

She has a 1 7/8" bore, but her ports are a massive 1/16", so I reckon you could build her half scale.

Jo

[Captain Jerry]

The more I think about this it becomes clear that for an air operated engine with no expansion, early cut-off is not important and could not be used to govern speed so there is no need to spend time on that part of the design.  If a working governor is to be fitted, it will have to be of the throttle control type but may be just ornamental.  I guess the trips will just be dummy or left as a footnote.

At the moment, I am favoring a one piece aluminum cylinder block with drilled passages and since I am going to simplify the valve linkage, I think I will keep it on the small side,  5/8" bore x 1 1/8" stroke.

I'll try to post a preliminary model of the cylinder tonight.

Jerry

[Captain Jerry]

Really, Jo.   Half scale of a massive 1/16" port, becomes a miniscule 1/32" port.  What do you cut that with?

Jerry

[Jo]

The same cutter I am going to use on my engine to cut the ports

Jo

[Captain Jerry]

This is a section view through the cylinder block



.  It presents no production problems that I can see.  Another option would be to have the main steam and exhaust galleries milled as closed end slots from top and bottom and sealed with a bolt on plate, much like Arnolds idea except the block is only one piece.  That might be better than the drilled galleries that are shown which will have to be sealed at the ends which might interfere with the cylinder heads.

Jerry

[steamer]

it can be done........
http://craftsmanshipmuseum.com/images/Corliss1.JPG

By Jerry Keiffer....

[ausdier]

Here is some what of an idea I had as how to do accurate ports for the main cylinder.
Machining the ends and soldering the blocks in first.
Next machine the valve ports.
Then the bore for the cylinder.
Machine the cylinder and solder in place.
I hope the pictures are some help.