Author Topic: A small vertical twin cylinder steam engine  (Read 736 times)

Offline Zephyrin

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A small vertical twin cylinder steam engine
« on: February 14, 2019, 04:33:34 PM »
Here is a model of a small steam engine that I just finished.
It is a small engine (13 mm bore and stroke, ˝”x ˝”); a 2-cylinder vertical double-acting marine type engine, with Stephenson valve gear.
I don't have the boat to put it in....
The link for the plan here    http://jean-luc.soumard.pagesperso-orange.fr/bicylindre.htm
I started this construction after a gift from a member of my club who gave up this build; namely, a small batch of CNC machined parts (aluminum base, brass standards and bronze eccentric rods).
As my garage, where my "main" workshop is located, is far too cold in this season for my arthritic joints, I found this was an excellent opportunity to use my little Toyo lathe & mill, at warm and comfortably installed inside my house.
It took me longer than expected to make all these tiny parts; cylinders, by assembling brazed parts then machining, steam chests cut from the solid, and all these small linkage difficult to hold for machining.
All the machining operations were made on the little Toyo, except for the crankshaft.
 
I did the crankshaft blank from one piece of flat steel hot forged and then machined on the lathe between centre.
For the 2 main rod blanks I made zinc alloy sand castings, just for fun and some practise, rather than starting from a steel chunk.

The air and steam tests of the finished engine went well, the engine runs well on steam.
The boiler used for the tests was too small, not providing enough steam to supply the 7 cm3 displacement at more than 1 bar and say 700 rpm.
I have not performed a power test.

I am surprised by the important “slip” of the expansion link on the die block during the run; it seems to me to be a large "lost movement".
I wonder if this could be detrimental to the mechanism?
This doesn't result from sloppy fits, since on the computer model, ( C. Dockstader package) such a slip clearly appears too, a thing that I didn’t see before cutting metal!
The positions of the linkage pivot points may not be optimal.
Anyway, this little engine waits for a proper boiler...

« Last Edit: February 14, 2019, 04:37:07 PM by Zephyrin »

Offline Chipswitheverything

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Re: A small vertical twin cylinder steam engine
« Reply #1 on: February 15, 2019, 01:55:26 PM »
Thanks for posting the video and information on your very lovely small engine, which runs very sweetly and is a beautiful piece of work.   Dave

Offline Zephyrin

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Re: A small vertical twin cylinder steam engine
« Reply #2 on: February 15, 2019, 06:24:43 PM »
Thanks for your comment !

I put pictures on the construction in a Google album

https://photos.app.goo.gl/JVpKWZxCFWzMZ1ao6

Offline yogi

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Re: A small vertical twin cylinder steam engine
« Reply #3 on: February 15, 2019, 09:01:34 PM »
Beautiful little engine Zephyrin!  :ThumbsUp: :ThumbsUp: :ThumbsUp:

 :popcorn: :popcorn: :popcorn:

Offline Zephyrin

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Re: A small vertical twin cylinder steam engine
« Reply #4 on: February 16, 2019, 08:21:29 AM »
thanks for this appreciation Yogi
 

Online Roger B

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Re: A small vertical twin cylinder steam engine
« Reply #5 on: February 16, 2019, 08:49:17 AM »
Very nice and runs well  :praise2:  :praise2:
Best regards

Roger

Offline scc

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Re: A small vertical twin cylinder steam engine
« Reply #6 on: February 16, 2019, 09:31:03 AM »
Lovely :ThumbsUp:         Terry

Offline steamer

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Re: A small vertical twin cylinder steam engine
« Reply #7 on: February 16, 2019, 11:52:25 AM »
She's a runnah!

Die block slip is something that full size stuff worries a lot about, but it's due to the wear on the block.   In our little ones, it's less of a problem as they're usually over oiled and under used.

Nice engine!

Dave
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Offline b.lindsey

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Re: A small vertical twin cylinder steam engine
« Reply #8 on: February 16, 2019, 01:41:15 PM »
A fine running little engine and very well finished too Zephyrin. What are you thinking of as to a boiler for it?

Bill

Offline Zephyrin

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Re: A small vertical twin cylinder steam engine
« Reply #9 on: February 16, 2019, 10:15:52 PM »
Thank you everyone for comment...

Most likely the boiler would be fired by a central flue tube butane burner as it is common for marine models.
I have contact with a friend for testing it in boat this spring...I'm anxious to see it (her ?) "in action".

Offline fumopuc

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Re: A small vertical twin cylinder steam engine
« Reply #10 on: February 17, 2019, 05:50:35 PM »
Hi Zephrin, a lovely engine, very well made.
Kind Regards
Achim