Author Topic: The Sabino Compound Engine  (Read 29400 times)

Online crueby

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The Sabino Compound Engine
« on: February 23, 2022, 04:26:47 PM »
This is an engine model that I have wanted to build for a long, long time. When I was a kid we visited the Mystic Seaport Museum quite a few times, seeing the real ships and models there got me into a number of hobbies - ship models, carving, and eventually steam engines. It was watching the compound engine in the passenger steamer Sabino puffing away during the cruises on the river there that first got me hooked on steam engines, though it would be years before I started building any myself. Back in the early 1980's I got a copy of the plans for the Sabino from the museum, and built this RC model of it:

which we took down to the museum the following year. The crew in the shipyard got a kick out of seeing it built from the plans they made during a major refit they had recently done, and the captain had fun sailing it around in the water by the ship too:

The first of the morning cruises they took up and down the river, the model got to ride in the engine room

while we went up to the upper deck. The captain called me up to the pilothouse, and had me at the wheel for the entire cruise (right over my shoulder keeping an eye and telling what signals to send down to the engineer! ). Quite an experience.  Years later after getting into the machining hobby, I started looking for more details and plans for the Paine compound engine in the Sabino, but with no luck. The museum had never measured it for plans, though they had done detailed plans for the rest of the ship.

It was this past fall that Ron Ginger (who I got to know from this forum after he posted pictures of the Lombard log hauler up in Maine, which I eventually got to measure and build a model of) and I were talking, and he started doing some digging since he was also interested in modelling that engine. Ron was able to get just the right person on the phone at the museum, and arranged for us to get access to the ship to spend the day measuring the engine. More great fun, to finally see the engine up close from all angles rather than just looking down from the gallery around it. So, that day Ron

and I


spent the day crawling around the engine room with tape measures, rulers, calipers, protractors, and cameras getting all the detailed measurements plus close up pictures of all the pieces. Around that time I was also in contact with 'Steamer' Dave from this forum, who was the engineer on the Sabino for years - lots of great information from him on how the engine worked and was run, plus he got me some photos and drawings by Greg Young, another engineer there back in the day, who had build a truly amazing model of the engine that had a unique feature, the front of the engine block was removeable to show the inner passages.

Using all those photos and measurements, this past winter I drew the engine up in Fusion 360, creating a CAD version from which I made a set of prints with full size measurements and also a version scaled down to 1:8 size for a model. Here is a render of the CAD model:

A copy of the full size plans went to the museum for their collection, and for reference I had a smaller scale (smaller than the 1:8 size) version 3D printed:

With the other recent projects all complete, its now time to finally get to work on the Sabino engine! I would have started it this past week, but when gathering up the bar stock I realized that the 5/8" thick bars I was planning to use on the engine bed were actually 1/2" thick....   :zap:    :wallbang:   So, the proper thickness bars are out for delivery today, I'll get them stress relieved in the oven this afternoon and can start making swarf after that.   :whoohoo:
In the meantime, the last couple days I decided to make the display base for the engine as a section of the ships hull. After digging out the plans for the ship from the pile, er, um, careful stack, I spent some time with the table saw, band saw, and glue, making up this base:

I already had picked up a 12" long bar of 1144 stressproof steel, from which a couple blanks for the engine blocks were cut. The engine block on this engine is an interesting setup - it is made from two pieces, joined in the middle between the valves with bolted flanges around the edges of the joint. The valves are spool valves, with the HP valve an inside admission, and the LP valve an outside admission arrangement. The two blocks can be gotten out of a 3.5" diameter round bar, and with the tapered shape of the blocks the stressproof steel seemed like a good choice. Plus, lots cheaper than brass these days, especially when I found a place that had the 12" bar as a cut-off drop at a low price.

On the left of the photo you can just see another great find - a 4-blade prop just the right size that I was able to get from the Prop Shop over in England, which specializes in scale props for RC models. They happened to have this one already cast in stock, and they drilled/tapped the hub for me as well. I may attach it to the engine as a (fairly dangerous) flywheel, or just have it sitting next to the model. It is the correct size/pitch for the model - its amazing how much power a small steam engine has to turn a large prop. The 3D printed model is sitting on top of the base in the photo, it is a lot smaller than the metal model will be.
More updates in the next couple days as the pieces for the engine bed get made...

Chris 
 :cheers:

Online Jo

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Re: The Sabino Compound Engine
« Reply #1 on: February 23, 2022, 04:33:09 PM »
 8) I like that

Jo
Enjoyment is more important than achievement.

Offline Dave Otto

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Re: The Sabino Compound Engine
« Reply #2 on: February 23, 2022, 04:36:29 PM »
Another interesting build to follow along with.

Dave

Offline Dan Rowe

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Re: The Sabino Compound Engine
« Reply #3 on: February 23, 2022, 04:52:01 PM »
Time to order popcorn in bulk....this is going to be fun to watch. 
:cartwheel: :cartwheel: :cartwheel: :popcorn: :popcorn: :popcorn:

Cheers Dan
ShaylocoDan

Online Jasonb

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Re: The Sabino Compound Engine
« Reply #4 on: February 23, 2022, 05:06:55 PM »
That is quite an attractive engine, nice light slender construction and should make a great model.

What sort of sizes does the 1/8th scale rendition give?

Online tghs

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Re: The Sabino Compound Engine
« Reply #5 on: February 23, 2022, 05:35:11 PM »
this one will be great to follow..
« Last Edit: February 23, 2022, 08:26:09 PM by tghs »
what the @#&% over

Offline cnr6400

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Re: The Sabino Compound Engine
« Reply #6 on: February 23, 2022, 07:23:45 PM »
 :ThumbsUp: :ThumbsUp: :ThumbsUp: :popcorn: :popcorn: :popcorn:

I see you built the display base early - just for the hull of it, I guess?   :Lol:   :cheers:

Online crueby

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Re: The Sabino Compound Engine
« Reply #7 on: February 23, 2022, 07:26:39 PM »
That is quite an attractive engine, nice light slender construction and should make a great model.

What sort of sizes does the 1/8th scale rendition give?
The engine bed is a little over 4"x6", the pistons are 0.875" and 1.75" diameters, .75" throw/1.5" stroke on the crankshaft. The fastener sizes will be right in the 2-56 to 5-40 range, which is great. I picked the 1:8 scale to let me put in maximum details, going to try and put in everything on this one....

Online crueby

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Re: The Sabino Compound Engine
« Reply #8 on: February 23, 2022, 07:28:04 PM »
:ThumbsUp: :ThumbsUp: :ThumbsUp: :popcorn: :popcorn: :popcorn:

I see you built the display base early - just for the hull of it, I guess?   :Lol:   :cheers:
Gotta be a good comeback on that one....  :shrug:   Hmmm, just back from big lunch out with friends so the brain is slow, time for a nap....    :cheers:

Offline bent

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Re: The Sabino Compound Engine
« Reply #9 on: February 23, 2022, 07:31:39 PM »
Neat stuff!  :popcorn:

Online tghs

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Re: The Sabino Compound Engine
« Reply #10 on: February 23, 2022, 08:37:42 PM »
sounds like a nice size. the linkages looks like there will be lots of motion.. is it piston or slide valves tucked between the cylinders? how about a view without the cladding.. yes always start from the bottom and work your way up (come hull or high water)
what the @#&% over

Online crueby

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Re: The Sabino Compound Engine
« Reply #11 on: February 23, 2022, 08:49:55 PM »
sounds like a nice size. the linkages looks like there will be lots of motion.. is it piston or slide valves tucked between the cylinders? how about a view without the cladding.. yes always start from the bottom and work your way up (come hull or high water)
The valves are piston (spool? ) type, LP one is larger diameter.  I was able to find a couple pictures of the real engine with the cladding off from a newspaper article done during one of the re-fits. Ignore the arrow, that was added for an email to Steamer where I was asking what that valve was (to dump exhaust to the smokestack in case of problems with the condensor).


In that picture you can see the vertical flanges/bolts up the side in the middle in black, and across the top in red, which marks the two halves of the engine block. Either side of the horizontal top flange are the cover plates for the valve tubes. On top of the cylinders is a normal top cap/gland, above that with the concentric groove patterns are insulating covers. I'll be showing more views with internal passages later on when I get to the engine block construction.

Offline RReid

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Re: The Sabino Compound Engine
« Reply #12 on: February 24, 2022, 12:46:46 AM »
I really like the look of the engine, and will enjoy following along with the build. That hull section/display stand is a great idea!  :ThumbsUp: :popcorn:
Regards,
Ron

Offline propforward

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Re: The Sabino Compound Engine
« Reply #13 on: February 24, 2022, 02:46:28 AM »
I can see that this is going to be another amazing build.
Stuart

Forging ahead regardless.

Online crueby

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Re: The Sabino Compound Engine
« Reply #14 on: February 24, 2022, 03:13:00 AM »
Thanks guys! This afternoon got the bar stock for the engine frame stress relieved, tomorrow will get the pieces rough cut to length and start thinning them down.
I realized I forgot to include this little video snippet of the CAD model animated. It was done partway through the CAD modelling, so not all the details are right, and if you look close you can see the reverse control lever moving since Fusion doesn't make it easy to connect up things like the slide links on the reverse gear. But, you get the idea of how it will look. The tail-rods on the pistons out the top are part of this engines charm.