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Chris's Build of Steering Engine

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After all the design work on the steering engine and having put the Ransome Saw model on the back burner to figure out its valving better, time to get started on the build.  For those who have not seen it, there is a thread over in the Chatterbox section where Michael and I were discussing this engine, and he very kindly shared many pictures, videos, and drawings of the original engine he restored. Here is a link to that thread:


Short version is, on larger ships in the steam era it was not practical to have the ships steering wheel just connected directly via ropes or chains to the rudder - the rudders were just too large, and the forces on them too great, requiring a lot of effort by the helmsman to steer the ship. So, enter the steam powered steering engine (later replaced with hydraulics and electric versions). The one that Michael restored has a two-cylinder steam engine that powers the unit. As the helmsman turns the wheel, a worm gear advances a traveler nut which opens the valve on the engine, which runs and counter-turns the traveler nut back, closing the valve when it has reached the point that the helmsman turned the wheel to. Very much like the servo-centering on a modern radio control model, except all done with gears and steam engines. 

Here is a picture of an original steering engine:

More pictures and videos on the other thread mentioned above!

I turned the pictures/drawings/measurements he sent me into this CAD version so I could generate a set of plans (posted on the other thread if you want to build one).

On with the build! I decided to model the engine at 1:6 scale, and plans were generated for that size. That scale makes it large enough for practicality, and small enough to fit on my Sherline lathe/mill. Going to start with the base and work my way up. A tooling plate was mounted on the mill table, and a piece of thin plywood added as a spacer so I can drill/mill through the part and not chew up the tooling plate.

The locations for the screws were picked so the front two are where drain holes will be under the crankshaft, and the back two are in an area that will be cut out later. Then, drilled matching holes in the brass blank to bolt it securely to the table. I put a printed out copy of the base plan on it for reference. I will NOT be using it to position holes or edges, its just there as a double-check that I have not miscounted the number of turns on the handwheel. Printed paper copies are not reliable enough for cutting to - in my days developing printers for Kodak, I learned how many ways there are for errors to creep in as paper is fed, how much paper moves with humidity/temperature, and how many ways the printers themselves subtly change positions to round to its mechanics.

When I generated that version of the plan, I located the origin at a lower left mounting hole, and all measurements to hole centers are referenced from that position. That will let me do my version of CNC - Count Number Cranks - on my manual lathe. Once that position is moved to the handwheels were zeroed, and all holes/edges will be referenced from there. Before each set of holes I move back to there and do the X/Y moves out to the start of each row, and count turns/ticks from there.

Here is a picture after going round and drilling the mounting holes around the perimeter and the rest of the drain holes under the crankshaft.

Next session I'll start in on the mounting holes for the crank bearings and the vertical walls, those holes will all be tapped 4-40.
Thanks for following along!

 :ThumbsUp: :ThumbsUp: :ThumbsUp: :popcorn: :popcorn: :popcorn:

A great start!  :cheers:

Thanks CNR!  Lunchtime and a lunch out with friends came at a perfect time, all that drilling was making the wrist/hand tired. The tapping jig will get a bunch of use on this one...

Michael S.:
Applause 👏 here we go. An interesting introduction to building the steering machine.
I think you'll be done for a long time when I start with the model.
I still have so many construction sites.
I like your way of processing the base plate in this way and it is really a demanding job.
I very much looking forward to progress.


Thanks Michael. There are so many ways to make just about any part, it will be interesting to see how you do things. A lot depends on what materials and what tools are available.


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