Author Topic: Chris's Build of Steering Engine  (Read 17141 times)

Online crueby

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Chris's Build of Steering Engine
« on: September 16, 2022, 04:15:55 PM »
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:

https://www.modelenginemaker.com/index.php/topic,10962.0.html

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!
Chris

Offline cnr6400

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Re: Chris's Build of Steering Engine
« Reply #1 on: September 16, 2022, 06:01:40 PM »
 :ThumbsUp: :ThumbsUp: :ThumbsUp: :popcorn: :popcorn: :popcorn:

A great start!  :cheers:
"I've cut that stock three times, and it's still too short!"

Online crueby

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Re: Chris's Build of Steering Engine
« Reply #2 on: September 16, 2022, 06:29:13 PM »
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...

Offline Michael S.

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Re: Chris's Build of Steering Engine
« Reply #3 on: September 16, 2022, 06:51:46 PM »
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.

Michael

Online crueby

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Re: Chris's Build of Steering Engine
« Reply #4 on: September 16, 2022, 08:04:41 PM »
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.
 :cheers:

Online crueby

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Re: Chris's Build of Steering Engine
« Reply #5 on: September 16, 2022, 08:10:02 PM »
After lunch I got the rest of the holes drilled...

Then started in shaping the outer profile of the base. I went back to the zero point from the drilling, moved in the radius of the end mill cutter and re-zeroed the handwheel, then moved out again the distance to the edge of the finished block. Milled off the front face in several shallower cuts:

Moved back the distance to the rear face plus diameter of the end mill, and trimmed off that edge too

Then started in on the first side

The curved area near the front will have to be done on the rotary table later, I want to do as much as possible in the current setup first. And again, the paper is still there just as a double check on my moves, I am not using it to set the cuts. Along the outer edges, the face will get trimmed back more to form the bottom bolting flange, leaving the vertical gussets in place.

Online steamer

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Re: Chris's Build of Steering Engine
« Reply #6 on: September 16, 2022, 08:41:39 PM »
Damn bubba....that's going to be some whittling!!! :o
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Online crueby

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Re: Chris's Build of Steering Engine
« Reply #7 on: September 16, 2022, 08:50:03 PM »
Damn bubba....that's going to be some whittling!!! :o
Thats why I love brass, so much fun to whittle!

Online Kim

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Re: Chris's Build of Steering Engine
« Reply #8 on: September 16, 2022, 09:09:24 PM »
Great start on the steering engine, Chris!  :popcorn: :popcorn:

Are you planning to make it all out of brass?

Kim

Online crueby

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Re: Chris's Build of Steering Engine
« Reply #9 on: September 16, 2022, 09:19:39 PM »
Great start on the steering engine, Chris!  :popcorn: :popcorn:

Are you planning to make it all out of brass?

Kim
The base plate and the two vertical walls, plus the gears will be brass. The two worms are steel, using off the shelf Acme rod for those. The rest will be mainly stainless steel, other than bearings and the valve sliders.

Offline Michael S.

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Re: Chris's Build of Steering Engine
« Reply #10 on: September 16, 2022, 09:21:03 PM »
Hi Chris,
my first thought was to put the base plate together from several parts.
Maybe aluminum. Everything is glued, screwed and made to look like a cast part with epoxy resin filler.
But milling everything out of brass is also quite time-consuming and you have to work very concentrated.
How do you want to mill out the troughs under the eccentric and crank of the crankshaft?
The sheet metal tub under the worm wheel is only screwed on. On remains of editions of the base. They broke off.
But you could also attach the tub differently.

I wish you a strong and steady hand

Michael

Offline Michael S.

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Re: Chris's Build of Steering Engine
« Reply #11 on: September 16, 2022, 09:27:52 PM »
Another thing that comes to mind about the color of the machine, the green color is not the original color scheme. It could be that the castings were originally gray.
The green color came later. Because all the main engines in the Dresden fleet are green.
So you can still think about the color.

Online crueby

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Re: Chris's Build of Steering Engine
« Reply #12 on: September 16, 2022, 09:34:42 PM »
Hi Michael,
I considered piecing it up, but even if I did, there would still be a lot of milling and shaping involved, maybe more since all the joints would have to be cut, along with the requirement to keep everything aligned and flat along the base plane. I've done previous models both ways, and I don't think there is a big time savings either way. I do like machining in brass for this sort of thing, very easy cutting. I don't really like aluminum, seems like whatever alloy I pick and what speeds/oil I use, at some point I get the aluminum building up on the cutter tips and making a mess. Just a personal preference.
For the troughs under the cranks, I may cut them down flat and add in a curved piece in the opening, that could even be done with some JB Weld epoxy, have not decided that yet.
For the trough under the worm gear, in the picture from the one on the ship, in the picture I showed in this thread, I zoomed in on the original photo, and in that one the center trough is part of the base casting, not added on. It may be they made them different ways, or on yours it broke or rusted, and was replaced with a sheet metal one.

Online crueby

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Re: Chris's Build of Steering Engine
« Reply #13 on: September 16, 2022, 09:35:19 PM »
Another thing that comes to mind about the color of the machine, the green color is not the original color scheme. It could be that the castings were originally gray.
The green color came later. Because all the main engines in the Dresden fleet are green.
So you can still think about the color.
Interesting - I really like that green color, it sets off the steel and bronze color well.

Online Vixen

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Re: Chris's Build of Steering Engine
« Reply #14 on: September 16, 2022, 09:42:12 PM »
Hello Chris

Just a thought. The base plate 'casting' would look great if you were to us something like a 1.5R x 6 or a 2R x 6 bull nose, radiused cutter to machine the webs in the base plate. Other sizes are also available. A bull nose radiused cutter would create a neat fillet rather than a sharp edge. You will find a bull nose radiused cutter is so much nicer to use than a ball nose and leaves a smooth flat surface between the fillets

Cheers

Mike
It is the journey that matters, not the destination

Oh! sod the journey, lets hit the bar and pool instead.