Chris's Build of Steering Engine

[Michael S.]

I would imagine that a valve was placed further down the pipe. So that you don't have to reach between the gears. This valve was always slightly open when the machine was in operation. As a result, condensation water could always run past the guide rod. I think I misinterpreted it when I put a locking cap down there.
I'll have to change something there. Let's see if I still have a nice old valve and dented copper pipe.

Michael

[crueby]

I would imagine that a valve was placed further down the pipe. So that you don't have to reach between the gears. This valve was always slightly open when the machine was in operation. As a result, condensation water could always run past the guide rod. I think I misinterpreted it when I put a locking cap down there.
I'll have to change something there. Let's see if I still have a nice old valve and dented copper pipe.

Michael

Since they had the sheet metal cover over the engine when it was placed in the pilothouse, it would make sense that they would put the valve farther down the pipe so it could be operated without removing the cover.

[crueby]

Here is the gear set with the spokes repainted to black:

A subtle difference, but I like it. With the wheels in place too:


So, back to making parts! The next ones will be the control valve, that takes steam in, exhaust back from the cylinders, and directs which pipes get which at the steam chests on the cylinders. I got out the plan sheet for the valve, and was studying that, and realized that I should change the back end of it slightly to make it easier to do the pipe connections later on. I have a bag of Regner steam line fittings, including compression fittings for 3mm tubing that I'd like to use for the connections. As scaled down from the original, the back wall of the valve behind the valve ports is quite thin, not leaving much room for drilling/tapping in for pipe connections. Before I start cutting metal, I'm going back to the CAD version and move a couple wall locations in the valve to give myself more room.
Here is the valve body as drawn:

I am going to move the pipe connections, screw locations, and back wall around slightly to make them more practical at model size, which is only about 1" tall overall.

[crueby]

Updated view of the control valve, using the 3mm Regner compression fittings and also moved the screws on the cover plate out to match 2-56 size.

[Michael S.]

Chris, it's good that you changed the shape. It's going to be a tight box and I'm curious how you can create the steam channels.

Green, black and wood is gorgeous!

Michael

[crueby]

Chris, it's good that you changed the shape. It's going to be a tight box and I'm curious how you can create the steam channels.

Green, black and wood is gorgeous!

Michael

The passages are pretty straightforward, will mill in from the open side to form the ports, and drill to meet them from the side, the pipe fittings are centered on the passages. To get a smooth valve face I'm going to make a thin plate like you did on the real one and epoxy it down in the box. I have several sizes of very small end mills that I use on parts like this, they have 1/8" shanks, hold them in a small collet. Light cuts!

[derekwarner]

Back online thanks Chris..............[but thru the back door]

3 weeks of being banned due to opening MEM from my Hospital bed & an alternate IP address was not fun 

I am sure  hope Jo [Admin] will be able to kill the glitch 

Happy readings for me about the steering gear now

Derek

[MJM460]

Hi Derek, good to see you back.  I assume the fact that you are back is good news on the hospital front.

Frustrating at the time but good that the system is working, or at least acting on the safe side.

MJM460

[MJM460]

Hi Chris, I suspect that the valve has the second gland at the bottom to remove the unbalanced load on the valve rod.  The leakage through the gland would require a drain for the resulting condensate, otherwise the pressure in the cap would build up to the supply pressure, which just restores the unbalanced force. 

The force depends on the steam supply pressure, but I imagine it could be hard on the helmsman (person?) who had to to resist the force over a long watch.

Great progress on the model, a joy to follow.

MJM460

[crueby]

Hi MJM,
That cap at the bottom is on the end of the guide for the valve rod - if it did not have the drain pipe below it, they would not need a gland there around the rod, just a sliding fit on the rod since all it would be doing is keeping the rod from twisting to the side, just like the end guides on a lot of Stuart Turner steam chests where the valve rod goes through into the far end. So, no issue around pressure building up behind the rod.

But, since there is a drain pipe there, I would expect no gland there either, since you want condensate to be able to get past the end of the rod, there might even be an extra channel next to the rod for the water. There is no doubt that condensate would build up in the valve body, since it is only sending on steam to the engine when the wheel is turned, and then for a brief period.

Chris

[crueby]

This morning it was time to get started on the control valve body. New plan sheet (attached) has been generated from the updated drawing. I looked through the bar stock supply shelves, and spotted a cut-off piece (I think from the Sabino engine) that looked to be pretty close in size to what is needed. Held it up to the plans, and its perfect! Just needed to be squared off to get rid of the sawn edges.

Set up in the mill, and started taking back the ends, leaving metal for the front bolting flange


and on the sides too

The valve body so far. The top/bottom of the flange gets trimmed back to a curved shape later to let it clear the boss from the lower gear shaft.  Next steps will be to hollow out the chamber (very carefully, dont want to go through the sides! )

[cnr6400]

 

Looking great Chris! and I like the black accents on the paintwork too. 

[crueby]

Looking great Chris! and I like the black accents on the paintwork too. 

Thanks! 

[crueby]

Got started excavating the chamber in the valve body this afternoon. Started with a normal 1/8" end mill, took it down as deep as that would go and outlined/removed the middle of the space, then switched to a longer 7/32" end mill to take the opening down to full depth.


That left the lower part of the corners a larger diameter, so I got out one of the smaller 1/8" shank cutters, which reaches the bottom of the hole when extended a bit in the collet. Used that to take the inside corners to a smaller radius. In order to keep the side walls strong, I've made them slightly thicker than the scaled down original would have had, making the chamber slightly smaller, but its still plenty large for the normal sized valve slider, even with the slight radius on the vertical corners.


As I expected, the bottom face of the opening is the correct dimension but not quite smooth enough for a tight seal against the valve slider, so I am going to make and glue in a thin plate for the port face. First I'll drill pairs of holes, one pair for each port opening, down to the depth where they will intersect the passages from the pipe fittings on the sides. To make sure THOSE passages drill cleanly, I'll drill them first then connect into them from the top. The thin plate will have the rectangular holes like a normal steam chest would have, but being seperate I'll be able to lap the top surface before installation.


Lots to keep track of! 

[Michael S.]

very good 👍

That's exactly how I did it. The plate is then lapped and glued in place.