O.B. Bolton Marine Triple Expansion Steam Engine using castings by AJ Reeves, drawings by John Bertinat

[NMBROOK]

Not so much a progress update, but more an update on purchases needed to finalise the design of some additions to the original drawings.

I have purchased the three gauges for monitoring the valve chest pressures. There are three different ranges on the scales as pressure drops in each valve chest

I have also purchased six small Globe valves for the cylinder drains.Adapter pieces will need turning to connect to the cylinder blocks due to the tapering nature of the block.

 

[NMBROOK]

Bolton part twenty six

I am now on with machining an aluminium block to form a housing for the three gauges which will be screwed to the cladding. I came up with a design that disguised the pipe connections as I feel they spoil the scale fidelity of the gauges if left on show.
I have also drilled and tapped the drains for the cylinders.

As they say, a picture says a thousand words. The three holes behind the gauges are clearance for the projecting screw in the back of each gauge

 

[Roger Pellett]

I have trouble making the love button work. A great example of “cosmetic engineering” I always look forward to your posts.

Roger

 

[Namabiiru]

I have trouble making the love button work.

Story of my life

 

[NMBROOK]

Bolton part twenty seven

Kinda one step backward before moving forward for this small update ( currently working six days a week so progress has slowed)

I produced one of the extension pieces to take the cylinder drain valves but deemed the design too fragile and a light knock could result in breakage.

I decided to bore the six tapped holes out to take 1/4" Stainless extension pieces that would later be held in with locktite bearing retainer. This elevates the step in diameter and means I only have a threaded bore to take the valve, much stronger.

I have purchased some billet brass to machine the oil tank and lid that will be fixed to the cylinder block alongside the gauges. Pipes from this tank will supply lubrication to the crank main bearings simply by gravity. I have chosen to machine this tank from solid as it will give a much crisper appearance than folded soldered brass sheet, plus the tank will be tapered in plan to suit the tapering of the block so the outer face is parallel to the centreline of the engine.

 

[Roger Pellett]

Nice work as usual.

Full scale marine engines injected tallow into the steam to the HP cylinder to lubricate it. I have an indicator from a Great Lakes Steamship that still reeks of tallow.

Is it necessary to lubricate the cylinders of your engine, and if so, how is it done?

Roger

 

[NMBROOK]

Nice work as usual.

Full scale marine engines injected tallow into the steam to the HP cylinder to lubricate it. I have an indicator from a Great Lakes Steamship that still reeks of tallow.

Is it necessary to lubricate the cylinders of your engine, and if so, how is it done?

Roger

Hi Roger

Yes it is. Commonly a displacement lubricator is used inline in the steam feed before the engine containing compounded steam oil.
In this model I have plan to use a mechanical lubricator as the displacement lubricator looks out of place for a scale appearance. The mechanical lubricator takes a drive from an additional eccentric on the crank to operate a lever and ratchet which in turn operates a piston which pumps small amounts of steam oil into the steam inlet via a non return valve
I hope to purchase this item soon and will post pictures when I receive it

 

[Roger Pellett]

Nigel,

A brief post to show a real instrument from the age of steam. This is an indicator. Its purpose is to make a paper trace of pressure as the piston moves through the cylinder. This was used to adjust the “cutoff”; the point where the valve stopped admitting steam to the cylinder. It was used on a Great Lakes aSteamship and is in my collection.

Roger

 

[NMBROOK]

A day off work today so I was able to drive through to Blackgates Engineering and purchase the mechanical lubricator.The one inch square steam oil reservoir contains a small piston that will pump small quantities of steam oil into the high pressure valve chest of the engine.An additional eccentric on the crankshaft will operate the ratcheted drive arm on the lubricator.The outlet out of the bottom of the lubricator contains a non return valve.Whilst there I also bought some tiny laser cut spanners which are very slender to access tight areas on the engine.

The lubricator will be stripped down to enable painting of the outside of the tank

 

[NMBROOK]

Behind the scenes I have been painting completed parts as I go. Once the paint has cured, the holes are retapped and clearance holes are drilled through again to remove paint which may cause an issue given that the through holes are only 0.1mm bigger than the studs that go through them.
The goal is to have a full set of completed parts that just require bolting together at the end.

The paint appears slightly darker in the pictures than in real life.

 

[Daniel20]

Behind the scenes I have been painting completed parts as I go. Once the paint has cured, the holes are recapped and clearance holes are drilled through again to remove paint which may cause an issue given that the through holes are only 0.1mm bigger than the studs that go through them.
The goal is to have a full set of completed parts that just require bolting together at the end.

The paint appears slightly darker in the pictures than in real life.

View attachment 554836View attachment 554837View attachment 554838View attachment 554839

Those parts look like professional production pieces from a multi-million-dollar international corporation.

 

[Peter Voogt]

Behind the scenes I have been painting completed parts as I go. Once the paint has cured, the holes are retapped and clearance holes are drilled through again to remove paint which may cause an issue given that the through holes are only 0.1mm bigger than the studs that go through them.
The goal is to have a full set of completed parts that just require bolting together at the end.

The paint appears slightly darker in the pictures than in real life.

View attachment 554836View attachment 554837View attachment 554838View attachment 554839

So far I have only looked at your work with admiration and given it the necessary 'likes'. All that beautiful milling work. But now for a substantive comment on your paint job. It looks really nice and sleek, Nigel. My compliments!
Regards, Peter

 

[Roger Pellett]

Nigel,

A highlight of each week’s SOS readings is following your progress building this wonderful and complicated steam engine. Great work!

A question relating to to steam powered equipment. Are you familiar with a steam reversing valve? For the past several months I have been building a pair of 1:96 scale non-working models of steam winches. Photo below. The cylindrical object between the two cylinders with the operating lever attached is the valve in question. By moving the lever it reverses steam flow to the slide valve. It eliminates the need for the reversing gear on the slide valve push rods. I have seen it used on a steam powered windlass as well. I’d be interested in your observations.

Roger

 

[NMBROOK]

Thanks Guys

Roger, that is a question and a half.

Gonna take a bit of an educated guess here.Obviously no Stevenson reversing linkage here. I suspect that the two cylinders have piston valves driven by a rod running inside off the winches frame. Notice the "blocks " inboard of the cylinders and what looks like an eccentric bearing block inboard of the cranks main bearings.
Piston valve set up as opposed to slide valve can be changed in direction by a rotary valve which I believe is what the lever operates.A rotary valve has four ports and the rotation changes what was the inlets to exhausts when rotated, changing the direction of rotation.
Some steam winches use oscillating cylinders which makes valving easy and requires no pushrod from a crank eccentric, however the engine in your picture has fixed cylinders

 

[NMBROOK]

Bolton part twenty eight

I have turned, drilled and tapped the six cylinder take offs for the drain cocks out of Stainless steel. These have then been bonded into the cylinders using Locktite 603. A heat resistant bearing retainer.

The photos show the globe valves temporarily in place to illustrate how it will all go together. Whilst the steel cladding is a nice fit around these pieces, I may open the holes out a little, it will be very snug once everything is painted.

The stainless extensions will be grey, I am tempted to also paint the Globe valve bodies in the same grey, rather than leaving them black