The project I am working on, is to put together a finished Stuart engine, a nearly finished boiler made to a Tubal Cain design, and some sundry other kit, laid out as a working display (sort of basic "Diaorama").
Some of the photos of two of these items below have been published individually on another site about a year ago, but I hope I am forgiven for re-using them in this context.
Compared to many other beautiful projects on this site, this is admittedly a basic, beginners' project - albeit somewhat lengthy to describe. I do hope it may encourage a few to look at "steam" as a viable alternative to compressed air.
A bit of background :-
Soon after starting "the hobby", my wife gave me for my birthday 2 years ago, a Stuart kit of their simple horizontal engine (10H). She wanted to encourage me in my new workshop, bless her, and I slowly (very slowly) built it on my new lathe over the next 6 months. I made a bit of tooling first to get to "know" my first little lathe - with mixed success until I felt confident enough to start the engine proper.
I had no real problems with the kit contents, or castings and none in building it, apart from getting to know what some of the plan symbols and terms meant. I made a real bosh of the (built up) crankshaft at the first two goes - using Loctite, but eventually got it right the third time (my first essay at Silver soldering). Once I had got the valve timing properly set, it ran beautifully on compressed air at less than 10 p.s.i. I was really really happy that I could do it - my first ever build of any "proper" engineering item.
During the build, I had bought a number of books on building model engines, including Tubal Cain's pair on simple model engines and boilers. After much re-reading of these (his text gives a blow by blow recipe of how to make various boilers from scratch - excellent instruction), I decided it would be a good challenge to make a proper boiler and "steam" the engine.
The last project in his book 2 is to build a simple twin oscillator, mounted atop a sort of "cabinet" housed boiler - he called it "Wenceslas" - after a similar ready to run German model, by Bing, for sale in the 1930's I think? Marketed according to TC as "GROSSEDAMPFMASCHINE"!
The boiler itself is a sort of simple "Babcock" water tube design according to TC, but I was told recently it is properly known as a "Smithey's" (?spelling) boiler.
The main barrel is a small horizontal copper tube of 20swg - approx. 6" by 2" with 18swg end plates.
I flanged these from copper sheet on lathe turned steel flangeing blocks - great to learn a new skill - and quite satisfying to do. Needed to anneal the copper many times and go slowly and carefully with the hammering.
The boiler has a single gun-metal horizontal stay down the centre, screwed and silver soldered into bronze fittings at the centre of each end plate.
One end plate, to become the exposed boiler backhead, was marked out and drilled for a number of bronze bushes, turned up and tapped on the lathe, to accommodate the various fittings - pressure gauge, water gauge glass and clack valve for a boiler feed. With the boiler diameter being so small, the top fitting for the gauge glass had to be built as a small extension over the backhead - looks like the top of a periscope!
Steam take-off is from a copper dome atop the boiler barrel, with a suitably "Victorian" looking brass cap, into which goes the safety valve - made up surprisingly simply to TC's design.
I purchased the gauge glass fittings and clack valve from Reeves - a bit expensive, but the gauge glass lower fitting came with a blow-down valve as well - Reeves had run out of plain stock and gave me that "better" one as a freebie! (A very nice lady on the telephone at Reeves had a sympathetic ear when I said I could not afford the more expensive fitting - unusual and most welcome in today's financial climate!)
The final items necessary were a bronze bush for the filler cap, and two blind bushes for the support mounts of the barrel below the top plate of the "cabinet".
I also made a quick and dirty displacement lubricator, (shown in pic. of all the bits below), but I may well make a new one with a control needle to limit the oil flow - the exhaust steam could get a bit messy with too much oil I think - we shall see later.
Anyway - her is a pic. of all of the bits used to make the boiler.
At the time this photo was taken, I had only made three of the four water tubes, and they were not bent properly. I made a simple tube bending tool from a plan in a back copy of ME and made a fresh set of tubes which looked and fitted a lot better.
I also made a simple jig and bushes to align the gauge glass in the backhead.
Just as an aside here, you will note the glass "build plate" the boiler components are resting on :- this has proved invaluable in setting up all kinds of things. Its just a sheet of scrap plate glass (from a fish tank originally I think) placed on a similar sized sheet of blockboard, with a sheet of graph-paper as the sandwich filling. (I use metric sized graph paper, but imperial would be just as good). I ran a 3B draughting pencil over the thicker graph paper lines to make them stand out more. The whole sandwich is held together by linen gaffa tape around the edge. The surface is to all intents, truly flat, it is easy to clean - glue, paint, epoxy, Cyano etc. all "slice" off with a razor blade. The graph paper helps in alignment/parallelism and setting up items during fabrication. I used to use a rubbery/plastic/so called self-healing cutting mat, but the surface became unuseable very quickly.
Not a new idea but passed on here in case it might be of use to someone else!
It took a while to silver solder it all together. I found the use of rivets, loosely inserted around the end plates to be essential to prevent the ends from moving when soldering them into the barrel.
Here some pics of the finished boiler.
I made some blanking plugs to screw into all of the various bushes, and hydraulic tested the finished boiler. I had set the safety valve for 40 p.s.i. as per TC's design. Using a small hand-pump (an old Stuart one I think from the 1950's - acquired together with a small copper water tank from a friend), T piece and domestic water pressure gauge, filled the boiler to the brim and slowly pumped up the pressure, bit by bit, watching for weeps/leaks. One of the blanking plugs was not good, but some ptfe plumbers' tape did the job. I got it up to 90p.s.i. and it held rock steady for 10 minutes! It was strange to "feel" the boiler material actually moving and changing as pressure went up - I guess it was hardening up the previously annealed state of the copper.
I should have added - at present I do not intend to steam the affair publicly - I am building it for my pleasure. I may eventually take it to an exhibition, but only once it is working properly and safely. Being built to a "proven/tested design" and of small size/working pressure, I don't think there will be any problems, but I shall eventually have the hydraulic test re-done by one of the boiler testers at my local club - but that is a long way away.
On to the boiler cabinet.
The frame was made from brass angle strip to TC's design - I changed a few of the dimensions a bit, but it is basically the same. The boiler is suspended from the top plate, which has to accommodate all of the various top fittings of the boiler (dome/safety valve, filler cap, gauge glass top fitting).
By this time, I was getting fairly adept at scrounging "metal stuff/off-cuts" from local sources, and was very fortunate in getting some highly polished stainless steel sheet off cuts (marked as "heat resistant") from a local steel fabrications' business - they had just finished a huge commercial heating project of some sort, and let me have a free rimmage in their scrap bin. I also blagged some weird brass plated iron pipe which would make a good funnel (gas stack).
Stainless steel sheet is a bu**er to to drill and bore out, I discovered. Fortunately by that time I had got my little mill, which made the job somewhat easier. Even so, it was a difficult job to get the cut-out for the dome and associated steam take-off bored and finished. I destroyed one boring tool in the process by running it too fast and with insufficient suds.
Here is the basic frame and top plate, with cut-outs for the boiler top. The lower plate (drilled for secondary air - to aid the burner) inserted for temporary fitment/sizing.
TC's design originally included a steam control valve taken off the side of the steam dome. I have dispensed with this, and blanked it off on one side. I shall make a separate steam globe valve to be fitted further down the line.
Here is a trial fit of the boiler with safety valve and filler cap to the frame.
That is really as far as I had got up until earlier this year.
I got sidetracked a bit with building a Chinese Stirling engine, (posted separately), but thanks to all those kind souls who encouraged me to get it going it does finally work. I need to take a video of it running, but am not having much success with the digi camera here.
Back to this project:-
My next problem was to decide what form of firing the boiler would be best.
TC's original design was to use solid fuel tablets (Meta) in a tray.
He suggested in his book the option of using Meths/wick burners.
After a few experiments I discarded both ideas - messy, smelly, possibly dangerous, and largely uncontrolable.
My wife, bless her again, agreed I could have a propane gas/ceramic burner system as my last Christmas present - so I had talks with Maccsteam (usual disclaimer) about what size of burner etc. and he fabricated a small square burner with a propane tank, pipework and fittings - all safety certificated. The good bloke at Maccsteam felt the rate of water evaporation with even this small burner would be more than sufficient, given the design and size of the boiler, and to keep the gas turned down very low. He felt a hand pump to replenish the water via the clack valve will be essential during steaming. We shall see!
So this is the point I am at now.
I finished the cabinet plate-work, and after thoroughly de-greasing it all, spray painted it all black - using car engine enamel. I used about 4 coats, rubbing down gently in between. The side plates are "gilded" with three brass portholes, which also allow secondary air into the cabinet.
I am presently lagging the barrel with mineral board lagging - some off cuts from British Rail Engineering - used in lagging diesel engine (railcar) silencers. (Thanks Ian).
Here some pics (sorry about the crude editing - in haste) of the almost finished and lagged cabinet, with funnel/stack. There is an internal baffle plate behind the boiler barrel to help duct the burner gases along the underside of the boiler and up the stack.
I have also made the basic display board/base. Just mdf boarding, edged and covered with Slater's Plasticard, with a timber planked walkway down the centre - to add a bit of texture. The boiler cabinet, water tank frame etc. will be affixed to this by locating pegs let into pre-drilled holes - as per next pics. The plastic mock stonework etc. will be painted/textured later.
Interconnecting pipe runs could be a nightmare, but I have built the baseboard so that it is raised on dwarf walling, hiding a sort of "well" area - pipework can thus go down through suitable holes and run underneath the board and back up to where it is supposed to go. Waste pipes (steam, blow down and engine cylinder drain cocks) will be fed down to a sort of "sump" outlow pipe.
I am not sure yet, but am thinking that the main steam line from the boiler might be routed through the boiler cabinet, using the burner heat as a sort of "steam dryer" and then to the lubricator/engine. Not sure yet.
Similarly, the water feed from the pump could be routed the same way to "pre-heat" it?
I am also toying with fitting an oil separator to the exhaust line to keep things a bit cleaner.
Next to do is make another set of rollers for the pipe bender to accommodate the various sizes of pipe to be used.
I bought, off flea bay, a roll of 5/32 auto brake pipe - copper,nickle iron type - its already pre-annealed and silver solders well - a hell of a lot cheaper than buying small bore copper tubing from the usual sources.
Finally I have been making pipe fittings, olives and so on - pics to follow.
I made a form tool from a piece of old car rear leaf spring (gauge plate) I had blagged from our local garage scrap pile. Following a drawing/article in the Gauge O Guild handbook, found on line it gives a good plan of how to fabricate "globe" valves for steam/water control. The form tool cuts the globe shape in brass hex. Will post that next.
So - up to date now and will carry on a bit with more pics. as things develop.
As I said at the beginning - I am building this for my pleasure - its not all blinged up and not built as an "exhibition work", so please forgive any errors, but I have had fun and satisfaction getting this far - and I hope to finish the challenge of making the whole thing work.
