Small steam engine

I've been giving some thought to trying my hand at making one of those
little oscillating steam engines with the vertical column. I should mention
that I'm not 'into' steam engines - it's more about seeing if my fledgling
machining skills have reached a point where I can make something
machine-like rather than the 'bits' I've done so far (like simple tools and
gadgets).
I've been looking at a few plans culled from the internet and I think I see
the principle of operation. Are there any gotchas that I should be aware of?
One thing I'm not sure about is choice of metals - I want to run it from
real steam which makes me wonder about the metals used in the piston and
cylinder. I'd like to make both from brass - would there be a potential
problem with thermal expansion?
Another is how to go about making a pressure regulator/relief thingy. My
thoughts on this are to make somethng like a carburetor needle valve - a
screw with a tapered pin that I can adjust manually. I believe I'm right in
thinking that the resulting pressure is a function of the setting of the
screw and the heat that's input. I've had a go at making something and used
an MT2 taper, since the compound was set for that already. Would that work?
--
Wally
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Wally
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Not quite the answer to your question, but the Stuart Turner V10 is the standard kit to get you going in that direction (It's not an oscillating engine, but one with a valve) It's just under 6 inches tall when made. As well as a kit, there is also a little booklet published to guide you through MOST of the machining. Larger kits only come with blueprints, but not instructions.
The set of raw castings (complete kit, BTW, includes all the metal) is about £60; a set of machined castings about £150; and a working painted model about £320.
IF YOU GET YOUR SKATES ON AND GO TO CASTLE DONNINGTON TODAY OR TOMORROW, THE MIDLANDS EXHIBITION IS ON AND STUART TURNER ARE THERE WITH THEIR OWN STAND.
Reply to
Airy R. Bean
Thanks for the info, but these are too pricey, I'm afraid. I'm looking to build with the bits that I have lying around.
That's rather a long from my neck of the woods. :-)
-- Wally
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Wally
Oops! They're now trading as Stuart Models from the Channel Islands. They bought the rights from Stuart Turner who are still trading in other capacities from Henley-on-Thames, but not associated anymore.
Stuart Models Ltd, Braye Rd, Vale, Guernsey, GY3 5XA
Tel (01481) - 49515 FAX (01481) - 47912.
Sorry, I don't have Internet details for them.
In fact, to answer your question, ISTR that they have recently come out with a cheaper kit which _IS_ an oscillating engine; however, the V10 has been the standard starter kit for some years; I've recently finished mine.
Reply to
Airy R. Bean
My first attempt at a steam engine was a small oscillating type. It was described in Tubal Cain's book 'Building Simple Model Steam Engines' (ISBN 1854861042). This gives full instructions on how to build this and three other models. There is also a second book (ISBN 1854861476) with another 4 models. Most model engineering suppliers, as well as Amazon.co.uk etc can supply these books. Models in the books are built from bar stock/sheet, with a couple requiring castings.
My result can be seen at
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There are also plans for simple engines available on the internet, although the instructions for building these are either not very comprehensive or non-existent. I would recommend reading the above books first to get an idea of what is involved..
Good luck!
Anthony Remove eight from email to reply. Website:-
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Reply to
Anthony Britt
Well, at the risk of making a fool of myself in front of real engineers , here's my six pennorth:-
I made my first effort from a small mild steel block with a brass piston. Didn't use any plans, just worked it out as I went along based on stuff I'd read. You really need dissimilar metals for cylinder & piston, though I suppose it depends on lubrication & how long you run it for, before you want to make something better ( about 1 hour in my case!) The first one worked, & the sense of achievement was really quite pathetic, since I was using a 2.3KW hotplate to boil the water in a lashed up boiler just to get a 1/2"X3/4" steam engine to run!!! Make sure your safety valve works on the boiler - you can get the idea from a pump up garden sprayer if you haven't access to a real boiler. test it with air pressure first. Don't make the stroke too short, & don't make the distance from the trunnion to the crankshaft c/l too long. i.e. make sure you have a largish ocillating angle, so as to allow for drilling the ports inaccurately(!). Time spent lapping the cylinder:port face is well spent, but try hard to get the trunnion absolutely perpendicular to the face in any case. ----------------------------------------------------------------------------------------------------- snipped-for-privacy@boltblue.com John Lloyd - Cymru/Wales
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John.LloydUNSPAM
Am I right in thnking that a little oil can be added to the water? If so, would something like 3-in-1 do?
I was thinking of a tin can and a propane blowtorch. :-)
Would a car footpump be okay for this? I'm all out of compressors at the moment.
Is ease of positioning the ports the only reason for keeping the trunnion-to-crank distance shortish? My sketchings in CAD give me a cylinder oscillation 'dead angle' of 6 degrees (between one port having just closed and the other about to open) and a full swing of 17. The ports are 2mm dia, centres spaced 6mm apart. In terms of crank rotation, the ports are each open for 140 degrees.
Yup, I'll be seeing what I can do to get this as good as I can - mill flat first, smooth off with emery and then do much lapping. I read that toothpaste can be used as a lapping paste...
I think that, and things like port positioning, should be okay - I'll be drilling on a small mill.
-- Wally
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Wally
Well you are supposed to have a little displacement lubricator in line. This is just a little pot you fill with oil for each run plumbed into the steam line before the cylinder. As the steam condenses in the "pot" the water being heavier than the oil sinks to the bottom & displaces a bit of oil into the steam line. With my first, I didn't bother & just squirted a drop of SAE30 into the cylinder before each run.
Should be OK as long as it has a pressure guage. I think I set my safety to about 10PSI. If you are making a boiler proper, then note you should pressure test it with WATER not air, at at least 150% of working pressure, though I suppose you could immerse a little boiler in a bucket of water & pump it full of air- you'd get wet if it burst though! Wear safety specs.
Tubal Cain in his book on building small steam engines ( NEXUS ISBN 1 85486 104 2 - wish I'd got it BEFORE I made one!) reckons to have the ports JUST about touching, so that at TDC there would be a minimum gap via the cylinder port & the inlet & exhaust. That would mean for a 2mm cylinder port, drilling the other 2mm holes at 4 mm centres. Depending on your degree of precision, I'd be inclined to say 4.5mm or even 5 mm if you have a decent flywheel. Plenty of time to worry about getting better performance when you've made the first one run. >> Time
Fine valve grinding paste is great & you can finish with Brasso if you're picky. Don't know about toothpaste.
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John.LloydUNSPAM
Just did a google on that and I've got the idea.
Is the oil type important? Would ordinary motor oil or two-stroke oil be okay?
Is that a calibratable thingy? My readings so far have only mentioned a "pop off", which seems to be a bit of tight-fitting rubber tube which pops off if the pressure gets too high - the amount of overlap of rubber over the metal tube it sits on determines the pop-off pressure.
Is the idea to fill it so that all possible leak points are wet, and then see if anything squirts out?
Aha. Duly noted.
I think I can position the holes to that kind of precision (using the indexing collars on the mill). I made most of the flywheel yesterday - it's steel, about 44mm dia, 15mm thick. I machined 5mm deep channels in each face to put a larger proportion of the mass towards the outside. On my digital kitchen scale, it's 142g at present, with some more material still to be removed.
I don't know about toothpaste either. :-) I'll do the right thing get some grinding paste (I'm after some polishing pastes and cutting gunks in any case...). Should the column and cylinder faces be the same material?
-- Wally
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Wally
"Wally" wrote
NO, water is incompressable and this ensures when the boiler is under test pressure there is little energy in the system, if the boiler fails it goes pop... fill it with air and there is a lot of energy in the system, if the boiler fails it goes BANG.
Making pressure systems should be aproached with caution, and steam systems even more so.
Even a small jet of superheated water and steam from a sudden leak in a boiler could scar you for life.
For a low pressure air system useing a foot pump, if you are not going to use a proper safty valve you might plumb in a toy baloon..... -- Jonathan
Barnes's theorem; for every foolproof device there is a fool greater than the proof.
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Reply to
Jonathan Barnes
: > : > > Should be OK as long as it has a pressure guage. I think I set my : > > safety to about 10PSI. : > : > Is that a calibratable thingy? My readings so far have only mentioned a : "pop : > off", which seems to be a bit of tight-fitting rubber tube which pops off : if : > the pressure gets too high - the amount of overlap of rubber over the : metal : > tube it sits on determines the pop-off pressure. : > : > : > > If you are making a boiler proper, then note : > > you should pressure test it with WATER not air, at at least 150% of : > > working pressure, though I suppose you could immerse a little boiler : > > in a bucket of water & pump it full of air- you'd get wet if it burst : > > though! Wear safety specs. : > : > Is the idea to fill it so that all possible leak points are wet, and then : > see if anything squirts out? : > : NO, water is incompressable and this ensures when the boiler is under test : pressure there is little energy in the system, if the boiler fails it goes : pop... fill it with air and there is a lot of energy in the system, if the : boiler fails it goes BANG. : : Making pressure systems should be aproached with caution, and steam systems : even more so. : : Even a small jet of superheated water and steam from a sudden leak in a : boiler could scar you for life. : : For a low pressure air system useing a foot pump, if you are not going to : use a proper safty valve you might plumb in a toy baloon..... : -- : Jonathan : : Barnes's theorem; for every foolproof device : there is a fool greater than the proof. : : To reply remove AT : : : > : :I can run my doule acting vertical engine made of scrap steel by blowing into it. 1/2" bore & 3/4" stroke approx Chris
Reply to
Chris
Ah, got the idea.
Duly noted.
As a sort of expansion chamber, you mean?
-- Wally
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Wally
That's about the size I'm working with at the moment (12x20mm, single cylinder). If it can be run just by blowing into it, then I think that would be fine for getting the engine tested. I can then tackle the boiler as a seperate thing.
-- Wally
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Reply to
Wally
: : >> I can run my doule acting vertical engine made of scrap steel by : >> blowing into it. 1/2" bore & 3/4" stroke approx : : That's about the size I'm working with at the moment (12x20mm, single : cylinder). If it can be run just by blowing into it, then I think that would : be fine for getting the engine tested. I can then tackle the boiler as a : seperate thing. : : : -- : Wally :
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: Things are always clearer in the cold, post-upload light. : : : It races away for an hor or so when connected to the steam pipe of an electric wallpaper stripper. Cheapest boiler available albeit low pressure! I found it best to used demineralied water on small engines when Engines used in a hard water area as they suffer from scale sticking in the cylinder piston and seals etc.
Chris
Reply to
Chris
In part... dual function, it will smooth out the pump input, but it's also a safety measure. Even in my worst moaning Jerimia mode I don't think of a bursting balloon as "a dangerous failure of a pressure vessel" :-)
-- Jonathan
Barnes's theorem; for every foolproof device there is a fool greater than the proof.
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Reply to
Jonathan Barnes
In article , Jonathan Barnes writes
Cue group of URME posters lining up to burst a balloon behind Jonathan's ear as he takes a finishing cut...
:^)
Reply to
Nigel Eaton
Depends whether it is one of those terribly thin transparent balloons made by the London Rubber Company... ;-)
Regards, Tony
Reply to
Tony Jeffree
Wally writes........
But do mind your eardrums in your enthusiasm !
Reply to
Mike Whittome
Filled with aceylene?
Mark Rand RTFM
Reply to
Mark Rand
By risking a coronary I could JUST get my first attempt to run by blowing! I took a lot more care, or probably more accurately, gained from the experience & made a second engine(double acting this time) which ran nicely with a gentle blow. Most satisfying!
My pressure relief valve was a dead copy in brass of the plastic version on my wife's garden sprayer. It was just a little ball held against a seat by a light spring whose tension could be varied by a screw cap with a couple of steam relief holes. Took ages to get it to blow at ~10PSI 'cos my original spring was way too strong. ----------------------------------------------------------------------------------------------------- snipped-for-privacy@boltblue.com John Lloyd - Cymru/Wales
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