How to Build a Steam Engine from Scratch


For this page of our blog we’ll be using the first chapter from Dad’s book on how to build a steam engine from scratch, with some of the others following in due course – BUT NOT ALL – although some drawings, dimensions and images may well be a little unclear.  To get around that, just download the PDF’s. Links will be left at the end of this page and other chapters as and if they are loaded up.


The whole book can be found on Amazon THROUGH THIS LINK which covers the ebook at a minimal price and there is also a printed version with a soft cover costing a little more owing to printing and delivery charges.


There is to be a full PDF version at less than $5.00 through Paypal and ready for download soon if you want it all in one go, but be warned, it is a big book so will take some time if your connection is abysmal, like mine.


So we’ll start off with the first chapter which can be found here in PDF if that suits you better  CHAPTER 01 PYRTE BOILER


Chapter 2 is here – the Firebox Construction – if you need the next chapter in PDF to allow better images and drawings



Chapter 1 – How To Build A Steam Engine From Scratch – The Boiler

Welcome, and thanks for your interest in building PYRTE (stands for Pull You Round Traction Engine by the way) with the revised edition covering the latest (2012) steam regulations allowing this machine to be used in a public place (providing a boiler certificate is obtained first along with the appropriate insurance).

The good news is…

Here you have the chance to learn how to construct this easy build traction engine in a step by step manner, from start to finish, with literally everything explained along the way.

You’ve taken the first step to owning your own live-steam traction engine and with just a little persistence it will not be long before you are driving your own live-steam engine, built with your own hands, being pulled around easily as you watch the crankshaft and flywheel spinning almost silently right in front of your eyes as you trundle along.

And just so we all know what we are talking about with thread sizes, there are basically two thread types here, the BA threads and the ME (Model Engineer) threads. The BA’s come in specific sizes and teeth numbers per inch or mm.

The ME’s have overall thread diameters in inches although there are versions with different numbers of teeth per inch so please watch out for this, all available from model engineering suppliers here in the UK.

They are not the confusing American thread sizes as some have thought, and also so far there appears to be no metric threads for add-on steam fittings as required.

So let’s push on with the build…


Building the Boiler

For scale: that’s an 10 inch diameter rear wheel in the picture

And just so that we will all be reading from the same script, and you will not be confused (myself as well) with regards to the metric measurement system, I shall give the imperial sizes (followed by the metric size in mm – if I remember).

And for the pictures and the drawing, for those people not too familiar with computers, if you want to enlarge the pictures, simply have them on your screen and press the control button and at the same time press the + or – button to alter the size so that you can see it comfortably for yourself.

Building the boiler for this live-steam traction engine P Y R T E is very straightforward and requires no professional skills at all, just a little common sense and care, although many of these pictures are from the original model (pre-steam regulation upgrade requirements) and should be used only as a guide.

Everything is covered below.

Tooling requirements to build the boiler for P Y R T E:

• Use of a lathe
• Use of a blow torch
• Use of a battery-powered drill – preferably with a low torque setting (this is purely for tightening the nuts and bolts to save your finger ends).
• A set of small sockets.
• A bench drill with stand – A hand drill can be used, but the bench drill is a little more accurate.
• One 3.6mm drill (tight clearance size for 4BA bolts).
• One 4BA nut spinner (a bit like a box spanner that fits into a 10mm (⅜) drill, just to save your finger ends).
• One 5BA nut spinner.

The 4BA bolts usually have 5BA heads, just to make things more confusing, but the 4BA nut spinner has the correct sized cavity for the 4BA nuts and the 5BA nut spinner is the correct size for the 4BA bolt heads.

• 4, steel hex head 4BA bolts X ¾ inch (19mm) length. • 8, steel 4BA nuts.
• 8, brass hex head 4BA bolts X 1 inch (25mm) or brass 4BA studding. (Countersunk screws can be used just the same, and if you are using studding, then 16 of the 4BA steel nuts are needed).
• Taps and die to produce the threads on the stay @ ¼ inch x 40 (6mm x 1).

Materials required to build the boiler for PYRTE

• 1 length of 12 inches (300mm) of 4 inch (100mm) diameter 16 gauge thick (¹/₁₆ inch or 1.5mm) seamless copper tube (for the boiler barrel).
• 1 copper plate, 12 inches (300mm) square of 13gauge (around ³/₃₂ inch or 2.5mm) – (for the two boiler end plates – you can use 2 x 4” squares if that is more convenient for now, but you will be needing more as the build progresses).

• 2 lengths of 12 inches (300mm) X ¼ inch (6mm) square copper rod (for the external anchor rings).
• 1 length of 12 inches (300mm) x ¼ inch (6mm) diameter phosphor bronze rod (the central boiler stay).
• 1 length of 1½ inches (38mm) of ⅜ inch (10mm) hexagonal phosphor bronze rod (to make the 3 nuts for the stay).
• 2” length of ½ inch diameter phosphor bronze round (the 5 bushes on the rear boiler plate). • Silver solder and flux.
• A couple of pieces of 4 inch + square plywood and a 12 inch + length of ⅜ inch/10mm studding with nuts and washers (to act as a carrier for the boiler in the lathe).

The original total time to produce this simple boiler for P Y R T E is just under

3 hours in experienced hands – compared to a conventional boiler of this size at around 30 + hours, (going onwards to 60 hours or more) assuming no leaks are found with the complicated boiler.

To get you started off with building this very simple boiler for your live steam traction engine, you need a seamless 16-gauge copper tube (that is approximately 1.5mm walled thickness – (16 gauge is ¹/₁₆ of an inch or around 1.6mm) as the barrel for your boiler, being 4 inches (100mm) in outside diameter and 12 inches (300mm) long and squared at both ends.

The 4 inch (100mm) size is readily available here in the UK, whereas the original dimension of 4½ inches is not, now that we are all going over to the metric sizes, so by reducing the diameter a little, the water will boil a little sooner, although it means being more aware of the water level in the boiler and needs a little more frequent, but lesser action on the pump to keep it topped up to the central height.

You need to be aware this book was written up before steam regulations were updated around 2012 calling for twin water feeds, twin relief valves set at different pressures and various other safety measures, but this build has been adapted to suit these changes to the regs.

You will need two lengths of ¼ inch (6mm) square copper rod, long enough to fit tightly inside the circumference of the copper tube. These lengths are just less than 12 inches (300mm) each for the above diameter.

You will also need two circles of 13-gauge (approximately 2.5mm) copper plate to act as the ends of the boiler, one at each end, and they must be a very close fit to the inside of the barrel.

Plus, you will need (and this is purely for safety’s sake) a 12 inch (300mm) length of ¼ inch (6mm) diameter phosphor bronze rod, centre drilled at both ends for later tail-stock support, and threaded at each end with ¼ x 40 tpi (6mm by 1.0 threads per mm) to a length of ¾ inch (20mm), to act as a brace (commonly called a stay) between the centres of the two end plates, along with three ¼ inch (6mm) deep nuts made from ⅜ inch (10mm) hex bronze, all threaded ¼ x 40 tpi (teeth per inch)(6mm x 1.0mm).

One point here is that if you are thinking of scaling this engine up to 1.5:1 or running it at a higher pressure of say 75lbs/sq”, then doing it at 1.5:1 is about the most you can get with a copper boiler owing to the linear strength of copper, plus at the larger size, using a 6” diameter copper tube, the end plates would need more stays, another 4 spread out evenly over the plate area with 1 sitting centrally. 6 would be even better for higher pressures as well.

You could use metric taps and dies if you wish, but the ones I have are really inferior quality, as, if I cut a nut at 6mm from one set of taps and then cut a bolt, again at 6mm from another set I have, the two will not even thread together despite them supposedly being the same size and thread pitch.

I think they were produced in different parts of the world by different manufacturers, so it was asking for trouble. For that reason I tend to stick with the old imperial sizes for taps and dies as they produce a far better result.

The pressure you should be running at with PYRTE would not normally need this additional stay, but if you decide to run the engine at more than 50 lbs/sq. inch or accidentally go over-pressure (safety valves do stick sometimes) then this will allow you time to remove the heat and let off some steam with a good safety margin.



So starting at the beginning, the boiler barrel of PYRTE, your soon-to-be Traction Engine, the basic frame that everything is attached to on the usual traction engine or roller, needs both ends cleaning up of burrs and a carrier inserting to support it in the lathe while the ends are squared and a few marks put on it to make life easier a little later on.

If you cut two pieces of half-inch plywood, or whatever other scraps of wood you may have, (ply is easiest as the crossed grain gives it better machining abilities and makes it sturdier) to a little over 4 inches diameter, centre drill them to match the diameter of a piece of studding you have (threaded bar), 3/8inch (10mm) diameter is fine, which needs centre drilling at both ends so that it can be carried in a centre in your tailstock), and turn them down on your studding – nutted tight both sides of both pieces of timber – to a tight fit so they just fit inside your barrel.

Spindle supporting boiler barrel

The picture shows the 6mm studding I originally used, but this was not really sturdy enough. The white area on the copper tube is merely where the glue from the label was attached by the supplier and can be ignored.

With one piece of timber inserted in the tube at the chuck end, sitting close to the chuck so the jaws are not gripping inwardly on unsupported copper tube, and the other piece of timber sitting around 1/2inch (13mm) inside the tail-stock end of the barrel, with barely an inch of the studding protruding beyond the timber, and both pieces of timber nutted tightly both sides in place, you can support the tailstock end on the tailstock centre, as in the picture.

The tailstock end can now be skimmed, using a sharp tool, but be very gentle with your cutting, and cut toward the studding rather than away from it, and also heading towards the chuck, otherwise the tube will simply move towards your tailstock if it is not gripped tight enough by your timber inserts.

If you find the wooden inserts are a little too small and the cutting point digs in and stops the rotation rather than trimming the tube, it is possible to add extra width to the diameter by wrapping insulation tape/cellotape around the outside edge of the timber inserts – but make sure you apply it in single layers so there are no odd overlaps causing the tube to wobble.

Talking about wobbling, you will not get your tube to run perfectly true, as the manufacturing process does not demand perfection and concentricity, regardless of any handling problems the tube has endured, so you will have to try to get it wobbling as little as possible before you begin.

Skim the end near the tailstock, and then de-bur it and turn the whole lot round end to end, adjust the carrier positions, true it up and skim the other end. You are aiming for a foot in length, but building machinery in general calls for very slight modifications regarding measurements – this part is not critical, especially as it is your first attempt, providing at least one end (the rear end that everything else attaches to) is dead square.

In fact, my boiler barrel length ended up at ten and one quarter inches (it was just a tube I had available at the time). It looks a little stunted now she’s built up, but a longer barrel will allow longer periods between top-ups of water and a better balanced power output, plus yours will look more like a proper engine.

While it is in the lathe it is best to place a few marks on your barrel, so attach a scriber to your tool post and gently scribe a line along the side of the barrel.

Providing you can see it, it is OK for now, as it will have a few light saw cut marks on it for ease of seeing, as this line will most certainly disappear from general eyesight with heat treatment during the building process.

Take a piece of foolscap paper (big enough to go right round the barrel (diagonally?) and wrap it tightly around the barrel, marking where the overlap point is. This gives an exact measurement for the outer circumference, so all you need to do is to fold that length in half and mark it on the paper again.

What this has done is to give two positions on the paper, which can be applied to the barrel, showing the exact top and bottom of the barrel. Now if you assume the already scribed line is the top, and hold the original overlap mark on this line, then the second mark is the bottom centre line as you go round the circumference of your barrel.

This point needs marking on you barrel, and with the scriber point aligned with this second mark, a second line can be lightly scribed along the length of your barrel, that way giving you a top and bottom line to work to.

If you wish, you can provide these same marks using a piece of angle iron by sitting the angle iron along the length of your boiler and scribing along one edge of the angle iron, that way a line can be drawn truly along its length.

Using the paper method the other side can be found and a second line marked in the same way.

Three more marks need to be added. These are around the circumference, ⅛ inch (3mm) in from each end (these are to give a guide for the centres of the anchor rings, which in this case are ¼ inch or 6mm wide). The third line denotes how far the smoke-box has to be pushed on the outside of the front end of the barrel, and therefore needs to be at ⁵/₁₆ of an inch (8mm) from the front edge.

You also need to mark, very lightly with a junior hacksaw, the position of the two long lines where they end at either end of the barrel, with the upper rear one being very faint on the end, but can be more pronounced on the outer face, say ¹/₁₆ of an inch long (a couple of mm). These marks will be used for the setting out, so will need to be obvious, but not overly so.

All but one of these marks will be hidden and not on obvious show when the engine is completed, and will not be detrimental to the operation or appearance of your engine.


If you mark out your 4 inch (100mm) circles on the 13-gauge copper plate, also marking a straight line through the centre point on one (this will be for the end nearest the driver – the rear) to allow a guide for the water gauge fittings to be installed, incorporating a fitting for the steam take-off, plus the injection points for the water supply/drain for the boiler barrel.

These plates are slightly oversize for the inside circumference of the barrel and should the barrel not be perfectly round, as I have found many times since the building of other boilers, with a circle marked to match the inside of the barrel, the plates can be skimmed or filed down to fit closely inside the barrel.

The front plate needs a ¼ inch (6mm) hole boring in the centre for the stay to poke through when the rear plate is soldered in place.

This process is all in preparation for applying the silver solder to fix the plates to the ends of the barrel, but before this can proceed, the anchor rings (the two ¼ inch or 6mm square rods) need to be shaped to a tight fit inside the barrel ends.

First these rods have to be softened, and this is done by heating them to a dull red colour and quickly dunking them in cold water.

To check they are soft, simply tap one with a screwdriver or something similar and the sound heard should be a very dull sound. If there is any ring to it, you have not got the metal hot enough (dull red is plenty) or you have taken too long to cool it down and it needs doing again.

Next, you need a former to bend the rods around, and for this I used one of the pieces of half-inch plywood that was used as a carrier for the barrel, with a nut and bolt (with a one inch washer either side to hold it straight being helpful, although not used here in my early engineering years) through the centre.


The diameter was reduced in the lathe to a depth equal to the thickness of the anchor ring rod, (that was a ¼ inch in my case) along one half of the circumference, that way allowing some support of the timber carrier/former as the rod is gripped in your vice.

With the carrier/former held gently in your vice, with one end of a rod trapped between a jaw and the reduced size of the former, simply bend the rod round the shape of the former. I got mine a very close fit with the aid of a light rubber hammer.

The whole lot will need to be rotated in the vice, but this is very easy to do, until you find the last little bit is not going to fit, and that’s where the rubber hammer comes in.

Try the shape of the newly formed pressure ring inside the barrel (for the front end only), gripping it with mole grips or something similar, but don’t forget to use some padding on the outside so the jaws do not leave marks on the barrel, and get it to a good tight fit. You will have a little too much length to make a complete circle, so what you have to do is to bend it sideways and overlap it a little.

The more work you do (tap, bend, anything regarding the shaping) to the ring means it loses its softness and the harder the ring will become. The last thing you want is fractured or strained metal being used in the build, so if you need to re-soften the pressure ring, feel free to do so, as this makes the process that much easier.

Trim the length of the overlap so that a complete circle is formed inside the end of the barrel, with barely a gap between the two mating ends.

This pressure ring is firstly going to be temporarily bolted to fit inside the end of the barrel, making it a flush fit with the end of the barrel, as this pressure/anchor ring is the anchor point for the front plate (the circle of 13-gauge (2.5mm) copper plate – sitting to the rear of the pressure/anchor ring) and a strengthening point for the attachment of the smoke-box at the front.

This view (a bit blurred, I know – a poor quality camera from some years ago) is looking straight down on the front end with the pressure ring temporarily bolted in place with steel bolts, and sitting directly on top of the supported front plate, just before the clean-up before soldering, although this one does not have the ¼ inch (6mm) central hole yet.

Doing it this way saves all that fancy flanging of plates – the usual way of doing these joints – which leads to no end of leaks through poor fitting joints, and produces a far simpler and more robust joint altogether, and a much better anchoring point for the smoke-box.

This pressure/anchor ring needs to be silver soldered to the inside of the barrel, as soft solder would simply melt with any heat applied to it in normal running practice.

As an aside here, some builders have used two pieces of the ¼ inch (6mm) square copper ring in the front end as they have drilled slightly cock-eyed through the ring and punctured the boiler itself using the one ring, so that way using two rings rather than the one and bolting through the outer one allows a little leeway.


Part of Chapter 1 has been removed regarding guidance on silver soldering, to reduce the file size, making it easier to download and read in one go, after all, this build is for the novice engine builder with little experience in workshop crafts. The silver soldering is the next section to be posted and it continues, showing how to go about it and also how to clean and repair faults. 

This section also covers the softening of your copper, using an acid solution to neutralize any flux, checking for leaks and pressure testing and can be found by clicking this green paragraph.

Otherwise, if you wish to continue, it can be found here and can be opened in a new page so you keep the original.


Next we go to the back end of the boiler.

The same process needs to be done here with the pressure/anchor ring, but before this is done the rear 13-gauge plate needs to be marked and drilled for its necessary parts.

This drawing is wrong as there should be 4 x 15/32 inch (12mm) diameter holes and 1 at A @ 13mm with the central one at 1/4inch (6mm).

From the drawing you can see the upright centre line is marked and the two upper hole centres are 1/2inch (12mm) either side of this line and 5/8 inch (16mm) down from what will be the outside edge of the boiler tube, so that makes it 9/16 inch (14mm) from the inside edge of the tube, or 1 and 3/8 inch (35mm) up from the central crossing point.

A is the steam take-off point and the other top one is the top fitting for your sight gauge with the bottom one sitting centrally at the bottom of the boiler plate.

From the central crossing point a horizontal line needs to be marked at 1 inch (25mm) below centre with marks at 1 inch (25mm) either side to provide the two water inlet points B and C.

B is the water connection from the mechanical water pump and C is the connection for the hand pump.

Centre punch each of these points, along with the central one for the boiler stay to poke through.

If you now trim it down to just fit inside the rear of the barrel, and with the line upright as in the picture, the central hole needs to be drilled 1/4inch (6mm) to match your phosphor bronze stay rod diameter and the other four can be drilled with a 15/32” (12mm), with A drilled at 13mm.

The next item on the agenda is to produce five phosphor bronze bushes


Four are from a 1/2inch (13mm) rod as per this drawing, but the hole is drilled at 7/32inch and tapped through with 1/4inch x 40 for the water feeds and the two sight gauge bushes, while the steam take off connection (A) starts as a 9/16inch (14mm) diameter bush for 1/16inch (1.5mm) and reduces down to 13mm for 3/16inch (5mm). The internal thread is 7/16inch x 32. Preferably using the 13mm rather than 1/2inch to allow for the depth of internal thread.

The last one, the steam take-off connection (A) is a little bigger as it has a larger flow through it and needs a tap built into the fitting beyond the bush to shut the steam off.

(If you are planning on buying the fittings for your three cock water gauge (a requirement of the latest steam regs), rather than making them yourself, then stick with the internal imperial size as metric is not available commercially so far – that I am aware of) – more of this is shown in the pipework chapter.

The reason for the larger fitting is that the feed piping needs to be 5/32” (8mm) outside diameter to accommodate the flow of steam should the relief valves lift, whereas the water feeds and sight gauge do not need to be so big.

One point here is that you should not use brass for your bushes as brass tends to corrode slowly with water and heat and will fail over time, whereas bronze will definitely outlast your model traction engine. This is the reason that bolt-on fittings are made of brass as they are more readily replaced when faulty (although twenty or thirty years is no problem for brass fittings, depending on the chemical make-up of the brass).

Once these items are completed, the second pressure ring can be shaped and drilled in the same way as the front end, but for the final assembly things need to be altered a little.

Firstly, you need to produce three nuts at ¼ inch (6mm) deep from the ⅜ inch (10mm) hexagonal phosphor bronze rod, tapped ¼ x 40 (6mm x 1), and the bronze rod needs centre drilling and ¼ x 40 (6mm x 1) threads running down for ¾ inch (19mm + ) at both ends as the rear 13-gauge plate needs the bronze rod nutting to it with the end of the rod level with the top of the proposed outside nut and the inside nut pinched tight to the plate.

Doing it this way allows the remainder of the rod to sit inside the barrel and just poke through the front central hole by ¼ inch (6mm) which is ideal for the remaining nut height on the front end, which will be added later, once the back end is soldered.

The rod needs to be in place to support the rear plate about to be soldered, and if the barrel is sat on a flat surface on its front end, then the rod should hold the plate in the right position, with the rear edge of the back pressure ring being beautifully in line with the back end of the boiler barrel.

If you started off with the barrel a little shorter, then adjust the rear pressure ring so that it sits flush with the rear end of the barrel. The rod length can easily be reduced to match the length of the boiler barrel once the parts are soldered together.

Take the whole lot apart and clean it up ready for the soldering of the rear end, including the thread where the nuts sit and the underside of the nuts against the plate (but not where the nut will be at the front end for now) and upon re-assembly, make sure the upright line on this plate matches up with either of the lines along the barrel.

If you have already chosen one line on your barrel as the upper one, then make sure you have the pressure ring the right way up. This is most important, as these lines are what everything else works from.

If you have a preference for the top and bottom parts of the barrel, then it can be pointed out here that the whole barrel is not seen when the engine is complete, as half will be in the fire-box and the other half will be encased in lagging.

With everything cleaned and fluxed, just like on the front end, with brass studding or bolts replacing the steel bolts, anoint the inside of each hole and also the thinner part of the outer body of the bushes (making a point of not to get any flux on the internal threads), not forgetting to shine around the bush holes, and place the bushes in their appropriate holes.

With insulating blocks around the work, you can now begin the warm-up.

If you start heating directly at the top on the pressure plate, just to build up the temperature evenly, once you see the flux turn to a clear liquid and shortly after, your solder is applied and runs, simply work around the pressure ring before adding a blob to each of the bushes and finally the central nut and rod, making sure the solder is showing all around the various protruding parts, but make a point of not getting any in the centre-drilled end of the rod.

The bushes, being threaded internally, allow for any expansion of air due to the heat, and that way everything is safe, as the last thing you want is to be heating a sealed container.

Once it has cooled sufficiently to be handled, up-end the boiler so the front is uppermost and clean the plate around the screwed bronze rod and the underside of the remaining nut. Apply flux to both, including the thread, and tighten the nut on the rod, making sure there is the necessary gap for the solder to run (finger tight), and simply solder it in place.

The boiler barrel is now taking shape, so after cleaning and checking the seals, a method of checking the pressure holding capacity is needed.


What I have done is to use a brass tyre connector (the sort of thing you can find at any tyre depot and generally used on commercial vehicles).

It is basically a ⅜ inch ((10mm) piece of brass, one inch ( 25mm) square, with a hole drilled right through ¼ inch (6mm) in from one edge and another drilled to meet it around halfway along its length. This forms a hollow T shape, with soft soldered brass fittings attached to each hole.

The first is a ⁷/₃₂ by 40 thread, which attaches to my pressure gauge (imperial sizes again – if you have a pressure gauge with different sized threads, then work yours accordingly). The second is ¼ by 40 and attaches to a flange on the barrel being tested, whilst the third is a valve (ex-lorry ones are best, as they have a brass body with the valve itself removed before soldering commences, otherwise the plastic and /or rubber core parts will be melted with the heat) which connects to your pump.

If you make up one blank from 10mm (⅜) hex brass, threaded ⅜ by 32, plus another three with a ¼ x 40 thread, these can be inserted into the holes in the back plate and the pressure can be pumped in through the other through an adapter.

The blanks may leak just a little, so wrapping a little PTFE thread tape around the threads before installing the blanks will cure that.

If you give it around ten pounds of pressure as a trial, you may see small bubbles rising through the water you are testing it in. If you do, simply bore out that particular point with a fine drill and insert some bright, fluxed copper wire of a slightly smaller diameter and then solder it up again. If the leak is on a seam or joint, then plugging it with small wedges of clean copper before applying the flux and solder once more may do the trick.

Otherwise, it may simply be a case of re-melting the solder to get it to flow better, but try to keep the part you are heating in a horizontal position, or as the silver solder melts and becomes a liquid, it can flow away from the point you want to seal if your gaps are too large.


Once you have achieved 10 pounds per square inch on air with no sign of bubbles, then it is best to do a hydraulic test in stages up to one hundred pounds pressure (double the proposed working pressure – that way incorporating a good safety margin when under steam).

Fill the barrel completely with water and repeat the air test up to 50 lbs pressure and let it stand for around half an hour. Water being denser will take longer to escape from the boiler should there be a leak. The pressure should drop, but only fractionally. What happens is that the water absorbs some of the air because of the pressure difference.

If after half an hour, you are still around 45/50lbs, then congratulations are in order.

Pump more pressure in up to the 100lbs mark and wait again.

If you find the pressure drops quickly, then doing an air-only test at higher pressure will reveal any leaks when submerged in water, and can only be remedied by sealing the leaks by soldering in copper wire or small wedges of copper.

This hydraulic test should be done in front of your boiler examiner once you are happy with it so he can verify it holds the pressure without too much distortion at the required pressure. The examiner wants to be able to see the boiler shell holding tight before he can consider giving the necessary documentation.

However, that is only part of the test before the documentation and certification number can be given (and before he can stamp that number on the boiler showing it has been fine at double the proposed working pressure) as there needs to be a live steam test at 1.5 times normal working pressure including all the required fittings.

An alternative for your own testing is to have it on your bench and dab some water containing a little washing up liquid (soap) all around the boiler. Any bubbles being blown show where the leak is and requires attention, but you will need to do the hydraulic test before having the inspector check it out.

Once you have her tested for the pressure she’s complete, and the next part of the build is constructing the tender, (the rear part behind the boiler where the ‘man’ stands on to control the full-sized engine and also where the water tank, tooling and coal reserves are kept.


An improved version, still from the original concept can be seen at 97136694 which shows what can be done by a novice with a first attempt. In fact the same chap has also posted a short video of his same engine in steam and pulling him along, which should get your build interest fired up all the more.


Chapter 2 is here if you need the next chapter in PDF to allow better images and drawings


Again, if you want the whole construction details in either an ebook or a soft-backed printed version, the LINK is HERE


More to follow regarding how to build a steam engine from scratch…

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