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machines which I have made, am making, or intend to make, and some other stuff. If you find this site interesting, please leave a comment.

Tag: Trevithick

Back to the Trevithick Dredger Engine Model – the lagging.

The only surviving Trevithick dredger engine, in the London Science Museum, shows no signs of ever having been lagged.  I know this, because I examined it closely, recently, during my UK trip.

No lagging, no marks in the paintwork, which would indicate wooden lagging strips ever having been attached.

But, we know that Trevithick readily adopted ANY improvements to his designs, and lagging was appearing on engines at about the epoch of the dredger engine design. Plus, his engines were in use as late as mid 19th century, and lagging was well established as a normal feature by that time.

And, my model definitely needs some efficiency improvement.  Using a 40kW burner to power an engine of this size is ridiculous.   So I Have added some lagging.

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Equipment for applying lagging, from the left…   scroll saw, super glue (I used 6 tubes), strips of wood (in this case, Australian Jarrah, grinder for shaping, Dremel for shaping, good light, and the engine with some of the strips glued in place.

I used about 48 strips of wood with some spares.  These were cut and sanded in advance.  5mm x12mm x 130mm.

The Super glue is used to hold the wood strips in place temporarily, until the brass boiler bands are installed.

I started at the top, and worked my way down on both sides.  Most effort is made in fitting around  pipes and boiler bosses.  Unsatisfactory strips are levered off and scrapped.

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A rebate was milled on every wood strip, to permit removal or tightening of the boiler end plate nuts.

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I used rubber tree ties to maintain pressure until the glue dried, but in most cases I just applied finger pressure until the wood stuck fast.

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Some pipes and fittings necessitated grooves being made with round files.

Super glue does not provide a permanent bond to copper for some reason.  And it certainly will not survive the heat from steaming.  But it is fine for a quick and temporary bond.

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After making and applying the brass boiler bands (this was covered in the “6”vertical boiler” posts) I used olive oil to seal the wood.  See discussion which follows.

I chose olive oil to seal the grain openings of the jarrah.  I know from previous firings that the temperature of the boiler shell does not exceed 100ºc.  Olive oil will not smoke or flame until the temperature exceeds  200ºc, which is higher than any other common oil.  Also, as a failed olive farmer, I have plenty of old olive oil.   At worst, my engine steamings might smell like a fish and chip shop.  And refreshing the oily surface will be quick, cheap and easy.  And the olive oil will not form a skin which might peel or flake.  Anyway, this is “model and experimental” engineering.  If it does not work, I will make some new lagging, alright!.

And I took some more photos with my Panasonic Lumix 100-2 camera…….

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Still some more painting required to the end plate, and some fittings.

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That domed boiler end with the cylinder protrusion also needs some paint.  But the lagging looks good hey?

Even SWMBO has relented…  “It can go with the other engines”.  It will, when it is finished.  Still requires more painting.

London Museum of Science Revisited

I am back in oz as of a few hours ago.  Freezing and wet.  Was 26c in London today.

On my last afternoon in London I had a few hours spare.  So I caught the tube to have a final farewell to the Trevithick dredger engine and to reshoot some photos which I had messed up at my visit 3 weeks earlier.

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Trevithick dredger engine in the LSM.

…and I spent a very pleasant hour photographing the engines in the Energy Hall again.

And on wandering further into the building I discovered that on the previous visit I had totally missed about 2/3 of the entire museum, including the model of the Trevithick road vehicle which had been made as a concept model by Trevithick’s brother in law, a clock maker.

Unfortunately it was bottom lit and behind glass, so very difficult to get good photos.

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From above

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From the side.

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The model is more akin to his road vehicle “Puffing Devil” than the rail locomotive.

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Quite modern looking lathe by Richard Roberts 1807.  With lead screw and outboard gears for threading.

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Beam engine designed by James Watt 1797.

 

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Model of a steam powered workshop, with many tiny exquisitely modelled lathes, shapers, presses, saws, and a steam engine.  Those lathes are about 3″ long.

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And a 1:12 model of a pressure gauge of James Watt, 1794.  60 years before the invention of the Bourdon tube.

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And this one amused me.  It is a 1987 Colchester CNC lathe, with Fanuc controller.  It is 2 years newer than my Boxford CNC lathe.

This really was the finale of my adventures in the UK.

 

BT. Before Trevithick.

Before Trevithick were Savery, Newcomen and Watt.  And way before them, Hero of Alexandria (1st century AD)

Thomas Savery, a military engineer from Devon, took out a patent in 1698 for a steam operated pump.  It had no moving parts, except some valves.

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It had 2 low pressure boilers.  Steam from one boiler was introduced into one chamber, and water was then introduced which condensed the steam, forming a partial vacuum, which sucked up water from below.  Steam from the other boiler was then introduced, which pushed the water upwards.  As a pump it was a failure, and it is not known if any were made.  Modern reconstructions have also been unable to pump water successfully. But the patent lasted, and forced Newcomen to involve Savery with his invention in 1712.

Thomas Newcomen was an ironmonger and Baptist lay-preacher from Dartmouth, Devon, and he is the reason that I am currently in this pretty Devon town.  There is an original Newcomen “atmospheric engine” in Dartmouth.

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(taken at an angle to avoid window reflections)

The Newcomen pump, (for pumping water from the mines was its purpose) also used the condensation of steam creating a partial vacuum, as its principle of action, and it was quite successful.   So successful in fact, that more than 600 of them were built, and they continued to be built well after the improvements of Watt and Trevithick, into the nineteenth century.  In the diagram above, the 22″ power cylinder is on the right, and the pump cylinder is on the left.  The genius of this design is that the pump can operate in the depths of the mine (or canal or military trench) while the engine remains above ground.

It is incredibly inefficient in thermal terms, converting only 1:200 of the energy from burning coal into the mechanical energy of the pump, but it was by far, more powerful than any pumps driven by man, horse, wind or water at that time.

The room in which the Dartmouth engine is housed is just bigger than the 15′ high engine, so pictures are difficult.

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All wood, except the power cylinder on the right, and the pump and pipes (not seen).  The curved ends of the big wooden beam keep the piston rod and pump rod vertical.  Cylinder boring had not been introduced yet, so the gap between piston and cylinder was up to 1/4″.

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The valves to admit the steam and water were originally operated by hand, but later some automated simple levers were introduced.  Note the square nuts (original).  It appears that the woodwork is mostly original, albeit repaired in places.

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The pump connection

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This power piston has a bore of 22″ (560mm), but they were built increasingly bigger, up to 80″ (2032mm).

The Newcomen engines were simple, and effective.  Their main problem was that they consumed vast quantities of coal.  They were widely used, but there was/are no coal deposits in Cornwall, and transporting coal from Wales was costly, and taxed.

James Watt‘s big contribution to steam engines was to add a condenser to the engine, which was separated from the power cylinder.  That doubled the efficiency.  He also sealed the top of the cylinder, so both strokes of the piston rather than just the down stroke, were power strokes.  But it was still a vacuum powered engine, and therefore had an absolute limit of working pressure of something less than atmospheric pressure (15psi).

Richard Trevithick‘s main contribution in 1800 was to increase the steam pressure available, by inventing the “Cornish boiler” which produced steam at 50psi, and even up to 145psi.  This more than doubled again the thermal efficiency of the steam engine, and made it much more compact, leading to his applications of steam engines in road vehicles, railway locomotives, ship engines, and industrial stationary engines (like my model dredger engine).

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Watt modified Newcomen engine on the left, Trevithick dredger engine on the right. Size comparison.

Tomorrow I am driving to Portsmouth.  So I will leave the west country inventors of steam engines.  It has been a fascinating journey.

First stop, Fort Nelson.  To renew my acquaintance with the Ottoman bombard, which was the subject of my blogs several years ago.

 

First Steam Locomotive.

In 1802 a Richard Trevithick designed engine was made by the Coalbrookdale company.  Not much is known about it, but is recorded that the steam pressure reached 145psi!  Trevithick had previously operated his road steam locomotive up the Camborne Hill, but this was the first one to run on rails.

The next one was made for the steelworks at Merthyr Tidfil, Wales.  It was a Trevithick engine which ran on rails.  The owner made a 500 guinea bet with a rival (an astronomical figure.  Somewhere I read that it would be equivalent to a million dollars these days), and in Feb 1803 the engine towed 5 wagons, loaded with 10 tons of iron ore (or coal, not sure), and 70 odd bods, a distance of 10 miles.  There was dispute about whether the bet had been won due to some technicalities, and no record of it being paid, but it was a moral victory.  The age of steam had really begun.

The biggest problem was not the locomotive, but the rails.  They were not strong enough, and frequently broke.  It took the genius of George Stephenson to solve that problem, by using forged iron in preference to cast iron.  And his son Robert to increase the efficiency of the engine and boiler in the form of “Rocket”.  But that is another story, for 30 years later.

Unfortunately the original of the Merthyr Tidfil loco has not survived, but several replicas have been made, based on original drawings.  I saw one of them at Swansea, Wales, not far from Merthyr Tidfil.  Not a steaming day.  It does run.

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Not great photos.  The lighting conditions in the National Waterfront Museum were difficult.

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The typical big, skinny Trevithick flywheel, and driver’s wagon.

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Square main shaft.  Hex nuts were not around in 1802.  

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And that is a view that you don’t often see.  The pressure gauge is definitely a modern requirement, as I discovered with my dredger engine.

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Notice the fish belly rails.  Originals were cast iron.  “Fish belly” shape to increase the strength, but alas, not strong enough.  Hex nuts again!  And those gears have modern shaped teeth.  Quite a few compromises in this replica.

And I have now arrived in Camborne, Cornwall, Trevithick’s home, and the site of his famous trial of the steam road loco.

I made a pilgrimage to Fore St (“Camborne hill”), then to his statue, to pay homage.

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Richard Trevithick.  Genius.

 

Trevithick Dredger Engine at The London Science Museum

I landed at Heathrow at 6am, dropped my bags at the BNB, then caught 2 buses to the Science Museum.  Not jet lagged, but on a high, to see the only intact Trevithick Dredger Engine known to exist.

The room which houses the Trevithick, also contains 4 large beam engines, a Parson’s turbine (of “Turbinia” fame), and a very large 2 cylinder compound.

Disconcertingly, the first atmospheric beam engine, with wooden beam, was partly obscured by a souvenir stall and racks of clothes for sale.  WTF!   Don’t they realise the historical importance and rarity of these engines.  And 3 further moans, to get them out of the way.   The descriptive labels on all items had minimal information.  Nothing like dimensions, power, etc.  The attendants knew virtually nothing about the engines.  And often, items were behind glass or perspex which was reflective, and prevented good visualisation or photography.   To be fair entrance was free, but to get past the entrance desk it seemed pretty clear that a “donation” of 5 pounds was expected, (which I was happy to contribute).   Those complaints aside, I have to say that the collections were fabulous.

I could see the Trevithick at the far end of the room, so to curb my mounting excitement, I forced myself to not rush up to it, but to try to look at every exhibit on the way.

Eventually I was there and it was there in front of me.

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It was one of the smallest engines in the room (The “Energy” hall).  The older beam engines were many times larger, but that was a major reason this engine was so successful..  more power, lighter, smaller, and several times more efficient at converting coal to rotative motion.  No one could tell me why there is a huge divot in the cast end of the boiler.

The con rods, stands, standard cross tie, and chimney are not original, but were added when the engine was restored in ~1875.  But that is now part of its history.

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From that side it was apparent that the main shaft was square over its entire length, something not previously known to me.

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The boiler feed pump was relatively tiny.  I do not know if it is original.

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The firebox has been re-sleeved.  The chimney mount is part of the end plate casting.  And I think that I got most of these items pretty close to right on my model.  Does anyone know what the incomplete flange at 5 0’clock would have been for?

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Note the odd bolt pattern around the inspection hatch.  I got that wrong.  My change to the oblique slide rod stay angle brackets was correct.

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safety valve weight is adjustable.

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Water preheater pipe detail.  Aren’t the square nuts great!

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The throttle restraints are curved, and have fixed position holes for pins.

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Boiler feed tank.  Cast iron.

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Engine supports appear to be cast integrally with the boiler.

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Flywheel hub

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Flywheel spoke detail.  Likely original.

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Chimney mount detail

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Finally (although I do have more photos), a nice view from above.  I do like the crosshead shape.  I wonder if it is original.  Remnants of another Trevithick dredger engine  not currently on display, reveal a wooden crosshead beam.

So there you are.  Fascinating to me.  Interesting enough I hope to you.  I could see no evidence of wooden lagging at all, but i still intend to install some on my model to slightly improve its efficiency.

i have heaps more photos of other exhibits which I may post later.

 

 

A Fraternal Photo

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Me and my brother Peter.  No doubting the genes.

My brother also makes steam engines, but he prefers the ones which move on steel rails. Unfortunately he lives a long way away, in the deep north of Australia, so we see him and his wife only once a year or so.

Trevithick Engine by Lumix, and an Ottoman cannon.

Some more photos with the Panasonic Lumix LX100M2.

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The Trevithick dredger engine, still lacking lagging and paint.  The chimney has a chimney extension connector, sitting a bit crooked.

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I am very impressed by the quality of these photos.

And some shots of the 1:10 model Ottoman Dardanelles cannon, which I made a few years ago.  It was intended as a practice run in wood, before making it in bronze.  The wooden model is 600mm (2′) long, and since finishing it I have not felt the need to make a bronze example.  I plan to visit the original at Fort Nelson, Portsmouth, in a few weeks. Watch out for a video/photographs on johnsmachines.com

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I think that you will agree that the quality of these photos is excellent.  The photographer is still learning.

Video of the gas burner which works

The first 6 minutes of the video  is getting up to 40psi.  Then a couple of minutes of the engine working.   Big file, so be patient.

At Last, a burner which does the job!

You are probably fed up with my burner trials.  I certainly was.

Fundamentally, I was trying to get enough heat into the Trevithick model dredger engine boiler, and just not managing it.  My boiler is a scaled down version of the original, in copper.  It takes a lot more heat than the 6″ vertical boiler which I made last year and I think that the reasons are…

  1.  The Trevithick design, although revolutionary for 1800 was and is a very simple, primitive, relatively inefficient design by later standards.   No water tubes and only one fire tube (the flue).
  2. The linear dimension is scaled down 1:8.  The surface areas (heat exchange surfaces) are scaled down 1:64.  The volumes, representing power output, are scaled down 1:512.  So the scale is a major factor.
  3. The firebox is 60mm diameter.  I had no success burning coal or wood, although I gave up on that one quickly after one attempt.
  4. Absence of lagging.  Reproductions of Trevithick’s engines have wooden lagging, but there was no indication of lagging on the LSM engine, or in the 1819 drawing.  I do intend to install wooden lagging, in fact I have cut and prepared the strips ready to install.

So my colleague Stuart suggested that I try his Sievert burner…

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This is a Sievert 2954.  Stuart tells me that at full blast it puts out over 40kW!   The ring is steel, machined to fit the firebox, and a close fit to prevent cold air being sucked around the edges.

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Fitted into the firebox.  It coped reasonably well with the back pressure at about 1/2 strength. 

This unit raised steam from 2500cc of cold water in 10 minutes, and got to 20psi in 14 minutes.  The target of 40psi was reached in 18 minutes.

At 40psi the safety valve operated, and despite continuing to pour in the heat, the pressure did not rise above 40psi.  So I am expecting that the boiler inspector will be happy with the safety valve.

I then ran the engine for 45 minutes, turning the boiler feed pump on and off to keep the boiler water level up.  All went well.  I have made a video of the event, but the upload failed last night, so I will try again later.

Next, to contact the boiler inspector for the final (I hope) inspection.

 

More Gas Burner Experimenting

First I tried the Sievert 2943.  I tried different gas settings, and different positions of the burner in the fire box.  I quickly discovered that an opening had to be present next to the supporting flange.  Despite that, steam was produced in 10 minutes, and 20psi was achieved in 15 minutes.  My aim is to obtain 40psi, and maintain 40psi during engine operation.

Unfortunately this burner does not work if there is any significant back pressure in the system.  Stuart has advised me to try the Sievert 2954 which he says will cope better with back pressure.  The Sievert 2954 has a similar appearance to the 2943, so I have not photographed it.

I have borrowed a Sievert 2954, but it needs some setting up, so I thought that meanwhile I would try a burner style which had been mentioned earlier.  It is a tube with multiple transverse slots.  Despite being constructed rather roughly and quickly, it produced a good hot flame.  Perhaps a bit small, but promising.

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If the next Sievert is not satisfactory I will come back to this style, and experiment with different slot numbers and sizes.

If you are becoming a bit bored with all of these gas burner experiments, I understand.  When the burner is finally sorted I will be delighted and relieved.

I have machined some wood to be used for lagging.  It is West Australian Jarrah.  A dark coloured wood which is often used for exterior flooring.  I will apply it to the boiler soon.

 

A Coal Grate. And Monster Emperors of Rome.

Firstly, the book review.  It is short, because I did not enjoy it.  Not that it is badly written, or poorly researched.  But it is really shocking.

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EMPERORS OF ROME.  THE MONSTERS.  by PAUL CHRYSTAL

From Tiberius to Theodora.  AD 145-548

This book is one of the series published by Pen & Sword on the architects of terror. Other volumes include Al-Qaeda, The Armenian Genocide, Bloody Mary, Einsatzgruppen, to give you an idea of the scope of the series.

Now that I have finished with the book, I am examining my own motives in choosing it.  I have read many books about ancient Rome, and find the era fascinating; the personalities, the reasons for the rise and fall of the empire, why the military was so spectacularly successful etc etc.

But to be truthful, I did not actually finish the book.  I had a similar reaction when I read about the Nazis and the concentration camps.  Just too horrible to contemplate.  And I closed it after reading about half.  And will not reopen it.

Paul Chrystal is a well-respected author who has written many books about ancient Rome. He states an aim to use primary sources, and to balance the horror with the mitigating aspects of the monsters. The book is 127 pages long, and it covers 10 emperors, so there is not a lot of space to give a balanced view. Mostly, despite its aims, the book is about rape, murder, treachery, nasty and insane men and women with absolute power doing whatever they felt like doing.

And to be realistic, even the “good” emperors started wars, executed rivals, instigated massacres and mass maimings.  That was the way things happened in ancient Rome. And twentieth century Germany, China, Cambodia etc etc.

So, if you enjoy seemingly endless descriptions of sadistic torture, rape and mass murders, with many illustrations, this book might be for you.

Not for this this reviewer though.

John V.

Now, back to getting enough heat into the 1:8 Trevithick Dredger Engine.

I have made a grate to place into the firebox, and which will replace the gas burner, which has proved to be inadequate, despite many, many experiments with improving it.  So here is the grate.

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Putting a rather unpleasant book to good use.

The holes in the grate are tapered, with the smallest part of the holes uppermost.  The fold at the back is to prevent coal being pushed off.  The taper is to prevent clogging the holes with clinker, and possibly to improve the velocity of air flow through the fire.

And how did I drill so many small holes so neatly?

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CNC of course.  Took about 45 minutes.

But after that I had a conversation with Stuart Tankard.  He reckons that I will do no better with coal than I have with propane to date.   Hmmm.   Might give it a go anyway.

Stuart’s suggestion is to try one of these….

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It is 50mm diameter, has a large jet (0.81mm diameter) and has a fearsome flame.  Looks more like a silver soldering torch.  If I use it I might get a flame coming out of the chimney.  Hope that it does not melt the silver solder.

 

 

Painting the Dredger Engine

OMG!

You are not painting?

You know that…

1. You always get runs

2.  You always get hairs in the paint

3.  You have NO artistic sense of colours

All of the above is true.

So I have relied heavily  on opinions from my readers about how to put some paint on the Trevithick dredger engine and the colours.

Firstly, yes, I got some runs, and sandpapered them out between coats.

Secondly, yes, some brush hairs ended up in the paint on the engine, but I was on the lookout for them, and removed most of them.  The few remaining were sandpapered out.

Thirdly, yes, I have no artistic sense of colour, but neither did Trevithick so I am in good company.  Most of my readers said to paint it black, so that is what I am doing.  Matt black.  (SWMBO says that matt hides a multitude of painting sins.)

But, I am leaving most of the brass unpainted, so that I can polish it up for special occasions.   I will paint the boiler.

 

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So here I am painting the chimney.  Note that I have found a good use for the 4 jaw chuck.  Apart from holding the Xmas tree steady. 

I am brushing on the paint.  I have an air brush, but there are a lot of surfaces which I do not want to get paint on, so I am brushing.

I am using matt black epoxy enamel for most surfaces, and pot belly stove black for the hot surfaces.  No primer (except on the base).  2-3 coats.

 

Trevithick Blower

I am sure that my readers will have gathered by now that I am not an expert.  At least in matters of metalworking, model engineering etc.  I am, or was, an expert in my profession, some years ago.  But this blog is about how a non expert copes with  problems in model engineering.  It aims to be entertaining, occasionally helpful, and a diary of my workshop doings.

When Trevithick designed his revolutionary engine, (“revolutionary” in all senses), he arranged for the exhausted steam to be funnelled into the chimney, after pre-heating the boiler feed water.

It was a matter of convenience apparently.   Rather than ejecting the spent steam directly  into the air, it would go up the chimney, away from the operator.

But almost immediately it was noticed that the fire in the firebox was more vigorous, hotter, more efficient  Thus was born, the steam engine blower.

So I made the junction between the exhaust and the chimney as per the plans, at an angle of 90 degrees.

But, I noted that on the exhaust stroke, the fire in the firebox spluttered, and occasionally went out altogether.

In more modern steam engines, the exhausted steam is inserted into the chimney, but parallel with the chimney, not at a right angle.

So, I thought, do I stay with the Trevithick design, or the more logical more modern design.  I was having problems with my fire, so the decision was easy.  I would pretend that Trevithick would adopted this design.  Maybe he did.

But that meant breaking the silver soldered join, inserting a new angled copper tube, and rejoining it all.

 

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As Trevithick designed it on the left and on the right as I remade it today

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Right is the exhaust piece between the preheater and the chimney.   Left is the new blower tube, which must be joined end to end, and then poked up the chimney.

This was going to be tricky.  And end to end join of 2 pieces of 9.5mm copper tube, and the join being right where the tube enters the chimney.  But then I remembered a tool which had sat unused for several years…

OK,  This is probably very old hat to most of you.  But it was exciting to me.  First I had to assemble the tool.   Sorry I missed the camera.

 

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I decided to solder the pipe join first.  Rested the end with the flange on a lump of scrap brass, to act as a heat sink, and protect the flange join.

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That worked well.

Then I soldered the assembly into the chimney, after bolting all of the parts into their positions.  Sorry.    Forgot to take a photo.    But it all worked well.   I like the tube expander, but it needs some extra fittings so it works on smaller tubes.

 

 

Oh Shit!

PART 1

I was drilling a hole in the end of the Trevithick burner today.  The burner was securely held in the vice, but the heat annealed brass was not as strong as the torque in the 6mm drill bit.

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After the initial self hatred at misjudging the situation, I thought …oh well, I will have to make another one.    Then I thought, …I wonder if I can repair it…..

I still have the wooden forms which I used to make the burner originally, so, roughly twisted the part back into shape.  It was pretty malleable still.  Then forced it into the wooden form.  And beat it into shape with the copper hammer.   This was looking promising.

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Then forced in the other part of the form, and applied the 20 ton hydraulic press.

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The curved shape was pretty good, but there was still some twist.

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I still had to drill an 11.5mm hole, so this time I used the form, successfully.   Then removed the twist by hand after knocking out the form.

Tapped a 1/2″ x 26tpi thread, and assembled the burner.

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All beautiful again.  And now the burner tube is properly secured.   The bulge under my thumb was pushed straight.

 

PART 2

My reader/advisor Huib, suggested filling the tube with stainless steel scouring wool, in order to improve the flame.

I asked SWMBO, and was directed to the appropriate supplier.. the local supermarket.

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Bought 3 types of stainless steel scouring pads.  The finest grade was available only impregnated with soap.  I am not sure how soap burns, probably pretty well, but I do not need that added complication.  Fortunately it mostly came out when tapped.   All very inexpensive.

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Then I experimented with all 3 grades, various degrees of packing it in, and using various lengths.  I even tried mixing the different types of steel wool.  It cuts easily.  Eventually I decided the best way was to have a loose wad of the fine mesh in the first 1-2 cm of tube, then a very light piece of the fine mesh in the distal 10cm.

It has improved the flame;   there is no back lighting of the jet itself, and there is a more even flame along the length of the tube.   I think that I will be able to improve the flame further, but will wait until I can test it inside the boiler itself.  In the video the roaring of the flame drowns out my voice somewhat.  You will not miss much.    I am varying the gas control.

So, sorry about the voice track.  The stainless steel stuff is interesting.  It is like swarf, but not sharp.  I wonder how they make it.  I imagine that it works in the gas-air tube by creating swirls and eddies, and better mixing the gas and air, without impeding the flow much.

Back in the workshop tomorrow.  A few connectors to make, check the feed pump, then make an appointment with The Boiler Inspector.

By the way.  The parcel opening post was apparently not very interesting, so I wont bother with that format again.  I am aware that my video technique was pretty ordinary, but I am not inspired to try that one again.  Pity.  I enjoyed making that one.

 

 

Trevithick Engine. Tweaking the gas burner. Winning?

Looking at yesterday’s photo, the yellow flame indicates inadequate air for the amount of gas going in.  The air holes at the gas jet level were already at maximum size, so I drilled some holes in the burner base itself.

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Yesterday’s photo.  Feeble flame.  Not enough air.   So I drilled holes in the burner end, next to the gas inlet.  (thanks for the suggestion Huib!).  Unfortunately, the improvement was minimal.  And gas flames shot out backwards towards the operator and gas jet.  A bit disconcerting.  And, I wondered, could the ceramic burner itself be restricting the flow?

So the next step was to remove the ceramic burner, and make changes to the spreader tube beneath.

The ceramic burner broke in pieces during the removal.  Possibly still useable.

But I thought, maybe I will see what the flame is like without the ceramic burner altogether.

And this is what the flame looked like…

Now, that is more like it!  (you can see the holes which I drilled in the end of the burner to increase air intake)

Admittedly, the flame will change when the burner is back inside the boiler, but this is the most encouraging flame yet.  Minimal yellow.  The gas flow will need to be reduced.

Next session, I intend to experiment with the hole sizes and number and angles.  I do not expect to be using the ceramic insert in the final version.

Model Trevithick Dredger Engine on Steam. Fail. Well, maybe a bare pass.

Well, I was really not expecting this.

After all, the engine was running well on compressed air at 30psi, and the burner appeared to have a good flame.

And Stuart was coming to be involved with the big event.  So nothing could go wrong!

I set up the iphone on a tripod.  Checked the light.  Oiled the bearings and slides.  Filled the boiler.  It takes 2 litres of water.  And hooked up the propane.  when Stuart arrived I lit up the burner, and sat back to see how long it would take to raise steam.

Some steam leaks were expected, on this first steam run.  Leaks don’t show on compressed air, unless they are severe.  As the water heated up, some leaks appeared.  The water feed clack valve and the sight glass were bad.  The clack valve just needed some goo.  Later I disassembled the sight glass, and cleaned the valve, with some improvement, but more work needed.  Or a new sight glass valve.  A couple of other trivial leaks were easily fixed.

So we watched the clock, and checked the temperatures.  Ot took 20 minutes to start raising steam.  That is a bit slow.  Eventually it reached 20psi, but the pressure refused to go any higher, despite fiddling with the gas and air controls.

At 20psi, I opened the throttle and gave the flywheel a swing.  You can see the result.

After that, we let it cool down and fixed the clack valve leak.  The sight glass valve leak was looked at later, but could not be fixed simply.

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The burner flame.  A bit feeble.  A bit yellow.  And occasionally blown out by the cylinder exhaust gas puffing into the chimney.  Stuart says that I need to angle the cylinder exhaust gas upwards in the chimney.  Apparently Trevithick did not do that on the full size models, but perhaps he should have.

The burner was definitely not up to the job, so in this last video, it got some assistance.

It does go!   Just needs a few tweaks.  Lovely sound.

Drilling is not boring

Firstly the base.  I wanted to drill all of the wooden pieces together, to make sure that they aligned, even if the lengths weren’t absolutely accurate.  Wood is like that.

So, using the bottom piece as a pattern, and squaring each piece as it was placed, I glued them together using PVA glue.

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And squaring each piece as it was placed.

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Those angle blocks made handy glueing weights.  The short bits are intentional.  That allows the flywheel crank room to rotate.

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My workbench.  I needed some room, so I tidied it.

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That is better!

Now some short videos of the drilling.  Sorry the videos are so short.  If my Internet connect was better I would have stitched them into one video, but alas…

I was intending to show making a 5mm drill bit longer, by silver soldering a piece of 5mm drill rod to the bit, end to end.  I have done this before, quite successfully.  Silver solder is very strong.   Almost as strong as the parent metal.  But in this case it was unnecessary, as the videos will show.

 

 

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With the base complete and bolted to the engine, I made the last pipe connection joining the feed pump to the pre-heater.

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Ready for the first run on steam next session!

A Long Drill Bit

I have not been looking forward to attaching the Trevithick Dredger Engine to its base.

I needed to drill through the steel plinth and the wooden plinth, and then through the top part of the base.  Trouble was that the boiler and engine were in the way.

And it was not feasible to tip the whole assembly upside down and drill from underneath.

Ahah! what about a long drill?   I measured it.  The drill would need to be 450mm long!  Even a long drill bit, ferociously expensive, comes at a maximum length of 150mm.

So, I made a long drill bit, 5mm diameter, 600mm long

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That is a new 5mm cobalt drill bit, silver soldered into some 8mm drill rod.  Could have been a bit shorter, but it was long enough.

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Using the long drill bit, I was able to drill through the steel support, and through the top wooden layer of the base.   Then bolted the parts together.   And was then able to place the engine and the wooden layer on their ends, and to drill the remaining holes from below, confident (fairly confident anyway), that nothing could go wrong.   As in the above picture.

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Meanwhile, I had added the valve which controls the boiler feed pump output, and connected it to the boiler feed pump.

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Boiler feed pump valve.  This valve was left over from the vertical boiler project.  Just right, when I have repainted it.

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Next I must drill a 5mm hole through all layers of the base.   150mm!  4 holes, one in each corner.   The long drill made today will not do because the 8mm shank is too thick.   I must make another long drill, with a 5mm diameter shank.  Watch this space!

 

 

Moon

I know that this blog is titled “johnsmachines”, but I do get interested in “other stuff” too.

I came across this video on YouTube yesterday.  It runs for 4 hours.

The footage was shot by an amateur astronomer, through telescopes which anyone can buy.  A 9.5″ Celestron  reflector (Schmitt Cassegrain I think),  and an 80mm Orion refractor.

I used to be an amateur astronomer, and still retain an interest.  One of my worst decisions ever was to give away an Orion 10″ reflector about 10 years ago.

Anyway, back to the video.  It shows the surface of the moon, concentrating on some interesting areas.  Following are some screen shots.  It is titled “Live Moon Surface Observation”.  Worth a look.  Suggest jumping to 28minutes and watch maybe 5 minutes, zooming in and out.

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80mm refractor.  Look at the protruberance in the top left crater.  Looks like a clenched fist.  That is really unusual.  Impact craters often have a central spike, and it is thought that the moon has had volcanic activity in previous aeons.  But there is no atmosphere to cause wind erosion, and no surface water.  Just traces of ice in the depths of craters at the poles.  So how could that shape have arisen?   And look at the bottom right crater…. that rectilinear shape.   Circular shapes are meteor impacts, in many case impacts upon impacts.  So how do you explain straight lines like these?

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The same craters through the reflector scope.  Image reversed.   Look closely at the areas surrounding the craters.  Do you see the other rectangular and square shapes?

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Close up of the fist.  Pixellation appearing.

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Earth’s moon is strange.

It is the largest moon in the solar system relative to the parent planet.

It is much less dense than earth. (why? if it is made of the same rock).  (5.51g/cm vs 3.34g/cm.  Thought to be due to Earth’s metal core.)

It almost exactly blocks the disk of the sun during a lunar eclipse.  Coincidence?

The other side of the moon always faces away from earth.  Until the space program, no human had ever seen the other side of the moon.  The other side, incidentally, is quite different from the side which we see.  Much more cratered, no large flat areas.  Presumably most meteors come from the direction away from the sun (because they are scooped up by the gravitational field of the sun).

One moon day is exactly the same length as a lunar month.  It is the only moon in the solar system where this applies.  That is why the other side of the moon always faces away from earth.  Another coincidence?  (correction.  Pluto – Charon also exhibit this behaviour, so it is not unique, just unusual.  Thought to be due to “tidal locking”- thanks Gene).

OK.  I know.  You came to this site to look at my machines, particularly the Trevithick dredger engine.   I am still fiddling with small details which are not very photogenic, but necessary before I run it on steam.  Currently hooking up the boiler feed pump.

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I was intending to pull apart the pump to show you the components.  It is more complicated than the exterior shows.  Piston, O ring, 2 stainless steel balls, one spring.  I machined that 3 way junction box from a gas fitting, adding the delivery union to the top.   Nothing tested yet.  I hope that it works!

 

 

 

Sight Glass on the Trevithick Boiler

Not real happy about this one, but it is necessary if I am to run the dredger engine in public, at club meetings etc.

The original dredger engine had 3 taps to check on the boiler water levels,  like this.

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An earlier stage of construction, using taps to reveal the boiler water level.

Unfortunately that setup is unacceptable for boiler certification, so I have installed a sight glass using the same penetrations.

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The red colour does not help.  But when I run the engine on steam, this is what will be seen.   Functional, but nothing like the original.  If I use compressed air, or steam from an outside boiler (i.e. my burner not being used), I can reinstall the taps.

The sight glass is a bit short, but it should comply with the regulations.

I have spent another half day experimenting with different spring configurations, so that the safety valve releases at 40-50psi.  Eventually I decreased the coil pitch of the spring, and the valve now releases at 45-50psi.  That will do.

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