johnsmachines

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: dredger engine

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.

 

 

Trevithick Dredger Engine. Almost There.

Firstly some pictures.

 

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So, I have reassembled the engine and the burner and the base.

Did you notice the base?

No?   Excellent.  That is the idea.  A nondescript matt black base which is barely noticed.

Yes?  OK,  well it must be OK.

Then a trial of the burner inside the firebox, using the changes which have evolved over the past few days.

During the video I am constantly changing the propane flow, and there is a clear “sweet spot” point where it looks really good, and feels very hot.  I have not yet tried to steam with it.

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.

A Tour of the Model Dredger Engine

Now that I have a tripod for my video camera (an iPhone), I have become a bit more enthusiastic about making videos.  Terrible standard of video compared with Joe Pieszczynski, and This Old Tony, and Stefan Gotteswinter, but maybe better than just text and photos.  I will be interested in your responses.

The Dredger Engine is still not quite fully made, but while I had the video set up for the spring making exercise yesterday, I added the following.   It is totally unscripted, and unedited, so there are errors.  “pressure valve” instead of “pressure gauge” for example.  Have fun counting the errors.   The final 30 seconds is me having difficulty turning off the camera!

 

Making Springs and Other Stuff

Other stuff first.

MOVING STEPS

SWMBO has always considered that having a winch on a vehicle is a bit of a wank, but I have used it many times getting out of bogs, getting other people out of bogs more often, moving machinery, pulling down/moving trees, straining fences etc etc.   SWMBO was intending to replace these concrete steps, because they were crooked with respect to the house which she is fixing up.  I said that I could straighten them.

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This is after straightening.  I jackhammered the path slab, lifted the floor slab with the 4WD high lift jack, and pulled the steps with the Landcruiser winch.  Easy as.  Took 30 minutes.  SWMBO was delighted!   

MAKING SPRINGS

And I used my new spring tool.  Brilliant!  Recorded on videos.  Again, apologies for my lousy video technique.  I had forgotten to bring the spring making instructions, so it was all trial and error.

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This was my first effort.  Aluminium wire, just to try the tool.  As you can see, there were multiple errors.   Feed rate too slow for the RPM, forgot to enter a stop command at the end, feed rate much too slow at the beginning on the left.

So I started with aluminium, making many mistakes, sometimes repeatedly, but eventually learning.  Progressed to soft iron wire, and eventually to stainless steel spring wire.

Following is a series of pics and videos.

 

 

The mandrel was 4mm diameter, and there was a bit of spring back, with the final ID of 4.4-5.0 mm.

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Initially I secured the end of the wire by catching it in the collet, but quickly replaced that method, and drilled a 1.5mm hole in the mandrel.  Again, I forgot to issue a stop command in time.   The starting coils were hand wound by manually turning the spindle and jogging the feed.  If I was making multiples of the same size spring that would be simple to program on the CNC.

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Ah!  Getting the hang of this!  That one looks good!

In the next video, a good spring is made.  The mandrel wobble is occurring because I had bent the mandrel, when the steady was not hard enough against it.  Bend straightened afterwards.

 

 

 

 

 

 

And the safety valve with its new spring…

 

 

But screwing in the safety valve was a bit of a struggle…

 

 

And re-installing the safety valve lever was almost comic..

 

 

So, that’s it for this post.

How did you like the videos?  I suppose that I should have stitched them together into one long video.  Maybe I will do that later for YouTube.   And to edit out all of the errors.

Later today I will post another video, this time a longer one, a tour of the Trevithick engine.

Trevithick Dredger Engine Burner

Reader Huib suggested that I would need to modify the gas burner for my model steam engine even before I had tried it.

He was absolutely correct.  The burner was difficult to light and keep going, unless I blocked off at least half of it. (see previous post).

So, today, I modified the burner along the lines suggested by Huib.

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I added this stainless steel tube with drilled holes to the bottom of the burner, underneath the fire clay burner.  It is wedged into position.

And this was the result.  The burner li up easily when gas was admitted.

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From above you can see that the fireclay burner is red hot over most of its surface.  And hottest at the end which is deep inside the boiler.

I measured the temperature of the burner, and it was 790ºc.  I think that it will do nicely. After that, I sealed the fire clay burner into the brass container with a high temperature boiler sealant.

Yesterday I received in the mail a tiny pressure gauge.  3/4″ diameter, 0-80psi.  from EJ Winter, Sydney.  Order was placed Wed, arrived Thurs.  Great service.  Thanks Ben deGabriel.

Trevithick would not have had a pressure gauge in 1803, but modern boiler regs insist on one, so I have bowed to the inevitable, and will install this gauge on top of the boiler.  Photos to follow.   I expect to be running the engine on steam next time I am in the workshop.   WooHoo!   Not tomorrow though.  Baby sitting.

 

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