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.

Trevithick Dredger Engine. What was the original design?

As I am progressing with building the 1:8 model of the dredger engine, I am experiencing doubts about the authenticity of the design by Tubal Cain 1985, and redrawn by Julius DeWaal 2016.  Those plans are based on the engine in the London Science Museum, which we know was incomplete when found in a scrap yard (?) and reconstructed in 1886.  There are no known or published original plans.

Look at the following photographs.  The first two are boiler components labelled as Trevithick, although incomplete, appear to be unmodified.

The following drawing comes from Rees’s Cyclopaedia, published first in 1819, when many of the engines would have been operating, and given the quality of the drawing, is likely to be fairly accurate.

Finally, the engine in the London Science Museum, which shows some Victorian era features which are highly unlikely to be as Trevithick designed them.

 

Trevithic boiler tubes

The firebox and firetube, riveted to the end plate.  Note the inspection hatch has no rivet or bolt holes.  How would the hatch have been attached?  

 

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Showing the end plate bolted to the cast iron boiler shell.  Interestingly, the penetrations are mirror image of the LSM engine.  Does anyone know where this boiler is currently located?  And why are there no rivet or bolt holes around the inspection opening?

 

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Drawing from circa 1819.  Note 1. the wooden support at the chimney end of the boiler, 2. the flange for the chimney attaches directly to the end plate, as does the inspection hatch and the firebox door.  None of these protrude beyond the end plate.

 

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This is the best photograph I know of from the reconstructed LSM engine.  There are multiple inconsistencies with the Rees drawings…

The inconsistencies which I note are:

  1. The support under the flat end is metal, not wood.  It is cast or fabricated, and curved.  Unlikely to be original.
  2. The rear support in the Rees drawing is metal which sits on wooden bearers.  Quite different shape from the Cain/deWaal plans.
  3. Some of the flywheel spokes have a moulding, some are plain.  I imagine that plain is more likely original.
  4. The connecting rods are bent at the top.  They are straight in the Rees drawing.
  5. There are no rivets or rivet holes around the firebox.  There appears to be a new cylindrical insert into the firebox. Unfortunately the Rees drawings do not show the firebox.   The firedoor hinges appear to be welded in position.  There are holes in the firedoor which could have been used for strap hinges, which would be more likely in use originally.  There is no provision for air intake control.  I wonder if Trevithick would have provided an adjustable flap?  I am told that some early Cornish boilers did not have any flap.
  6. The inspection hatch looks realistic.  But the hatch sits away from the end plate, presumably to permit access for the end plate to flange bolts.  Would Trevithick, I wonder, have designed such a complex setup?  Bearing in mind that every piece of iron or steel must be shaped in a forge by a blacksmith, then riveted or bolted into position, or cast iron, then bolted into position.   The rather irregular position and shape of the inspection plate and bolts looks authentic, but I have my doubts about whether the inspection hole itself is authentic.  Could this have been cut out later, when boiler repairs were required?

I have not looked closely at the engine details.  No doubt further inconsistencies will be apparent there.

So I am in a bit of a quandry.  Do I make the Cain/deWaal model, removing the obvious inconsistent features but including the dubious ones?  Or do I guess at what Trevithick would have designed, based on the technology which he had available?

Any opinions or thoughts/advice would be welcome.

 

 

 

 

Drilling holes into the Trevithick Boiler

Nothing much to add today.  I had only an hour in the workshop.  But here is a photo.

 

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The wooden plug is to prevent squashing the boiler shell in the vise.  Note my ambidexterity regarding metric and imperial dimensions.  

And as a matter of interest, a stranger turned up at our working bee in the exhibition cage, with 2 models about which he wanted some advice.   The models are beautifully made, and we hope that the stranger will join our little club.

 

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A Stuart Turner 5A with Stephenson’s link reversing mechanism.

 

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And I could hardly believe my eyes when I saw his 5″ boiler.  It is made to the plans upon which I based my 6″ boiler!

He inherited the models from a relative.  Lucky!

 

 

 

Trevithick Dredger Engine- First silver soldering session

Today I fitted the chimney right angle piece, drilled and soldered on its flange, and drilled the end plate to accept the flange.  Then I CNC drilled the big bronze end plate to accept the flange.

 

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The angle piece is a commercially available plumbing part.  The stainless steel square nuts came from China.  Joins are silver soldered.  In a departure from the Tubal Cain/Julius deWaal plans, I decided to attach the chimney flange directly to the flat end plate.  I reckon that’s what would have been done in 1806, and it is what shows in the 1820 Rees Encyclopaedia drawing.   Note the unwanted threaded holes, now filled with stainless steel threaded rod.

Then I carefully positioned the bronze end plate, the firebox and the firetube, and silver soldered them together.

 

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The parts are fluxed and pushed together, ready to apply some serious heat and expensive silver.

 

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Not pretty, but I am happy with the silver joins.  Minimal retouching required.

Next, the inspection hatch will be soldered to fill the rectangular hole.

Then the main bronze flange will be permanently attached to the boiler shell.  I intend to silver solder it, but considering bronze brazing.

 

 

 

Back to the Trevithick Dredger Engine

The 6″ vertical boiler is virtually completed.  Well, actually, I still have to make a Duplex steam pump, fit a steam injector, make a steam delivery manifold, paint some bits….  but yeah, emotionally, for me it is finished.   I will get back to those bits as the mood takes me.

So I have picked up the bits of the Trevithick steam dredger engine.  I will concentrate on the boiler, so I can get the AMBSC certification, then take a leisurely approach to the engine.  You know, 2 weeks to the boiler certification then another 4 weeks to finish the engine.  Or something like that.

 

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As you can see, I have redesigned the inspection hatch, and made the new version.  This is still not quite authentic, but it is much closer to the London Science Museum example.  The inspection hatch will be permanently closed, silver soldered shut.   And the wording reflects the fact that this is a model.  The model hatch is circular, whereas the LSE example is something between a circle and an ellipse.   Trouble is that we do not know what is original Trevithick and what was altered in 1870.   So I do not feel too guilty that I am guessing.

 

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Sorry about the poor focus.  I will retake this shot later.  You can read my new AMBSC ID number.  I do feel presumptuous writing my name the same size as Trevithick.

 

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I have marked the boiler perforations and will drill the holes then make the bronze bushes.

 

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A hi res photo of the dredger engine in the LSM.  You can see that the inspection hatch is something between a circle and an ellipse, not a rectangle. And that firedoor hinge is definitely sus.

 

 

 

 

 

How does a 6″ vertical boiler enhance house decorating?

When I was making the 6″ vertical boiler, SWMBO commented, “you needn’t think that is staying in the house!”

Well, she did say,  after the boiler bands went on “Hmm.  That looks quite interesting”.

So I took that as my invitation to put it somewhere….  in the house….

 

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This desk is just inside the front door.  The boiler sort of melts into the background, don’t you agree?   SWMBO has not spotted it , yet.

 

6″ Boiler Lagging -3, and back to the Dredger Engine.

The brass bands which secure the wooden lagging strips were installed.  5 bands were required to make sure that every piece of wood is held once the glue lets go.  The bands are only 4.75mm wide.   The bolts which apply the tension pass through small brass blocks which are silver soldered onto the ends of the strips.  (thanks Ben De Gabriel of EJ Winter for that tip!  And for the band material!)

 

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The boiler sitting on our kitchen table.  I will eventually paint the ashpit door assembly and angle plate at the base.

 

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The setup for holding the small blocks in position during silver soldering.  In order to not close up the gap between the small block and the brass strap, I centre punched the blocks, raising small dimples, which produced a thou or two of separation between the parts, allowing the molten silver solder to flow.  That silver solder wire is 0.5mm diameter. 

 

 

And back to the Trevithick Dredger Engine….

 

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The redesigned inspection hatch.  The bronze rectangular bit plugs the hole in the end plate.   I have plugged the unwanted 14 holes in the end plate, using stainless steel threaded rod.   And metal worker’s hands, cut, dirty, dry thick skin (SWMBO “don’t come near me!”).

 

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Four of the plugged holes around the firebox opening, 10 more under the inspection hatch (hidden), and the inspection hatch.  I will make the inspection hatch a little bit smaller.  It will be decorative, permanently attached and unable to be opened.  The dredger engine in the London Science Museum has the manufacturer’s name cast into the plate.  I am contemplating just inserting Richard Trevithick’s name and the date the first high pressure engine was made (1806).  There will need to be a separate area on the boiler wrapper the AMBSC identification.

 

 

 

 

Boiler Lagging -2

The Tasmanian Oak lagging looked too pale white to my eyes.  With use, steam, oil, dust, water, workshop grime and sunlight, it would have gradually acquired a well-used patina, but I prefer instant gratification.

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So after consulting my resident wood finish, artist, architect, expert, (SWMBO), I applied some wood-stain.

 

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Too orange, too patchy, she said.   And the white in the joins looked wrong.

Too orange, too patchy, and too much white showing.  “Put on some black boot polish” she directed.

So I did as I was told.

 

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With a boot polish brush…

 

 

 

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—and a toothbrush…

 

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… hmmmm.   I better clean her toothbrush before putting it back….

…(acknowledgments to Tubal Cain for using his old gag…)

 

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That’s the look I was wanting.

Now just waiting for the brass bands to arrive.

Ben De Gabriel from EJ Winter, Sydney, had sent me a remnant piece of banding to try, in my last consignment of parts from him.  It was perfect, but not enough for the 5 bands which I require.  So I rang him.  He thought that was the last of his stock of that particular size but he would check and let me know.  Sure enough, he returned the call, and he had found a couple more bits, and they would be just enough.  Old stock, a bit shop-soiled he said.  So I could have it for nothing!

Readers who have been with me for some time will know that I have bought 3 sets of engine castings and plans from EJ Winter.  The Bolton 7 horizontal Mill engine, the Bolton 12 Beam engine, and the Bolton 9 triple expansion engine.  A bit of very interesting news is that Ben is planning a new set of castings for the triple, using the lost wax casting technique, which gives a finish which should require machining on the mating surfaces only.  That sounds so good that I am almost tempted to make another triple.   Almost.   Some months until availability though.  (Hope that you don’t mind my premature announcement Ben.)

 

 

 

6″ Boiler. Lagging.

Lagging.  As in boiler insulation, not as in failing to keep up.  I have been working on the boiler for about 3 months, so I am actually happy with the progress.  And more than happy to have passed certification!

I decided to apply wooden lagging strips for the appearance and for ease of handling, rather than any minimal improvement in performance of the boiler.

After use, the boiler shell is too uncomfortably hot to handle, so there is a waiting time of 30 minutes or so to allow it to cool.  I am hoping that wooden lagging will reduce the waiting.

And wooden lagging will hide the splodges of silver solder around each boss and join.  And it looks the part IMO.

But how to attach it?  None of my books mentioned any method.  I presumed that the brass strips are the main method, and that is certainly so, on full-size boilers.   Then I found a short video on YouTube by Keith Appleton and I decided to copy his method.

The method uses Super Glue as a temporary securing method while positioning the strips, then applying brass strips to hold the wooden strips in place long term.  The boiler heat and expansion-contraction will result in the glue bond being temporary, and if the wood strips have to be removed later, for any reason, that will be possible. It also means that an insulating blanket cannot be inserted between the copper shell and the wooden strips, but I was not planning on using a blanket, so not a problem.

 

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The strips are 3x8x265mm.  I chose Tasmanian Oak which is actually an ash, because it is hard, fine grained, and I had some in old floor boards.  I cut the pieces to length a bit oversize, then ripped them to size on the bandsaw.  It is difficult to avoid fingers being close to the blade with small pieces like this, so I used a push stick.  I needed 65 pieces.  The blade teeth are a bit too coarse for this job, but I was too lazy to change it for a finer one.  Note the saw blade guide.  I did not like the one which was provided by Metabo, so I made that one.  Works well!

 

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Then I used a belt sander to remove most of the sawing marks.  The resulting thicknesses varied from 2.8 to 3.4mm but I hope that variation will not matter.

 

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Some hand sanding to remove wood fur.

 

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Hope that this will be enough pieces!

 

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The boiler feels out of place in all this woodworking rubbish.

 

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SWMBO was away, so I set up on the kitchen table.  Here deciding on the final length of the strips.

 

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Each piece is cut to length, then fitted into position.  Shaping the wood to fit around bosses and fittings is done with a small sanding drum in the Dremel.  It is a slow process.  Then each piece is glued into place, and held with rubber bands.

 

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It has taken about 4 hours to apply about 1/3 of the strips.  The Baileys was to keep me in an appropriate mindset.  I am looking at the slightly ragged top and bottom edge in the photo.  Looks a bit rustic and authentic, or just rough?   The wood will be darkened after oiling, and possibly staining.  And Tasmanian Oak darkens with exposure to light.

That was yesterday.  Today I hope to complete this job, but SWMBO is home, and not appreciating the dust and mess, so I am exiled to the outside.

I have realised that to secure all of the wooden pieces I will require 5 brass bands.  I do not want it to look too brassy, so I am ordering narrower strips than the 6mm material which I had previously bought.  I think that 4.75mm will be about right.

 

 

 

 

 

 

 

 

VR-18-18

VR-18-18 Stands for Victoria, Geelong Society of Model and Experimental Engineers, 2018, 18th registered boiler for the club.

So this morning I fired up the boiler with the boiler inspector closely watching.  The gas was turned to maximum, and the water was showing full.

Steam appeared about 10 minutes later and the Sandberg safety valve started popping at 100 psi. Every couple of minutes the safety valve released and the pressure remained in the 97-100 psi range.  This went on for about 20-30 minutes.  All to the satisfaction of the inspector.

He was happy with the standard of the build, the pressure test, the accumulation test, and that all requirements had been met.

The boiler is now certified for 4 years.  There has been a change in protocol about which I was unaware.  The previous certification rule was for 12 months only, and retesting was required for a further 3 years.  So this new rule is much less time consuming for me and the inspector.  He is happy that before the next testing I will have a steam pump and a steam injector installed.

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I was so delighted with the result that I treated myself to a trip to the non ferrous metal supplier, and bought a selection of hex brass stock for the workshop.  When I returned to the workshop there were still a few hours of daylight, so I spent the time making the new inspection hatch for the Trevithick dredger engine.  Not quite finished, so no pics yet.

The next step for the boiler is to make and attach the wood lagging and to put on some paint.

New Skills in Retirement.

When I retired from my profession almost 4 years ago, I had an aim to become proficient at in CNC machining, and 3D CAD drawing.

I have definitely improved in those areas.  Trouble is, that as usual, the more that you learn, the more you realise that you need to know.

And in making some items, you encounter the need to learn skills entirely unexpected, like bronze brazing.

And all the while, your eyesight is deteriorating, your memory has gone somewhere (I forget where), and by mid-afternoon, all you are thinking of is sitting down with a good red.

One unexpected skill which has surfaced, which I am really enjoying, is cooking.

My wife, who is still working at what she loves,  announced a couple of years ago that since she is now the bread winner, that I could take over the cooking.  That was OK.  In fact it was something which I wanted to do when I was a teenager, but my rather traditional Mum did not think was appropriate.  So except for doing the camping cooking and barbeques, I did not cook until in my late 60’s.

Then I started cooking the evening meals.  And really enjoying it!  And my wife loves the freedom from the chore.

Trouble is that I detest shopping.  So the solution was a box of recipes and ingredients delivered once weekly.  HelloFresh.  It has been superb.

Then recently the cardboard box was not delivered.  Or at least it was not there at 7am on my doorstep, having been delivered at 2am.  A date stamped photograph was proof of delivery.  So it had been delivered, and stolen.  I am suspicious by nature, and having had no thefts here in 40+ years, I wondered about the delivery person.

Hellofresh took no responsibility.  I had no evidence to support my suspicion.  So we ate toast and cereal and take away for a week.  But I was really pissed off.

So I have spent several days installing a surveillance camera system.  I had installed a similar system some years ago in my workshop, so I felt reasonably confident that I could manage it.  Buying the system was straightforward.  Seems that they are commonplace.  4 cameras.  Recording machine with 2 terabytes of hard disk!  And connected to the Internet, so I can see what the cameras are seeing at any time, on my iphone!  And get alerts if the motion plus heat detectors are triggered.  Amazing!

Trouble is that I had to install the system myself.  It seems that the legal system has pushed professional installers to extinction, by making them legally responsible for thefts where systems are in place.

And at 68, I did not enjoy getting up and down ladders installing cameras and cables.  Or scrambling about amongst the spiders and crap under the house.  But at the time of writing the system is in place.  And working.    Another retirement skill.

And the clarity of the 4K pictures is outstanding.

What I will do if the alarm is triggered is another question to be pondered.  This is Oz, not US, so going outside with guns blazing is not an option.  Thank goodness.

A steam driven water pump, and a whistle.

Boilers, whether full size or model, get through substantial volumes of water.  When my 6″ vertical boiler is working hard, so is the water pump, to replenish the water which is turned to steam.

At present, the water pump is a manual pump, and it needs to be operated almost continually when the boiler is steaming hard.

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I am not sure whether operating the hand pump (lower right), or the propane burner, consumes more energy.

So it was with great interest that I viewed the steam pump in operation which was built by Stuart Tankard, at last night’s meeting of GSMEE.  I have plans and castings for the same unit, and expect to make it later this year.  It is a Worthington type pump, and the castings and plans were supplied by Southworth Engines.

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Stuart’s latest.

 

In this video, for the demonstration, the pump is running on very low pressure compressed air.  The larger cylinders are the steam powered driving cylinders, and the smaller ones are the water pumps.  So whatever the pressure of the steam, the water pressure will be greater, and able to be pumped into the boiler.

And finally, I bought a steam whistle.  It was supplied by Microcosm.engine from China and it was very reasonably priced. ($US39).  I have not tested it yet, but it came highly recommended by Keith Appleton.  It is certainly very nicely made.  I screwed it onto the boiler as a bit of bling because I showed my boiler progress at last night’s meeting of GSMEE.

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Almost ready for the boiler inspector.

Almost ready for the boiler inspector!

It feels like the countdown to the finals medical exams!

So today, I drilled the gas jet from 0.22mm to 0.3mm.   A drill bit to drill 0.3mm, is, at least to my eyes, barely visible.  It is finer than the finest sewing needle.  If I pick up a 0.3mm drill bit I can not feel it.  It has no discernable weight.

So this is how I increased the jet size from 0.22 to 0.3mm.

Oops!  I forgot to take a photo.  I bought a set of micro drills from Jaycar, and the smallest bit was 0.3mm.  So I mounted it in the Dremel, and ran it at 10,000 rpm.   for a vise I used my fingers.  The drill went straight through the millimeter or so of brass with no detectable resistance.   Managed to miss my fingers.

0.22mm to 0.3mm diameter is almost a doubling in area of the jet orifice, so I tested the flame.  It was (not surprisingly) much bigger!   And still a good blue colour, with minimal yellow.  So I stopped there.   I also installed an adjustable propane regulator Huib.

Then I made an angle piece to secure the boiler to its baseplate.

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I needed a non rusting disk, 165mm diameter, with a 152mm hole.  The disk was 2mm thick.  So I roughly bandsawed it out in 2mm brass sheet, then set it up in the lathe as shown above.  Turned the outside diameter.  The brass sheet is held just with pressure between the headstock and the tailstock, and the disks of wood.

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Then I held the disk in the 3 jaw chuck and used a parting tool to cut out a disk to form the middle.  The waste middle came out with a bang.  I was careful to stand to the side, anticipating the decapitating scythe.   And I was not disappointed.  I did have to check that my head was still attached.

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Again, I was so involved with the machining that I forgot to take pics.  The vertical part of the angle piece is a slice of copper tube which I had reserved.  It was silver soldered to the brass  disk, then screwed to the boiler wrapper.   Some further fitting, and it ended up like this.

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The hand pump has been mounted.  yet to be connected.  A steam driven water pump will eventually occupy the spare space.  And just to make quite sure that there is enough water pumping capacity I will also be installing an injector.

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And another nice bit of bling (John).  This globe valve was made by Stuart Tankard.  I have borrowed it, pending me making one of my own.

Another pressure gauge.

Stuart Tankard rescued this large pressure gauge from being scrapped, and restored it.  It is now often on display at our club exhibitions.  I confess that I did not pay it much attention, until my recent interest in boilers and pressures.

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It is a big gauge, and the works are all on view.  The blue light is aesthetic I think.

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You can see the Bourdon tube, the link, the quadrant.  The nice aspect is that this gauge is very accurate.

 

 

6″ Vertical Boiler- the ID plate

Last task before the boiler inspector.  The unique identifier.  In my case the VR-18-18 code is stamped on the boiler in a safe location, or engraved onto a plaque which is silver soldered to the boiler shell.

I chose the latter method.  And used the opportunity to put my name and date on it.

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CNC’d the info onto a brass plate, and bent it into shape,  I use V-Carve Pro for engraving jobs. 

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Then silver soldered it into position.   In this case I used a lower temperature silver solder… “StayBrite”, so I did not risk melting the previous joins.

 

6″ Boiler. First Steaming.

Today I put water in the boiler, about half way up the sight glass, hooked up the gas, and lit the flame.  Very nervously.  What if it blows up?  What if one of the soldered bosses blows out?  What if the safety valve does not work?

Admittedly, before that I had pressurised the boiler with water, with the fittings, to 150psi, and without the fittings to 200psi, and that seemed OK except for a leak in the sight glass.  But even so, a steam test has a lot more at stake.

I had set the safety valve to 100 psi with water, but steam is a quantum leap in risk.

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This is what it currently looks like.

The burner works OK, but I am expecting that it can be improved.

It took 5 minutes to get to 25psi, 6″ to 50psi, 7″ to 75psi, and 9″ to 100psi.  At that point the pop safety valve released, suddenly and loudly, giving me quite a start.  For a few psi under 100psi it had been releasing small amounts of steam, but the “pop”, in the confines of my workshop, was really impressive.

And a video of the boiler at 100psi.  Sorry about the commentary.  Must brush up on my video skills.

 

 

Boiler. The Pressure Gauge.

I have learned a bit about pressure gauges from Frank, who used to manufacture them, and from Stuart, who made a 5″ vertical boiler which was the inspiration for my 6″ build.

For one thing, pressure gauges become less accurate as they become hotter, so steam should not be allowed into the Bourdon tube.  Which means that there should be water in the line between the steam and the gauge.  That can be managed with a pig’s tail coil of copper tube, or a water reservoir, which is what I made.

For another thing, gauges have varying accuracy, and I am fortunate in having a friend who has calibration equipment, so I can obtain information about the degree of accuracy of my selection of British and Chinese gauges.

Then there is the aesthetic appearance of the gauges.  A matter of taste, but I really like the older “Smiths” made in UK gauge.

So this is what I ended up installing.  I might change my mind later, but for the moment…..

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These are the gauge components.  The Smiths gauge itself (needs a 100 psi red line), the brass support made today, and the copper tube which provides the water barrier.

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I like it!  Hope that you agree.  Still need that shed tidy-up.

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Boiler flame fixed, and firedoor progress

The propane burner was fixed by RTFM.  There I noted that the burner was intended to be run straight off the bottle with no regulator.

I replaced the jet with one of the original size, and connected the supply hose directly to the bottle without a regulator.  Resulting in a beautiful clear blue flame.  Which did not show up well on a photo so you will just have to take my word for that.  I intend to experiment with slightly larger jet openings to fine tune it.

Then to finish the workshop session I made some fiddly little bits for the fire door.  “Bling” as my friend John would characterise it.

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You might notice the latch limiter, and the handles on the latch and the vent.  M2 screws.  All of those bits work well.  Some finish filing still to be done.

Boiler stand, gas fire, and firedoor latch/catch.

The boiler will most often be fired on gas, but it is being made so that it can also use coal-wood.

So the base needs to cope with ash from coal or wood, and also have adequate clearance to fit a gas (propane) burner.  And to look OK.  And to be not too heavy to carry.

This is what I have come up with.

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Two plates of 6mm aluminium, separated by brass pillars.  It should polish up nicely.

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This is the first burning test. Fail!  Too much yellow.  Not enough blue.  Back to the drawing board.  Propane – air mix is not correct.

So I increased the jet diameter……

The flame size increased, but the mix did not improve.   A work in progress.  Another jet change, and an adjustable regulator to be tried next.

To do something positive, I made a firedoor latch and catch.  Some CNC and filing.

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Not finished, but going OK.

 

Just how strong is a silver soldered join?

I bought some 6mm x 0.7mm brass strip to hold on wooden lagging on my 6″ vertical boiler.   Trouble was that I could find suppliers who had the strips only in 300mm (12″) lengths.  So I decided to join 2 of the strips to provide the 450mm lengths that I need.

I have made band saw blades with silver solder, quite succesfully, but the ends were scarfed so the join was over a 5mm or so length of the blade.

I wondered whether I could butt join the brass strips with silver solder, and if so, whether the join would be adequately strong.

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So here are the brass strips end to end, fluxed and weighed down so they do not move.

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And here is the silver soldered join.  Not particularly neat, but OK for the purposes of the test.

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The other side.  As I said, not particularly neat. And I did not even bother with an acid soak.

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So I drilled a hole in the end of the joined strips, and wired on a hefty weight.  The top end was held in the vise.   Seemed OK so I increased the weights.

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Looking down the strip from the vise.

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By this stage I was standing back, expecting the soldered join to give way.  But it did not.  Hmm.   Must do a tidy up soon.

 

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21 kg, 46.3lbs.

At this point I stopped adding weights.  I think that the soldered join should hold the wooden strips to my model boiler!

Are you impressed?  I am.

 

 

 

A new skill- riveting stuff

And I don’t mean pop riveting.  I used some solid copper rivets on the vertical boiler today.  I tried to avoid them, hoping to use small bolts and nuts instead, or even soldering,  but ended up doing it properly and using solid copper rivets.

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They do look the part.  No?  This is the ash pan door.

The copper rivets are already annealed.  You need an anvil with a depression which is the same same shape and size as the rivet head, a hammer, holes drilled and a method of cutting the rivets to length.

I secured the anvil in the vise.  The anvil was a bit of steel rod into which I bored a hemispherical depression with a ball nose end mill.  I super glued the boiler parts together, then drilled them.

Then hand held the parts containing the rivet, used side cutters to cut the rivet to length so that about one diameter of rivet was protruding, placet the rivet head onto the anvil, then gave the cut end a few taps with the hammer, to pean it over and secure it.  Easy as!

Those are the first solid rivets I have used.   Ever.

Then I silver soldered the handle in place.

The next job was a bit trickier.  I made some holes in the smoke box lid to let the safety valve and dry steam header poke through.  I tried drilling them initially, holding the lid with my hand, but the inevitable happened….   the drill bit grabbed, spun the work around, threw it and left a row of little dents on the copper surface.  I had been contemplating polishing the copper or painting it.   I guess this little accident means that I will be painting it.

So next I held the lid on the wooden form which I had used to make it, and held the form in the drill vise.  No more grabbing and throwing, but it was a bit tense.  I gradually worked up the drill sizes, and when it became close to the desired measurement, I filed the last bits.

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Those taps are vertical.  They appear to diverge because the iphone has a wide angle lens.  2 penetrations made.  One more to go.

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