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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: copper boiler

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.

Oxy-acetylene or Oxy-propane for silver soldering (and bronze brazing)?

There has been a big learning curve for me in making the 6″ vertical boiler and the Trevithick dredger engine.  I have used silver solder for previous projects, and I thought that I had the method under control.

I have always used oxyacetylene for my earlier, smaller projects, presuming that the higher flame temperature would produce results more easily.  That is what I tried to do with the 6″ boiler project.  But I struggled.  In order to produce a broad flame, and not burn the copper, I used a big, number 26 nozzle.  Initially it produced a lovely big hot flame, but within minutes it started popping, and blowing out.  Faulty acetylene gauge?  Gun not up to the job?  Acetylene cylinder running low?  So I replaced the acetylene cylinder. Cost $AUD100.   Seemed to fix the problem temporarily, but then the popping resumed.   Faulty gauge?  A borrowed replacement gauge produced the same result.

So back to the welding and gas supplier.

“You cannot run a nozzle bigger than No 15 when using acetylene.  The acetylene does not come out of solution in the cylinder quickly enough”.

OK.  So what do I do?  “Use propane”.  “but you need different hoses, different gauge, different mixer and nozzle”.  OK, give me those….  cost $AUD 260.   And it worked!!!

Propane and oxygen burns at a lower temperature (~2820ºc) than acetylene and oxygen (~3420ºc) , but the gas volume delivery of the propane is MUCH greater than the acetylene.  So the delivery of the heat is much greater.

For me, I will be returning the acetylene cylinder and permanently switching to propane.  Much cheaper and much more heat.  But, that heat can lead to unintended consequences…So, here we are on the Trevithick dredger engine.  I needed to bronze braze the join between the firebox and the firetube. (a boiler inspector requirement).  Bronze melts at 836-1030ºc which is not far off the melting point of copper.  And my first attempt ended in disaster!  I melted the copper firetube!!!  An expensive blob of copper and bronze!!! (no photos.  I was too cross with myself).

The next effort was an improvement, but not pretty.

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Using a holesaw to cut a 38mm hole in the 64mm copper tube.

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The angle was not quite right, but fixed with some careful filing.

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Setup, ready for bronze brazing.  The firebricks are holding the pieces in position.

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After bronze brazing.  It is not pretty, but I am a beginner at this.

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The end plate was used as a jig.

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And then I accidentally dropped it. (#$#%&**#)  Restored to proper shape with some careful blacksmithing.

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My great great grandfather was a blacksmith.  

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OK.  It is not pretty.  But not bad for a gynaecologist.

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And to show you what Trevithick’s blacksmiths made to his design.  I count at least 19 individual iron pieces, riveted together.  This was the firebox and firetube of the first high pressure boiler.  Incredible!

 

 

 

 

 

Trevithick Dredger Engine- the flat end

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The 6″ vertical boiler has had its first brazing session, and has been put aside while I wait for the boiler inspector to give the “go ahead” so I can proceed to the next brazing session.  I am told that the first braze is the most difficult.   The next braze is bigger, but the components are all on or near to the surface, and it is consequently more straightforward.

So, while waiting, I pulled out the Trevithick Dredger Engine, and decided to make the flat end plate and flange.  These are machined from LG2 bronze disks 13mm and 8.5mm thick.

bronze blanks

204mm diameter.

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An aluminium sacrificial plate was made and held in the milling vise.  The bronze disks were CNC drilled.

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The disk which will become the flange is tapped.

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The holes in the end plate were CNC’d on the mill, which died during the procedure.  The Z axis went crazy.  Fortunately I managed to hit the panic button and the end plate was not destroyed.   Currently Stuart & I are trying to determine the cause of the robot madness, but that looks like being a lengthy process.   The rebate being completed on the lathe in the pic would have been an easy CNC mill process, but the workpiece was quite thin to be held in the lathe chuck.

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Showing how the end plate was held in the lathe chuck, with double rare earth magnets holding the plate away from the chuck jaws permitting the tin workpiece to be turned.  A bit tricky, but went well.

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The flange on the left will eventually be brazed to the boiler shell.  The end plate on the right will be bolted to the flange. 

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The end plate and the flange mated together

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The big tube 65mm diameter will become the firebox,  the smaller one 38mm dia will be the firetube exhausting to the chimney.

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None of the tubes are yet cut to length, but starting to take form. 

 

6″ Vertical Boiler- First silver Brazing

So what is the big deal?

Well for a start, this is a big deal financially.  The materials to be joined are expensive, and some are difficult to obtain.

And the silver solder itself is expensive.  We ended up using 4 sticks of 45% silver solder, and an unknown quantity of oxygen, acetylene and propane.

And the end result will be inspected by an expert boiler inspector, and if it is substandard, it will be rejected.  No argument.

So yeah, it was a big deal.  Look at the pics.   A few friends called in to watch and help.  It was a cold wet winter day, and I had the workshop wood heater working to keep the troops happy.

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I used steel wool to expose the elemental copper.

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Me applying flux.  Note the silver solder rings which were made on the lathe.  Don’t ask where the brush originated.

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The firebox wrapper was placed on the aerated concreted form to keep the tubeplate level, and allow the tubes to penetrate exactly 2mm.  The tube ends were fluxed, and silver solder rings placed into the join.

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The 44 fluxed firetubes with their rings of silver solder are in place.  The top tube plate will not be brazed at this time.  It is there to keep the firetubes in the correct position.  The firebox tubeplate is also fluxed and sitting in position on its Hebel block.

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Me on the left with the propane weed flamer applying gross heat, Stuart with oxyacetylene applying local heat and silver solder, and Swen cheering.  Brendan is the photographer, trying not to get burnt.

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We probably should have reshaped the forge to reflect the heat more efficiently.

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When the brazing seemed to be finished, the work was allowed to cool to 200c, then quenched in water then a 15″ soak in 20% sulphuric acid to remove any remaining flux, then a further water soak to remove any acid.  Yes, the top plate is upside down.  Yes, it will be reversed eventually.

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Inspection from inside the firebox.  Most firetubes have taken the silver solder properly, but a few of the inner circle and the flue require a second application.  The brazing heat looks to have been inadequate near the centre, probably due to the density of the firetubes.

So, not a perfect result, but not bad for a beginner.  Stuart opined that the job would have been better if my silver solder was the older, (more dangerous) but more runny type which contained cadmium.

6″ Vertical Boiler. Ideal soldering set-up block. Concrete!

OK.  My non machinist readers will have no idea what I am talking about.  And I suspect that my machinist readers wont either.

I need some precisely machined and measured blocks to set up the soldering for the boiler.  I want them to not suck up my soldering heat (so no metal), and to not stick to my silver solder (so not steel, copper, etc).

How about concrete?  More specifically, aerated concrete.  Hebel.

Look at the pics……  I need a cylinder, about 100mm high and 110mm diameter, which will not absorb heat and not stick to silver solder.

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This is a 600x400x75mm Hebel block.   Cost $AUD4.60.  It is part of my forge, but will be replaced easily.

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Marked out the bit I want.

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So I cut it on the bandsaw.  It is aerated concrete.  Hebel.

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Cuts quickly and easily.  Probably not good for the blade.  But we will see.

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How accurate is the thickness??   Pretty amazing IMO.  within 0.1mm.  The second measurment is after a quick touch up with emery paper on a flat plate.

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And this is the first setup, ready for soldering.   Watch this space.  soldering in 2 days.

 

6″ Vertical Boiler Chimney Flare

I was relieved from duty with the ankle biters for a few hours today, when my wife took them to the local animal sanctuary.  They petted a Tree Python (OMG!), and a Koala, and were entertained by the talking Sulphur Crested Cockatoos, one of which is aged 91 years!

Making the most of my temporary freedom I visited the workshop.  Soldered the chimney support to the smoke box roof, and made a chimney flare.  It probably has a more technical name, but when you see it, you will realise where it goes.

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6″ Vertical Boiler- Chimney flange

I was not required for childminding for a few hours yesterday, so a quick visit to the workshop.  Not much to show, but I did make 2 circular flanges to attach the chimney to the smoke box lid, and soldered them in place.

Getting a flange to be exactly perpendicular to its tube was tricky.  I set it up in place, and soldered it, only to find that it had moved significantly out of position.  To fix the problem I turned a steel collar to fit around the chimney, re-heated the soldered pieces with oxyacetylene, trying not to overdo the heat so I did not melt the brass flange, but enough to melt the silver solder, but not allowing the solder to join the steel collar to the brass or the copper.   Then I lightly tapped the flange onto the turned collar, hopefully into the correct position this time.  Sounds simple?  But applying the heat, and tapping the flange required one or two more hands than I possess.

But it turned out OK.

I had drilled and tapped the holes prior to soldering, and they all matched well.

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The chimney is about 300mm long.  The bottom part has been dipped in suphuric acid, hence the clean appearance.  Still considering options for the chimney flared section.  It needs some form of decorative flare.

 

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The bottom flange is soldered to the “Heldon” labelled tube, which will be soldered later to the smoke box lid.  The fasteners are M3 stainless cap screws, which will be reversed on the boiler with nuts showing above the flange.

6″ Vertical Boiler. The final flange on the smoke box.

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This is the smoke box lid.  The chimney comes out of the middle but it requires another flange.

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So this is the cover, with the extra flange.  How did I make it?  Read on…

First a video.  Click on the arrow.  Listen to my dulcet tones.

 

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The setup on the hydraulic press.   The copper cap has been annealed, and a 19mm hole drilled to just admit the steel taper pin.

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After pushing the steel pin with 20 tonnes pressure.  Re-annealing required. 

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After the next 20 tonne push.  Re- annealing again required.

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After the third annealing and a final push with the press.   A bigger press might have done this in one step, but at the risk of the copper splitting. 

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and a 10 minute soak in 10% sulphuric acid…

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—and a tidy up of the edges in the lathe.  The intermediate piece is pushed into place, ready for silver soldering.   A couple of circular flanges to be soldered in place to hold the chimney.

Considering the force exerted on the wooden forms, I would not have been surprised if the wood had split on the hydraulic press.  But it held up.  Even so, another time I would be tempted to make the forms in steel.

6″ Vertical Boiler, Using Clekos, and dropping the Traction Engine into a hole.

Tha firefox wrapper is made, and today I fitted a butt strap.  The butt strap will be riveted to the wrapper, and brazed later.  In order to drill the rivet holes, the parts needed to be held together, Clekos proved perfect for the job.

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Using the external clamping Clekos to keep parts in place while I drill the first hole.

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Then as each hole was drilled an internal Cleko was inserted.  Worked very well.

Then, a Bit of fun on the TRACTION ENGINE

Oh Bother.  Where did that hole come from?  And why isn’t this traction engine a 4 wheel drive?  Had to uncouple the trailer, and two men to push it out of the hole.

The redesigned steam regulator worked very well, as did the steam driven suction pump.  The new oiler filled up with steam, so I need to fix the non return valve.  Probably a bit of grit in it.

 

6″ Vertical Boiler

Today I made a start on the vertical boiler.  I will be working on this as well as the Trevithick dredger engine, trying to coordinate the boiler inspection stages for both projects.  I have most of the materials, including the boiler cylinder copper tube and the copper plate for the boiler ends.  So today I made the top tube plate and the foundation ring.

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The tube plate was a similar process to the Trevithick boiler end which I described in the previous post.  I made another form but this time I used Gippsland blue gum.  The European oak form which I made for the Trevithick did not last the distance with all of the hammering, and it broke.  The blue gum is an incredibly hard tough wood, and it did not even show any marks after making the boiler end today.

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The end is quite flat.  It is an easy sliding fit.  Holes for firetubes and flue yet to be drilled.

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The electronic thermometer is quite handy, making sure that the copper is adequately heated.  I take it up to 600c, and maintain it there for 30 seconds before quenching.  Dull red is 500c, bright red is 600c.

THE FOUNDATION RING

The foundation ring is made from square section copper 9.5×9.5mm.  I rolled the rod to form the circle so it just fits into the boiler tube.

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This is after 3 or 4 passes of the un-annealed square rod, through the home made ring roller.

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The ring is almost closed

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Measuring the external diameter of the ring.  The large calipers are made of aluminium, were  inexpensive, and are surprisingly accurate.

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At this point I needed to bend the very ends of the copper rod, so I annealed the copper, and bent the ends by hammering over a steel form.  The ring roller does not bend the last 30-35mm.  The weed flamer gives out a lot of heat; nice on a cold day.

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The red hot glow of copper is a superb irridescent colour.

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Then the ends were trimmed (after cooling) and bronze brazed.  I would have silver brazed the join, but I misjudged the position and needed to fill a gap, so bronze was required because of its gap filling property.

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Tidied up in the lathe, and cleaned with a brief soak in sulphuric acid.

So, making progress.  A beautiful winter day in the workshop in Victoria, Australia.

Trevithick Boiler End

The first part to be made for the Trevithick dredger engine is the domed end of the boiler.  It is formed from copper plate which is 3mm thick.  first a circle is marked out, then bandsawn from the copper plate.

I decided to make a wooden form.  Fortunately I have a CNC lathe (see earlier posts about the CNC conversion of a manual lathe), so drawing the profile and generating the G code using Ezilathe was, well, easy.

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CNC’ing the wooden form for the boiler end plate.  The roughing steps.  Carbide tip which has been sharpened to a cutting edge, suitable for wood.

This is the final roughing cut, and starting the finishing cut.

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CNC turning.  Light sanding required to remove the fur.  The wood is European oak.  Central hole for a locating pin.

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The oak form was attached to a red gum block which was held in a 6″ vise.  I have already commenced shaping the copper disk here.  The copper is cramped to the oak form after annealing, and gradually hammered to shape.  Tapped rather than hammering.

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My “forge” is a few fire bricks in a steel shell, and a roof of steel to help retain the heat.  The torch is fuelled with propane.  It was originally a weed flamer, used to burn serrated tussock.

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Red heat was achieved in 90 seconds.  This is 600 degrees centigrade.  copper melts at 1084c, so there is a good safe margin.  I quenched to cool, for speed.

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This welder’s clamp proved to be the most effective method of holding the copper disk to the form.  I fitted  copper and  brass heads to the tapping hammer to minimise the chance of “bruising” the copper.

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Progress

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About 10-12 heating-hammering cycles in 1.5 hours to get to this stage.

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Getting close.  I will finish it tomorrow.  Might wash up before cooking dinner.

Buying Copper Pipe for Model Boilers

My next 2 projects require 150mm (6′) copper pipe for the boilers.  The Trevithick dredger engine will operate at only 30psi so the wall thickness needs to be only 2mm thick to comply with the AMBSC regulations.  But the other project, the vertical test boiler will operate at 100psi and the copper needs to be a minimum of 2.5mm thick, or preferably 3.0mm or 3.2mm.

I had purchased a 350mm long x 2.8mm wall thickness piece of 6″ copper pipe at an engineering club swapmeet, so I thought that would be OK for the test boiler, but when I examined it closely I noted some scribed lines from the previous owner’s intended project.  There were also some drilled holes, but they can  be used or filled.  The scribed lines were unacceptable, so thinking that they were not very deep I carefully skimmed the cylinder surface on the lathe.

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The headstock end is held lightly in the 3 jaw chuck.  The tailstock is centered in a piece of fitted Delrin.

Taking off 0.05mm per pass, and using a sharp Diamond lathe tool (from Eccentric Engineering), when the marks finally were removed, the wall thickness was down to 2.45mm, just below the minimum thickness for the test boiler.  Bummer!  I can use that piece for the lower pressure Trevithic engine, but what to use for the test boiler?

So I contacted every Australian copper pipe supplier that I could see on the Internet, every model engineering vendor, and visited every plumbing supplies vendor in my region.  2mm thick pipe is available but nothing thicker.  Then to overseas suppliers.  Eventually I located some at MaccModels Engineering Supplies in the UK.  £7.67 per inch for the 3.2mm x 6″.  So my 12″ piece will be almost £95 ($AUD190) plus postage.  I took the opportunity to stock up a few other sizes which I will need for the 2 projects.  Postage came to $AUD170.   A bit painful.

So, to end this expensive story, my 3.2mm thick copper pipe is on its way.  I do feel a bit guilty about the Avgas being burnt to get it here, the kilogram x kilometers of air pollution and CO2.  And the annoyance that it is quite possible that the copper ore was mined in Australia, but I had to go to the other side of the world to buy a bit of the manufactured product.  Or is copper still mined in the UK?

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Gradually accumulating the materials.  The copper sheets and disks are 3mm thick.  The square section rod is for the boiler foundation ring.  I don’t want to start cutting until I have all of the materials.

BOILER FOR MODEL STEAM ENGINES

Now that the model triple expansion engine is working on steam, I feel able to put it aside, again, and move onto the next project.  The triple is not quite finished.  It needs cylinder lagging, control rods for the cylinder drain cocks, drain tubes for the cylinder drains, and an extra pump for the condenser cooling, and some paint, possibly.

It also needs a boiler.  I would like to exhibit the triple at club demonstrations and public exhibitions, but for that I need a boiler which is certified by our boiler safety authority.  So I intend to make a boiler to AMBSC code, and big enough for the triple or any other engines which I might make in the foreseeable future.

This is what I have in mind….

boiler assembly

This is a copper boiler with a 152mm (6″) diameter barrel, a superheater, gas or coal fueled, and firetubes (most not shown).  The plans call for a 5″ barrel, but I have been unable to find any suitable copper tube, and I have some 6″, so that is what will be used.  I am currently drawing up the plans.

The certification process here in Australia requires the following steps:

  1. Preliminary discussion with the boiler inspector (done)
  2. Submission of 2 sets of plans to the boiler inspector.  If acceptable, one set is signed off and stamped and returned.  The other set is held by the inspector.
  3. Inspection of the prepared components by the inspector prior to soldering/brazing/welding.
  4. Inspection of the firebox and tube assembly after soldering/brazing/welding.
  5. Inspection of the barrel and outer wrapper after soldering/brazing/welding.
  6. Testing the boiler after completion.  This involves a hydrostatic test, at double working pressure for 20 minutes, then a steam test at 10% above working pressure.

If it passes, the boiler is certified for 12 months, after which it must be retested.  If it passes the retest it is certified for 3 years.

The certification process is performed by volunteer inspectors attached to model engineering clubs, and is done at no cost.

However the materials for a boiler like this are quite costly.  I managed to obtain some  copper tube for the wrapper, and bought some copper plate for the firebox and boiler ends on Ebay.  Bronze for the bushes from a local bearing supplier (LG2), and firetube copper tube from local plumbing supplies.  All up, so far, is approaching $AUD1000.  And yet to be factored is the safety valve, various cocks, sight gauge, hand pump silver solder.  And I intend to make and fit a steam driven feeder pump, and possibly a steam injector.

If there is any interest in this project I will post progress notes and photos.  Let me know.

First taste of steam for the MODEL TRIPLE EXPANSION ENGINE

I made a video of this first run, but I am experiencing great frustration uploading it, due to our totally pathetic Internet speeds here in Australia.  I will include it later in this post, but the resolution is way down.  I will upload a higher res version next weekend.

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Stuart Tankard’s superb gas fired vertical boiler, was also getting its first run powering a steam engine.

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We did not connect the condenser until later.

OK, so here is the video.  Again, apologies for the low res quality.

Making a copper boiler

The boiler which powers the Bolton 7 steam engine is 250x100mm. The case is 1.6mm thick and the ends are 3mm thick. It has 7 x 6mm copper stays. The safety valve, pressure gauge, sight glass and valves were bought items. It operates at 60 psi but has been tested to 120 psi. Propane gas fuel.

Bolton 7 working with live steam

This is the first run of this engine using steam. I have previously had it going on compressed air, but there is nothing like real, live, hot steam!!

It did show up a few problems which I will have to fix. A few minor leaks, need for a displacement oiler, and need to adjust the length of the piston rod. You will hear a knocking sound in the video. I think that is due to the piston just touching the cylinder cap at the end of each stroke. Not difficult to fix, but will require a complete teardown of the cylinder=piston.

to see it click on the link below.

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