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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.

Category: Triple Expansion Miniature Steam Engine

How to time a Model Triple Expansion Steam Engine

The daunting aspect of timing the triple delayed the completion of mine by at least 6 months.  In the event, it was not difficult.

If timing a steam engine is not a particular concern of yours, I suggest that you turn off now.   Otherwise this will be particularly boring.  This post is in response to a request by a reader.

The engine needs to be pretty much completed and assembled.   Everything fitting.  Crankshaft rotating.  Valve rods tightened.  Stephenson’s reversing mechanism assembled and working. Cylinder drains installed.

Next I suggest that you make or buy a 360 degree protractor, and attach it to the crankshaft at the high pressure end.  Like this.

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Note that top dead centre (TDC) of each piston is marked (H,I,L), there is a pointer, big marks at 120 degree intervals, and identifiable marks at 10 and 5 degree intervals.  I added a rotation arrow later, because it is easy to mistake clockwise and anticlockwise directions when making adjustments.

Next, decide where in the cycle you want steam to be admitted.  On expert advice from a marine engineer who is also a model engineer, I decided to admit steam at 10 degrees after TDC. (thanks Rudi!).  I also decided to cut off admission of steam at about 70% of the  power stroke. (pretty standard).

The easiest valve to time is the low pressure valve.  It is on the end of the engine.  It is the biggest, and there is not much engine stuff getting physically in the way.  Despite that, I decided to start with the high pressure valve.  It also is on the outside end of the engine.  The reason is that I wanted to follow the passage of the steam flow, in order to understand what was happening.  Each cylinder is timed separately, independently.  So the order is, high pressure, intermediate pressure, low pressure.  Forward direction first, then reverse, for high, then F & R for IP, then F&R for LP.

The timing is adjusted by 1. changing the distance between the crankshaft and the valve, usually by adjusting the length of the valve rod and 2. by changing the position of the eccentric on the crankshaft.

Firstly, the valve must move equally over the steam inlet slots. (the top and bottom ports). The point at which the inlet slot starts to open is noted on the protractor for both steam inlet ports.  The number of degrees before or after TDC is noted for the top port, and the procedure is repeated for the bottom port.   For the bottom port Bottom Dead Centre (BDC) is the reference point on the protractor.  The angle should be identical for TDC and BDC.  If it not identical the length of the valve rod needs to be adjusted.  On my machine, that was done by adjusting the nuts holding the valve rod to the valve bracket, but it could be the valve rod to the eccentric strap.

Determining the point at which the steam inlet port starts to open is easy.  Remove the valve chest cover, bolt the valve chest to the cylinder block, and rotate the crankshaft by hand until the port is obviously visually open.  Cut a sliver of paper 5-10mm wide, (I used copy paper), measure the thickness of the paper (0.1mm in my case), insert the paper into the open port, rotate the crankshaft to close the port until the paper is jammed, then while applying tension to the paper, slowly rotate the crankshaft to open the port, until the paper just starts to move.  At that point the port will be open by the thickness of the paper.

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The valve cover is off, a sliver of paper is pushed a centimeter or so into the port, the crankshaft is rotated to jam the paper then the crankshaft is rotated in the direction that is being adjusted until the paper is just released.   At that point the port is open by the thickness of the paper.  I calculated that 0.1mm was equivalent approximately to 3 degrees of crankshaft rotation.  So whatever was displayed on the protractor, I subtracted 3 degrees to get to the exact point of port opening.

when the valve moves exactly equally up and down over the steam entry ports, the point of opening is noted on the protractor relative to TDC of BDC, depending on which is being measured.

The eccentric grubscrew needs to be loosened, and  rotated on the crankshaft to bring the point of port opening to 10 degrees past TDC.  Then the grubscew is tightened.  BDC will automatically be correct if the centering process has been done accurately.

I had bored a hole in the eccentric strap to allow access to the grubscrew from underneath the engine.  That meant that the crankshaft had to be in a certain position to allow access to the grubscrew, not necessarily TDC or BDC or whatever.  That does not matter.  What matters is that the eccentric is rotated a certain number of degrees on the crankshaft.  I did this by using the Allen key to loosen the grubscrew, then using the Allen key to hold the eccentric fast, while rotating the crankshaft.  Then tighten the grubscrew, being careful to not move the eccentric.   The measurements need to be rechecked of course.   With practice, it is not difficult, and can be accomplished first go in most cases.

If this all sounds complicated and difficult, it really is not.  But I did need to make a record of every step and measurement and direction.

For the intermediate cylinder, the HP cylinder block needs to be removed.  The HP valve chest can be retained, just swung out of the way, retaining the previous settings..  You have to be careful, but this method does save a heap of bother.

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One thing I would suggest.  When the opening points of both IP inlet ports are determined and set, I suggest that before the HP cylinder block is reassembled, that the IP valve rod is measured above the IP valve chest.  And that the measurements are recorded and placed in a secure vault.  Those measurements can be used for any future adjustments of the IP valve, without the time consuming and very fiddly necessity of removing the HP cylinder block.

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I have determined the opening points for the intermediate cylinder using the paper method.  With the depth micometer on the valve rod above the valve chest, I am measuring and recording those positions, for possible future use.

And I have a confession.  The next photo shows the HP upper cylinder drain, and the same view at top dead centre.  As you can see, at TDC the piston blocks the drain.)!*!)  Read on.

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There is another method for determining the opening point of the valves.

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Plastic tubes are pushed on suitable points for the cylinder to be set, in this case the HP. The valve is pushed against the valve face, in this case with rubber bands.  One blows into the appropriate tube while rotating the crankshaft.  When the port starts to open, you can hear your exhaled breath coming through (if your hearing is OK, which mine is not).  The protractor reading is recorded, and used as before.   Note:  the drain cock passages MUST NOT be occluded by the piston at TDC or BDC.  In my case, this proved to be a problem, hence the use of the strip of paper method.

So, I hope that this is of some use.  If my description is jaberwocky, please send a message and I will try to help.    John.

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.

Model Triple Expansion Steam Engine. First taste of steam tomorrow!

I was very excited to see my triple running reasonably well on air recently.  But it was tight, and required a decent gutful of air pressure to turn it over.  But it did go!

Then it seized.

The cause was the intermediate cylinder valve rod seizing in its guide.  Probably a bit tight,and not getting any oil.

So I have loosened the gland, installed a displacement oiler, and made and installed a flywheel.  I also finished the pipework around the condenser.

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Displacement oiler top left, brass flywheel, and pipework.  The condenser on a marine engine would have been cooled with seawater, pumped with a separate pump, but I have used the 2 pumps on either side of the Edwards air pump.  In future I might install another pump.  The book “Marine Steam Engines and Turbines” has been been very useful.  

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I just like all of the brass and copper and components in this picture.

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The flywheel is too big for the scale, but my model does not have the weight and momentum of a propeller shaft and propeller, so a sizeable flywheel seemed appropriate.  Later I will add some gear teeth on the flywheel and a cranking handle on a removeable pinion, which some medium size engines had to assist with cranking to a starting position.  

So, tomorrow I will hook my triple up to Stuart Tankard’s vertical boiler, and see what happens.  I am sure that steam leaks will be revealed.  Hopefully there will be a video worth posting!

TRIPLE EXPANSION MODEL ENGINE- FIRST RUN (air)

This is a short video of the first run of the Bolton9 Model Triple Expansion Steam Engine, which I have been building on and off over the past 3 years.

The video is a bit shakey, because it is taken on my hand held phone while I am using he other hand to operate the controls.  I really did not expect the engine to work!

It runs a bit roughly, and is still quite tight, but settles down in the final few seconds.

It is not running very smoothly, because it is on air rather than steam, and because it is probably only powered on the high pressure cylinder, and maybe a bit on the intermediate, and not at all on the low pressure cylinder.

The next day it would not run.  Very frustrating.  I suspect that one of the eccentrics slipped on the crankshaft, and threw the timing out.  Not the easily accessible low or high pressure valve, but the intermediate one, which needs another teardown to get to it.

But Hey!  It will work.  I can see the light at the end of the tunnel.

One of my readers has requested a description of the triple engine timing procedure, so that will appear on this blog soon.  Unless you have a particular need for the timing info I suggest that you give that post a miss.

Back to the Triple Expansion Steam Engine

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I installed these cylinder drains on the triple, but was not satisfied with their appearance because they looked too big.   So I bought some of a different pattern from Reeves UK.

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The new cylinder drains are smaller, and have a handle which is suitable for joining all 6 drains to one control handle.

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The new cylinder drains are a more realistic scale.  I suppose that I should have made them myself.  

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From above.  Getting them to line up was a fiddle.

 

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The crankshaft protractor now has a (temporary) pointer.  When the timing is finally adjusted, the protractor and pointer will be removed.  I am planning to make and install a crank positioning gear and pinion and lever.

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The crank positioning gear and pinion shaft on the full size, ship’s triple expansion steam engine at The Geelong Showgrounds.  It is on the low pressure end of the engine.  I will make something like this to act as a flywheel on my model triple.

More Wierd Stuff

Since my “Strange Lights over Geelong” experience I have been looking at all sorts of weird posts on YouTube.  UFO’s, crop circles, megalith structures, evidence of buildings on the moon and on Mars.  There is a mountain of information out there, and while a lot of it is lies and rubbish, some is harder to dismiss.   It is not inconceiveable that Governments have information which they are witholding from the general populace, about aliens, UFO’s, ancient civilisations and so on.  Indeed, there are YouTube interviews with ex astronauts about UFO’s on the moon, and ex government ministers and officials about UFO’s and aliens, and Rothwell.  It may well be that the current increased talkativeness is due to a recognition by governments that they can no longer keep a lid on the previously secret information, so they are gradually allowing people to talk.

One line of posts which I have followed is evidence that something is going on in Antarctica.

And one source of information is Google Earth.  One post related to a strange set of giant “steps”.  I checked on the post information by checking the coordinates in Google Earth.

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Look at the middle of the photo.  That series of “steps” does look unusual.  You can check on this yourself by entering the coordinates on the photo into Google Earth.   The “staircase is about 2.5km long, with each step about 250 meters.

Anyway, to continue with my story, as I was zooming out from this point, I noticed a bright shape about 138km towards the south.

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The object which caught my eye was the white rectangle above the word “Coast”.  This section of Antarctica is directly south of Western Australia.  The rectangle is about 380 km from the coast.

And this is what shows up on Google Earth as I zoomed in.

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The image is from 1999.  The black rectangle is 21 x 7km…  Quite a size!   I am unsure what the bright white is.  Possibly sunlight reflecting off a shiny surface.  Or a rough attempt at concealing the rectangular area?    This is at latitude 70.2 S, longitude  87.2 E.

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Also, there is a faint streak from the rectangle heading about 100km to the east.  It is also 7km wide.     The staircase area is also visible to the north.

So that is it.  I can find no reference to this structure, but if anyone knows anything about it, please enlighten me.   If you have any interest in this weird stuff, you might the posts on YouTube by SecureTeam10 worth watching.

I am heading back into the workshop tomorrow.  Installing a steam powered boiler water injector on the Fowler traction engine, and bit by bit, finishing the triple expansion engine.

I have installed the new AC Servo motor to replace the spindle motor on the Boxford 125TCL CNC lathe, my expert friend Stuart Tankard has wired it up and reconfigured Mach3.  I am delighted to report that it has vastly improved the CNC lathe.  Will post some pics in a day or two.

Triple Expansion Steam Engine Cylinder Cocks

Some further progress on the triple.

I bought cylinder cocks from Reeves UK, and the picture shows them fitted.  In case I eventually install a mechanism to open all of the cocks simultaneously, they are in straight line, which necessitated making extension peices for the high pressure cylinder cocks.

The handles required bending to clear the pipework.

The cocks look a bit strange to me.  Too big, and the handles are wrong.   I am thinking about making a set from scratch.  But that can wait.

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Drain pipes from the cocks will be installed at some stage.  Still deciding where to run them. And whether to join them into a common trunk.

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The engine turns over by hand, but it is still a bit stiff.  There was a tight spot which took many hours to locate.  It turned out to be a valve rod thread which was about 0.5mm too long, touching the inside of the high pressure valve chest.   Fixed in a jiffy.

I hooked up the engine to a small compressor at 30psi, but general stiffness prevented the engine from rotating.  So I gave it an hour being rotated in the lathe at 200 rpm.  It is noticeably more free, and getting very close to working.  The valve timing is approximately correct (checked by my expert friends Thomas L, and Rudi V), but will need fine tuning at some stage.

Running in the Triple Expansion Engine

The Bolton 9 engine is assembled, almost completely.  The valves are approximately correctly timed.  I can turn it over by hand, just.  There are a few tight spots.

So today I mounted the entire engine in a lathe, oiled all bearings and slides, and tentatively ran it for a few minutes.   The lathe was set at 60rpm, in back gear.

All seemed OK, so I ran it for about 30 minutes.   Then increased the rpm to 90 for another 30 minutes.  After that the tight spots still exist, but much less pronounced.

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I kept a check on bearing temperatures with a laser thermometer, and none were running more than a degree or two different from any others.

The test did show that a low pressure cylinder drag link is touching the condenser, and will need some relief.  Also the high pressure cylinder eccentrics need to be repositioned a little on the crankshaft.  But nothing major.  And it was very nice to see everything moving in quite an impressive manner.

I will upload a video when the upload speeds are reasonable.

 

2 Triple expansion steam engines.

More Triple Photos

Reader Richard suggested that I include a ruler in some of the triple photos, for a sense of scale, so here it is.

It is approx 300mm long 200mm wide and 270mm high.  Weighs 12.4 kg.

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Triple Expansion Engine Update

Well, almost another whole year has elapsed, and still the triple is not finished.  Come December, and that will be 3 years that this project has occupied my thoughts and workbench.  With a few other projects in between.

Last week I assembled the components, in preparation for the Geelong Show.  GSMEE is a bit light on for new models, and it was suggested that the triple might fill some shelf space, despite being unfinished.

So I bolted it together.  All 429 fasteners!  And stood back and admired it.  It really is quite impressive, complex, and interesting.  So I took some pics.

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This is the condenser side, and the Edwards pump

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The other side is a bit lessy fussy, showing the steam inlet valve, the Stephenson’s links, weigh shaft  and controls.

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And the top, showing some of those 429 fasteners,

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The high pressure valve chest cover.  I will fill those holes where bolts cannot go.

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And the low pressure end, and links for the pump.

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And a close up of the steam valve and weigh shaft.

Not quite ready to run it yet.

It needs side covers for the cylinder block, drain cocks for the cylinders, and general freeing up.  It is still very tight.

Not to mention painting.  I expect that I will paint this one.   No idea of colours yet.

TRIPLE FINAL(?) ASSEMBLY

Just one photo to show that I have not totally ignored the triple expansion marine engine.   I have started to re-assemble it, having made almost all of the components.  But there were quite a few finishing tasks put aside until later, which I am now tackling.  eg lubrication points.  I suspect that this will not be the final teardown and assembly.

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The gunmetal base, with main bearings and crankshaft installed.  The eccentrics are not finally positioned.  

And some reminder photos from 2 years ago, of making the crankshaft.

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The centres were drilled on the CNC milling machine, after the locating the top of the bar

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Turning the second big end bearing.  Note the packing to support the crankshaft after the first big end had been turned.   The main bearings were turned last.

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The finished crankshaft.  Not much remains of the 51mm stainless rod.

A Base for the triple, and some oil holes…

Thinking about the options for a base for the triple expansion marine steam engine..

I looked at every photo I could find on the net, and thinking about whether I want to be historically accurate, or just really solid, or a bit interesting with an historical flavour.

At this stage, the decision is not set in concrete, but I am going with the last option.  Photos later in this post.

But first, I have pulled all of the major components apart, and I am spending time doing a few of those jobs which I had been avoiding because they are difficult and imprecise, and if they go badly it will be a major disaster at this stage.  Like drilling the oil holes and wells for the big ends.

Nothing precise about this.  The con rods and big end shells and bearings have been painstakingly machined, and I do not want to think about remaking them if I stuff up.  And drilling into curved surfaces, with a 1.5mm drill bit…

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That thread is 3mm dia.  The hole above the nut is the oil way, 1.5mm dia.  Very tricky and too anxiety provoking to be thinking about a video.   Amazingly, it all went well!   I now have 2 oil holes for each of the 3 big ends.  I will need to fill the well with oil with a medical syringe and fine needle, but.

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The crankshaft, turned from stainless steel a year or two ago, and the conrods.  The big ends now with lubrication points.

And here are the major engine components, after partial disassembly.

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At top left is the condensor, then the cylinder block in 2 parts, then the steam supply valve.  The square section tube is going to become the base.  And so on.  You get the picture.  I will count the bits at some stage.

Then I cut and drilled the square section aluminium tube for the base.

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The cast base of the triple, with main bearing studs and column studs in place.  All sitting on the square section alu.  Have not decided whether to bolt it together, or just Loctite it. 

Those holes in the square section were drilled and chamfered on the CNC mill.

 

Triple Expansion Steam Engine Pipework.

I am close to disassembling the Bolton 9, before gradually reassembling it in preparation for running it on air then steam.  Most of the components have now been made.  Most recently I completed the pipework associated with the Edwards air pump and the twin water pumps.

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This is the combined air and water pumps, and new pipework.  Most joins are silver soldered, but a couple are Loctited.  Loctite should be adequate.  These components will not get super hot.

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This valve is one of the few components on this engine which I have not personally made.  This one came from the effects of the late Harry Close, who was a valued member of our Model Engineering Club.

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The pipework adds to the overall interest , yes?  It will look good when polished.

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And the “tails” for the valve rods, which are attached to their respective steam chests.  The BA7 bolts are a bit oversized for the job.  The intermediate cylinder tail screws into place.  I am not sure why it is different from the other two.

So now I am making a list of tasks which need to be completed when the engine is taken apart, hopefully for the last time before it is run.  The list is not complete, and so far it runs to 3 pages.  Mostly like fixing parts which interfere with each other, and freeing up tight bearings.

I will take some pics of the components.

Cutting a thread up to a shoulder

A problem with some thread dies is that they have such a large “lead in” that they are unable to cut a thread up to a shoulder.

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A 3/8″ x 32tpi die.  Note the large lead in taper.

This results in the thread stopping a long way from the shoulder… undesireable in some situations.

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This is a thread made with the die in the previous photo.  I wanted it to go right up to the shoulder, but this is as close as it gets.  About 2mm gap.

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The screw in this upsidedown photo does not allow the shoulder to seat properly.

The solution?  Modify the tool.

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Here is the tapping die, held onto a magnetic chuck, within a machined steel disc to increase the magnetic attachment force.

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So I ground off the top 1-2mm of the die.  My surface grinder is out of action, so I used the tool and cutter grinder.   A bit rough but it worked.

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This is the die after grinding the surface.  Note that there is no lead in.  I ground the unlabelled face so I did not lose the specs of the die.

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And the screw after using the modified die.  The thread  now goes right up to the shoulder.  Incidentally, this is a zoomed photo using an iphone.  Not bad?

So that does the job.

The downside is that in future the thread must be started with the unmodified side of the die, and finished with the modified side.  Adds some time.  And the die is thinner and a bit weaker.

A pity that the dies are not manufactured with one “no lead in” face.

The particular set of ME dies will now all be modified in the same way.

 

A Turntable for the Triple Expansion Engine.

I have not weighed the Bolton 9 triple expansion steam engine, but I would guess that it is 20-25lb.  (weighed it.  25.5lb)

Access to the various bolt on bits and pieces has become increasingly difficult and tricky, and involves frequent repositioning of the engine.

I removed the bolt on base and that has improved the situation a bit.

Then I had a brainwave, thought bubble, inspiration  whatever, and I tried a ball bearing turntable….   you know….. one of those Chinese restaurant middle of the table gadjets.

It is incredibly useful!

Here are some pics and a video showing it in place;  just a demo of the engine at its current (unfinished) stage.  I think that the turntable might  become a frequently used tool for heavier models.

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The Bolton 9 on the turntable

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And the latest additional bits…   non return valves on the water pumps.

Edwards Pump for the Triple Expansion Steam Engine

The triple expansion steam engine has been progressing, again.  I started this project over 2 years ago, but I have taken many breaks, some prolongued.  One break lasted over 6 months while I made some cannons.

I cannot remember when I made the Edwards pump for the triple, but it must be over a year ago.   In the past few days I have returned to it, finalising the mounting to the engine, and joining the driving levers to the pump and the engine.

The Edwards pump creates the vacuum in the condenser chest.  It is an air pump.

Attached to the Edwards pump are 2 water pumps, which return condensed steam as water, to the boiler.  At least that is what I understand from the descriptions.  It feels a bit odd, making these components before understanding what they really do.

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The Edwards pump is the central cylinder and rod.  The water pumps, bolted to the sides, are just lumps of semi machined cast gunmetal at the stage this photo was taken.

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The step before the above picture, where the base of one water pump is machined.

 

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The Edwards pump, and the 2 water pumps, almost finished, attached to the engine.

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There is no clearance between the pump gland and the condensor, so the intitial hexagonal glands which I made (not shown) were unuseable.  So I made these cylindrical glands which required a tiny hook  spanner to tighten.  The hook spanner was made on the CNC mill from 1/8″ brass plate.  A little filing was required to shape the hooked tooth.  Works nicely.

 

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The pump unit, lower left, attached to the engine.  Actuating levers driven off the low pressure cylinder (not yet connected).

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The pump unit viewed from the side.

So I am at the stage where I would like this project to be finished, so I can get on with other projects.  It feels like it is close because there are very few castings remaining in the box.  But I know that the entire engine has to be disassembled, and painstakingly reassembled, freeing up some of the tight parts so it will turn over more easily.  Then the steam pipe hookups and valve timing.  Then hopefully, a video of it running!

Harold Hall Grinder Rest – modification; and triple expansion update.

Harold Hall has written many articles and several very useful books about metalworking, using a lathe, using a mill, and much more.

Recently he has been posting videos on YouTube.

He is a very knowlegable, dignified, elderly gentleman.  His books are precisely, beautifully written, and the plans and projects are excellent.  I have made quite a few of the project pieces in my quest to learn as much as I can about machining metal.

I came across his Youtube videos quite recently, and have been enjoying them.  One of them was about his grinding rest.

I made 2 of the HH grinding rests from plans in his book, and they have proved to be useful, reliable, and compact.  Here is a photo of one of them.

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The original HH plans specify that the footprint of the base is much smaller than I made it.  This one is 200 x 100mm.   The larger footprint adds some extra stability (IMO), and the slots permit the grinder to rest distance being easily adjusted.  It is a bit grimy because it is used frequently.  Polishes up quite nicely.

In HH’s video he mounts the rest on a metal plate, joined with a couple of switchable magnet bases.  Here is a link to HH’s Youtube video.

And in case you are wondering what has happened to the triple expansion engine, I have been working on the reversing mechanism.  The intermediate cylinder reversing curved slide would not fit into the available space, so I removed it, silver soldered in a new end, and ground it several millimeters shorter.  Then reinstalled it.   It is still a mm or so too long but I think that it will do.

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The high pressure reversing mechanism on the right, and the intermediate hiding behind, on the left of the pic.

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The intermediate cylinder valve rods and eccentrics.   Rather difficult access.

Assembling the Triple

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I got this far in assembling the model triple expansion steam engine, then lost courage and put it aside (again).  You can see the high pressure steam chest labelled “top”, the steam valve and handle, the drag links and levers for the reversing mechanism for the high pressure cylinder, and the worm and gear and control wheel for the reversing mechanism.   The reversing levers will need pinning with taper pins when the correct positions are finalised.  The short rod in the middle of the pic is temporary.  I need to make those properly.  The drag links clash with the condenser cover.  That was predicted in Bertinat’s notes.  The cover will need some material removed.  Slowly progressing, but taking frequent breathers.

The high pressure mechanisms are the most exposed, and easiest to access, and they were very tricky, and not yet compeletely installed.  I dread to consider what the intermediate pressure ones will be like, buried in the middle of the engine.   Then there is the valve timing.  Help!

A Full Size Weighshaft

The crowds were down at this year’s Truck Show at the Geelong Showgrounds.  Maybe the  38c weather prediction had something to do with that.

But those hardy souls who did turn up were treated to a feast of steam engines working on steam, and other antique engines popping away, as well as the magnificent trucks, tactors, and military vehicles.  There was a superb display of radio controlled trucks and excavators, and unbelievable machinery created with Meccano.

My interest was mainly focussed, for some reason, on the full sized triple expansion steam engine, which is the prize display in the vintage machinery shed.  it once powered a tug boat, and later a dredge on Port Phillip Bay.   And the following photos and video, if it will upload, show the bits which were of particular interest.

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The red control handle top right is the main steam control valve.  The one on the left is the reversing control handle.  Note the big steam piston centre bottom.  It is a steam powered reversing control piston.   This engine was made in 1951, so is just about the last gasp in triple expansion steam engine development.

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and the rod at top is about 5″ diameter.  It is the weighshaft, which carries the reversing levers for each cylinder.  On my model it is 5mm diameter.

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Another view of the weighshaft and the levers.   Massive.

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And note the drag links in the adjustable block.   That would have been set at intitial installation, and probably never altered since then.

Video of the big triple expansion engine working.  Maybe not.

For those following my triple expansion steam model engine build, I have put it aside again.  It is at the final assembly stage now.

Meanwhile, I am making some extra tool holders for the CNC lathe, and another ER40 chuck for the CNC lathe.

The ER40 chuck which I am currently using has an M5 shaft which is held with a drawbar, so I cannot feed work through the lathe spindle.  Plus it sticks out of the headstock a bit excessively.  So I have drawn up plans for a new chuck which I will fit to the lathe spindle and use the CNC to make the ER40 taper and threads.  Pics will follow.

And I really need some extra tool holders for the CNC lathe.  I have 5, but have material to make another 10.   The material is high quality cast iron off a scrapped T&C grinder.  I bought the grinder table cheaply (($AUD20 from memory) and have been gradually canibalising it over the last couple of years.   I have cut up the remains into rectangular 30x80x40mm chunks and will make the tool holders in the next couple of days, SWMBO and weather permitting.  Unfortunately there was insufficient material to make a long section, machine it, then cut it up, so each tool holder will have to be made separately.