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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

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.

Anyone for a swim?

High summer.

Hot workshop, wearing only shorts and boots.

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I think that I will stay in the workshop.

Today was my deadline to have the triple expansion steam engine assembled and working, ready to be hooked up to steam at the Geelong Truck show.

GSMEE (Geelong Society of Model and Experimental Engineers) has a display in the Vintage Machinery Shed at the show, with many small working steam engines and the odd IC engine running.  Plus the Vintage Engine group has many full size engines running….  always a really interesting place to visit.

Another full day in the workshop would have just about had the triple in the display.  Unfortunately, I lost a day having to get a dental root canal abcess reamed out.

Then the day before yesterday, I could not find the drag links for my triple.   I had made them in early December,  and I was sure that I had put them in the multi- compartmented box where I store all such bits.  Despite thoroughly searching the box, at least 20 times, they were not there.  Could I have put them down somewhere else in the workshop?  So I searched the workshop.  No luck.  So I tidied the workshop, putting tools away, sweeping up rubbish, all the while searching.  Still no luck.   So I cleaned and searched my car, my bedroom, the living room, every where that I could concievably have left them.  (OK, I did not actually clean the bedroom and living room, but I did search).   I grilled my wife.  Had she seen them?  No.

So I slept on the problem.  Next day was going to be hot, so at 7am I drove to the workshop (it is about 15km from home), and searched again.   Still no luck.

So I searched the multi compartmented box for the 21st time.  I knew that it was a waste of time, but I was seriously considering making a new lot of drag links and bearings, probably a 2 day task.

There were some tiny containers with tiny fasteners in the compartmented box.  The drag links could not be them because they are too big, aren’t they…..??

The first tiny container, contained, you guessed it, the drag links.!!  They were smaller than I remembered.

Relief!

Self disgust!

Age related loss of short term memory…..

I had to get that one off my chest.

The other thing that I wanted to mention, is a superb machining blog site.  Actually, 2 superb machining blog sites.

The first is by Joe Pieczynski, who is a Texan who makes his living from machining.  His techniques and teaching are really, very, excellent.  Aimed mainly at an audience who are beyond absolute beginners.  Do a Youtube search on “Joe Pieczynski”.  Look at his video on machining ultrathin materials.

The second, I have probably mentioned before.  An Australian  machinist, whose videos and machining techniques have to be seen to be believed.  Mainly with a clock making interest, but the techniques can be used by all of us.  For some reason I cannot cut and paste his Youtube connection, but you will find it by doing a search on “Clickspring”.  What is particularly exciting in Chris’s “Clicksping” is that he is soon to embark on remaking an Antikythera calculator.  Watch it!  You will be hooked.

 

 

 

 

 

SS Valve Rods

Making the new valve rods, as predicted, took me an entire day.  They required a high degree of precision, and being in stainless steel, not an easy material to machine, and quite thin and delicate, multiple stages in the machining.

But before I started on the valve rods I made myself a new spanner for the collet chuck on the CNC lathe.  I had been using an adjusting spanner, which was continually  going out of adjustment and causing angst.  The tool merchants did not have anything suitable (46mm opening, and thin profile), so I made my own.

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The 46mm spanner being cut from 6mm steel plate.

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It is a bit prettier after this photo and being painted.  The rounded jaws facilitate easy application to the collet chuck.

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Tightening the ER40 collet chuck with the new spanner.  It works very well.

So then I got on with the new valve rods.  Some end of day photos follow.

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The valve rod is the silver coloured rod.  Actually stainless steel.  This photo shows the high pressure cylinder valve and valve chest.  There are 2 other valves, one for each cylinder.  All different sizes.

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The high pressure valve chest and valve, the valve rod and guide.  On the right is the Stevenson’s link, yokes and eccentrics which control forward and reverse.  This setup is repeated for each of the 3 cylinders.  This is hooked upto the worm and gear which was shown a blog or two ago.  There are 22 components for each, not counting fasteners.

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The low pressure setup.

And thank you to those readers who responded to my whinge about likes and comments.  I will continue this blog until the triple expansion steam engine is finished, and hopefully running.  Not sure after that.

Triple Underbelly

“Underbelly” has a particular resonance for readers who know what the Yarra is and that Collingwood is a place and not a British admiral.

In the instance of my triple expansion steam engine, it refers to the bits and pieces underneath the cylinder block.  The glands which prevent steam leaks from the con rods and steam valve rods, the and valve rod guides.  These unsung heroes of the steam engine have taken 2 entire days to make.   And here they are….

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This is the cylinder block, upside down.   You can see the valve rods. the valve rod guides, the valve rod glands, the piston rods, the cross heads (unfinished), the piston rod glands,  and the cylinder bases.   Give yourself 2 marks for each correctly identified item.  The 6 hex plugs on the side are temporary, until I get around to making some cylinder drain valves.

I started to count the number of holes drilled and tapped in this view, but gave up at 100 and still not half way.  This engine better bloody work!

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Note the letter stamped into the cylinder base.  Many parts are similarly stamped.   The studs in the intermediate piston gland are temporary.

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Just a different view.

I have decided to replace the valve rods which are made of brass, with stainless steel ones. That will take an extra day, which might exceed my second, self imposed, deadline.  But if it does, well too bad.

By the way….   I am considering whether or not to continue this blog.   It does take time, and is not free.  If you read this and are not totally bored, the odd “like” would not go un-noticed.  A comment would be even better.

Broken Tap Removal

In a previous post I admitted to breaking a BA7 tap in the Edwards air pump of the Triple Expansion Engine, and being unable to remove it.

The hole being threaded was one of 4 to be used to hold a water pump to the air pump. It was 2.5mm diameter (i.e. pretty tiny)

I tried to grasp with pliers the fragment still protruding but it then broke below the surface.

I tried to break up the embedded tap, using a HSS punch, with partial but inadequate success.

I briefly considered drilling a hole from the other end, and punching in the reverse direction, but that would really have compromised the pump.

So I decided that the three remaining bolts would have to be enough.

A night sleeping on the problem.

Next day, with a fresh determination, I decided to attack the problem again.

I had some used carbide milling cutters 2mm diameter, and I was prepared to sacrifice one or two of them.   So I carefully set up the Edwards pump in the milling machine.

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You can see the three good tapped holes.  The carbide milling cutter chomped away at the broken tap, and using gentle pressure, and ignoring the metallic screeches, the tap was broken up and most of the fragments came out.  I was prepared to sacrifice the milling bit, but it seems to have survived this insult.  The harder metal always wins.   It was probably fortunate that the tap was carbon steel and not HSS.

Somewhat surprisingly, the tapped hole was in reasonable condition, and it accepted a BA7 bolt, although I will not be aggressively tightening this one.

Triple Expansion Steam Engine -The water pump

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The triple will not be finished by Xmas.  No chance of getting into the workshop while we are looking after 2 grandchildren.  So the new aiming completion date is Jan 6, in time to run the triple on steam at the Geelong truck show.   If I don’t meet that deadline, the next access to steam will be the end of 2017.  I really do not want to wait that long.

So the next component to produce out of a chunk of gunmetal is the water pump.

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There are two cylinders in the water pump.  The gunmetal castings appear to be good quality.

Most of the machining will be done on the mill.  But I need a datum surface, and have decided that the attachment plate is the most appropriate.

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I do not need the small cylindrical protruberance, but that chunk of gunmetal might be handy for something else (eg as a bushing), so I parted it off and saved it.  Lovely parting tool is from Eccentric Engineering.

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Then turned a flat surface.  On the mill I machined it to a rectangle.   Diamond tool is also from Eccentric Engineering.

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The two water pump cylinders are bolted to the air pump.  BA7.  A broken tap is entombed in the air pump forever.

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When I get back into the workshop I will machine the rest of the pump parts.

MAKING SMALL SPLIT BEARINGS FOR THE TRIPLE EXPANSION STEAM ENGINE

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The bearings in the drag link are not split, because they can be slid onto the shaft.  But if there are obstructions to sliding, (such as big ends on a crankshaft), the bearings must be split, and assembled when in position on the shaft.  The bore in the intact bearings in the photo is 4mm.  The split bearings have a 5mm bore.  They are all bronze, but the split bearings have been heated then dipped in sulphuric acid so the colour has changed.

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The first step in making split bearings is to machine 2 strips of metal, of identical dimensions.

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Next the strips are soldered together.

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The bearing holes are drilled and reamed exactly to finished size.

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The strip of soldered metals is attached to a sacrificial base plate and the outside of the bearings are machined to final size and shape.

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Holes are drilled to take the bolts which will eventually hold the halves of the bearings together.  (1.6mm holes in this case).  The bearings are then heated to melt the solder and separate the halves of the bearings.  Sulphuric acid was used to remove the carbonised crap left on the surface of the bronze by the heating torch.

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The bosses around the holes was an extra machining step.

Drag Links for Reversing Mechanism on Triple Expansion Steam Engine

A bit more progress today.

I spent the whole day making these drag links, and I was pretty happy with the result.

Then I realised that I need 6, and I had made only 3.  (well there are 3 cylinders you see).

So you know what I will be doing tomorrow….

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The drag links are the 3 items with the bearings at the ends, and the connecting rods.  Those rods are 1.6mm diameter (1/16″ inch), and the nuts are BA 10

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I dropped 2 of the nuts.  Gone forever.

The final 20% takes 80% of the time

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The weighshaft, supported on its brackets.  It will be pinned with taper pins to the shaft.  Also finished the reversing lever and reversing arm.  The reversing arm has gunmetal bushes.  About 2 x 8 hour days in the workshop to make these bits.  Just as well it is a fun hobby.

Triple Expansion Steam Engine resumes

Busy at this time of the year.

Making some wooden toys for the grandchildren for Xmas.

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Not sure whether these are ducks or chooks.  My talented wife brings them to life with colours.  When pushed by 1-2 year olds they waddle with an entertaining flap flap walk.  

Preparing the surgery building for sale.  Removing and storing 34+ years of medical records, moving furniture, arranging repairs and painting etc etc.  Feels strange to be no longer a registered medical practitioner, but I know that it was the correct decision to retire.  It has taken 2 years to totally burn the bridges by dropping my medical registration, and selling the surgery etc.

Model Engineering Club annual exhibition.

 

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This model quartz crusher at the exhibition was driven by a hit and miss engine.

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Another superb engine at our exhibition.

Plus ongoing military history book reading and reviews.

Slashing long grass, to reduce the summer fire risk.

Assembling and installing a kitchen into a rental property.

So it was a treat to get some time in the workshop today.  I had previously made the layshaft brackets for the triple expansion steam engine, so I spent a happy few hours setting up an angle jig on the milling machine to drill and tap holes to attach the brackets.

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This is the setup.  An adjustable angle plate was bolted to the milling table, and the angle was set so the columns were horizontal.  The layshaft brackets were Super glued to the columns with the shaft in place after filing to get the brackets quite level.  The holes were spotted through, then drilled (1.6mm) and tapped (2mm).

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The layshaft bolted in position with M2 nuts and studs.  M2 is very similar to BA7, and a lot less expensive, and is stainless steel.  Way to go!

 

After the triple

I am back onto the triple expansion steam engine, after putting it aside for most of 2016.  I am guessing that it is about 75% completed.  I have been struggling with this project due to poor plans, no instructions and some lack of skill and knowledge.

When I was well into the project, a colleague pointed out that detailed instructions existed in some articles published in 1985 (Model Engineer, Bertinat).  I obtained the articles, and subsequent progress has been greatly assisted, but unfortunately some errors had already crept into my work, and these have not been easily or completely rectified.

So now I am back into it.  And I would hope to have it finished and working by the end of the year.  Watch for pictures when there is something to show.

I am already thinking about what will follow the triple.  Maybe a Harrison 1 clock? (of “Longitude” fame.)  Looking for some plans.

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Or maybe some more artillery?  How about a working  model  trebuchet?  Now that does have some appeal.  There are some plans on the Net, but they look over simplistic.  I am thinking of a more historically accurate model.  The following picture is from an old French encyclopaedia.  But I might have to abandon my preferred scale of 1:10 because the original was about 12 meters long.  But on the other hand……

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It does have some interesting features.  The ratcheted windlass, the travelling pulley, the trigger mechanism (“pulling the pin”), and the projectile release mechanism (trying to avoid the projectile going up vertically).

 

BACK TO THE TRIPLE

It seems months since I made any progress on the triple expansion steam engine.  It is such a complicated build, at the limits of my abilities (or maybe beyond the limits), and many  components have been partly made and put aside to be completed later, that I was unsure just where I needed to resume.

But, Xmas/Saturnalia, New year, several exhibitions, several competitions, and an intervening Stirling engine build all conspired to “force” me to put aside the difficult triple build.  Then it was just too bloody hot to venture into the workshop.  But we now have some milder weather, and I have some free time, so back into the workshop to inspect the triple and see where to resume.

I decided to do some easier components, to ease back into the build.  So I started by making some of the steam pipes,  CNC’d the flanges, and silver soldered them.  Only to discover that there was inadequate access to tighten some of the flange bolts.   So a quick redesign of the flanges to use only 2 bolts per flange, CNC’s some more flanges, removed the bad’uns, and silver soldered the new ones.   All good now, except that I need to fill some unused threaded holes in the cylinder castings, and drill and tap some new ones.

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Checking the fit of the copper pipe, prior to machining and soldering the flanges

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The pipes with flanges all made and ready to be fitted.  Except that these 4 hole flanges had to be replaced with 2 and 3 holers.

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Inadequate clearance to fit the bolts.  So the flange was replaced with a 2 holer.

 

Today I made the bearings for the yokes on the Stephenson’s reversing mechanism.  These are made of gunmetal, quite small (9.5x8x4.7mm), need some precision drilling and reaming, and there are 12 of them.

After considering the “how to” options, I decided to use the recently installed 5C collet chuck on the lathe, having machined the gunmetal to fit neatly into a 3/8″ square collet.

The following pics were uploaded and the order was totally mixed up in the process.  From previous experience I know that trying to re-sort them will result in chaos and losses, so I will leave them as is.

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This is the final photo.   The 14 bearings (including 2 spares) are threaded onto a bright steel rod and the side decorative waist is milled.

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Showing one of the reversing mechanisms, with 4 new gunmetal bearings bolted into position.

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The square 3/8 x 3/8 lathe collet, about to accept the bar which has been accurately sized, drilled and reamed.   I used a parting tool to cut off the bearing at the correct thickness.

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Parting.  The blade is only 1.5mm wide.

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One of the yokes, with bearings bolted in place, and 2 loose bearings about to be fitted to the other yoke.

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precision drilling the bolt holes (1.8mm diameter) using the high speed spindle on the mill, at 6000 rpm.

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The three pairs of valve eccentrics, and reversing mechanisms.

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This should be the first photo.  It shows the gunmetal bar machined to size, drilled and reamed, ready to be drilled for the bolts, then parted on the lathe.