johnsmachines

machines which I have made, am making, or intend to make, and some other stuff. If you find this site interesting, please leave a comment. I read every comment and respond to most.

Tag: triple expansion steam

Thinking about future exhibitions….

Still recovering from The Royal Geelong Show, where my beam engine and the Trevithick      dredger engine ran for ~8 hours per day for 4 days, and required almost constant supervision. I was very pleased that they did so without a problem.

For future exhibitions I would like to also run the triple expansion steam engine using the vertical boiler, for which I recently made the Southworth boiler feed pump.  And there are occasions where I might run the triple and the beam engine together from the vertical boiler.  That arrangement will occupy a fair bit of bench space, and in this post I am considering options for the arrangement.

But first, I needed a steam outlet manifold to handle multiple engines, simultaneously, and hopefully to avoid a big tangle of pipes.  Here is the manifold.

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The manifold has 6 x ¼” outlets and one 3/8″  outlet.    

Option one lines up the boiler and engine like this….

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Option two is more compact, but ?less appealing.  Pics following..

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The lump of wood under the engine is temporary,  just to give an idea of the heights.

OK, this post is just an excuse to show some pics.  I have decided to go with option one.  It is closer to the appearance if the boiler and engine were actually in a boat, and also will make it easier to add the beam engine to the right of the boiler if/when I run the two engines simultaneously.

And I doubt that I will be able to avoid a jumble of pipework.  The triple has 6 pipes attached, the boiler has more, then there is the beam engine.  And, I will need a water container from which to feed the boiler.  That will be located behind the boiler.  Still considering whether it should be a squarish box on a stand like the railway water towers, or a cylinder on a low stand.   Any thoughts?

 

 

 

Model Engines on Steam

It is Geelong Show time again.  It is actually titled the Royal Geelong Show, but having had more than a gutful of royal non-entities visitors being adored by unthinking cringers, flocking around Harry and Meaghan Kardashian, Windsor, and being a committed republican, I refuse to bother with the “Royal” handle.  (they are probably very nice people, I just cannot stomach the hoo-ha).

More importantly, it gives us steam junkies a chance to run our small engines on real hot steam.

For a treat, I am sharing four short clips taken today.

The first is a small beam engine, made by Swen Pettig.

The next two engines you have probably seen before.  My beam engine, and the triple expansion engine.

The small engine to the right is a Stirling engine which is running on the heat from the exhausted steam from the beam engine.

The triple is leaking a bit more than it should, although it is running amazingly smoothly on 25-30 psi.  The valve glands need repacking.

And finally, a model IC engine, the really odd Atkinson.  A 100+ year old design.  2 stroke. Made by Rudi vanderElst

 

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.

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.

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.

Broken Cold Saw Blades are a good source of Tool Steel!

I needed to make a form tool to make the base for the air pump on my triple expansion steam engine.

It required a 1/4″ radius section and a 15 degree straight section.

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The dimensions for the cavity in the air pump, and the cutter to produce the cavity.  And the piece of cold saw blade which I used to make the form tool.

I considered machining the arc and the straight sections separately, but I did not have suitable tools, so I made a form tool.

A friend had previously suggested using steel from a broken cold saw blade to make form tools, and on this occasion I used his suggestion.  (Thanks Manuel!).

The blade was 1.6mm thick which was ideal.  I had some trepidation about cutting it.

The broken cold saw blade. The steel is superb.

The broken cold saw blade. The steel is superb.  Painted with layout dye.  The air pump base is visible lower right of photo, bolted to the engine base.

 

Using an angle grinder with a 1mm cutting disk. It cuts through the cold saw b

Using an angle grinder with a 1mm cutting disk. It cuts through the cold saw blade easily.  Like a hot knife through butter …  almost.

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Grinding the cutter to shape on an aluminium oxide wheel.

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Grinding the 1/4 inch radius arc.

Marking the shape of the form tool cutter

Marking the shape of the form tool cutter

Curodtting a 1.6mm slit in 10mm mild steel

Cutting a 1.6mm slit in 10mm mild steel rod.

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Initially I fastened the cutter steel to the rod using 2 grub screws, then, after checking the dimensions and the 15 degree angle I cut it to size. In use, I found the grub screws would not hold the tool steel securely, and I eventually silver soldered the join.

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The tool, prior to soldering. I ground the relief angles on my Quorn T&C grinder. (See old post). Except for silver soldering the tool steel into the rod, this is the finished tool.

 

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Commencing the machining of the air pump base cavity.  I had planned to do the machining using a boring head on my milling machine, but quickly realised that would not work. So I used the recommended method of a 4 jaw chuck on the lathe.  The 45 year old 4 jaw is still in excellent condition.

The end result. The complex cavity was initially centre drilled, drilled then bored to size. Then the home made tool was used to machine the undercut cavity. It worked perfectly!

The end result.
The complex cavity was initially centre drilled, drilled then bored to size. Then the home made tool was used to machine the undercut cavity. It worked perfectly!

I learned about using cold saw blade steel as a source of tool steel from Manuel.  I am aware of a professional contract machinist who uses this method to turn complex shapes in brass and steel, in preference to using a CNC lathe.

The material can be heated to red heat, (during silver soldering) and it does not lose its superb ability to take and retain a sharp cutting edge.  Very impressive.

Copper and Brass Repair

I accidentally damaged a gunmetal casting (an end plate of the condenser unit) of my triple expansion engine.  I considered soldering a piece of brass or gunmetal and filing it to shape, but decided instead to try one of the 2 part epoxy repair kits.  There are plenty of these with iron/steel coloured material, but for a long time I could not find a copper coloured repair kit.

The damaged, machined casting.

The damaged, machined casting.  I have punched some indentations to increase the adhesion of the filler, then washed it in acetone to remove all traces of grease.

Then I spotted this epoxy repair kit at an Aldi supermarket.  So I decided to give it a try.  Cost $AUD5

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DYNASTEEL, Copper Repair. And this initial blob applied to the defect.

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An hour later, after some paring with a knife and filing.

Next day, after some more sanding.

Next day, after some more sanding.  Appearance not too bad.  More shaping of the casting is intended.  The epoxy repair is meant to tolerate temperatures up to   200 c.    If it proves unsatisfactory I will solder in a patch.

Stephenson’s Link (2)

The next step in making the Stephenson’s link reversing mechanism, is to make the yokes for the links.  See the previous blog. I decided to drill and tap the BA10 holes, while the bar stock was still rectangular, for ease and precision of clamping the pieces.

BA, in case you are not familiar, stands for British Association.  BA threads were standardised in 1884, using imperial measurements (fractions of an inch), but to metric specifications.  All very confusing.  BA threads are rarely used these days.  Model engineers, instrument makers, and restorers of ancient British cars and motor cycles being the exceptions.  Builders of model engines often use them, because the bolt heads and nuts are nicely scaled for the models.

BA10 bolts are only 1.7mm diameter.  If a BA10 nut falls on the floor, it is gone forever.  I can barely see the thread of a BA10 bolt.  I shudder to think of using the even smaller BA12’s.

The tapping drill is only 1.4mm diameter.  A bit thicker than a human hair, (OK, many times thicker), but very delicate.  And the holes needed to be at least 5mm deep.  I do not possess a drill press capable of drilling such fine holes.  Any run out of the chuck, or excessive pressure would just destroy the drill bit.  Also, on working out the feeds and speeds of the drilling, it was apparent that the optimal drilling rpm’s would be 12,000 .  Twelve thousand.

So, once again, CNC to the fore.

I reattached the high speed head to my CNC mill, worked out the XYZ co-ordinates, and did a practice run on some scrap.  No problems!   Worked like a charm. 12000 rpm and feed 100mm/min.   Then to the actual job.   Centre drilled all pieces.  Then using the Pro-stop by Edge Technology  vice stop, repositioned the work pieces and deep drilled them using the 1.4mm twist drill, using CNC peck drilling at 1.4mm intervals.

Then to tap the holes.  The BA10 tap seems even more delicate than the 1.4mm drill.

I attempted to hand tap the holes, in the belief that holding the tapping handle in one hand, and the work piece in the other, would be the most sensitive system.  But these hands, which once performed microsurgery, were not up to the job.  It was inevitable that the tap would break in the job, so I abandoned the method before disaster struck.

The work piece was repositioned on the mill, again using the vice stop, and I used the CNC positioning to centre the tap fairly precisely squarely above the holes.  I made a spring loaded point to apply light pressure to the tap, and to keep it centered. (see photo below).  24 holes and about 2 hours later the threading was completed.   No breakages!

Tapping the BA10 thread.  Note the Protech vice stop, and the spring loaded centering tool.

Tapping the BA10 thread. Note the Prostop vice stop, and the spring loaded centering tool.

BA10 bolts OK.  Now to shape the yokes.

BA10 bolts OK. Now to shape the yokes.  (seen in the background.)

 

I had made a video of the CNC drilling, but the broadband downloading speeds here are so slow, that you will just have to imagine the excitement of the drilling.

OK, the video finally uploaded.  It is pretty crappy.  To see it, click on the link which follows.

TRIPLE CYLINDER BLOCKS JOINED

The heavy chunks of brass which form the cylinders, and the intermediate cylinder valve chest, have been machined externally, and bolted together.

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The low and intermediate pressure block on the left, the IP valve chest (with the round boss), and the high pressure cylinder block on the right. All bolted together. Almost ready for cylinder boring.

The IP valve case cavity has been machined, but 3mm too wide. I think that this error will not matter, but if it does I will silver solder some extra material to get to the specified dimension.  (the external  dimension of the steam chest is deliberately left too big at this stage.  It will be blended with the cylinder blocks later.)

Now that these pieces are together, I can do the cylinder boring and complete the external dimensioning and finishing.