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Author Topic: A second new engine for the model paddle boat Tanwen.  (Read 3829 times)

Offline Tony Bird

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A second new engine for the model paddle boat Tanwen.
« on: December 18, 2016, 05:12:44 AM »
Hi,

In a recent post I described a controllable engine to replace the single acting oscillating engine fitted in my model paddle boat 'Tanwen'.  This engine used modified replacement cylinders.  This engine worked fine but would have been to powerful for the hull.



So it was decided to make a much smaller engine of a similar design, the cylinder size being a 1/4" bore and 1/2" stroke rather than the 3/8" bore  and 3/4" stroke of the first engine.

The engine will be based on a small engine I designed years ago, this engine can be made single or double acting with bores of 1/4" up to 1/2", most built have been 5/16" bore all had a common stroke of 1/2".



The engine's column has been made of a light gauge aluminium square tube.



The port blocks and the reversing block with its valve have been made from some large brass angle that I have and was machined to thickness using a shellac chuck.
 


The small cylinders are fabricated in my usual way from some hexagonal brass rod and some K&S brass tube.








The K&S tube was soft soldered to its base and tippex (a correction fluid which contains chalk) was used to stop the solder contaminating the threaded hole.



The result of the first days efforts.



Regards Tony.

Offline DamienG

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Re: A second new engine for the model paddle boat Tanwen.
« Reply #1 on: December 18, 2016, 11:23:29 AM »
Nice work Tony. :clap :bravo :clap

Offline Delaunay

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Re: A second new engine for the model paddle boat Tanwen.
« Reply #2 on: December 19, 2016, 06:59:18 PM »
 :)Hello;
A good idea to make the cylinders with brass tube, no missed bore and good internal finish! :bravo
A small engine don I follow the construction, like all those proposed by Mr. Tony
Cordially.
François

Offline Tony Bird

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Re: A second new engine for the model paddle boat Tanwen.
« Reply #3 on: December 21, 2016, 04:58:40 AM »
Hi,

We have been away for a few days so I have only managed to screw the parts already made together.





I might get some more done tomorrow.

Regards Tony.

Offline Tony Bird

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Re: A second new engine for the model paddle boat Tanwen.
« Reply #4 on: December 22, 2016, 07:44:00 PM »
Hi,

Some more work has been done on the engine.  Flywheels have been turned and crank pins fitted.





The ports in the port block have been pilot drilled  then drilled to size and some of the steam passageways have also been drilled.




RH pilot drilled LH drilled to size.




Regards Tony.

Offline Tony Bird

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Re: A second new engine for the model paddle boat Tanwen.
« Reply #5 on: December 23, 2016, 04:57:00 AM »
Hi,

The worm and wheel for the engine arrived today and were fitted into the square section aluminium tube.



It was decided because the one end of the engine was so much heavier than the other the engine would be converted so that it was inverted.  This means that when it is fitted in the hull the engines weight will be lower down and hopefully make the model more stable in the water.  The two parts of the engine apart.



The two parts of the engine joined together.



All the steam passageways have been drilled in the port and reversing valve blocks.

There is quite a size and weight difference between the Mk.1 and the Mk.2 engines.



Regards Tony.

Offline DamienG

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Re: A second new engine for the model paddle boat Tanwen.
« Reply #6 on: December 23, 2016, 12:14:30 PM »
Great work Tony.  :clap :clap :clap

Offline Tony Bird

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Re: A second new engine for the model paddle boat Tanwen.
« Reply #7 on: December 24, 2016, 04:55:31 AM »
Hi,

As we are going away over Christmas only a bit of tidying up has been done on the engine today and it is likely to be the last work done on it this year.

Some relief was turned on the cylinders port face.



The cylinder bore and port face were lapped.





The plug holes in the port block were tapped the nut is being used as a depth stop.



Plugs were glued into the port block.



Some of the plugs were not cut back but used as securing points for the feet of the engine.

 

All the parts so far made.



That is it I suspect until next year, so everyone have a great Christmas and a Healthy New Year.

Regards Tony.


Offline derekwarner_decoy

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Re: A second new engine for the model paddle boat Tanwen.
« Reply #8 on: December 24, 2016, 07:12:10 AM »
That cylinder bore looks beautifully smooth Tony..... :clap.......[1200 or 2400 grade paper + Brasso for the lap?]

So as a group  :gathering....we look forward to your return to the workshop next year

Merry Christmas........ Derek :beer
« Last Edit: December 24, 2016, 07:13:54 AM by derekwarner_decoy »
Derek Warner

Honorary Secretary [Retired]
Illawarra Live Steamers Co-op
Australia
www.ils.org.au

Offline Tony Bird

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Re: A second new engine for the model paddle boat Tanwen.
« Reply #9 on: December 25, 2016, 03:40:45 AM »
Hi Derek,

[1200 or 2400 grade paper + Brasso for the lap?]

Just the Brasso, K&S tubes are very accurate and have a fine finish on their inside.  I make a lot of cylinders using them as a liner just gluing them in.  The attached photographs show a fabricated cylinder nearly 70 mm long with a 1/2" bore, it would have taken a long time to get a good finish in the bore without using a liner.
 



Have a good break.

Regards Tony.

Offline Tony Bird

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Re: A second new engine for the model paddle boat Tanwen.
« Reply #10 on: December 31, 2016, 04:22:26 AM »
Hi,

I hope everyone had a great Christmas.  I got back into the shed earlier than I expected after our break, I didn't think we returned until tomorrow.  A design change has taken place.  The idea was to pack out the cylinders with some wooden lagging, it is something I have done before when using K&S brass tubing for the cylinders.



And.



However it was realised that using a conventional type of helical spring to hold the cylinders to their port blocks along with a spring for the reversing valve would take up a lot of room in the square section tube.  It would also make it difficult to remove the cylinders without taking most of the engine apart.  So it was decided to use an external spring to hold the cylinders against their port blocks.  A pair of Mamod cylinders using such a spring which is held in place by some K&S brass tube which is drilled and glued to the cylinders.



So some brass was turned and drilled to beef up the cylinders.



This tube was cut in half to make the parts required.

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Tubes have been fitted into the reversing valve block to help its seal to the cylinder port blocks and the steam and exhaust pies have been soldered in place.



The engine has been test assembled and now looks like this.



The reversing valve next I think.

A happy and healthy New Year to everyone.

Regards Tony.



« Last Edit: December 31, 2016, 04:29:33 AM by Tony Bird »

Offline Tony Bird

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Re: A second new engine for the model paddle boat Tanwen.
« Reply #11 on: January 01, 2017, 05:00:22 AM »
Hi,

Today the reversing valve was made and its actuating lever attached.





With the reversing valve finished it allowed the steam passageways to be checked using a syringe and water.



The cylinder covers have been made and at the end of the day the engine looked like this.



A Happy & Healthy New Year.

Regards Tony.

Offline DamienG

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Re: A second new engine for the model paddle boat Tanwen.
« Reply #12 on: January 01, 2017, 10:06:25 AM »
 :bravo :clap :bravo :clap :bravo :clap

Offline Delaunay

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Re: A second new engine for the model paddle boat Tanwen.
« Reply #13 on: January 01, 2017, 08:39:56 PM »
 :)Hello;
I look and copy the technique of this engine for a future boat.  ;)
A well-done demonstration. :clap
cordially

Offline Tony Bird

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Re: A second new engine for the model paddle boat Tanwen.
« Reply #14 on: January 02, 2017, 04:44:54 AM »
Hi,

I finished the engine today and it has run OK on air.  The pistons were made and fitted with '0' rings.



The engine assembled looks lie this.







There is a bit of tweaking needed but nothing serious, I hope to run it on steam in a few days and will post a video.  The engine running on air is more than powerful enough to power I suspected a larger hull than it will be fitted in.  The engine is quite small less than 70 mm high about 2.5/8" and has a 1/4" bore and a 1/2" stroke about 6 mm & 12 mm.

Regards Tony.

 

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