BOILER

[Tony Bird]

Hi,

While overhauling my model steam railway layout after its winter lay up for its first exhibion of the year next month I have been thinking about the design and building of a boiler for the small direct drive steam engine previously described.  I was thinking of a model of the A.J.Goddard which is a simple prototype but it had a small water tube boiler which is very small when made near scale.  The first thoughts were for a small gas fired centre flue boiler which ran at quite a high pressure for a oscillating engine unfortunately it would have had a quite small water capacity.  So a pot boiler was considered is C of G would be an inch or so higher but its water capacity a lot more.  So after working on the layout I did some sketches of a boiler.  At scale even it would not carry much water so a drawing of AJG was played with its model OA length being just over three feet.  Using the chimney as a centre line the boiler was extended under the wheel house and the same amount into the cargo space.  Also the diameter of the boiler was increased.  Doing this would allow a boiler 150mm long and 60mm in diameter and the boiler's extra size didn't notice too much.  To make the boiler as light as possible the boiler barrel was rolled from 0.75mm copper sheet which has rivetted and a hard soldered seam.  The wood for the former came from a post that had held a tree upright in our road until a lorry backed into it.   A new tree with post had been planted but the old post had been left and had spent many weeks resting on the pavement.         

Turning former for boiler barrel.



Pinning copper sheet to former before rolling.


Boiler barrel rolled.


Boiler barrel secured with cable ties before drilling.


Boiler barel drilled and rivetted.


Boiler barrel hard soldered.


End caps next I think.  But this will be somewhat pretracted as they is still a lot of work to do on the railway.

Regards Tony.

[Tony Bird]

Hi,

Before starting on the end caps of the boiler it was decided to fit the internal part of the steam pipe.

Photographs shows the penentration of the solder into the joint and around the rivets.


Boiler barrel drilled for the safety valve bush, steam pipe and s securing screw for the steam dome.


Steam pipe going into steam dome. The other holes are for the screw to hold the steam dome in place while soldering the other hole allows steam into the dome.


The steam pipe coming out of the steam dome through the steam/water space to the underside of the boiler where it will be fitted to a super heat pipe.


The boiler design is a sort of cross between the boilers that Bowman and Mamod use on their commercially made model/toys.

Regards Tony.

[R.G.Y.]

Well done Tony. I do like the recycling, as much as the boiler.Geoff

[Tony Bird]

Hi,

I do like the recycling, as much as the boiler.Geoff

The 0.75mm copper for the boiler barrel was once a domestic hot water cylinder and the 1mm copper for the end caps is from a water heater.  The rest of the materilas used are new.

Trimming end of boiler end cap.


End caps finished and drill for a cntre stay, gauge glass, and banjo's for a pressure gauge and filler valve.


Dry assembly of boiler.


Except for a union on the steam pipe the soldering of the boiler is finished.


The boiler should be tested today.

Regards Tony.

[Tony Bird]

Hi,

The boiler test was successful.  Tested for a working pressure of up to 35psi (2 bar + a bit)


The boiler in the background was finished and tested yesterday evening.  Most Wednesday evening members of the CMES GR group come to the shed and make or repair their locomotives.  This boiler isn't for a locomotive but to power a Stuart 10V that Chris who made the boiler started to make when in his teens and was eventually finished last year in the shed many years later.  The boiler is made from a commercial 'T' pipe fitting which Chris bought in the US quite recently for $11!  The boiler is Chris's first and he has done a very good job.  It will take him some time to make the fittings, burner and gas tank unless he decides to buy them.



Regards Tony.

[Tony Bird]

Hi,

Not a great deal done today after testing the boiler.  I spent an hour or so folding up some of B&Q's galvanised steel sheet into the start of a boiler support/flame guard.  The boiler is held by it's extended stay to the rear support and just rests in the front support,  this will allow the boiler to expand when the two supports are connected together.



Regards Tony.

[R.G.Y.]

I am even more impressed.  The fitting you mate acquired in the U.S. is of interest. They are available in the U.K. used for cold room refrigeration. Much thicker than domestic pipe, having to withstand gas at extreme pressure, up to 600 bar?? Here is a photo of a elbow with a short piece of2.25 pipe.   Shown with a12mm tee as I haven't a 15mm elbow in stock. Just looking at it the moment  could be the inspiration for an unusual boiler. geoff

[Tony Bird]

Hi Geof,

Other pipe fitting ideas?

Small boiler made from a 35mm 'T' fitting to be fitted in a small model '0' tram locomoive


Gas tanks.


The second locomotive in this video has a boiler made using a 35mm 'T' fitting and a length of 35mm pipe.



Regards Tony.

[derekwarner_decoy]

Hi PD's.......600 Bar ? 99% pure copper has an ultimate tensile strength of approx 400 Mpa....so without the calculator  ...

A 4" section of a 4x4x2 unequal tee in 16# [or 1.6 mm thickness] may have a working pressure of 8 Bar

A 4" section of a 4x4x2 unequal tee in 8# [or 3.2 mm thickness] may have a working pressure of 12 Bar

   but . .....Derek

[Tony Bird]

Spent most of the day cold, working on the model railway layout though I did manage a bit of work on the boiler.

Made a conecting piece beween the two verticals and fitted a super heating pipe.




A start was made on the cover by making a measurement template.


Regards Tony.

[steamboatmodel]

It is interesting what you can find in copper fittings.
http://www.pexsupply.com/Copper-Fittings-130000
Regards,
Gerald.

[Tony Bird]

Hi,

Finished the flame guard today.



Securing nuts soldered in.


Boiler  to date.


Railway again tomorrow!

Regards  Tony.

[Tony Bird]

Hi,

Made up a tray and fired the boiler using Sterno and very happy with the results, due to a tight big end the starboard engine is leaking on its port face since repaired.  As the likely fuel will be gas the boiler could produce more steam.






VIDEO.


Regards Tony.

[R.G.Y.]

I happened to find the video to your work shop I am most impressed. Geoff