Building Dolgoch (Fletcher-Jennings )7 1/4

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    `The next images show the construction of the boiler. I was fortunate to have the use of large rollers at Beamish museum for rolling the boiler, the use of a barn in the the wilds of hexhamshire, and the help and guidance of an experienced boiler builder Robin Hedley( a fellow member of BMEG). In the later stages I had help from Brian Nicolls, Ian Spencer and Stuart Davison ,all members TSMEE. Oxy-acetylene, and two v. large propane torches were used. My bank balance still shudders at the cost of easiflow silver solder,.

    

    Robin showing the use of precision tooling in boiler construction.

  

I am grateful to Ken Swan for drawing the arrangement of tubes since it was decided not to have a superheater.( A black art to me. ) I made three fine scores on the tube ends to encourgage a good fillet .

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    Smike box tube plate upside down showing the regulator and the steam delivery pipe which also contains the slide valve push rod. during brazing this tube became slightly bent displacing the push rod and slide valve. I fitted a guide to keep the slide valve closed.

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Major parts assembled before brazing. At this stage I decided to make a frame to hold the boiler during brazing. This was principally to allow allow horizontal to vertical positioning during the same session

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  the brazing frame is made from recycled bedstead angle and proved particularly usefulin brazing the foundation ring and firebox. The boiler was secured with steel wire.

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  Showing the useof the brazing frame.

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   The dome was rolled from copper sheet wwith a butt strap. The three steam supply tubes have been inserted

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  The next few images show the firebox stays (1/8x1" rivets).  The extra external length was useful in getting heat into the stays particularly when brazing inside the firebox. A hydraulic test revealed a few weeping stays inside and outside , In  all we had to reheat 2-3 times In practice it took about 30 minutes to get the largely completed boilrr to brazing heat.

                                    

The discs around the stays are easifow 2 , additional rod braze was needed .

    Hydraulic test showing c.160psi after leak correction. The used bottle of Sauvignon blanc was used to top up the hydraulic pump.

    Fitting the backhead and firebox door plate. The confined space made brazing tricky but a combination of oxyacetylene and external propane heat worked.

              

Fitting the foundation ring ( 1/2" sq. copper)

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    The tube plates firebox and back head plates were nall obtained from Reeves and were entirely satisfactory except for the Throat plate which had to be returned. The photo shows the correct throatplate. Its a tricky shape.

but in the end it all fitted together.

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    A few facts about the completed boiler.

Using my bathroom scales measuring to 0.5 kg.

Weight of boiler including blanking pieces                                                48.5 Kg

                                                            +water                                      62.0 Kg

Difference                                                                                              13.5 Kg

Weight of water removed                                                                       14.0Kg 

Best estimate of water in full boiler                                                         13.75Kg

The spontaneous production of water in a boiler has not previously been recorded !

Working pressure is 80 PSI  ~   5.5bar

hence boiler is 13.75  x 5.5 = 75.6   bar-litres

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My Granson , Eddie Lythgoe< driving Dolgoch at BMEG ( Beamish Model Engineers Group)

                          

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