Boiler Y14 part 3, Smokebox tubeplate and throatplate

As the boiler parts are being made, the drawing gets attention too. 

The smokebox tubeplate is a relatively simple affair to make. In fact, these round plates were one of the first things my dad and I made in the early eighties when we started metalworking and model engineering. At that time it was our first experience in copper working, but the plates we made then were used as base plate for candle stick holders 😀. 

 A piece of 3 mm copper is cut into a circle. A surplus of about 10 mm is added to the final diameter. This will be the edge (or rim).  

Heating up does not take much time, but several heatings are necessary because the material will be compressed quite a lot. The 3 mm thickness increases to almost 3.5 mm on the edge. 

To have a close fit to the boiler barrel, the edge is shimmed off to the final diameter. 

Support in the lathe is the steel former on which it was hammered and a wooden block to firmly hold it pressed on the former. Light cuts were taken. 

An impression of size.

The throat plate.

The throat plate takes up a lot of more work and time. First, a piece of copper is flanged, the same way as the boiler back head plate. 

Then a second former plate is needed, made of a piece of scrap aluminum, for the outer rim. 

A circle is marked out.........

..... and cut by hacksaw and file. 

Positioning it on the former, where care should be taken to center it on the former and put it on the correct height. 

After clamping it in the vice, the first hammering session brings it into shape. Here the material is stretched, instead of compressed. 

There fore several annealing operations are necessary. 

The final forming operation (all done by hammering).

The rim (12 mm wide) is marked out and filed to height. 

The edges are still 3mm thick and will of course not fit in the small gap between boiler shell and wrapper. 

First, the overall height is marked out and cut to size.

An angle grinder is used for trimming down the thickness of these edges. They will start at the original thickness of  3 mm and be ground down to approx 0.5 mm. This way they will fit as close as possible in the wedge-shaped gap between the boiler barrel and outer wrapper. 

By test fitting, it becomes clear where to remove excess material. 

After a few fittings and grinding operations, the throat plate slides in the gap. 

A few final light taps with the hammer, ensures a close fit to the boiler. 

The wrapper is now cut to length. 

Holding it in the vice, with the aid of the forming block, makes it possible to file it to the correct length and square to the sides. 

Once this was done, the throat plate itself was marked off and cut to size. 

The final operation is the cutting of the edge. 

Roughly done with the angle grinder, and finished with a file. 

Almost there. The round corners of the outer wrapper can be made a bit shorter (closer to the rim of the throat plate).

Seen from the inside: a nice fit of both. 

Wrapper, boiler shell and throat plate in position. 

With an overall length of 441 mm, it is indeed for a 5-inch gauge locomotive a small boiler. All in all the size isn't that much different than that of my 5-inch GWR 14xx class loco. 

Still a lot to do 😃

If you want to know more about the construction and parts of a live steam boiler: this site provides some explanations:  

https://en.wikisource.org/wiki/Steam_Locomotive_Construction_and_Maintenance/Chapter_II

Boiler Y14 part 2: Firebox wrappers.

The Solidworks design is still under development, but more details have been added and some technical parts were updated. 

LNER number 5361 was chosen as the model's temporary 'work number'.  

This loco was built by the Great Eastern Railway in 1889 as number 836, changed to 7836 by the LNER in 1924, and later in 1946 to 5361. The British Railways added a 6 to the number, so as 65361 it was withdrawn from service on 16/09/1962.

The locos, of which 289 were built in several batches between 1883 and 1913, during their existence had some differences and underwent some changes.  

GER 836 was built in 1889 under work order T22 at Stratford.

See  https://www.lner.info/locos/J/j15.php  for more information

This version had the low cab cut out and the slotted shapes in the tender frames. 

The cab was laser cut and held together with some neodymium magnets. 

This gives a first impression of the size of the loco. 

Making the outer wrapper and the firebox wrapper; starting with cutting the sheet material. I can not cut 3mm thick copper with my guillotine sheer, so I used a large hand saw and some elbow grease.

Making a straight reference edge on the milling machine. 

      

A wooden former was made of a set of MDF plates, glued and screwed together. These plates were made with the CNC milling machine. 

Heating up the wrapper plate takes already a lot of heat and time. 

With a clamp, the copper plate is centered and aligned on the former. 

          

After annealing the 3mm plate can be bent by hand by pressing and rolling the assembly over the workbench.

Reheating for the next operation.

Clamping the top, the sides can be hammered down, with the aid of a large block, to spread the force and prevent dents in the plate.

Almost there, but due to the hammering, the plate get hard again and needs to be annealed again.

The flame of the propane burner curves around the surface. 

The final forming is done with a round piece of wood, that is used as a hammer. 

Final check against the firebox plate. 

The wrapper is now cut to length. A bit of extra width was taken into account, to correct a possible skewness. But in retrospect it was not necessary; the wooden former keeps it straight and aligned from the start on. 

The firebox plates and wrapper are ready. 

The outer wrapper is also made from 3 mm thick copper. Same working procedure as the firebox wrapper, however more heat is needed for annealing. 

Until here, all bending was possible by hand. 

Then the clamps and wooden blocks are used to bend the sides. 

For the final bending operation, once more the wrapper is annealed. 

A test with the backhead plate. Because we are making two boilers, Toin's backhead was used for the other side. 

Checking the wrapper on the frame of the Y14.  My 3½ inch Mona standing next to it, is also in the workshop for a 'general overhaul'. 

A lot of copper......