Main Cylinders

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For most of the photos on this page, you can click the image for a larger picture.

	The cylinder design uses imperial (i.e. inch) dimensions whereas birch ply comes in metric thicknesses. Tony is using some 1.5mm ply sections to compensate. You can see from where the sections sit on the drawing how the compensation is working.
	As the sections go into the box, the internal structure of the valve cylinder becomes clearer. In the centre, the wider gallery is the oil gallery
	September 2024 As Tony builds up the sections, we can start to see the internal layout of the valve cylinder. On the right we have an inverted section temporarily bracing the box. Working leftwards, the first section is not on the drawing; this is the pattern makers "print" which will support the ends of the core in the main mould. The next wider diameter section is the exhaust steam cavity where exhaust steam is expelled through passages to the blastpipe. Next left is a small recess that has no direct function. It probably avoids too much mass of metal in this area. The next recess is not reflected in the core at the moment. This is for the transfer ports where live steam is admitted to the main cylinder and exhaust steam is expelled - depending on the position of the valve piston. A loos piece will be used to create this cavity. Working leftwards, the next cavity is for lubrication oil admission. In the original design, atomised oil was introduced into this cavity and passed into the main cylinder through a number of small holes in the liner. We will be changing to direct lubrication so a "loose piece" will be added so that oil is conveyed direct to the liner. We will use the "loose piece" so that the pattern could be used for Britannia or Oliver Cromwell should they need a new cylinder. Finally on the left we have the steam chest where live steam enters from the superheater.
	Tony is now halfway through the sections for the valve cylinder core
	Tony and Ruth have been working on the 2 top halves (or quarters!) of the main cylinder pattern. The target is to get a good join between the 2 sections and for them to be sitting flat on the surface table. Here Ruth is working on the socket join of one of the sections.
	A surface table is used to ensure that the pattern is truly flat. It has to fit tight against the bottom half of the pattern.
	The 2 sections are then cramped together and the fit is checked against the bottom half of the pattern. These are checked for fit ready for gluing and being screwed together next week.
	Turning to the valve cylinder core box, Tony will need to form a radius on each change of direction along the core sections. To produce the convex curve, Tony has made a routing jig that will enable him to run round the edge with a routing tool - as shown in the photo. The radius is to assist when removing the sand core from the core box.
	Tony's task is to produce cores that will produce the final shape - in sand - as shown in the 3D model. The red arrows point to a core that will be needed to create the transfer ports - the ports contain live steam to the main cylinder and exhaust steam away from the main cylinder. The green arrow points to the exhaust posts where where exhaust steam is conveyed to the exhaust manifold in the smokebox saddle. The black section is the "print" that will support the core in a recess provided by the main pattern.
	Tony had a slight hiccup at the start of the New Year. While turning down the second half of the main valve cylinder pattern, he managed to break though into the central void - one of the pieces of timber was too thin. The offending piece of timber had to be removed. The photo shows the inside of the pattern before starting to rebuild .

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197 records found. Page 19 of 20 displayed.