Main Cylinders

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

	The valve cylinder is more complex than the motion cylinder and comprises of 5 sections. At the outside ends are the 2 exhaust ports where exhaust steam from the motion cylinder is taken away. Next inboard at each end are the 2 valve piston working areas . Finally, in the centre, is the steam chest, where steam comes down from the superheater before being directed into the motion cylinder by the action of the valve piston. This is the steam chest area almost ready for the final sanding operation
	The valve cylinder is 4 foot 10.5 inches long plus or minus 5 thousands of an inch. This is too long for Tony's wood turning lathe, so the pattern (like the main, motion cylinder) has to be made in 2 halves. In the photo, Tony is turning the tapered plug which will fit into a tapered socket on the other half of the pattern
	With the first half of the valve cylinder patter almost complete, it's time for tony to start on the second half - or 2 quarters. To make up the pattern, Tony will need to make up 5 layers per quarter. The centre of the pattern are the plywood boards - see earlier in this section to see how they are located together. 2 layers are on top, one below. Each layer takes three days to add so there is three weeks work to get the blank ready for shaping down to go on the lathe. A 'day' is only a couple of hours long but there are three operations combining the cutting, gluing and screwing and when the glue cures, removing the screws and adding the dowels. Tony says "As with most woodwork, waiting for the glue to dry is something we have to live with."
	The length of the valve cylinder pattern is pushing the limit of his lathe bed length. he says "I'd originally thought of moving the lathe a foot to give me a bit more freedom at the headstock end as I'm turning left handed but the thought of drilling out for the four 25 mm rawlbolts gave me a reality check. What I have done is to alter the final two quarters by reducing the blank size at the print end. So, another template later and a few cuts with the hand saw will reduce the chippings pile when I come to turn this one. You may wonder about the scales. The last blank was out of balance and I struggled to get the finished job parallel. This time I'm weighing each layer to try to get both sides somewhere equal. It's a bit of a fiddle but should pay of in the end."
	This is the raw material for the valve cylinder pattern - dressed Quebec Yellow Pine, which is a soft, straight grained and even textured timber
	One layer is added at a time. The layer is glued and screwed and then cramped up. It's a well known fact that you can never have too many cramps! For the first couple of layers, Tony keeps the 2 central plywood parting boards together to prevent cramp distortion.
	The glue cures overnight, the next day the screws are removed and 100 mm dowels are added. Tony can now split the assembly into 2 halves by splitting at the parting boards.
	Good morning all, The valve cylinder pattern has reached a stage where the last but one layer is ready for gluing and screwing. Tony says "By the beginning of next week the bench will be clear and will allow me to bring the first half of the motion cylinder back into play. My way forward is to work on these two halfs separately rather than joint them at this stage. When I've added all the bosses and live and exhaust steam sections, I can look at the sections required for joining up the two sets. I intend, where possible to do the joining 'dry' at first until much later in the build process, for no lesser reason than to keep the weight down until absolutely necessary."
	Tony reports "I put both halves together to check for any distortion and all checks out ok. So, today will see the last two pieces go on, ending the valve cyl blank construction."
	Tony reports "Yesterday saw the completion of the blanks for the valve cylinder. These two sections will now be planed down to the blue line ready for planing. These will come off the bench today. I'll be working on templates over the next few days to allow me to complete the final finishing of the first two sections which are on the lathe just now."

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143 records found. Page 8 of 15 displayed.