Scattergun 3.5” King Arthur ‘Sir Sagramore’

Tim Watson

Western Thunderer
After an inordinate amount of thinking and puzzling I have now made the front and rear damper linkages for Sir Sagramore.
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The rear linkage is simply a rod that links to the damper clevis and snuggles in close to the back head.
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The rod is located by a grooved bobbin that centralises it with low friction. The top is rebated and has a separate top hat 12BA bolt assembly.
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This rod has a rotating handle that locks it open by resting on the frames (a detent will be filed in when the boiler is next removed). To rest the concept, a lump of styrene was carved to shape. IMG_9057.jpg

This was then converted to metal and can be seen here with the handle in closed position. It will be prevented from moving medially by the support component of the front damper.IMG_9060.jpg

The pillar that supports the front damper lever has a rebate to locate the rear damper body when in the closed position.

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In this image, the dampers and drain cocks are in the open position; the brass nut will be replaced with steel.

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I have tried to maintain the style of Ian Jaycocks’ work with these new components.

Tim
 
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Tim Watson

Western Thunderer
The central trap door on the Sir Sagramore ashpan now has a control / locking device. It’s a bit unorthodox but it will hold the trap door shut when running.
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The linkages ended up with a rod pointing backwards at 45deg from the base of the footplate, with it pulled up to close the trap door. I therefore made a steel toggle that holds the rod in the open position:
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It rotates 90deg. and pushes in towards the backhead to open the trap door for ash disposal:
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I wasn’t convinced by the appearance of the toggle and it was also a bit slippery to handle. I therefore made a hand wheel to make it easier to hold and also reduced the locking pillar in size. The wheel was turned as a blank and mounted on a mandrel, Loctited in place. This was then drilled on the rotary table.
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The outer ring was then turned off to give the ‘grippy’ outer part of the hand wheel.
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After rounding off the edges the front face was given a rebate using a graver.
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The locking toggle components can be seen here, before assembly. The hand wheel was simply soft soldered onto the steel toggle, and held in place with a 10BA nut, with it pivoting freely on the rod - a piece of coat hanger suitably turned down & threaded.
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Finally an exciting video showing it in action!

Back to small scale stuff now.

Tim
 
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