18.11.2021 Skate wheel shutter slides.

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Thursday 18th 46-50F, leaden overcast with rain promised. It started at 10am and hardly paused.

Yesterday afternoon I notched the ribs enough to be able to thread the channel rail into position. The extension beyond the base ring can be seen in the first image. Not too extreme. The rail is cut rather long. To avoid it being too short if I need to add support beyond the run of the skate wheels.

First I aligned the rail to within a millimeter of the double, plumb line level using the laser rangefinder. [Repeated readings to confirm] Then marked the base ring to ensure it stayed that way.

The left shutter [seen from inside the dome] nestled perfectly against the channel. While the right shutter was badly skewed. [See second image] The right shutter seems to be rotated anticlockwise in plan.

It has occurred to me that the individual top drawer slides may not be parallel. The screws have started pulling out. A single, channel, top rail will guarantee they are both straight. Though not necessarily parallel to the lower rail unless I make it so.

There is also the matter of the height of the tops of the shutters when converted to wheels and channel. Will this change the height of the lower shutters? Perhaps I should concentrate on the upper rail first? I have to introduce the wheels between the shutter top boards and the dome zenith board. This is bound to affect the lower shutters. It might be risky to expose the shutter wheels to the weather on the outside in the long term. So it is arguably safer to have them positioned internally. Shame it is raining again! 

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