2" shaft mounting Pt 23: Adding a disk/plate bearing.

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Here I have fitted plastic 'feet' as friction pads to the tops of the studs. There was too much friction until I tried some silicone grease intended to stop car door seals from freezing together in winter. The silicone produced a silky smooth turning action on the shaft. The slight extra degree of friction may be useful for avoid too much sensitivity in balancing the OTA. The large flange bearings and their seals have very little friction in themselves.

I should have reversed the flange bearings by now to avoid having any bare shaft above the bearing. The minimum amount of cantilevering is desirable to avoid any chance of shaft flexure.

This image shows the brass ring I made in the lathe to resist the outward pressure from the Tollok locking bush's opposed cones. Which should ensure the Tollok bush contracts strongly onto the Dec shaft to hold the saddle very firmly.  That is not a gap between the shaft and the Tollok bush. It is just that the inner cone has withdrawn slightly inside the bush.

A thin, steel, expansion ring is supplied with these bushes but it was slightly too large in diameter to fit between the flanges of the channel section saddle. I had already had to grind small flats on the Tollok bush to fit the largest flange into the channel. Cutting away the light alloy saddle, to allow the bush to fit inside, would probably have weakened it. The small flats I ground and filed smooth will not affect the Tollok bush's strength at all.

Having the Tollok bush available has allowed the saddle to be supported with virtually no overhang. Every bit of unnecessary overhang means extra counter-weighting for the OTA. One just has to ensure OTA clearance for the large RA wormwheel.

Click on any image for an enlargement.

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