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Next Efforts
As planned, I made up the Declination ring cage. I needed to fix the separation between the rings so that I can later make their supporting points on the RA ring. I made the structure in the form of a cage so that I can slide it up and down the OTA struts to find the balance point when everything is attached to the OTA. I will fix the cage onto the struts near completion of the project.
I have made a protective top coverplate for the mirror box which clips on and off with the same clips as the OTA struts. (Still have to make a bottom one)
Next I have made up the bearing assemblies to support the RA ring. I used some aluminium bar, and have tapped holes through the centre, and across for the bolts to hold the bearings. Bearings were selected mostly by cost! Common sizes are much cheaper that exotic varieties. Then the mounting bolts were selected to suit the bearings.
The idea is that the RA ring will sit on the top of the vertically mounted bearings, and be held central by the horizontally mounted bearings. One of the vertically mounted bearings is mounted on one end of a pivoting bar, with the other end fitted with a section of teflon rod. (MUST be teflon). The weight of the whole assembly causes tboth the bearing and the teflon rod to come into contact with the base of the ring. The teflon acts as a brake to the horizontal rotation action. The pivot point can be moved to apply more or less braking affect to the base. At this stage I have made a guess. If there is too much, or too little braking, I will move the pivot point accordingly - hopefully it may be OK where it is!
I have spent about three days worth of activity setting up the bearings on the triangular base frame, and filing the RA ring to get it round. The roundness is important for the smooth rotational action. I figure I have another day's worth of filing to get it acceptable. Currently, it still binds a little at one section in the rotation.
Pics attached to explain better. More as it develops.
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