26.11.2020 RA wormwheel eccentricity

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I set up my digital dial gauge to measure the eccentricity of the 11" RA wormwheel. Having zeroed the dial gauge the maximum difference was only 0.02mm. The worm had been deliberately pulled away from its wheel to allow free movement in polar rotation. There was a lightly higher, dynamic reading during rotation which dropped back to a smaller reading when I deliberately paused. 

I was quite pleased with this small degree of eccentricity. It was far less than I had feared. The difference might even be the result of inaccuracy in my measurement technique. Or simply roughness on the wheel rim where I was measuring.

I was also able to measure a 0.02mm variation in the reading by applying heavy pressure to the Dec axis. To act as a lever when the telescope was pointing up at the Pole. Perhaps this variation could be reduced by pre-loading the axis flange bearings. If it was considered necessary. 

Unfortunately I was able to see flexure in the RA worm housing when I rocked the telescope in RA. This occurred after I had re-tightened the worm housing fixing bolts to the big 10mm support plate. The 5mm thick, tubular, box section, motor housings are obviously not adequate in stiffness without further reinforcement. There isn't much room for extra material so I will have to give this some thought.

The Moon was rising in the late afternoon. So I had a look with the binoviewers at various powers and then captured a couple of videos. Mars was just above but too "colourful" to be worth imaging when it was that low. The seeing was simmering fiercely. So I was surprised to have captured a hint of the central crater in Plato.

 

18.10 These images are hardly worth sharing really. Though it makes a change from solar. 

It might be worth leaving everything set up and coming out later when the moon is much higher. The seeing might have improved by then.

19.30 Went back out as the moon reached 35° but the seeing was still "boiling." Results were even worse than earlier. It almost immediately clouded over so there was no excuse to continue.

 

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