Observatory: Chair, OTA balance and drive problems.

Saturday: Fitted most of the "skirting boards" around the octagon base. Re-balanced the folded OTA on the mounting. Assembled the IKEA observatory computer chair. It has a gas strut, rise and fall and large, stable footprint. Light coloured, wipe clean plywood seat and back. Easy to find in the dark and can be left out in the observatory without worrying about damage to cloth upholstery.

I tried the laptop to control the mounting again without any luck. Engaging ASCOM via Stellarium Scope even stops the normal tracking. Stellarium has no memory of the changes I make even when I update. I might have more luck with Cart du Ciel.

Still trying to balance the folded OTA. It is still slightly too heavy for two counterweights but three is complete overkill. I have tried my stock of tubular brass spacers to move the weights in and out without success.

Adding a finder [or rather two] plus the binoviewer might make the difference to better match three weights. What I need is a quick release weight to simulate the binoviewer. Then I can simply remove the "dead" weight when the binoviewer is fitted.

A separate sliding weight for the Dec shaft might be too near the center of rotation to make much difference. Such weights ideally need to be well out from the "fulcrum" for maximum effect. This was very noticeable on the saddle sliding weights for tube balance. Every added weight affects the mounting in all planes. What works one side of the polar axis can be wrong on the other. Add a second OTA and it all goes haywire again.

In theory I should lower the pier by a few inches to place the center of rotation in the middle of the dome. At the moment the mounting is too near the top but clears the dome's nether regions. Not such a problem now that I have the much shorter folded OTA in place.

Sunday: Refitted the sliding weights to the cradle. Removed the spacer and fitted three counterweights. OTA now better balanced. I had been using a rubber roller as a belt tensioner but it was not ideal. I'm going to look for a pair of journal bearings instead. The rubber roller was responsible for some motor stalls further exacerbated by slight imbalances. Releasing the clutch screws is essential if a true balance is to be achieved. Reaching the three radial screws in the wormwheel bosses was always difficult until I used an extended hex driver with ball ends.

I'm examining ways of fitting the 6" solar telescope beside the 7". Lengthening the temporary plywood support rails may be the easiest method. Though the 6" hinged rings could be bolted through the frame of the 7" if it was slightly offset to make room.

The solar side of observation [and possibly imaging] opens up a far greater chance to spend valuable time in the observatory. Particularly in H-alpha. Staring at a featureless Sun in white light has its limitations as we descend into a deep lull in the solar cycle. Prominences add  a whole new level of razor sharp detail to be enjoyed.

Click on any image for an enlargement.

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