Folded OTA mounted at last.

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I needed the double stepladders and chain hoist to lift the folded 7" refractor onto the mounting. Two 5kg [10lb] weights balanced the OTA nicely. 

Rather than make some sort of bayonet mounting I sawed some 3/4" x 2.5" plywood strips to mount the OTA with screws through the framework. Not ideal, but the plan was simply to check out the balance, clearance and performance on the new mounting.

I had to cut and turn a 60mm length of brass tube to space the counterweights and retain the Dec wormwheel in the correct position. Otherwise the weights and wormwheel could slide up and down the shaft.

There is some backlash in the PA as I try to rock the OTA around that axis. The free play is not in the wormwheel/worm but in the 7" diameter PTFE clutch. I tightened the screws which force the nylon pads in the wormwheel boss onto the shaft and this helped. The Dec worm needs to be closer to its wormwheel to remove mechanical backlash.  Longer slots for the fixing screws are required.

Without more than very rough optical alignment I took an afocal snap of  440 yards distant trees with my TZ7. I would easily see something as small as a match head or fly at that distance. Nicely monochromatic result for a colour shot through a 32mm Meade 4000 Plossl and 7" f/12 refractor. I shall have to try my short zoom compact as it does a much better job of afocal snaps.

Not wishing to dismantle the mounting again. I used a mains drill with a small router bit at full speed to make the elongated holes in the base plate for the Dec motor/worm assembly fixing screws. It felt horribly rough while cutting but made quick work of the job. I finished off with a round file to smooth the slots. There is solid engagement of the Dec worm and wheel now. I used spring washers and ordinary nuts rather than Nyloc nuts for the moment.

The sun kept being obscured by thin cloud but still made a handy tracking target to check polar alignment. I added the full aperture Baader foil filter first, of course. The PA soon proved to be pointing too high but that was soon fixed. Azimuth is only set roughly by compass. I shall have to check the local magnetic variation from true north. [2° 50' East] 

I'm using the IH2 to track the sun without a computer. Solar rate is selectable from the handset menus. Just stopped for lunch but will continue 'playing' afterwards.

Eyepiece height is 90cm when pointing at the zenith.  A comfortable height for sitting on a normal folding chair as shown. 165cm high when viewing horizontally is perfect go for me for viewing distant trees. The wind is quite strong and is causing a slight flutter of the sun's image. This could be due to the rather flimsy stand. 

Click on any image for an enlargement.

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