Gina

For setting up the OAG you can focus the scope on anything (200m will be fine) and then adjust the OAG. As you change focus from near(ish) to infinity the OAG focus will go with it. That's one of the advantages.l

Part of pendulum suspension and the crutch. Top part of crutch is a vane that interrupts a light beam in an optical sensor to measure the pendulum timing for the auto-regulator. A lever will raise or lower the actual pendulum suspension to change the length below the tiny gap shown where the suspension spring fits.

That's a lot better.

Good focus is not important for guiding, in fact they say it works better if slightly off so that the stars as little circles rather than pinpoints. OAG is certainly better because there can be virtually no flexibility between imaging and guiding.

As I recall mine worked well but I went over to guiding through the main scope - OAG - which was better.

With two observatories you could image two things at the same time (or the same with different wavelengths) OR one for night and the other for day.

I've used the SW version. Would expect there to be any difference but you never know.

I thought it might have been from drawer runners. Saves having extra support structure Like it!

That's clever

Rough cross-section diagram of parts associated with minutes and hours. Top of diagram will be front of clock and the hands will fit on the axle and tube (minute and hour hands respectively). Starting bottom on minutes shaft, spring, great wheel and driven pinion (which also provides one plate of clutch), clutch plate combined with pinion to drive hours gear train. Other side of front (top) acrylic sheet is cam to start striking mechanism, large snail cam to control number of strikes attached to hour wheel which has tube to hour hand (not shown). On the right is a shaft with spur gear and pinion to drive the hour wheel from the minutes shaft pinion.

Modified rack design. The top of the rack needs very little strength as it only has to hold the weight of the rack whereas the bottom takes the force of stopping the striking action.

Changed to 60% and trimmed the top of the rack with side cutters to reduce its width and took photos of the lower and upper positions of the rack. This seems a lot better - the lower end of the rack can go behind on the minutes to hours intermediate pinion.

Trying to sort out the gear train for the striking mechanism. Tricky...

Reduced to 70% and I think this is probably alright.

Repositioned the pivot for the rack. Slight improvement in position of small snail cam (represented by small nut). OTOH a smaller rack and large snail cam seems the way to go. Fitting everything in whilst avoiding parts clashes and axles is not easy.

Scaled rack and large snail cam to 85% which seems not too far off. Maybe just a little smaller. The small nut roughly shows the position of the small snail cam. 1. Lowest position about to start 12 strikes - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 2. Highest and resting position.

I do the same from time to time ?

Here are photos with a thin test print of the rack placed on the clock. It is quite apparent that the rack is too big.

The striking rack will just fit in covering the space between 8 o'clock and 11 o'clock with resting position with its top at 11 o'clock. The bottom will only drop as far as the 8 o'clock position when striking 12. The simplest way of doing this is simply to rotate the whole striking works around the clock centre by about 30°.

In sorting out how it will all fit together and how it will look, the striking rack needs lowering a bit. As shown in the diagram in green below, the rack rests in its highest position and would cover the escape wheel, which though possible, wouldn't look right. This means the release parts will also need changing as the main shaft and pawl will need to be lower. The overall design is beginning to come together though there is still plenty to sort out.

You should be alright Jim, you're just starting and when you retire you will have the time - whether you will have the money is another matter. I have been astro imaging for 7 years now.

I didn't keep account of the costs of mine but 3K seems probable. I hate to think how much I have tied up in astro equipment but as a rough estimate 10K or more. Could even be 20K as it's amazing how everything adds up. I just wonder how great a garden I could make if I sold off all my gear!! Could afford double glazing too. I think if I don't use do more than a couple of nights of astro imaging during this dark season, it's a hell of a lot tied up in gear that doesn't get used. I could compromise and just abandon DSO imaging. I shall have to see how it goes and how I feel.

I examined the anchor and found I could adjust one of the pallets to provide the clearance required, put everything back together and the escapement now works. The acrylic sheets still have their protective layers so are not fully transparent yet. I'm leaving the protection on until I've finished drilling holes etc. Second photo shows the position of the minutes to hours gear train, very roughly drawn in on the protective covering, with a felt tip pen..

Been testing the clock as far as I've got with it. Bearings pressed into all their holes in the acrylic plates, gear train assembled including escape anchor, plus back and front plates attached to the two wooden side members with wood screws. It is not quite free. It will move by pushing the gears round but I think the pallets are just touching the teeth on the escape wheel where they should just clear. I can either adjust the pallets or reprint the escape wheel with slightly lower teeth - it's only a few tenths of a millimetre.

I used high quality redwood cladding which has proved very durable. I have plenty of natural ventilation in mine - lots of gaps - which seems sufficient. I also have a dehumidifier which automatically clears dampness above a certain level but that only seems to come on after a nighttime imaging session and closing the roof.