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POD - A HOLE in the DOME

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#1 Nebhunter

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Posted 29 January 2011 - 09:26 PM

I'd like to run this idea with Pod owners. Not sure if this idea has been discussed, but here goes. Zenith is an issue for Pod owners. Yes, I have a PZT table - but loosing light or wind protection, and dew, is a pain.

1] The first must have is the Pod or similar Dome Cover.
2] Pivot pins are removed.
3] Flange on one of the dome halves - that seals the two top halves when closed - one is cut off - maybe.
4] A large hole - 1/2 moon - maybe 3 ft dia - is cut into the fixed dome half only on the one side. The clam half that opens remains intact.
5] This would allow the clam side to still be pushed off onto the PZT table for normal light blocking etc, and the other half stays on the Pod to be rotated as required for wind etc.

The large hole allows for imaging at zenith or thru zenith - and dome can still be rotated as required for additional clearance. When done for the evening, simply rotate fixed half into position, push on other half onto Pod as per normal - do up two locking knobs - and throw the dome cover over top to protect. This lets the hot air out as well in summer.

Maybe keep the cut out part, screw some brackets on the outside part. Replace for winter time and snow load support. Push pivot pins in if required.

I'm sounding this out before attempting any surgery.

#2 piaras

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Posted 29 January 2011 - 11:19 PM

Interesting I will have to think that idea thru. The C11 that lives in the skypod has forced a rethink about getting the PZT table.

#3 Chris Schroeder

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Posted 30 January 2011 - 10:05 AM

Are you talking about moving the secondary dome half onto the PZT shelf? Before cutting the hole, I think a trail run with pushing just the secondary off and on my be in order, I'm not sure if the secondary can support its self without the hinge bolts, it may, like you said, just need them for winter snow load.

#4 Nebhunter

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Posted 30 January 2011 - 04:59 PM

Chris - yes - the half the folds up is what ends up push off onto the PZT shelf. The larger clam remains - so the guide rollers are all in place. Should be able to roll it around without loosing it.

That heavy plastic is formed, and should not spread or change shape if the other half is removed. Cutting out a hole in the shell may weaken it, but I think there is enough strength for normal use. Replace the "plug" during winter for snow load - or a piece of plywood?

#5 Craig in Tacoma

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Posted 31 January 2011 - 03:16 PM

As a POD owner, I too am often caught with the zenith just out of reach and wish for a better way to see up than the PZT.

I have thought about cutting a slot into the top and retro fitting the cut out piece(s) with some sort of edges so it would drop into place and seal when not in use.

Because of the design of the POD I think it would be a mistake to cut the top edges. A loss of rigidity may cause other problems beyond snow load losses and I haven't come up with an idea that would work without a major re- fabrication of the dome sections.

An idea I had was to move the whole dome using wheels you could attach to the lower 4 compass points that levered down. This idea would only work if you didn't have the bays attached, that might complicate things.

When the zenith was a target, the wheels would jack up the dome so you could roll it a few inches off center of the pier, opening up the hidden zenith.

This would remove any loss of the domes integrity and be simple to bolt to the base sections. A rubber tube glued around the base might replace caulking for a water tight seal when the dome was down off of the wheels..

Thoughts? :question:

#6 Nebhunter

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Posted 31 January 2011 - 11:13 PM

Yup - I tried something like that, but once the 3 bays got loaded with gear - extra counter weights - battery backup - too much weight.

So then I thought - what about just sliding the Pod around? Those green slippery plastic snow carpets - just put a bunch down on the deck and push as required. But with the bays loaded, this still has problems as the pressure on the rim inside caused the tabs to pop. The plastic would hang down and the guide rollers - the 3 with PZT or 5 - would rub on this. Difficult to describe. That's by leaning into the side of the Pod from inside. Guess you could go outside and push?

That large half dome is quite stiff and strong from the moulding process. I'm going to ask Wayne Parker - actually I live about an hour from them - about this idea and see what he says.

#7 Chris Schroeder

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Posted 01 February 2011 - 08:05 AM

How about a deck on top on top of the deck with wheels on the upper deck?

#8 Craig in Tacoma

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Posted 01 February 2011 - 06:39 PM

A Double Decker affair eh? Hmmmm

#9 John Fitzgerald

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Posted 01 February 2011 - 08:34 PM

The PZT table seems like such a pain. Why not get an Exploradome, and have zenith access AND wind protection. You would only need the dome, and adapt it to the POD base. It has been done before.

#10 Snaproll

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Posted 02 February 2011 - 11:14 AM

The PZT table seems like such a pain. Why not get an Exploradome, and have zenith access AND wind protection. You would only need the dome, and adapt it to the POD base. It has been done before.


Yes it has. More than once.

I do have a question on the PZT. Something that I've always been curious about. :question:

The way it looked to me is that a PZT can only be set up on one side or the other of the base. What if say you set the PZT up on the north side of the observatory, what happens if the wind is from the south? Can the dome no longer be rotated to offer any kind of protection? Can the PZT be moved? I would think the bays get in the way.


#11 skyguy55

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Posted 02 February 2011 - 02:36 PM

The way it looked to me is that a PZT can only be set up on one side or the other of the base. What if say you set the PZT up on the north side of the observatory, what happens if the wind is from the south? Can the dome no longer be rotated to offer any kind of protection? Can the PZT be moved? I would think the bays get in the way.


Hi Jim,

You are correct on all accounts and the PZT can not be moved. I have built my own table and works the same as the retail version. I think you can buy a light/wind guard from SkyShed that extends the wall height up another 20 inches or so. It may not be the best overall solution but it's one that works for me! :jump:

Hope this helps.

Gregg

Attached Files



#12 skyguy55

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Posted 02 February 2011 - 02:38 PM

and one more............

#13 skyguy55

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Posted 02 February 2011 - 02:39 PM

Here it is

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#14 csa/montana

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Posted 02 February 2011 - 02:44 PM

Very nice, indeed!

#15 Snaproll

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Posted 02 February 2011 - 02:53 PM

You are correct on all accounts and the PZT can not be moved. I have built my own table and works the same as the retail version.


That looks like a pretty sharp setup Greg. I also wondered how that PZT thing would work with snow and ice on it. Smart to have it open like that :bow:

#16 Craig in Tacoma

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Posted 02 February 2011 - 05:10 PM

That is a nice set up, Wow.

#17 Chris Schroeder

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Posted 02 February 2011 - 07:54 PM

Great looking setup Gregg :waytogo:

#18 Nebhunter

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Posted 02 February 2011 - 08:57 PM

Gregg does not have to worry much about snow on the PZT where he lives. He's more worried about the snow appearing at his temples. lol

I'm going to look at this hole in the dome thing, and may attempt the mod this spring. Pod is locked up and cleaned out for the winter at the farm. Weather becomes so bad during the winter with cloud and snow, it's no use leaving everything there. Starts to clear in February, but the temps will typically be around -25 F. Not anymore at least.

If it works like a charm - I will probably keep it to myself. :grin:

#19 Nebhunter

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Posted 03 February 2011 - 01:03 AM

John - I like really like the open view of the Pod. It's a well made product, and and like everything else, has some drawbacks. Having said that, I shoot film, mostly wide field with lenses. I love the wide open view, and the narrow slot of a shuttered system would not work for me.

Exposures can run 180 minutes in some cases and I need to keep a sharp eye out for airplanes and those dang blinking lights. One jet can ruin an image, especially after being into it for 120 minutes. During summer, the M8 area has heavy jet traffic and I've covered the lenses 25 times in a 90 minute exposure.

The Pod also allows me to sit back and just enjoy the night sky as the auto guider does the work. I can use binoculars, or view meteor showers and watch the movement of the Milky Way during the night.

If this one area of the Pod could be overcome with a hole, then it would be a bonus for me.

#20 carastro

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Posted 02 May 2013 - 02:38 AM

I've been frustrated with the Zenith problem with my POD dome, a zenith table would be too difficult for me to manage on my own in the dark, so was googling ideas and found this old thread. Just wondering whether the original poster ever cut his hole in the roof and how it went? Also has any-one found any other ideas. Only solution I have at the moment is at certain times of the year I have to take my kit out of the POD and set up outside to get those high objects. Rather defeats the point of an observatory though.
Carole

#21 Midnight Dan

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Posted 02 May 2013 - 06:29 AM

Hi Carole:

The usual advice is to center the scope mount about 8" towards the south to allow a better view of the zenith. Do you have your scope on a tripod or a permanent pier? If its on a pier, is there any way you could move the whole pod about 8" to the North?

-Dan

#22 mclewis1

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Posted 02 May 2013 - 09:48 AM

Carole,

Have you had the opportunity to have a look at and perhaps try out a POD with the PZT? I was also somewhat concerned about "manhandling" the dome on the table, I'm a big guy but have a bad back so I have to be fairly careful about lifting things ... especially when leaning out with my arms outstretched.

In actual use I was pleasantly surprised about how easy the dome moves on the table and how well the small synthetic ramps work in terms of lifting the dome up onto the wall. I find that it's more of a few short pushes and pulls rather than any real lifting to get the dome back onto the wall. Once it's roughly positioned back onto the wall it's another short pull towards you and then a bit of a spin to get it all onto the wheels. I simply reach over and pull on the rounded nuts on ends of the pivot bolts. It takes just a few back and forth movements to get everything lined up and positioned so the brackets can be re attached, but nothing is really tough or heavy.

I think I use more strength to control the closing of the dome than to bring the dome back off of the table. If you are handling the closing part every night then the moving the dome on/off of the PZT should actually be less demanding.

I have side by side scopes on my mount so I really need the table ... even with some pier offset my zenith access was really a problem. The PZT has made a world of difference in my use of my POD.

#23 Starhawk

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Posted 02 May 2013 - 07:23 PM

In any case, if you can't get happy with a stock POD kit, I suggest it would be better to not do a one off mod, but replace it with some setup more precisely to your liking.

-Rich

#24 carastro

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Posted 03 May 2013 - 02:16 AM

Thanks for the replies. I do have the pier offset towards the South West, but that just makes stuff on the opposite side less accessible.

No I haven't tried a PZT, they don't even sell them you have to make them yourself, and just supply brackets. I just find the whole idea scarey, and wonder whether I'll tip the whole thing off when trying to move it. Wpuld be great if I could find some-one who has one that I could try out. Might put a post on the UK POD forum.

Thanks

Carole

#25 Peter9

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Posted 03 May 2013 - 07:42 AM

Hi Carole and welcome to the forum.

I find viewing objects at the Zenith to be very uncomfortable and tend to view them when they are either side of. Is it possible that you can do the same. I know it depends on the amount of sky you can see from your location and being able to view them at a different time of the year.
Althou I do not have a PZT, most report that they are quite easy to use.

Good luck.

Regards. Peter.






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