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Exploradome vs Nexdome

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#1 rebelxts

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Posted 09 October 2020 - 02:31 AM

Hey All,

 

I narrowed down observatory choices to 8ft Exploradome and Nexdome. The dome will be fully automated and will have a UPS back-up for safe shutdown in case of power outage. The observatory will be remote, 100 miles from my home, in a safe location where security is not an issue. The weather is mild but can get rough during the winter with 20-30 mph wind. There is not much rain and no snow, the coldest temps are in the 30s and the hottest Summer days are in low 80s Fahrenheit.

 

My main decision criteria is reliability, as I want to minimize emergency trips (200-mile round trip) in case if dome shutter fails to close. Secondary decision criteria are ease of assembly/maintenance and cost.

 

If you either used or compared Exploradome and Nexdome, what are your thoughts?

 

From my research, Exploradome has been around longer and is a bit larger dome (92" vs 88" diameter). Exploradome has recently moved to MaxDome II control system, which is supposed to increase reliability. However, Exploradome is more expensive than NexDome, close to 2x (with full automation). Key question is how much more reliable Exploradome is compared to Nexdome.

 

Thanks in advance for your advice.



#2 MJB87

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Posted 09 October 2020 - 07:01 AM

I recently placed an order for an ExploraDome after comparing the available options -- or at least those whose suppliers were willing to respond to my inquiries.  (It is amazing how many didn't bother.)

 

I went with ExploraDome for two primary reasons. First, I like the idea of having a fully assembled and tested dome delivered as a unit, including with the automation installed.  It is just more convenient and I was willing to pay for that convenience.

 

Second, I preferred the bottom ring structure of ExploraDome, as it seemed more robust compared to the built-up plastic structure of NexDome. Again, I was willing to pay for that more robust structure.

 

Unfortunately, I have not yet installed the ExploraDome so I can't address the key question you raise.

 

Both ExploraDome and NexDome seemed to be decent options. In my case I was willing to spend extra for the ExploraDome. YMMV.

 

MJB



#3 kathyastro

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Posted 09 October 2020 - 07:45 AM

I don't know the NexDome, and I got my Exploradome before they switched to the MaxDome II automation system, so I don't know it either.  I know they had good reason to switch the automation systems, which implies that MaxDome is better / more reliable than their old one.

 

I like my Exploradome a lot.  It is very robust.  I have never had a rain leak.  I did get blowing snow coming in around the shutter edges in winter.  I weather-stripped the shutter with pipe insulation, and that has not been a problem since.  (The rubber weather seal rubbing on the plastic as the shutter opens sounds ominous, but it works just fine.

 

The aluminum rotation rings work very well.  The force to rotate it is 5 lbs at the ring gear, low enough that I am easily able to drive it with a stepper motor.

 

The one foreseeable thing that could interfere with remote reliability is ice on the dome.  The upper shutter motor has a huge amount of torque, and I assumed that it could push a bit of snow or ice off the back of the dome.  Wrong.  The ice was stronger.  What the huge torque did was snap the shutter cable!  One way to deal with ice is to heat the interior of the dome, but that has consequences for seeing.

 

Getting the shutter cables tensioned just right can be an issue.  Once you have it set up, it is quite reliable, but, prior to getting the tension adjusted, the cable can jump the pulley, jamming the shutter.  I re-learned this after replacing the cable that was snapped by the ice.  You should budget enough time to get it adjusted just right before leaving it unattended.

 

One thing I don't like about the Exploradome is their roof panels for the 10'x10' building plan.  The panels are not a good fit, and the result is that the inner edge, where the upturned edge of the roof panel butts against the rotation ring, fits poorly.  The roof edges drag on the dome retaining ring.  Short of rebuilding the roof with plywood, the only way I could solve the problem was to remove the retaining ring.  The dome works fine without it, and is aerodynamically stable even in strong winds.  However, I worry about a wind gust catching it if it is open during windy weather: there would be nothing to hold the dome in place.  I use a pair of turnbuckles to tie it down in stormy weather.


Edited by kathyastro, 09 October 2020 - 07:46 AM.


#4 MJB87

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Posted 09 October 2020 - 10:18 AM

I concur -- I also didn't like the plastic roof panels for the (optional) ExploraDome building.  They did not look robust enough for me and they might be prone to leaks. (I spent my youth as a roofer and take a conservative view on roof design.)

 

I plan to build my own, more robust, 10x10 building with a white EPDM flat roof. The dome ring will extend 6" to 10" (TBD) above that so clearance won't be an issue.


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#5 rebelxts

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Posted 09 October 2020 - 01:46 PM

MJB, completely agree with you on the goodness of pre-assembled and tested at the factory dome. Some vendors charge a hefty fee for this service.

 

kathyastro, I did research on Foster and MaxDome II controllers, and feel good about Exploradome’s recent move to MaxDome II. Thanks for the tips on the shutter cable tension and the ice.

 

Both Exploradome and Nexdome are good choices, they are just in different price ranges. I placed an order for Exploradome, and will report back in 2021 how it worked out.


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#6 gerald12

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Posted 09 October 2020 - 05:03 PM

I purchased an Exploradome last summer and like it. The MaxDome II controller works really well. One thing though is that the Exploradome uses a chain now and not cables as in the past, at least mine was sent that way and I did not have to adjust anything.


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#7 ChancesFate

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Posted 25 October 2020 - 11:46 AM

I have had my exploradome for about a year now.  It is the 8 foot dome on the 10’6 building, fully automated.   Unfortunately with the foster system and I have never been able to get it to automate properly.    I am not very technical but I can tell you all the problems I have had and am still having.    I have had to replace the upper and lower actuator for shutter control twice.   I have to press the actuator by hand to get the upper shutter to close.    It loses its tick count, so when I press left it will move 1 foot then stalls out.   I have not been able to get it automated.  No support.   Why oh why do they have all the doors so short.
 

I do like having an observatory so I don’t have to set up nightly, plus I have pets who would knock everything down.     It has never leaked.  Although we think it got struck by lightning once and had to get new control boxes.   A few scorpions got in but not much else.   I love not having to deal with dew or wind.   



#8 Rebel3

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Posted 28 October 2020 - 08:52 PM

Ditch the Fosters System and go with the MaxDome.  Other than the control boards, the only thing you need to swap it the optical tic sensor and the magnetic home sensor.  I struggled with the Fosters system for years.  The MaxDome system has been rock solid.

 

I have really enjoyed my Exploradome.  No leaks and rotation is smooth and easy.



#9 GeneralT001

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Posted 30 October 2020 - 11:33 PM

If you are looking for remote reliability then forget about Nexdome.

 

I have had a Nexdome (with dome and shutter automation) for 4+ yrs now and the shutter is just not reliable...period. The shutter needs constant maintenance in the way of waxing and use of teflon tape to get it to go up and down without undue friction. I have had numerable times where it would stop 1/3 - 1/2 way up for no reason whatsoever and would then require a manual reboot. It uses arduino boards with wifi for shutter control.

 

Don't get me wrong the maker is great to deal with and very quick to help with any issues. As well, the developer for the ASCOM driver is also very good at keeping software/firmware uptodate

 

The Nexdome is a good way to go if it is close by and you can tend to it.  Never any leaks and quite reliable - as long as you are there to baby it. Unless Nexdome has plans to redesign the shutter then I would steer clear of it for remote operations.

 

Heres a link to the FB page for anyone interested.

 

https://www.facebook...344433410160844

 

[attachment=1629121:Nexdome.jpg]


Edited by GeneralT001, 30 October 2020 - 11:36 PM.


#10 palaback

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Posted 06 November 2020 - 06:09 PM

I bought an Exploradome about 3 years ago. I assembled it myself and installed a 12v power system, with solar panel to recharge batteries and operate in remote area near my cabin. My site often gets wind gusts up to 100 mph, sometimes heavy blowing rain, and quite cold in winter, often -10 to -20F or so, mild in Summer. Anyway Exploradome has had no problems with high winds, and even when imaging with moderate winds it seems to protect scopes and have high stability. No leaks and no bugs.  It is sometimes is a bit stiff to open shutter with ice and snow, but have not had any problems manually operating it. Now that I am becoming more interested in imaging, I really want to automate it, so I can automatically calibrate my mounts, and run long exposures over the night without having to manually turn the dome. I heard so many problems with the foster system, and it was so expensive I was reluctant to go that way. Maxdome sounds good, but I decided instead to take a chance on the Nexdome rotation system. It looks much more simple to install is less than half the price of a Exploradome/maxdome system, and all comes in one compact unit. I bought a gear wheel for the Exploradome and will attach that to the motor of the Nexdome. Software can be calibrated for specfics of the dome. Still not sure on how to go with the shutter. Disappointed to hear about all the problems with the Nexdome shutter, maybe I will wait for an update on that before trying it out. Very interested in hearing how others are doing with dome automation.



#11 kathyastro

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Posted 06 November 2020 - 06:54 PM

For the shutter, I used the original motors that Exploradome sold with the Foster kit.  They consist of a geared motor driving a winch pulley for the upper door, and a pair of linear motors for the lower door.

 

I really wanted to avoid having some complicated wireless communication system, because that was one of the weaknesses of the Foster kit.  So I decided to use a pair of wiper contacts to provide power to the shutters, with the limitation that the shutters will only operate in the home position.  Worst case, I have to wait an extra 33 seconds for the dome to get home in the case of a sudden rain shower.

 

Signalling for the shutters is easy: positive voltage to open, negative voltage to close, and no voltage to stop.  I wired up a relay box to make use of the limit switch signals to control the sequencing of the doors.  With no electronics (other than some diodes in the relay box), the shutter sequencer is too stupid to fail.  Yes, relays can malfunction, but not nearly as often as a microcontroller can get its tiny brain scrambled.

 

I designed and built my own controller that handles rotation and shutter operation using an Arduino.  Rotation uses a stepper motor to drive the Exploradome rotation gears.  I wrote an ASCOM driver to communicate with the Arduino.  The Arduino implements rain detection, and will autonomously rotate the dome to home and close the shutter in the event of rain, without requiring any cooperation from the software running on Windows.

 

Part of my automation suite is a dome synchronization application.  It is not essential, since any ASCOM-compatible software with a dome module should be able to control the dome.  However, I ran into problems early on with software failing to compute the dome position correctly.  Since it was a multi-vendor problem (mount says it is on the east side while dome software thinks it is on the west side), I got a lot of finger-pointing and no solution.  Rather than hassle with poor tech support, I wrote my own.


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