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Why build piers in obs instead of just using a tripod?

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#51 aleigh

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Posted 15 January 2021 - 01:44 AM

Why build houses on foundations?

 

... because they weigh 200,000 lbs



#52 deonb

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Posted 15 January 2021 - 05:37 AM

Not everyone is DIY, either, so the costs can be much more once you add labor, engineering, and if you have to go through permits etc as part of the build. 

Trying to imagine the venn diagram of people who are DIY enough to build an observatory, but not DIY enough to build a pier...


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#53 aleigh

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Posted 15 January 2021 - 06:29 AM

Trying to imagine the venn diagram of people who are DIY enough to build an observatory, but not DIY enough to build a pier...

 

Well, it at least consists of all the people who don't hands-on build their own observatories, or perhaps some that do, but do so by simple means, like converting prefab shed kits. I think there are non-zero people that would be comfortable with a little framing, vs digging a hole they can stand in and filling it with cement. The entire concept that piers are an essential feature of an observatory also suggests to people who only have rooftops and decks that might be used adequately to house a modest observatory that to be successful they have to dig a hole in the ground.

 

All I am trying to do is point out for the sake of the discussion that concrete piers might not be the foregone conclusion / requirement that some make them out to be. And, they have drawbacks worth considering. And certainly, some advantages. I'd hope that an observatory is something that make astronomy easier, not harder. There are enough impediments to this hobby already. There's a guy in another thread on here that keeps his rig outside and he just puts one of those waterproof bags over it when he's not using it. Rain, snow. Wow. I admire that. Why even have a building? I'd sure prefer one, but it's food for thought. Perhaps a little ironically, his thread is about wanting to build a pier.

 

Personally, I like piers. If you can, and want to, you sure should. I am building right now and probably going to use tripods, but I have special circumstances like not being in the building much. I just don't think not-having-one should be an impediment to moving forward, because people can get good results with other methods. 



#54 deonb

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Posted 15 January 2021 - 09:08 AM

The entire concept that piers are an essential feature of an observatory also suggests to people who only have rooftops and decks that might be used adequately to house a modest observatory that to be successful they have to dig a hole in the ground.

Hmm. If you want an observatory on a lumber deck that's built by common building standards in the U.S, and you want to be anywhere on that deck while using the scope for either imaging or long FL visual, your only practical option is a pier.

 

I've tried an C11 on a CGX with its tripod on a deck for a few days. It's unusable. Not: "it's not ideal". It's unusable. Just shifting my weight from one foot to the other will change the field by 20%. Even when remote imaging a strong breeze will push the guidestars out of reach of PHD tracking through the OAG.

 

I'm not saying people who only have decks can't be successful at all under any circumstances. I mean Cuiv does it (though pretty sure his balcony isn't lumber though). But you shouldn't go through the effort & expense of building an observatory on a deck without a pier - that's just setting yourself up for disappointment.



#55 Ihtegla Sar

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Posted 15 January 2021 - 10:22 AM

Hmm. I used a 4" f/9 refractor on a fairly rickety second floor deck for over a year without issues. And occasionally set up my C-8 up there and it gave me less issues up on the deck than set up on grass. Granted, I used those Celestron vibration suppression pads, which seemed to work wonders at suppressing vibrations when set up on a deck. Would not have wanted to observe on a deck without them. And I'm visual only, unless you count cell phone pics of the moon. So "unusable" for guided astrophotography might be very different from what's usable visually. I never noticed the field shifting, though with manual visual use (no tracking) I might not have noticed a slight shift in field of view. Vibrations dampened in 1-2 seconds with the refractor and 3-4 seconds in the C-8, which is about the same as when set up on the grass.

Edited by Ihtegla Sar, 15 January 2021 - 10:59 AM.


#56 aleigh

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Posted 15 January 2021 - 01:24 PM

I have used both an ED80 and a C9.25 on my (cantilevered!) balcony on my third-floor apartment with no significant issues. I'll put it this way - usable. I image off it as well, although it is best nobody is walking around out there at the same time, understandably. But for visual, the scope settles out. Friends look through it, etc. The problem I have with muggles has nothing to do with the deck and just they seem to want to touch the telescope for some reason when looking through it. Like they hold the eye piece. 


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#57 Foundationer

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Posted 15 January 2021 - 05:17 PM

Chicken, then egg. 

I put my pier in the ground 2 years before the obs went up.

Observatory was the goal.

Instantly my equipment started to see more use 'cause all I

had to do was plop a scope onto the pier, easy peasy!

Now there is an observatory, so when more than one person

is over to do some observing, I'm setting up a tripod again, ugh.

Seriously thinking about sinking another pier for the guest scopes!


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#58 Ihtegla Sar

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Posted 22 January 2021 - 04:31 PM

I continue to go back and forth on this issue for my upcoming observatory project (if Exploradome ever sends me my dome).  One of the issues I have with a pier is I have no way of knowing what size (diameter or height) it needs to be since I don't have my observatory built yet nor do I know what telescope I may want to use in it.  Currently I have a couple four inch Taks and I have a TEC 140 on order but it won't arrive for 8-10 months.  Someday I may want to get a TEC 180 or maybe a 10" Zambuto Newtonian.  Until I have lived in the observatory for a few years and have tried it with multiple scopes, I won't know what scope to design the pier for, and the telescope being used drives the selection of mount and the height and diameter needed for a pier.

 

How could I possibly plant a permanent concrete pier when I have no idea what future telescope I may want to put on it?

 

So then I thought I could dig a 15" diameter three foot deep hole and filling it with concrete with some threaded j bolts  underneath the observatory's wood floor before building the observatory.  Then I could just cut a hole in the floor and install a metal pier at some point in the future if I ever decided a pier was needed.  That would allow me to use a variety of mounts/tripods/portable piers on a wood floor in the observatory with a variety of telescopes.  And if at some point in the future I decided I needed a pier, I would have the pre-constructed base ready to go under the floor.

 

The problem with that plan is there is no standardized bolt spacing for metal piers, so until  had the specific metal pier in hand, how would I know the correct bolt spacing?

 

My main goal of the observatory is just to have a dry place to leave the telescope, observatory chair, side table and some eyepieces fully assembled and ready for use, and to provide some wind, dew and stray light protection while observing.  Because of the complexities of figuring out size, height and bolt spacing for a pier, I am leaning more and more toward just building the observatory with a wood deck and just not worrying about a pier.

 

I am just not sure I really need a pier.  I am a visual only observer who observed from a rotting second floor wood deck for over a year without much issue with vibrations (and an elevated wood platform means less issue with thermals from the ground or vibrations through the ground from nearby traffic).  



#59 archer1960

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Posted 22 January 2021 - 04:39 PM

If you are a DIY type, here is one possibility: go ahead and build a concrete pier with the top below the floor, put in j-bolts at whatever spacing  you choose, and use the "disk brake rotor" process to make your own footing-to-pier adapter. Or your could go ahead and pour a sonotube pier to a reasonable height inside the obsy, and (again) use disk brake rotors to make the adaptation you need to get to the mount you end up using.


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#60 deonb

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Posted 22 January 2021 - 06:33 PM

If you are a DIY type, here is one possibility: go ahead and build a concrete pier with the top below the floor, put in j-bolts at whatever spacing  you choose, and use the "disk brake rotor" process to make your own footing-to-pier adapter. Or your could go ahead and pour a sonotube pier to a reasonable height inside the obsy, and (again) use disk brake rotors to make the adaptation you need to get to the mount you end up using.


Can you elaborate on the "disk break rotor" process?

#61 archer1960

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Posted 22 January 2021 - 06:41 PM

Can you elaborate on the "disk break rotor" process?

There are many threads here where people have used automotive disk brake rotors as pier adapters. They are typically a thick steel construction, but relatively to machine (drill, mostly). Typically, you use two of them to create the "rat cage" that you use as your mount adapter. The same basic technique could be used for making an adapter to attach a pier to a concrete base when you don't know ahead of time what exact bolt pattern you need for the pier.



#62 deonb

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Posted Yesterday, 10:48 AM

There are many threads here where people have used automotive disk brake rotors as pier adapters. They are typically a thick steel construction, but relatively to machine (drill, mostly). Typically, you use two of them to create the "rat cage" that you use as your mount adapter. The same basic technique could be used for making an adapter to attach a pier to a concrete base when you don't know ahead of time what exact bolt pattern you need for the pier.

Oh I see. I have one of those setups (from Dan's Pier Plates). Just wasn't familiar with the term. Thanks.



#63 John Fitzgerald

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Posted Yesterday, 11:09 AM

This will be unpopular with some, but I think it needs to be said:  if one doesn't have the mechanical aptitude to build a pier and observatory, then one will always be frustrated if one gets deep enough into amateur astronomy.  There are always projects that need to be tackled, things that need adjusted, repaired, upgraded,, etc.  If one cannot do most of that by themselves, or with a little local help, then getting deep into amateur astronomy with piers, observatories,  and such is probably not for you, and will likely result in endless frustration.  To me, mechanical aptitude and know how is a necessity for success in the hobby.

You cannot rely on sending things off to get them fixed.


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#64 John Fitzgerald

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Posted Today, 09:32 AM

Doesn't apply to homes, which are common to most everyone.  My statement applies to specialty items, where you cannot simply call someone locally to fix it.  Yes, I believe mechanically inept people will generally be frustrated if they get deep enough into the equipment side of the hobby.   Some folks simply are not cut out for it.



#65 Ihtegla Sar

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Posted Today, 09:39 AM

Doesn't apply to homes, which are common to most everyone. My statement applies to specialty items, where you cannot simply call someone locally to fix it. Yes, I believe mechanically inept people will generally be frustrated if they get deep enough into the equipment side of the hobby. Some folks simply are not cut out for it.


What kind of "specialty" items are you talking about?

#66 wrvond

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Posted Today, 09:50 AM

What kind of "specialty" items are you talking about?

You can call a plumber to fix your sink. Who are you going to call to repair the rollers on your observatory dome?


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#67 Ihtegla Sar

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Posted Today, 09:58 AM

You can call a plumber to fix your sink. Who are you going to call to repair the rollers on your observatory dome?


Those are basically just rollerblade wheels. Is there a reason why one couldn't order replacements from Exploradome or find the same size on the internet. How often do rollers go bad anyway?

Edited by Ihtegla Sar, Today, 10:01 AM.


#68 John Fitzgerald

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Posted Today, 10:13 AM

Sorry I got off topic.  We build piers for stability over the long term, and to take up little of the precious floor space in our observatories.   Floor space is especially lacking in small domes on round buildings the same size.  I experience that on a regular basis.  My little dome would be nearly unusable with a tripod.



#69 deonb

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Posted Today, 11:31 AM

Those are basically just rollerblade wheels. Is there a reason why one couldn't order replacements from Exploradome or find the same size on the internet. How often do rollers go bad anyway?

Who will replace them for you? 

 

But to answer your question - I had to take off a roller, add additional spacers, and put them back. Twice.

 

I would have been fairly stuck if the dome was just installed by someone else and I couldn't service it myself.


Edited by deonb, Today, 11:39 AM.


#70 deonb

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Posted Today, 11:34 AM

How could I possibly plant a permanent concrete pier when I have no idea what future telescope I may want to put on it?

 

For the person who doesn't know what size pier they need:

 

http://piertechinc.c...ers/pier-tech-2


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#71 Ihtegla Sar

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Posted Today, 12:01 PM

Who will replace them for you? 

 

But to answer your question - I had to take off a roller, add additional spacers, and put them back. Twice.

 

I would have been fairly stuck if the dome was just installed by someone else and I couldn't service it myself.

I doesn't sound that hard to replace a few rollerblade wheels or to add a few spacers.  I thought John was saying you had to be an expert at levelling and plumbing foundations and had to have a full metal shop with drill presses and lathes in your garage before you should consider owning an observatory.  Hence my question about what "specialty" work he was referring to -- I don't have a metal shop and don't have room for one and I wouldn't trust myself to get a foundation perfectly level or plumb -- hence I would hire out those types of things, but if you are just talking replacing a few parts that can be scoured from the internet or adding a few spacers, and stuff like that, then yeah I agree it makes sense to have some basic skills, although in my experience you don't have to make something in order to be able to figure out how it works and repair it, and it doesn't take MacGyver-like skills to handle stuff like that.  I'm no MacGyver but I grew up on a farm and can figure out how stuff works and repair it.  


Edited by Ihtegla Sar, Today, 12:31 PM.


#72 Ihtegla Sar

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Posted Today, 12:08 PM

For the person who doesn't know what size pier they need:

 

http://piertechinc.c...ers/pier-tech-2

Those look kind of spendy but they look really cool.  Especially if you were using a long refractor, it would be very handy to be able to raise and lower your mount on the fly.



#73 John Fitzgerald

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Posted Today, 12:45 PM

I doesn't sound that hard to replace a few rollerblade wheels or to add a few spacers.  I thought John was saying you had to be an expert at levelling and plumbing foundations and had to have a full metal shop with drill presses and lathes in your garage before you should consider owning an observatory.  Hence my question about what "specialty" work he was referring to -- I don't have a metal shop and don't have room for one and I wouldn't trust myself to get a foundation perfectly level or plumb -- hence I would hire out those types of things, but if you are just talking replacing a few parts that can be scoured from the internet or adding a few spacers, and stuff like that, then yeah I agree it makes sense to have some basic skills, although in my experience you don't have to make something in order to be able to figure out how it works and repair it, and it doesn't take MacGyver-like skills to handle stuff like that.  I'm no MacGyver but I grew up on a farm and can figure out how stuff works and repair it.  

No, I wasn't saying you need a full metal shop, or anything close.  Just basic skills.  If you can replace basic parts, use tools, and do troubleshooting on equipment, then you should be ok.  But, I have known people who didn't have ANY mechanical aptitude, and could not or would not learn.  Amateur astronomy is not for those folks, unless they confine themselves to small refractors on alt-az mounts.  Certainly observatories are not for them.


Edited by John Fitzgerald, Today, 12:46 PM.


#74 Ihtegla Sar

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Posted Today, 01:00 PM

No, I wasn't saying you need a full metal shop, or anything close.  Just basic skills.  If you can replace basic parts, use tools, and do troubleshooting on equipment, then you should be ok.  But, I have known people who didn't have ANY mechanical aptitude, and could not or would not learn.  Amateur astronomy is not for those folks, unless they confine themselves to small refractors on alt-az mounts.  Certainly observatories are not for them.

Thanks for clarifying.  I was thrown by the statement "if one doesn't have the mechanical aptitude to build a pier and observatory" since that sounded like more than just basic repair skills or troubleshooting skills.  It takes more/different skills to be able to design and fabricate things vs figure out how something works to be able to repair/replace with similar parts and materials.   I wouldn't hold myself out as having any skill to design and fabricate stuff but I can repair and trouble shoot just fine. So I should be okay. 




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