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Pier prep when you're not ready for a pier?

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#1 PolyWogg

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Posted 27 September 2022 - 12:21 AM

So I have some other work planned in my backyard, and they'll do a 8x10' pad for me plus a pier down 6' (frost line in our area is deep). So, I can actually have a pier foundation done. The problem is that I'm not entirely sure what I want to use for the actual pier part above the ground.

 

My intent was to buy a metal pier that is removable but if I haven't fully decided, what can I put on the top of the ground portion as a good "placeholder" for later?

 

So, my understanding is generally for most piers:

a. Gravel

b. Sono tube up to ground level

c. Plate with rebar or bolts up from the pier

d. Removable pier that goes from plate to mounting plate

e. Mounting plate

f. Mount

 

Alternatively, I could take the sono tube up to say 4' (or whatever height I choose) and then cap that. The problem is that I have several scopes, although the main one is Celestron NexStar 8SE. I've seen options that are basically a pier cap and then a spacer to the mounting plate, I just don't know where to get the pier cap / design until later when I decide what I actually want on top (either from ground up or from say 4' up). I see lots of solutions in the various posts, but they are all where the person KNEW what they were putting on it and what they wanted already, I'm trying to find a universal plate I guess?

 

Paul



#2 mikerepp

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Posted 27 September 2022 - 07:01 AM

Read the pier-engineering thread.   This will tell you everything you need to know about piers.

Don't think your going to find a "universal" plate.  You could make several different plates if you needed too for different mounts.   These could be made from car brake rotors for instance.


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#3 Ihtegla Sar

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Posted 27 September 2022 - 01:20 PM

I did something similar under the wood floor of my observatory so I can install a pier later if I want.

Sonotube shouldn't go below grade. You want the concrete against the native soil so it fills in all the voids for a snug fit.

I had four bolts set in the concrete using a piece of OSB (marked "this side up") and I saved the OSB so I can take it to a machine shop and use it as a template for a mounting plate if I ever decide to get a pier.
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#4 macdonjh

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Posted 28 September 2022 - 08:24 AM

So I have some other work planned in my backyard, and they'll do a 8x10' pad for me plus a pier down 6' (frost line in our area is deep). So, I can actually have a pier foundation done. The problem is that I'm not entirely sure what I want to use for the actual pier part above the ground.

 

My intent was to buy a metal pier that is removable but if I haven't fully decided, what can I put on the top of the ground portion as a good "placeholder" for later?

 

So, my understanding is generally for most piers:

a. Gravel not necessary, gravel won't help with anything

b. Sono tube up to ground level as Ihtegla Sar and others have said, no forms below grade, pour concrete directly against undisturbed soil.

c. Plate with rebar or bolts up from the pier You don't need a plate between your concrete and steel pier.  

d. Removable pier that goes from plate to mounting plate that is entirely up to you, and a good plan if you don't know what you want right now.

e. Mounting plate

f. Mount

 

Alternatively, I could take the sono tube up to say 4' (or whatever height I choose) and then cap that. The problem is that I have several scopes, although the main one is Celestron NexStar 8SE. I've seen options that are basically a pier cap and then a spacer to the mounting plate, I just don't know where to get the pier cap / design until later when I decide what I actually want on top (either from ground up or from say 4' up). I see lots of solutions in the various posts, but they are all where the person KNEW what they were putting on it and what they wanted already, I'm trying to find a universal plate I guess?

 

Paul

Paul, some comments in red above.  +1 to mikerepp, that Pier Engineering thread has a lot of good information.  A bit more comment about "c" in your original post: since you haven't decided what you want above grade you could leave your foundation at grade, slightly below grade, or even with the slab you're having poured.  Once you decide what you want above grade you can "dowel into" the foundation and add a concrete column or anchor bolts for a steel pier when you're ready.  That way you don't have anchor bolts or rebar sticking up out of your slab making a nuisance and tripping hazard while you decide.

 

As to concrete or steel for the above grade part of your pier, I chose concrete simply because I could do that work myself rather than having to pay for a steel pier to be fabricated.  I also ran some conduits through the concrete so all my cables go almost directly to my mount, which is nice.

 

As for deciding what you want to install on your pier, perhaps think about a mount which will handle all your scopes and install that, rather than making yourself crazy figuring out how to accommodate several different mounts.  Then you only have to install the mount once and change scopes when you feel like it.

 

Good luck with your project.


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#5 speedster

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Posted 29 September 2022 - 03:06 AM

Your basic options are to cast bolts in and then get a steel pier with a base plate that mates to your bolt pattern, or leave the concrete flat and drill holes and install anchors later.  We have several customers who buy the anchor bolt kit and get a pier later or do their own thing with that bolt pattern.  Info in the book shows you how to buy a base plate now, use it as a template to set your bolts, and build the pier any time in the future and know it will mate.  They can come back for a pier anytime and know it will fit.  For the mount plate, look at the website and see how the mount plates attach to the pier top plate.  We often prep mount plates for multiple mounts and also often do a separate mount plate for each of a customer's mounts so they can interchange quite easily and quickly.  You can prep your mount plate for whatever you have now and also for whatever you think you might want in the future.  If plans change, you can drill more holes in the mount plate for anything not anticipated.  For example, you could prep your plate for your SE and, while you're drilling, go ahead and drill 3 mores holes for Dan's adapters.

 

The pier engineering thread might be helpful.  You are proposing to do some things that actually work against you.  And there's always the book.  More info and you don't have to wade through a long thread.  Also has info for a DIY pier that nearly has the performance of the MOAPs.

 

A good pier is one of those things that cause you to ask, "why didn't I do this years ago?"  You'll enjoy it.


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#6 PolyWogg

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Posted 29 September 2022 - 04:07 PM

And there's always the book.  More info and you don't have to wade through a long thread.  Also has info for a DIY pier that nearly has the performance of the MOAPs.

Wait, what book are you talking about? DId I miss a link?

 

Paul



#7 speedster

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Posted 29 September 2022 - 04:28 PM

www.telescopepiers.com/diy-design-guide/


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