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Beginning to plan a cheap DIY pier project.

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#1 zakry3323

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Posted 13 January 2021 - 09:34 PM

I'm not sure it's fair to post in observatories. Of course that's the eventual goal, but with funds being limited and my skill set lacking in the realm of carpentry, maybe it's best to take this one step at a time and see what happens.

I've posted a couple times over the last few months. I've saved up darn near half my adult life for this property- a hillside with a decent view, bortle 3-4, in West Central Pennsylvania, where the sun shines on occasion and the stars do less frequent.

I've got conduit run, a 20 amp breaker, and exterior recepticals ready to go on the flattest part of the whole 18 acre hillside... problem is that there's a 24ft pool sitting on top of it.

I've got a young kiddo and an adamant wife, so I guess the pool is going to stick around for a few years. What's a poor astronomer to do?

I've got a Telegizmos 360 cover that's seen me through rain, sleet, and hail. Besides having become the perfect place for wasps to build a nest a few summers ago, it's been otherwise a huge facilitator for a demi- permanent mounting solution for my CEM60 back in the 'Burg.

Now that I've been out in the cut for a few months I've been chomping at the bit to set up an astrophotography base of operations. I've been enjoying the 3 or 4 clear-ish nights we've been having over the last few months with short observing sessions using wide angle binos and my daddy's 8" dob. All the while I couldn't help but spend time distracting myself about how the signal to noise ratio is vastly improved compared to my last couple decades of city livin'.

So it's time to get cracking.

I can't do much about the pool for now, but I can set something up adjacent. I'm thinking of a poured pier- something I can set my mount on without fear of the wind (and it gets gusty over here!) blowing it over. Maybe a few years down the road the pool goes away and I have plenty of room for a 10 foot structure and dome, maybe
even a warming/processing room ...that just happens to have an exterior pier for relaxing visual observations whilst the imaging rig does its thing.

For congruity's sake I'd like to possibly connect the two via cement walkway, making the space a complete observing area.

I'm thinking this may take more pre-planning than I had supposed. I'm also aware that the entirety of this plan may be beyond my physical abilities. However, a poured pier- I think I can handle. We'll see, anyways. If the Arctic blast keeps away for a bit longer I'll start digging the footer tomorrow. Not much point in trying to find info about freeze/frost levels around here, I'm just going to dig and hope I don't hit solid limestone after 2 inches :)

Wish me luck!

#2 terrypaula

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Posted 13 January 2021 - 10:54 PM

If you're going to build a pier and build it right don't be cheap. You will regret it later.


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#3 c2m2t

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Posted 13 January 2021 - 11:03 PM

Hi Zakry!

You sound like a young fella with a many good years in front of you. I am sort of at the other end. Pennsylvania up on the highlands is not a whole lot different than my location here in Ontario...likely a bit warmer with average winter temps in the 15 to 25 degrees F range. I am a retired architect and have spent several years building custom homes...so I have had my hands dirty on many occasions. In fact I am still trying to finish my own home. If only my adult children would stop finding jobs for me!! grin.gif Mind you, the grand children are a huge distraction!!

 

When it comes to piers, mass is your friend. With regards to frost that you could anticipate, 4 feet to the base of the pier would be a minimum that I would consider for your location and 5 feet would be better. Are you familiar with  the "Bigfoot" pier bases? Here is a link:

https://www.bigfoots...s.com/index.htm

 

As you will find out as you read the promo, there is a wide range of pier diameters that can be incorporated with this base. Larger diameter, more concrete. Are you hand mixing or will you order in a truck with ready mix or mix as you go? Things that you will need to think about are:

1) How much weight will the pier have to handle and is the weight of the mount centrally placed over the pier. SCT's on wedges create a cantilever that can present some tipping forces.

2) You will need to confirm the diameter of the pier that best suits the way you wish to attach your mount...lots of people using disc brake rotors but there are other ways. I think a bit of net surfing should yield many approaches. 

3) You will need to isolate the pier from any concrete walkways to minimize transfer of vibrations. You might consider a wooden deck/sleeper system. Standing on concrete can rob a lot of heat from your legs even in seemingly warm nights. Eyepieces falling on concrete is fatal. I have added a 3/8"rubber matt made from recycled tires inside my POD. The rubber will insulate as well. 

4) You will likely want to bring up conduits for power and data cables within the pier... a larger diameter pier makes this a bit easier.

 

There are likely several other things to be thinking about but that will give you a starting point. The Bigfoot provides a better anchor in the ground and is less susceptible to frost heave and better counter-acts any tipping forces on the pier. If you are very close to bedrock that presents some other issues especially with limestome. Limestone is porous and retains water, therefore being susceptible to frost action...but you can insulate against that. You might want to dig a test hole to see what you are up against and if you find something unusual or unexpected we can talk some more.

 

Keep us posted on how you are making out. Good luck!!

 

Cheers, Chris.  


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#4 speedster

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Posted 14 January 2021 - 03:59 AM

We are very familiar with bigfoot.   Great bit of kit in certain applications.  One of our Central America projects is featured on their webpage, "Bigfoot in Belize".  For a telescope pier, bigfoot is working against you, as is any buried spread footing.  Search this site for a thread called Pier Engineering and you will find some helpful info.



#5 zakry3323

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Posted 14 January 2021 - 08:25 AM

Hi Zakry!

You sound like a young fella with a many good years in front of you. I am sort of at the other end. Pennsylvania up on the highlands is not a whole lot different than my location here in Ontario...likely a bit warmer with average winter temps in the 15 to 25 degrees F range. I am a retired architect and have spent several years building custom homes...so I have had my hands dirty on many occasions. In fact I am still trying to finish my own home. If only my adult children would stop finding jobs for me!! grin.gif Mind you, the grand children are a huge distraction!!

 

When it comes to piers, mass is your friend. With regards to frost that you could anticipate, 4 feet to the base of the pier would be a minimum that I would consider for your location and 5 feet would be better. Are you familiar with  the "Bigfoot" pier bases? Here is a link:

https://www.bigfoots...s.com/index.htm

 

As you will find out as you read the promo, there is a wide range of pier diameters that can be incorporated with this base. Larger diameter, more concrete. Are you hand mixing or will you order in a truck with ready mix or mix as you go? Things that you will need to think about are:

1) How much weight will the pier have to handle and is the weight of the mount centrally placed over the pier. SCT's on wedges create a cantilever that can present some tipping forces.

2) You will need to confirm the diameter of the pier that best suits the way you wish to attach your mount...lots of people using disc brake rotors but there are other ways. I think a bit of net surfing should yield many approaches. 

3) You will need to isolate the pier from any concrete walkways to minimize transfer of vibrations. You might consider a wooden deck/sleeper system. Standing on concrete can rob a lot of heat from your legs even in seemingly warm nights. Eyepieces falling on concrete is fatal. I have added a 3/8"rubber matt made from recycled tires inside my POD. The rubber will insulate as well. 

4) You will likely want to bring up conduits for power and data cables within the pier... a larger diameter pier makes this a bit easier.

 

There are likely several other things to be thinking about but that will give you a starting point. The Bigfoot provides a better anchor in the ground and is less susceptible to frost heave and better counter-acts any tipping forces on the pier. If you are very close to bedrock that presents some other issues especially with limestome. Limestone is porous and retains water, therefore being susceptible to frost action...but you can insulate against that. You might want to dig a test hole to see what you are up against and if you find something unusual or unexpected we can talk some more.

 

Keep us posted on how you are making out. Good luck!!

 

Cheers, Chris.  

Gosh I love to be called a young fella, thank you :) I hope the pandemic lets me travel again soon- it used to be that I would travel up to Niagara or Toronto at least once every year for the Ice Wine Festival or concert. Beautiful place, and the weather does remind me a great deal of home!

 

Thank you for your kind suggestions. It's anyone's guess how digging will go- I was thinking today's the day, but then it started snowing :) I don't think I'm going to hit bedrock, much more likely around here are glacial limestone boulders. Anywhere on the property I've dug so far has them in abundance- some small enough to pull out with a tractor, but others are several tons. 

 

In any case I will absolutely check out those bigfoot footers and start digging a test hole ASAP, and will post my progress. 

 

Cheers!


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#6 jfgout

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Posted 14 January 2021 - 08:55 AM

If you want to build something simple, cheap, and that you can easily take down when you are ready for something more substantial, may I suggest the Todmorden pier + roll off shed combo. I built such a combo last year and I'm extremely happy with it: https://www.cloudyni...se-observatory/

I've added some strong ground anchors for windy days (two levels of anchoring: smaller anchors that I connect to the base with heavy-duty turnbuckles + big anchors (4 feet into the ground!!!) that I connect to the top with some ratcheting tie down straps, only for when the forecast calls for big storms). The shed itself, without any anchoring, has resisted to some 35mph winds without any issue (the anchors where added a few weeks/month after the shed was completed).

 

Clear skies!

 

jf


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#7 c2m2t

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Posted 14 January 2021 - 09:13 AM

Hi Jfgout!

I really like the concept...shows some real ingenuity and practical thinking. Makes some sense for a lighter mount and scope combination and someone who is not planning to do much serious astro-photography.

 

Cheers, Chris.

 

P.S. Very Nice Personal Website...some beautiful images!!


Edited by c2m2t, 14 January 2021 - 09:14 AM.

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#8 c2m2t

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Posted 14 January 2021 - 09:22 AM

Hi Speedster!

I am not sure that I would agree with regarding the spread footing. Everything has it correct application especially in frost prone soil.

 

Cheers, Chris.



#9 speedster

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Posted 14 January 2021 - 07:09 PM

Nothing wrong with the buried spread footing per se.  It's not needed for carrying the load and the issue is in the backfill of the over excavated hole to accommodate the BigFoot.  It's not practical to moisture condition and compact that small space to optimum density.  Even if thoroughly "stomped", it's still loose compared to undisturbed soil.  That backfill is providing little lateral resistance and the pier is a simple lever with its length being the sum of the above + below ground lengths.  That can certainly work just fine.  On the other hand,  a drilled pier can be considered a cantilevered column and the length subject to deflection is only the length above ground.  It's a lot less work, a little less cost, and a good deal stiffer when considering sub arc-sec allowable deflection.  Both can work fine and we're splitting hairs to some degree but one design has some advantages over the other.  Don't bump the mount and keep it out of the wind and I don't think anyone could tell the difference.



#10 t-ara-fan

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Posted 14 January 2021 - 08:53 PM

  Are you familiar with  the "Bigfoot" pier bases? Here is a link:

Ugh :(

 

   For a telescope pier, bigfoot is working against you, as is any buried spread footing.  Search this site for a thread called Pier Engineering and you will find some helpful info.

If you can swing it, the most stable pier is concrete poured into an open hole that has been augured into the ground past the frost line.  Add a sonotube or concrete form for the top few inches so the top of the concrete is neat and tidy.

 

A BigFoot means you have loose fill poured around the pier. Not good. It can tilt. And Bigfoot means the pier is in a sonotube that will rot way over a number of years - leaving a space between the concrete and the soil.

 

OP if you do hit solid limestone after 2" that is actually a good thing.  Bedrock is pretty solid ;) and you will need less concrete.



#11 c2m2t

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Posted 14 January 2021 - 10:09 PM

Hi T-ara-fan!

Soil compaction is a very easy process and will more often than not provide stiffer and denser soil around the pier.

 

Cheers, Chris.



#12 jfaldo

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Posted 15 January 2021 - 07:21 PM

 

Gosh I love to be called a young fella, thank you :)

You have to realize in this group it's a relative term. Most of us old guys see that you have a young'in (I'm pretty sure that's a proper Appalachian term. I grew up in the foothills not far from you near Wheeling, WVa) and figure you're probably young enough to be one of our kidslol.gif


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#13 StarmanDan

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Posted 15 January 2021 - 08:36 PM

Hi Jfgout!

I really like the concept...shows some real ingenuity and practical thinking. Makes some sense for a lighter mount and scope combination and someone who is not planning to do much serious astro-photography.

 

Cheers, Chris.

 

P.S. Very Nice Personal Website...some beautiful images!!

If you need a beefier pier you can always double up on the cinder blocks like I did.  I no longer have the LX200 fork and now use an Orion Atlas with 32lbs of AP gear on top.

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Edited by StarmanDan, 15 January 2021 - 08:37 PM.

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#14 speedster

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Posted 16 January 2021 - 02:16 AM

Hi T-ara-fan!

Soil compaction is a very easy process and will more often than not provide stiffer and denser soil around the pier.

 

Cheers, Chris.

Do a Proctor on the fill material and then a Density after in place and you may be shocked at how less dense the fill in an over excavated telescope pier hole is compared to the undisturbed soil around it.  It is possible, at least in theory, to achieve maximum density by hand but is far from easy or quick. 


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#15 c2m2t

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Posted 16 January 2021 - 10:15 AM

Hi Speedster!

Depends on the soil that you are using and the methods to compact. Sounds like Zakry is going to be removing nuggets all over the place just to get to depth, so his hole is going to be anything but a clean dig...will likely be 5 to 10 times what he is going to need and possibly more. Soil density to 4 and 5 foot depths can be very variable. Zakry is building a telescope pier, not a multi-story building. Lets not complicate it for him!!

 

Cheers, Chris.


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#16 zakry3323

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Posted 18 January 2021 - 02:11 PM

Thanks for all the responses and advice folks! To better illustrate the area that I'm working with I took a few photos: 

Capture.JPG

This is sort of a close-up overhead shot that I grabbed from Google Earth. If you click on it, it's much more readable. I've labeled it-

 

1. The number 1 in the circle is the first best pick for me. It provides the best views, until I can get that pool removed. I may not have even a big enough footprint for one of those Todmorden deals, as jfgout kindly suggested and linked for me. It looks fantastic, but I don't think I'm going to go in for an enclosure around the pier at this time. Most likely I will get by as I have the last couple years with my 360 Telegizmo shroud and take stuff in if there's a bad thunderstorm in the forecast.
2. Number 2 in the circle is second pick for a pier site. It's advantages are that its a little closer to AC power and marginally more conveniently located. That's also the disadvantage, because it's closer to the house I'd have less Northern horizon (just enough to get Polaris), and basically no sight lines to the East at all. 

3. The dashes indicate a steep dropoff from the flat portion of the property. From there westbound, it drops at about a 15% grade (the kiddo loves it for sled riding) and into the pasture. As you can see, either spot I end up going with is located closer than I'd like to that dropoff, and I'm very concerned that digging too much or too deep would cause erosion that might in the long run even effect the ground that the house is sitting upon. 

 

Here's spot #1 - my pier would be to the right of the firepit and left of the big stupid pool: 
 

spot1.JPG

 

Spot #2 is already on a downhill slope. It's gentle enough to not be a huge issue, but still. Now that there's snow on the ground I have some additional time to make smart choices smile.gif
 

spot2.JPG

 

 

Speaking of smart choices, thanks for helping me make them. As just a young'in of a mere 40 years I may not know much, but I've learned to not repeat (some) of the mistakes hard-learned by those more experienced than myself smile.gif


Edited by zakry3323, 18 January 2021 - 02:15 PM.


#17 c2m2t

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Posted 18 January 2021 - 03:34 PM

Hi Zakry!

I am guessing the dashed line to the top of the Google Earth image is a property line...or is it a rough line of the worst of the slope. As long as you can get access to Polaris, position "2" would be my initial choice. You just need to make sure that you are not going to be hauling trailers into the back yard...space appears limited. Nice spot..good vantage point to the south and west sky. The pool location will be the ideal location for a permanent observatory, with better access to the eastern sky. Ahh...to be forty again...I began my own home construction in that auspicious year!! I am guessing the septic system is in the backyard.

 

Cheers, Chris.


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#18 zakry3323

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Posted 19 January 2021 - 08:43 AM

Hi Zakry!

I am guessing the dashed line to the top of the Google Earth image is a property line...or is it a rough line of the worst of the slope. As long as you can get access to Polaris, position "2" would be my initial choice. You just need to make sure that you are not going to be hauling trailers into the back yard...space appears limited. Nice spot..good vantage point to the south and west sky. The pool location will be the ideal location for a permanent observatory, with better access to the eastern sky. Ahh...to be forty again...I began my own home construction in that auspicious year!! I am guessing the septic system is in the backyard.

 

Cheers, Chris.

Hi Chris!

 

Yes, the dashed line marks the steepest dropoff- it's very nearly a cliff at around 35% grade. Probably cut into the hillside and not backfilled. Continuing West (or Up) our property line extends for another two acres downhill. It's a fenced-in goat pasture surrounded by more trees- rocky and sometimes a little wet. The goats like it, anyways smile.gif The septic tank is in front of the house, passed the sharp dropoff (but the sewage line isn't anywhere near where I'll be digging). Sometimes it doesn't matter much, but other times just being a couple hundred feet up above all that makes a big difference when it comes to frost and fog. The bottom of the property is at about 700ft while my house and planned pier options are at around 1000ft. 

You make an excellent point about hauling stuff around. Spot #2 would ensure that I don't run into any issues moving things around with the tractor, as I often dump off branches and such for the firepit around area #1. Flat space is limited around here, and flat space with a view is rare. Otherwise we're on 18 acres of rocky hillside. The "backyard" is about 2 yards worth of shaded, gravel-covered french drain abutted by a cliff, nothing but woods back and beyond up the hill Eastward. The pool, how it taunts me! I just need to be patient - that area will be mine before I know it. And there's plenty to do in the meantime! 


Edited by zakry3323, 19 January 2021 - 08:47 AM.

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