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Old 07-08-2019, 10:54 PM
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StarChildDazee (Dazeford)
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Question New Elivated Peir Construction Q's

Hi all, this is my 1st post here and I only joined recently.
I need to replace the end part of my house length Patio which is of timber construction.

What I'd like to do is construct a Viewing deck on top of the end part of the Patio, and then with a concrete pier prob made from concrete blocks (Bessa Blocks) up to the deck level then have either a concrete filled Storm Pipe (200mm) or a steel pipe up the remaining of the height required to take my telescope a Celestron Nexstar SE8. Currently AltAz but will later make a Wedge for it).

At the base at ground level there is concrete which I'm thinking of cutting a 1msq hole then digging a cubic meter hole below and filled with reinforcing and concrete to steady/brace everything.

For the Pier, up from the ground I am thinking 1 and a 1/2 blocks square filled with concrete and reinforcing rods.
Deck height above ground is about 8 feet, then approx. another 4 foot to the scope baseplate.

My Q is, is this over kill or not enough to keep my scope steady when viewing and imaging and from vibrations?
The ground in general is Clay.
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Old 07-08-2019, 11:33 PM
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Welcome Dazeford.
Sounds good but is there any chance of getting down to bed rock ? Clay although reasonable dies expand and contract. If that's what you have perhaps keep it moist. I was in real estate an old houses on clay would get cracks in protracted dry spells but an architect client told me his truck with his oldie as to not let the ground dry out.
Perhaps the important thing would be to make sure the pier is isolated from the deck so that walking on the deck will not carry to the mount. But I am not an expert so hopefully someone who has done similar can share their experiences. I would drive in star pickets and pour your concrete so it holds onto say 18 inch of the star picket....probably over kill but hey here is nothing wrong with overkill...good luck and let us know how you go...maybe a thread so others can learn from your hopefully successful venture.
Alex
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Old 09-08-2019, 02:21 PM
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Thank you Alex for your input...
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Old 09-08-2019, 06:39 PM
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Sunfish (Ray)
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You may find that digging hole and filling with concrete is no better than bolting steel to existing slab if it is reinforced correctly and is on good footings.

I have a steel pier on a slab on filled and reinforced concrete block work, again on footings and piers in clay. I can walk around while imaging.

The problem is the additional weight you are adding with a tall concrete pier unless it is above existing concrete footings of a reasonable standard. And then , in clay , it would require deep drilled concrete piers to keep stable over time and moisture levels depending on slope and clay depth. Only an engineer with a drill log report could answer these questions more exactly.
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Old 10-08-2019, 11:26 AM
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Quote:
Originally Posted by Sunfish View Post
You may find that digging hole and filling with concrete is no better than bolting steel to existing slab if it is reinforced correctly and is on good footings.

I have a steel pier on a slab on filled and reinforced concrete block work, again on footings and piers in clay. I can walk around while imaging.

The problem is the additional weight you are adding with a tall concrete pier unless it is above existing concrete footings of a reasonable standard. And then , in clay , it would require deep drilled concrete piers to keep stable over time and moisture levels depending on slope and clay depth. Only an engineer with a drill log report could answer these questions more exactly.
Hello Ray, ok then sounds like sound advise.
The concrete patio floor I would expect is as per standard concrete laying. its been down some 30yrs.
I now have to decide what size steel pipe to use.
It has to go up about 2.3m to the proposed deck height then I am anticipating going up another 1.4-1.5m for the scope and mount to sit upon.
For this I am also thinking 200mm dia.
Any suggestions??
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Old 10-08-2019, 03:01 PM
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For that height the bigger the better. I think you would have to add two or three diagonal pipe braces and perhaps fins from the slab up to to below the next level in different directions to prevent movement and perhaps fill part of the steel to dampen it down. Still easier than cutting a cubic meter hole in the slab. Perhaps you can find a calculation for the size and thickness required above the braces to get vibration to an acceptable level. It is a challenging height for mounting a scope.

The cost of the steel and welding and bolting may be more expensive than a new location higher on the site.
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Old 10-08-2019, 04:13 PM
Wilso (Darren)
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I like the steel pier option myself, a lot easier to manufacture and you could also add three stainless steel turnbuckles and wire to stabilise the pier . Perhaps fill 1/3 with sand.
Sounds like a fun project!
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Old 27-08-2019, 12:58 PM
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I think solid pipe braces would be better as they work on either tension or compression and are less likely to vibrate. The heavier the better. That or chemset some starter bars right in the corners of your slab over the footings and cast a concrete pier in form tube or Hardie's cfc pipe to the next floor level
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Old 05-03-2020, 09:49 PM
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Viewing Deck Plan Change

Hi everyone, just an update about the elevated Viewing deck I was going to construct at the end of my Patio.
Well, that's not happening now and in its place I an putting a low deck upon which I will put my spa and the deck will extend out to the pool.

As for the Telescope, I am currently building a viewing deck further up the back of my yard. From there (with an elevation of just 800mm) I will have a reasonably clear field of view from Sth West to Sth East and also clearing my house as well as the neighbours. To the north I will have a fair field of view though there is trees but I hope to be able to convince the local council to possibly trim those trees a wee bit. There is a vegetation strip at the back but its not a reserve or protected land.

Once I get the viewing deck done I will then look at putting sides on and a sliding roof.
I will have a Steel Pier atop a reasonable concrete base. 1400 deep round hole with a 600x700x400 square section as the top area.
The steel pier will be 225diameter with a wall thickness of 12mm. It will be approx. 1 to 1.2m high.

Q. A. Is it better to leave the steel pier empty?
B. Fill/half fill it with concrete?
C. fill it with expanding foam?

Then atop of the pier will be a top plate to take a HEQ5 pro mount and a Celestron ALT/AZ mount.

As of this Saturday 7 March 2020 I will have all of the concreting done.
Cheers.....
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Old 05-03-2020, 09:57 PM
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Quote:
Originally Posted by Sunfish View Post
I think solid pipe braces would be better as they work on either tension or compression and are less likely to vibrate. The heavier the better. That or chemset some starter bars right in the corners of your slab over the footings and cast a concrete pier in form tube or Hardie's cfc pipe to the next floor level
Hi Ray, I think what I'm now undertaking is a lot simpler idea. Keeping the viewing deck low is a much sounder idea which in turn is a lot more stable. But thank you for your input. Sorry for the late reply too.
Cheers, Dazee....
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Old 06-03-2020, 08:29 AM
appiice (Ed)
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Hello Dazeford

Over on Cloudy Nights in the Obs forum there is a guy who backs up his comments with engineering calcs, basically what he is saying is that you will see little if any improvement going from say 200mm pipe to 300mm pipe, gussets look good but don't really increase the stiffness of a steel pier.

Filling the tube with sand ( I've never heard of foam before ) or concrete again isn't really doing anything for stiffness.

What my take away from the ongoing comments he is making to questions is that we all over build our mass bases.

I did to, my mass base is about 6 tons with a 250mm 8mm wall thickness gusseted pipe on top, the pipe is bolted to the block with 8 16mm threaded rods about 1m long, leaning on or bumping the top of the pier shows no movement on screen ( 11" sct on top )

My advice would be to do what you are comfortable with keeping in mind your budget and skills, don't over think it just get on with it.

Ed
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Old 06-03-2020, 09:56 AM
Imme (Jon)
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My DIY pier is 1.8mm high, 200mm diameter and approx 8mm thick.....no gussets, no internal filling. Base has braces welded up the side of the pier approx 400mm. Although it is in an OB's it doesn't have significant protection.....Scope sits in corner of 6m x 6m space and pokes its nose above the roofline about 300mm (so wind is a factor)

Base is dyna-bolted (6x75mm) to concrete shed slab

Sitting on this pier I have an EQ-6 carrying approx 14.5kg.

I have no movement when using that I can see from wind or any other factor.....I have auto-exposure cancel on SGP/PHD2 set at 1.25 pixels and very rarely (if ever) lose a sub......I've recently done almost 100x10 minute subs on a project I'm working on and lost 2 due to a guiding error -
this may not even have been pier related. (925mm focal length on 3.75um pixels)

If i give the top of the pier a hard knock i will get a vibration however it clears up within a couple seconds......by hard knock i mean with force equal to a hard slap/punch

I've said it before and I'll say it again.......I think many people really over engineer their piers and mounting points.

There are many imagers out there creating amazing pictures on a tripod sitting on grass/dirt.......anything bolted down to a concrete slab has to be an improvement!
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Old 08-03-2020, 11:43 PM
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Quote:
Originally Posted by appiice View Post
Hello Dazeford

Over on Cloudy Nights in the Obs forum there is a guy who backs up his comments with engineering calcs, basically what he is saying is that you will see little if any improvement going from say 200mm pipe to 300mm pipe, gussets look good but don't really increase the stiffness of a steel pier.

Filling the tube with sand ( I've never heard of foam before ) or concrete again isn't really doing anything for stiffness.

What my take away from the ongoing comments he is making to questions is that we all over build our mass bases.

I did to, my mass base is about 6 tons with a 250mm 8mm wall thickness gusseted pipe on top, the pipe is bolted to the block with 8 16mm threaded rods about 1m long, leaning on or bumping the top of the pier shows no movement on screen ( 11" sct on top )

My advice would be to do what you are comfortable with keeping in mind your budget and skills, don't over think it just get on with it.

Ed
Hello Ed, oh ok kewl and thank you for your advise. That's what I do generally anyway. just being new to all things astro I thought it might be prudent to ask advise but more so prob to make check that I'm on the right track, which by the sounds of things I am....
I normally am able to just look at a project and decide what needs to be done over a few days. then get on with it. Now that the concreting is done, it wont be to long before its up and running. Ill do the deck and pier first then later do the sides then the sliding roof.
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Old 08-03-2020, 11:55 PM
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Quote:
Originally Posted by appiice View Post
Hello Dazeford


Filling the tube with sand ( I've never heard of foam before ) or concrete again isn't really doing anything for stiffness.

What my take away from the ongoing comments he is making to questions is that we all over build our mass bases.


Ed
Hi Ed.
Filling the pier with something maybe just to minimize the chance of dropping anything down it ie top plate nuts/washers. I'll probably will fill with expanding foam to facilitate this...
My steel pier will prob be around 1200mm long. ish……
From what I've heard, filling with sand, concrete etc. is done to reduce vibration/act as a dampener... But I'm no engineer
Dazee

Last edited by StarChildDazee; 09-03-2020 at 12:03 AM. Reason: add more info
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Old 09-03-2020, 12:13 AM
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StarChildDazee (Dazeford)
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Quote:
Originally Posted by Imme View Post
My DIY pier is 1.8mm high, 200mm diameter and approx 8mm thick.....no gussets, no internal filling. Base has braces welded up the side of the pier approx 400mm. Although it is in an OB's it doesn't have significant protection.....Scope sits in corner of 6m x 6m space and pokes its nose above the roofline about 300mm (so wind is a factor)

Base is dyna-bolted (6x75mm) to concrete shed slab

Sitting on this pier I have an EQ-6 carrying approx 14.5kg.

I have no movement when using that I can see from wind or any other factor.....I have auto-exposure cancel on SGP/PHD2 set at 1.25 pixels and very rarely (if ever) lose a sub......I've recently done almost 100x10 minute subs on a project I'm working on and lost 2 due to a guiding error -
this may not even have been pier related. (925mm focal length on 3.75um pixels)

If i give the top of the pier a hard knock i will get a vibration however it clears up within a couple seconds......by hard knock i mean with force equal to a hard slap/punch

I've said it before and I'll say it again.......I think many people really over engineer their piers and mounting points.

There are many imagers out there creating amazing pictures on a tripod sitting on grass/dirt.......anything bolted down to a concrete slab has to be an improvement!
H Jon, that's sound advise too. I'm sure mine wont be too over engineered. Once I get the deck laid I'll then have a think on how to do the mount and base plate.
Thank you Jon for your input.... Dazee
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Old 29-03-2020, 03:34 PM
Spartan1 (Philip)
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Pier mount for 8" SCT

This was my only attempt at a home-made pier mount but it was highly successful.

Concrete base fashioned by hand, in situ, on a tiled rood terrace. A few sheets of newspaper placed on the tiles first to stop the base adhering.

A length of 6" drain pipe pushed at right angles into the wet cement, allowed to dry and then filled to the top.

8" diam 1/2" stainless steel plate with four drilled holes to support the final 8" diam mount plate, plus one central hole to secure the lower plate to the concrete filled pipe. 4 x 6-8" bolts/nuts secured the two together and provided an exceptionally rigid 'cage'.

The 'cage' was to allow access to the mount bolt underneath the Vixen SP GEM to secure it to the top plate and allow easy removal. It depends what your existing mount requires.

The square base was very stable and easy to shuffle around by one person - or lifted by two, if necessary. A round base would not have been so stable. I welded some fixing points on the top plate that gave polar alignment to the mount in Dec, so no need to re-align.

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