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Mount extension vs pier plate

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#1 Paul Freeman

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Posted 26 July 2014 - 01:19 PM

I am going to put a pier in my backyard, and I read about someone who used a mount extension instead of using a "Dan's Pier plate".

Here is the extension build: http://www.tungstent...ion/tabid/68...

The pier plate is more versatile, but using the extension saves $150-$200.

I appreciate any advice.

#2 MJB87

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Posted 26 July 2014 - 03:19 PM

Either approach might work. All I can say, having just put one of Dan's plates on top of a BYO Omega pier, that the plate is a thing of beauty and matched the pier and my mount exactly. The combination is rock solid. Also, if at some point in the future I change mounts (unlikely) I can get a new pier plate -- no need to revisit the pier itself. Is that worth $150? Hard to say but in my case the answer was "yes."

Marty

#3 Paul Freeman

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Posted 26 July 2014 - 05:44 PM

Thanks for the response Marty - I love your Rich Neck Obs build BTW. I am also leaning toward Dan's plates. Having it "just work" takes one variable out of a hobby that has a lot of variables.

Any advice on the concrete pour is also appreciated. I see many concrete piers that appear "rocky" rather than smooth. Is that ok, and I just shouldn't worry about it?

#4 MJB87

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Posted 26 July 2014 - 06:14 PM

A rocky pier suggests indifferent workmanship to me at least, or maybe a suboptimal mix of sand, stone and cement. I'm not an authority in these matters however.

My concrete pier ended up being 3x3x4. Importantly, it has both rebar and fiber reinforcement for structural stability. I didn't know about the need for fiber reinforcement but the builder I used (quite good in these matters) insisted.

The frost line here is only about 18" and the pier rises about a foot above the surrounding ground so I've got 18" below the frost line.

#5 HunterofPhotons

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Posted 27 July 2014 - 11:54 AM

.... I see many concrete piers that appear "rocky" rather than smooth. Is that ok, and I just shouldn't worry about it?


No, that's not okay.
The linked pier was the work of someone who had no clue as to what they were doing. The mix was too stiff and they didn't work it enough.
Had it been done correctly it would have turned out stronger.
A pier extension doesn't have to be expensive. I had this one made for an old visual setup for $50:

Posted Image

dan k.

#6 ur7x

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Posted 27 July 2014 - 12:43 PM

.... I see many concrete piers that appear "rocky" rather than smooth. Is that ok, and I just shouldn't worry about it?


No, that's not okay.
The linked pier was the work of someone who had no clue as to what they were doing. The mix was too stiff and they didn't work it enough.
Had it been done correctly it would have turned out stronger.
A pier extension doesn't have to be expensive. I had this one made for an old visual setup for $50:

Posted Image

dan k.


I completely agree, wet concrete is... well... wet. It will flow, slowly to fill the voids. leaving a smooth pillar with a flat top. Ya a 80lb bag of ready-mix needs about 3 quarts of water. They key word there is "about" on a cold higher humidity day you will need a little less. If you are pouring concrete in the middle of a desert on a 100 degree day you will need a fair bit more.

If the pier in that link was mine I would not post photos of it or give advice based on it... Other then having people learn from that mistake.

Concrete is easy to screw up, it is more of an art than a science. A telescope pier is not the place to try this for the first time. Which I would bet is the case in that link. If you have any doubt, have a tradesman pour your pier/base.

#7 Paul Freeman

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Posted 27 July 2014 - 11:37 PM

Everyone - This advice is very helpful. Thank you. If I should hire a tradesmen, I am now reconsidering concrete. I was going this way because it was the least expensive & easiest option.

It also seems to me that the veterans use steel piers. Is this a Honda vs Cadillac thing where they both get you there, but you enjoy the Cadillac more? Or are there real functional benefits. I love the way steel piers look, but are they really $1K + the cost of the mounting plate?

I must sound incredibly naive to many of you, so I appreciate your feedback.

I fully expect the next post to say, "Paul - this project costs $1,500. Have a professional pour you a concrete base, order a steel pier that matches your needs, and a mount adapter and move on. Everyone who does this project a second time does it this way. Learn from our mistakes."

#8 ur7x

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Posted 28 July 2014 - 08:55 AM

Let me offer this on Concrete vs Steel pillars.

Both have there advantages and both have there issues.

Done right, there is nothing wrong with a concrete pier. However, the pier in the link is a mess, the mix was too dry, it lacks a nice heavy base, it is week, funny looking, will not perform well and will likely be replaced.

A counter example, a friend of mine has a 16" LX200 on the roof of his house, the concrete pier is over 20' tall and extends through two stories of his house to a reinforced 10'x 10' x 6' base dug down to bedrock.

The cross section of the pier is about 3' x 3', weighs about 20 tons, and looks like a chimney as it passes through the house.

His massive telescope nails gotos all night long and hasn't been aligned in over a year.

If you are comfortable working with concrete, go for it! If this the first time mixing a bag of readymix in a wheelbarrow... Maybe look at other options.

#9 Paul Freeman

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Posted 28 July 2014 - 11:22 AM

Maybe I should practice my concrete skills. I am sure my wife would love a dozen or so of these in the yard.

Posted Image

Seriously - I appreciate the help. Please add on with more advice.

#10 Ramses

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Posted 28 July 2014 - 10:07 PM

I love the way steel piers look, but are they really $1K + the cost of the mounting plate?


I went to a local metal fabrication shop with a drawing of the pier I wanted. I walked through the shop with the owner and found some scrap metal pipe (9 inch diameter and 1/2 inch thick wall) which he was willing to sell to me cheaply. The whole pier including labor and milling the top to accept my mount adapter was around $125.00.

I just built my observatory and mounted it on a cement base poured into a 24 inch sonotube 48 inches below grade and 16 inches above. It is rock stable. I mounted it to the cement base with 3/4 inch stainless J-bolts sourced from Dan's Pier Plates.

#11 roscoe

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Posted 02 August 2014 - 06:43 AM

Another thread here just suggested the use of a used brake disc (free at any auto repair shop) as a mount adapter, a couple of these excellent 1/2" thick discs and a hunk of pipe, and....insta-pier!

I'm a small-town contractor, I agree that a pier shouldn't always be a person's intro to concrete work....because it IS art as well as science....but a couple hours watching videos or hiring a contractor for an hour or two will give you a good end product.

#12 Alex McConahay

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Posted 04 August 2014 - 08:14 AM

As to the quality of the pier and it's "rockiness."

 

Yes, a wetter mix, more working it in (sticking it with a rod to push it in more on pouring), and smacking the side of the sonotube to get rid of air bubbles would have been better. \And it looks a little thin to me.

But it will probably hold your scope firmly enough.

 

So, enoy it. Give it a while. If it stays functional, don't worry about it.

 

Alex



#13 Paul Freeman

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Posted 20 September 2014 - 05:41 PM

Just finished. I went with Dan's pier plates & a concrete pier. 

 

syxg1k.jpg

 

Thank you everyone for the advice. It will of course now rain for the next five days ...


Edited by Paul Freeman, 20 September 2014 - 05:56 PM.







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