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Construction of an EQ6/Atlas Pier

Introduction

The following is a brief description of how I built a permanent mounting or pier for my Atlas EQ-G telescope mount, also known as an EQ6. I am lucky to have a large front yard with decent views of the skies and trees and shrubs partly shielding the road. Although I’d love to have a proper observatory I figured a pier is a good way to get started. This document is written journal style with new sections added as work is completed and photos taken.

Status 5/22/07

Parts

I bought the Orion extension set for the Atlas mount, part 07394. At first I had intended to have someone local build an adapter for a different pier adapter Orion also sells but this quickly got very expensive. I then realized that 07394 has all the parts I needed to mount my telescope on a concrete pier.

Hole dug in the yard.Digging

Once I picked the spot I started digging. I figured with the metal pipe of the extension kit I’d need about 2 feet of concrete pier. 8” Thick should be plenty strong. The frost line here in Connecticut is 42” deep. I started digging with a regular spade and garden tools. I got about 1.5’ deep. Time to get a post hole digger. I bought a Stanley one with glass fiber handles for about $30. Digging with this takes some getting used to but I made decent progress. Great exercise for your shoulders I should add! Mine were still sore from a workout the day before and it was pretty painful at times. Stones mixed in with the sand made digging a little hard but eventually I got to 42”. Also about the deepest I could reach with the post hole digger for this narrow a hole. At the bottom I flared it slightly so that the post can’t creep up. Creep is unlikely anyway because it’s below the frost line but better safe than sorry.

Shopping

I went to the local Lowes and got a few 10” Carriage bolts in the ½” size and the right size nuts to go with that. I could have bought stainless all-thread but I didn’t really see the need for that. Properly cared for galvanized steel of this size will last forever. So for less than $10 I had all the mounting hardware I would need. I also got a 4’ piece of  8” diameter tubing for the pier, some rebar, 240 Lbs of concrete mix and a mixing pan.

Drilling

Plate with holes drilled.To make the pier adjustable I decided I’d use 3 mounting bolts. That meant drilling 3 holes in the bottom adapter plate that comes with the extension set. Luckily the exact location isn’t very important except for aesthetics. Of course I wanted to optimize the rigidity of the setup by pushing the bolts as far apart as possible while still being able to fit the nuts and possibly tighten them from the top with the extension pipe mounted. So I drilled the holes 15mm from the edge. I eyeballed the location with some helper lines. Since I have a drill press it wasn’t hard to drill nicely perpendicular holes although it’s always surprising to see these big ½” drills have a mind of their own. I think it ended up OK. Here are also two pictures showing the partially assembled extension. To make sure the bolts are mounted correctly in the concrete the whole assembly will be pushed into the pier and leveled when the concrete is still wet.

Bolts mounted to plate

Assembled extension kit and bolts

Status 5/31/07

Well, it’s done. Last weekend I poured concrete and this week I’ve started enjoying my pier. Here are some pictures to show you how I proceeded:

First step was to insert the Quiktube into the hole and level it. I used a 2x4 and some rope to prevent the tube from falling in the hole. The tube is 4’ tall and the hole was about 42” deep so it went about halfway down. I then used 3 pole holders and rope to level the tube. The pole holders have a screw on the bottom end so they can be secured in the dirt. They are typically used for umbrellas and the like. As an added bonus I was able to turn each holder and thereby tighten the ropes as needed.

I decided to use one piece of central rebar. I got two pieces and tied them together with some metal wire (plastic coated but that was because it was all I had). I placed the rebar in the center of the hole and used some more wire to center the rebar approximately. When I dug the hole I filtered out the plethora of rocks we have here in Connecticut and after washing them I tossed them down the tube to line the bottom of the hole.

And

As I filled the tube with concrete the spreaders weren’t needed anymore so I took them out. As I filled the hole with concrete I stopped every now and then and used a long wooden stick, in fact a martial arts fighting stick called a ‘bo’, to force the concrete down and pack it tight. An 80 Lb bag of dry concrete takes surprisingly little water, less than 3 liters. Mixing the concrete in a pan with hand tools was hard work, you understand why people use powered mixers for this stuff or simply have a truck deliver it. But, this was very cheap, less than $15 for 3 bags of concrete, another $4 for the pan and $5 or so for the tube. Can’t beat that plus you get a workout carrying those 80 Lb bags of concrete around.

When the tube was nearly full I took the 3 bolts I had assembled before and pushed them into the concrete. The mix was just slushy enough that I could work it down and stiff enough that the bolts wouldn’t just sink in. I had wrapped the exposed part of the assembly in plastic to keep it clean. As I filled up the rest of the tube I used my gloved hand to tap it down. I ran out of concrete a little early and didn’t feel like opening another bag for just another inch or two of pier so I left it at that:

The disk doesn’t look quite centered. I’m not sure if I re-centered it after the picture was taken. It looks better now although it’s certainly not perfectly aligned. Needless to say I had previously figured out how to turn the disk so that the assembled pier and mount points North for polar alignment.

The quiktube instructions say the tube needs to be removed within 24 hours if it’s not going to stay in place so that’s what I did.

Here is the finished pier with the adapter still in place. As concrete continues to harden for days if it’s kept wet I put a few wet towels on the concrete and put a plastic bag over it:

After a few more days I removed that too. As is clear from the following picture the bolts ended up being pretty crooked. The problem is that my yard has a significant slope so it’s easy to be fooled as to what’s level and what is not:

But no matter, that’s why I used 3 bolts in the first place. As you can see from these two pictures of the completed setup it’s now perfectly level:

The second picture shows that I aligned the camera with the ground instead of the pier. Not to worry, it really is pretty level.

Final thoughts, plans for the future

I am delighted that I persevered in building this pier. Already this week I enjoyed having my scope ready when I was. It’s now feasible to observe for just an hour or so without feeling you wasted all this time on setup and teardown. The pier did end up a little short. This is OK for now but may become an issue if I ever build a deck around it or even an observatory. In that case I’ll probably take it down and pour a new one. Not a big deal now that I know how it’s done. It may also be possible to extend the steel pipe or even put a concrete cap on top of the pier to raise it. At some point I plan to plaster the outside of the pier so it looks a little nicer.

This file was uploaded on Thursday, May 31, 2007 at 4:39:17 PM

      

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