My pier is finally finished so I thought I should post a few pictures and some details of how I went about building it. It's not the greatest design or the prettiest to look at, but it does what it was built to do very well.
I started by finding 8 x 40kg bags of premix cement in the shed that I could use for the foundation. Then I guesstimated that a 700 x 700 x 500mm deep hole would probably swallow up all the concrete and leave it just below the surrounding ground level. I decided to make the top of the concrete slightly below ground level so it can easily be hidden in future, rather than have to try and dig it up.
So the first step was to get a bit of unwanted exercise by digging the hole for the concrete foundation. (pic. 1) The ground was slightly damp which made it fairly easy going, in summer it would have been rock hard. I made the walls of the hole on a slight reverse taper so the concrete would lock in a bit better.
The next step was to pour the concrete. (pic. 2) It was easy enough, but it turned out that the hole I dug was slightly larger then it needed to be. I realized this when I was about halfway through pouring the concrete in. That was easily fixed by throwing a few old house bricks into the mix to raise the level a bit.
I left the concrete to set for a couple of weeks while I was organizing the steel components of the pier. I managed to get 2 pieces of 150 x 100 x 1600mm rectangular tube from work that was going to be cut up and scrapped (pic.3). I welded the two pieces together side by side and cut them down to 1100mm to make the main vertical section of the pier.
For the base of the pier and the two top plates I used some 20mm mild steel plate that I got oxy cut to size. The base is 500 x 500mm and the two plates on the top are 300 x 300mm. Total cost for the cut steel was $100.
I drilled the base plate with 8 x 13mm holes for dynabotling to the concrete. I also counter bored the holes so the maximum length of the bolt would go into the concrete foundation (pic. 4). For the top plates, I decided to use M16 galvanized threaded rod ($8 for 1 metre - far cheaper than bolts) to hold them together, so I drilled 4 x 17mm holes through both of the top plates. While I was doing this on a CNC mill at work I also circle milled a spot face and hole to mate with the base of my EQ6 mount. (pic. 5) I also put in the tapped hole (M10 from memory) to attach the spigot for fine adjustments to the north/south alignment of the mount.
Next step was welding… I’m a good machinist, but I can’t arc weld to save my life. Anyway, I managed to splatter enough on there to hold it all together. After some wire brushing I gave it a coat of paint. After the paint had dried I sat the pier on its foundation, lined it up to the south, and drilled the holes in the concrete ready for the dynabolts.
After a quick cleanup everything was ready for final assembly. I got the main body of the pier level and bolted it firmly to the foundation. Then I attached the M16 threads and the top plate (pic. 6). I put the EQ6 mount on the top plate and used the bubble level in the mount to get everything nice and level.
After that it was time for a test run…. Everything worked without a problem! A hard thump on the side of the pier only caused vibrations at high power for a few seconds, so I was happy. After the successful test I took the mount off and gave the pier its final coat of paint, and the job was done. (pic. 7&8)
The effort in making the pier was well worth it. It saves so much setup time which means more viewing time for me. For around $200 and a couple of weekends work this is probably the best value for money accessory I have.
Any questions or comments are welcome, of course.
. I was originally going to put a big radius on the corners while I had it on the CNC at work but I just didn't have the available time on the machine to do it. I might do something about it one day.
...I look forward to seeing it up and running...
