[See bottom of page for February 2015 update]
Like most amateur astronomers I have met, I have always wanted a permanent telescope pier in the garden at home.
Until now, it has just been a dream. I have always been put off by the following:
a) the cost (commercially available telescope piers cost typically £500 to buy, before any installation)
b) the necessary installation work, which normally involves a lot of digging, followed by casting a large concrete block in the ground. Plus, the concrete base usually needs very accurately aligned and positioned mounting studs for the pier to bolt onto.
Of course, the benefits of a permanent telescope pier are easy to appreciate – much reduced set-up time for your telescope, leading to more frequent use, plus more accurate polar alignment.
So I have been trying to come up with a design for an easy to build yourself, low cost telescope pier. And over the last couple of days, I have made one.
Here is my design described below. I don’t know yet if it’s any good, but I will use it properly soon, come the darker autumn nights and I will report back here.
The pier is based on a timber gate post, 8 inch square (200mm). This cost about £30 from a local supplier. Timber is said to be a surprisingly good material as it damps out stray vibrations, which of course you do not want for good astronomy seeing and imaging.
On top of the timber pier, is a home made levelling adapter made from two aluminium plates obtained from a local metalworking shop for £20. The leveller uses 12mm (M12) threaded studs, cut from a one metre length, which I bought for £7.
Here’s how I made the pier..
I used a fencing bar with a small blade end, to cut a box-shaped hole. This was quite hard work of course.
I wanted to go down to about 3 feet, or ideally 1 meter, but found my arm was not long enough to scoop out the earth spoil! So I got down to about 33″ finally. Hope it proves to be deep enough…
Step 2 – Cut the gate post to length
Some internet research suggested the finished height for the pier should be in the 36-42 inch range.
So having measured the depth of the hole and bearing in mind the levelling adapter I would fit to the top, I carefully cut the post square at 65″ long, so as to end up 32″ above the ground.
Step 3 – Make the levelling adapter
I had been told it is not super-critical to ensure the top of your pier is level, from the standpoint of good mount tracking.
However, I decided that was poor advice and would take no chances. More adjustment is always better than less, I think.
Also, the adjustable adapter will let the top mounting platform move up and down, to accommodate different length telescopes.
So I set out to make a levelling adapter. I mentioned above, I had got two plates of aluminium (10mm thick) from a local metal work shop. The plates came from an off-cut piece of sheet they had. They charged £20 for the two plates, including cutting out to 9″ by 9″ square. (I might have gone larger had the off-cut allowed it, but this seems big enough so far)
I drilled the plates on each corner to 12mm diameter and fitted four threaded studs, each cut to 8″ (200mm) long. Lock nuts above and below, should accurately position the top plate.
The bottom plate is fixed to the post by five M8 coach bolts. I drilled pilot holes for the coach bolts with a 6mm drill bit. Even with plenty of oil lubricant, I tightened the bolts very carefully to avoid splitting the post, which seemed to be a risk.
Step 4 – Concrete the post in place
Having trial fitted the adapter plates on top of the post, I decided all was promising. So it was time to permanently set the post into the ground.
A post spirit level was used to get the post perpendicular and it was held in place using some scrap wood. Then “Postcrete” (ready mixed special post concrete, sold in 20kg bags) was used to secure the post. It was quick – set in about 30 minutes, however I left it undisturbed for a full day to hopefully acquire full strength.
Conclusion (part 1)
So far so good! Looking very promising.. my first permanent telescope pier is done. (made and installed for well under £100)
Please see Part 2 of this article about fixing my Skywatcher EQ6 equatorial mount to the pier.
UPDATE FEBRUARY 2015
Coming up to two years after it was installed, my diy telescope pier (based on a big timber gate post) is working extremely well.
When capturing images or during visual observation, tracking is very good with no discernable movement. You can even accidently hit the post with your foot, without any noticeable effect. Except, to your foot!
The long bolts of the diy levelling adapter are useful at times for adjustment, but can be adjusted right down. This can minimise the distance between top and bottom plates, while still allowing access to the central stud holding the EQ6 mount adapter securely.
The pier now has a DIY roll-off roof observatory around it.
This observatory was built from scratch using CLS timber studding, some old plywood sheets I decided to reuse and a lightweight plastic corrugated roof. As it’s working well, I am now considering recladding the observatory with some pretty log-lap timbers to replace the plywood sheets.