Dug the holes for the stumps of the wooden deck for the coming SkyShedPOD that is. The deck is going to be 3.3x3.3 M and 560mm high and will allow for good air circulation for quick temperature equilibration. The hole for the piers concrete foundation is a full meter deep. Hopefully the whole thing will be ready before the POD arrives.
This was a lot easier than digging by hand and cost was very reasonable.
THe pier is being fabricated and below is a picture of my design. The aim was to have as little obstruction around the mount head as was possible to allow for maximum travel before a meridional flip was required.
It will be good not to have to worry about being caught in the rain and setting up and breaking down.
No Terra is fine. I metaphorically buried a lot of charletans. Just like their beliefs they were not real. In fact Mick reckons they did not add to the volume of concrete at all.
Here is a higher res pic of Terra 400kB http://avandonkbl.bigblog.com.au/dat...0926221144.jpg
Geoff we were sitting there having a beer and coffee trying to see if everything was correct before the concrete set.
We checked again this morning and all is where it should be.
More pics below. The pier support goes more than one meter deep to clay.
By adjusting the nuts on the eight bolts it was easy and quick to get the pier level.
Bert
Was the Dingo's auger able to excavate the entire width of the pier hole, and to what width did you make this?
If you don't mind me prying, what sort of cost is involved in hiring a Dingo for the day? I'm starting to get serious about starting to build an observatory soon...
Chris a dingo has three sized augers 200mm, 300mm and 400mm. I settled for all 300mm holes as the Dingo guy only had that size with him. The minimum charge is $180 and that gives you up to two hours. This was ample for what I had done. I think each further hour was $65. It was worth every cent. It also only needs about 1.2m width for access.
Here are a few more images. I am about to drill the pier for the three 6mm cap screws that hold the EQ6 in place. Orientation is important so that the horizontal adjuster on the EQ6 is in range of true south ie SCP.
Note how clear the the pier is at the top. This gives me maximum travel past the meridian before a flip is needed.
The EQ6 also has no gearboxes instead it has belt drives and heavy duty steppers all run by a Mel Bartels system. The drives are extremely smooth and have no discernable backlash. This makes autoguiding almost as good as it gets ie limited by the seeing.
Thanks h0ughy, I did a back of the envelope calculation and this pier design should have about the same lateral deflection for a given lateral force as the usual 150 mm to 200 mm steel tube with gussetts only at top and bottom.
The bottom gussetts are the most important as they have the highest bending moment.
In other words it is better than 150mm but not quite as good as 200mm tube mount.
Resonance should also be suppressed as there are no easy harmonics.
When you look at the pics of Berts backyard, it looks full of trees.
But believe me, he actually has a fairly good view of most of the sky. The only blocked side is good as that tree blocks the street light out front of his house, so it serves a good purpose.
)
