I've decided to go for concrete piers in the observatory - cheap, solid, deflection and vibration free.
What's the best way to cast one? I've seen 300mm diameter steel duct in 1.5m lengths on eBay. To my mind that seems ideal. Any better suggestions?
Is a cubic meter of concrete under each pier necessary or will 0.5 cubic meters be sufficient?
I laid my North/South line last weekend using Pole Star and verified by solar noon sunshine. So soon I can mark out the plot, remove the kiddie's climbing frame and start digging.
Mark
You can get cardboard tube used for casting pillars, you can cut it off afterwards. Or see if your local carpet fitter has some old inners!
Cardboard tube sounds like a good idea. But I think I would leave the cardboard in place to help with thermal insulation - don't want warm air currents rising up from the pillar when planetary imaging.
Quotewarm air currents rising up
:o
I thought the observatory was going to be in the UK :-?
I'm thinking about those summer nights following hot sunny days with stifling shed temperatures.
Well, I can dream can't I?
Quote from: MarkS on Apr 24, 2013, 15:47:22
Cardboard tube sounds like a good idea. But I think I would leave the cardboard in place to help with thermal insulation - don't want warm air currents rising up from the pillar when planetary imaging.
I have come across people (on the web) who carpet the concrete pier so that it hurts less when collided with in the dark, also it's a nice warm covering available in a variety of colours and patterns to match the rest of the decor :)
It'll have wall to wall carpet so it might as well have carpet on the concrete piers as well ...
Altair Astro suggest about 1/2 sq M for their Skyshed pier
Well when I installed mine, every-one kept telling me 3' deep, and 2' 6" x 2'6" square which is what I have got.
I have the Skypod Pier.
No idea what that is in Sq M
Carole
QuoteNo idea what that is in Sq M
Nearly a Sq M
Ah, just worked it out. Comes to roughly 1.5 Sq metres.
Carole
Actually 0.53 sqM
Can't be bigger than 1 because of sides less than 1 metre
Thinking back to my school days, don't you multiply 2'6" x 2.6" x 3' to get the cubic measurement? Not had to do these sort of calculations since then. I converted it to yards first, which is why I said approximately, couldn't be naffed to also convert to metres as yards are pretty close.
Yes I think I worked it out in cubic yards instead of square metres, in which case no idea how to do that!!!
Never mind I don't need to do these sort of calculations any more so will leave it to the experts.
Carole
:o :o
Hardly the right person to be called an expert - I hate maths, but................
Calculate in feet then divide by 27 to give yards (which is close enough to metres)
That was the long way - this is the easy way
http://joshmadison.com/convert-for-windows/ (http://joshmadison.com/convert-for-windows/)
;)
an easier way is to measure in meters first, no conversion then. :cheesy:
How many chains in a meter then :(
I need a new rule :-?
Quote from: Carole on May 04, 2013, 15:44:30
Thinking back to my school days, don't you multiply 2'6" x 2.6" x 3' to get the cubic measurement?
Yes you do, but these imperial measurement converted are only 760mm x 760mm x 900mm which when multiplied together equates to .519m
3 and as Mick was saying if none of the measurements were over a metre then you would never achieve 1m cubed or over.
Tony G
PS.........I went to skool that day.
QuoteHow many chains in a meter then
We still use them on the underground to measure curves.
And the answer is 0.05 chains in a meter.
A chain is a unit of length. It measures 66 feet, or 22 yards, or 100 links,[1] or 4 rods (20.1168 m). There are 10 chains in a furlong, and 80 chains in one statute mile. An acre is the area of 10 square chains (that is, an area of one chain by one furlong). The chain has been used for several centuries in Britain and in some other countries influenced by British practice
How many Rods in a meter, that's an allotment measure :-)
Quote from: Rocket Pooch on May 06, 2013, 08:18:38
How many Rods in a meter, that's an allotment measure :-)
No, that would be how many Beans in a Furlong :lol:
Tony blew me away! I only know how many inches in a foot :oops:
Well that got every-one thinking!!!
:cheesy: :cheesy:
QuoteTony blew me away! I only know how many inches in a foot
easy, its five toes.