Aligning pier.

[K3ny0n]

Hey people,

I've got a pier half way in the making (which has been on the back burner for a long time) and I am just wondering when it is all complete and time to set it in to the ground, will it be sufficient if I set the azimuth pin north using a compass then when the mount is attached I can carry out the polar alignment? 

I've attached a image with the progress I have at the minute.

Rob.

[Kropster]

I think that as long as you are within a few degrees you should be ok. the mount adjustments should take care of it.

Likewise, you don't need to be perfectly straight and level.

[michael8554]

Magnetic North is 1 deg 49' west of true north in Middlesborough at the moment.

I'm not sure you could measure to better than plus or minus 5 deg with a basic compass anyway.

Michael

[r3i]

Hi Rob,

The amount of azimuth adjustment on the NEQ6 is very generous so there's no need to be hyper accurate. Basic alignment with a compass should be good enough IMHO.

[Peter Drew]

If the top plate can still be rotated, I would pop the mount mount on it with the azimuth adjusting screws tightened equidistant from the N peg and then sight through the mount's polar scope if it has one. Once rotated into position either tighten it down or mark it. Most mounts are balanced to enable this to be done freestanding.    

[K3ny0n]

Thanks for the replies guys,

I think I will have to get it some were near using a compass and hopefully will have the adjustment when I get the mount attached.

Peter, I don't have the luxury of rotating the adapter plate, not ideal I know but that is how it has ended up being made. I could maybe try and design a new adapter plate so I could rotate it but if the first option would be okay I will go for that one. Only problem is once I get the concrete set there will be no going back.

I've just had a thought while typing the above,

I have yet to make the bottom plate to attach to the steel rod which will be set in the concrete so I could design a bottom plate which could offer me the rotation.

Excuse the shabby drawing but it is considerably hard to draw using a laptop. (I hope you get the idea. Made easier of course by the great drawing)

[Astroboffin]

How high is that pier ?

You will really need to burry in at least 12" of concrete, have you got enough height to do that, it is hard to tell from your photo

Regards

AB

[K3ny0n]

Hard to know what your saying mate, the bottom of the pier still hasn't got the bottom plate on which will be fixed to the concrete which will have screwed rod set in. So the tube isn't getting set in the concrete.

If that's what's you mean.

Rob.

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[Peter Drew]

I think it's better to bolt the pier to the concrete rather than embedding it, you could then take it with you if you move.  

[K3ny0n]

I think it's better to bolt the pier to the concrete rather than embedding it, you could then take it with you if you move.

Peter, yes that is how I have planned to do it for that reason.

Rob.

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[fondofchips]

As long as your are within 30 degrees you should be OK.  I had to dismantle mine & drill another azimuth mounting hole in between the existing EQ6 adaptor holes (x 6), so around 30 degrees is about the maximum you can be out of line.

Cheers,

Fondofchips.

[K3ny0n]

As long as your are within 30 degrees you should be OK. I had to dismantle mine & drill another azimuth mounting hole in between the existing EQ6 adaptor holes (x 6), so around 30 degrees is about the maximum you can be out of line.

Cheers,

Fondofchips.

Thanks for the info. I am going to make the bottom plate with a small amount of adjustment aswell to give me that little bit of extra if I need it.

Rob.

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[Oddsocks]

I couldn't use a compass when setting up my pier, local geology plus the steel rebar I added to the concrete pad made magnetic north a very variable affair depending on how high above the ground I held the compass, maximum declination was 14 deg from true north at ground level and Polaris was hidden by trees in my neighbours garden so I had to find another method and used local noon solar transit time to cast a midday shadow across the pier pad.

Providing the sun is shinning of course, just suspend a plumb line above the centre of the concrete pad using a tripod of garden canes or bits of wood, allow enough set up time for the plumb line to stop swaying and shield from any breeze, go to the Solar Computer page at arachnoid.com, link below, and zoom/drag the map to show your location, click your location on the map and your lat-long coordinates will be auto entered in the solar computer, check the date is entered for the solar transit time you require and note the transit time quoted, finally go to the plumb line with an accurately set watch and make a pencil mark over the shadow from the plumb line as it crosses the edge of concrete pad at the transit time given by the Solar Computer, in your own time, no rush, make another mark on the concrete pad where the plumb line hangs above the centre point of the pier pad and use a straight edge to draw a line between the two points, extending the line across the full pad width if desired.

If you make the edge mark on the pad within thirty seconds of the local transit time then the pencil line will be pointing to within approximately 0.2 degrees of true north (depending on latitude).

The only thing that can catch you out is to remember that the Solar Computer calculates the transit and quotes it using U.T. (or GMT if you prefer) so remember to adjust the transit time quoted for any local daylight saving time that may be applicable otherwise you will be an hour (or more) off true north.

http://www.arachnoid.com/lutusp/sunrise/

[Astroboffin]

Hard to know what your saying mate, the bottom of the pier still hasn't got the bottom plate on which will be fixed to the concrete which will have screwed rod set in. So the tube isn't getting set in the concrete.

If that's what's you mean.

Rob.

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Sorry, didn't realise it isn't finished yet, that makes sense now

Regards

AB