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Concrete Pier Preparation and Construction

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#41
citaylor

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When you do the pier itself (as opposed to the block), make sure you have enough concrete left to do it in one go, otherwise you will get a weakness across the pier where the join is. The block isnt so important as most of its job is just to add weight and stability. Again, I would only put the rubble in the block as you could get a weakness in the pier...

Cheers

Edited by citaylor, 30 April 2011 - 08:52 PM.
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#42
Bizibilder

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I should have said - when you come to do this, unless you have several strong men (and women!!) around to do the job it is well worth hiring a concrete mixer. Concrete is HEAVY and you would soon tire of mixing it. It really should be mixed and poured in one go and it does not "bond" very well if you make lots of small amounts.
If you are in any way "not quite as fit as you should be!" then a mixer is almost essential - a damaged back is not much fun - so I've been told.

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#43
Gina

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It's alright - we have one :D Yes, that sure would be a lot to mix by hand!!

Thank you for confirming that I shouldn't use rubble in the pier, Chris :) And, yes, I realised the top part of the block and the pier wants pouring in one go. I'll do the bottom half or so of the block and see how much it uses. Then make sure I have more than enough to finish the job.

Gina
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#44
Gina

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Googling I came across an article on making a concrete pier using a mailing tube mould like I'm proposing, except his is 8" diameter and mine is 7". Here's the link :-
Astro Pier Construction

Gina
SW Explorer MN190 - Esprit 80ED Pro - Evostar 80 ED DS Pro + 0.85x FR/FF x2 - one with Baader SteelTrack focuser - ST80 x2 - EQ8 & NEQ6 Pro mounts - Guiding OAG with Lodestar X2 & PHD - Atik 460EX mono x3 and 314L+ mono Filters Astrodon 5nm Ha, 3nm OIII, 5nm SII - Baader LRGB - Atik EFW2 filter wheel - 35, 55, 85, 105, 135, 200, 300mm lenses - EQMOD ASCOM CdC APT SharpCap DPP DSS PS Artemis Capture


#45
Chris Stacey

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Googling I came across an article on making a concrete pier using a mailing tube mould like I'm proposing, except his is 8" diameter and mine is 7". Here's the link :-
Astro Pier Construction


I think I'd feel happier with a bigger hole then he dug (and i'd render it lol) ....but it looks fine, and clearly does the job.

#46
Gina

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Yes, I agree, I thought that too.

Gina
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#47
malc-c

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The mix he used was a bit dry by the looks of it. One thing I don't get is everyone bangs on about having 1cu mtr foundations, then solid piers but then support the weight of the mount and scope on three relatively thin bolts !
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#48
Bizibilder

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Its all to do with "amplification" - the tiniest movement or vibration at the pier base will be much bigger at the telescope. It also has a damping effect - large masses are better damped than small ones - so any vibration dissipates much more rapidly. The bolts people use - usually 12-16mm are at the "light" end of the system - I would be much more concerned by the relativly flimsy attachment of dovetails to mounts and the thin walls of most scope tubes.

Edited by Bizibilder, 01 May 2011 - 08:53 AM.

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#49
Gina

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I think I might widen out the pier at the bottom to reduce the stress where it's greatest. I have yet to work out how I shall support things while the concrete sets but we have plenty of bits of wood so shouldn't be a problem. I don't like having a sharp change of angle just where the stress is greatest. A conic section pier, smaller at the top and bigger at the bottom with a curved transition to horizontal would be my thoughts of an ideal structure. Or even a wider angle conic section going out to the edge of the block.

Gina
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#50
Gina

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Been hammering iron pipes and things into the bottom and sides of the hole. Two one inch galvanised water pipes and two pieces of rebar hammered into the bottom and extending most of the way up the pier. The four M14 threaded rods will overlap these and continue the reinforcement up the pier. I've bent the bottom end of the threaded rods to prevent them possibly pulling out

Edited by Gina, 01 May 2011 - 04:38 PM.

Gina
SW Explorer MN190 - Esprit 80ED Pro - Evostar 80 ED DS Pro + 0.85x FR/FF x2 - one with Baader SteelTrack focuser - ST80 x2 - EQ8 & NEQ6 Pro mounts - Guiding OAG with Lodestar X2 & PHD - Atik 460EX mono x3 and 314L+ mono Filters Astrodon 5nm Ha, 3nm OIII, 5nm SII - Baader LRGB - Atik EFW2 filter wheel - 35, 55, 85, 105, 135, 200, 300mm lenses - EQMOD ASCOM CdC APT SharpCap DPP DSS PS Artemis Capture


#51
Gina

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Got a couple of large plastic plant pots which I've cut the bottoms out of. These will fit below my 7" ID cardboard tube to widen the pier base out to about a foot diameter. That should increase the strength at the point of greatest leverage.

Hoping to start pouring concrete tomorrow. Bought some more ingredients today - realised (was told) I didn't have enough.

Gina
SW Explorer MN190 - Esprit 80ED Pro - Evostar 80 ED DS Pro + 0.85x FR/FF x2 - one with Baader SteelTrack focuser - ST80 x2 - EQ8 & NEQ6 Pro mounts - Guiding OAG with Lodestar X2 & PHD - Atik 460EX mono x3 and 314L+ mono Filters Astrodon 5nm Ha, 3nm OIII, 5nm SII - Baader LRGB - Atik EFW2 filter wheel - 35, 55, 85, 105, 135, 200, 300mm lenses - EQMOD ASCOM CdC APT SharpCap DPP DSS PS Artemis Capture


#52
Gina

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The steel plates for the mount have arrived so one step nearer :) OTOH the very chilly easterly wind has got up more and black clouds are gathering with spits of rain in the air so concreting is postponed for now.

Gina
SW Explorer MN190 - Esprit 80ED Pro - Evostar 80 ED DS Pro + 0.85x FR/FF x2 - one with Baader SteelTrack focuser - ST80 x2 - EQ8 & NEQ6 Pro mounts - Guiding OAG with Lodestar X2 & PHD - Atik 460EX mono x3 and 314L+ mono Filters Astrodon 5nm Ha, 3nm OIII, 5nm SII - Baader LRGB - Atik EFW2 filter wheel - 35, 55, 85, 105, 135, 200, 300mm lenses - EQMOD ASCOM CdC APT SharpCap DPP DSS PS Artemis Capture


#53
Gina

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Having measured up my mount I have come up with a simplified design for the pier adapter.

Apart from the top steel plate (250mm diam x 10mm thick), I plan to use a 5mm aluminium plate with a 65mm diameter hole as shown in the diagram attached. The steel plate will have a hole cut to take the boss of the mount. Then the mount can be attached with a 12mm bolt, washer and spacer. The top steel plate I propose to connect to the bottom steel plate with 4 12mm bolts (or threaded rod) around the edge to allow space to get to the mount attachment bolt. The lower steel plate attaches to 4 14mm threaded rods embedded in the concrete pier.

Attached Thumbnails

  • Pier-Adapter.png

Gina
SW Explorer MN190 - Esprit 80ED Pro - Evostar 80 ED DS Pro + 0.85x FR/FF x2 - one with Baader SteelTrack focuser - ST80 x2 - EQ8 & NEQ6 Pro mounts - Guiding OAG with Lodestar X2 & PHD - Atik 460EX mono x3 and 314L+ mono Filters Astrodon 5nm Ha, 3nm OIII, 5nm SII - Baader LRGB - Atik EFW2 filter wheel - 35, 55, 85, 105, 135, 200, 300mm lenses - EQMOD ASCOM CdC APT SharpCap DPP DSS PS Artemis Capture


#54
Gina

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Here's the design of the whole pier top section. M14 threaded rod in the concrete attached to steel plate. M12 bolts or threaded rod to the top steel plate then aluminium plate to provide base for mount as described above.

Anyone see anything wrong with this design? Or any suggestions for changes? Saves a lot of money on a manufactured pier adapter.

Attached Thumbnails

  • Pier-Top.png

Edited by Gina, 05 May 2011 - 04:43 PM.

Gina
SW Explorer MN190 - Esprit 80ED Pro - Evostar 80 ED DS Pro + 0.85x FR/FF x2 - one with Baader SteelTrack focuser - ST80 x2 - EQ8 & NEQ6 Pro mounts - Guiding OAG with Lodestar X2 & PHD - Atik 460EX mono x3 and 314L+ mono Filters Astrodon 5nm Ha, 3nm OIII, 5nm SII - Baader LRGB - Atik EFW2 filter wheel - 35, 55, 85, 105, 135, 200, 300mm lenses - EQMOD ASCOM CdC APT SharpCap DPP DSS PS Artemis Capture


#55
malc-c

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Looks good to me... I'll be using your design when it comes to doing mine... as you say, cheaper than having a custom one made up out of steel etc.
Regards

Malcolm

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#56
Gina

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Thanks Malcolm :) Got the steel plates and now have the aluminium plate on order. It's 200mm square by 5mm thick. I'll have to trim off the corners to stay within the 250mm diameter of the steel plate but that shouldn't present any problem.

Gina
SW Explorer MN190 - Esprit 80ED Pro - Evostar 80 ED DS Pro + 0.85x FR/FF x2 - one with Baader SteelTrack focuser - ST80 x2 - EQ8 & NEQ6 Pro mounts - Guiding OAG with Lodestar X2 & PHD - Atik 460EX mono x3 and 314L+ mono Filters Astrodon 5nm Ha, 3nm OIII, 5nm SII - Baader LRGB - Atik EFW2 filter wheel - 35, 55, 85, 105, 135, 200, 300mm lenses - EQMOD ASCOM CdC APT SharpCap DPP DSS PS Artemis Capture


#57
Bizibilder

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Not quite sure why you have put the Ali plate in? (Maybe I'm missing something!). Otherwise it seems a good design.

Edited by Bizibilder, 05 May 2011 - 05:24 PM.

Roger

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#58
spaceboy

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This was my effort. Made from mild steel I had lying around.

#59
rawhead

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This was my effort. Made from mild steel I had lying around.



Is that the one in your obsy?
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#60
spaceboy

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No, this is one I knocked up for my refractor. I mounted the EQ & tripod dock directly to the concrete pillar in my obsy. Adapters are OK if you want to remove the mount regularly but what you have to think if your pouring 1/2 a ton of concrete in to the ground and pier you don't really want to end up relying on only 3-4 M12 studs holding your mount and scope. Just doesn't seem worth all the effort put in to creating a stable pier if your going to introduce a weak link.




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