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Ideas for Pier Extension

Gina

By Gina
in DIY Observatories

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Gina

Gina

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Replacing my NEQ6 mount with the new EQ8 has meant that I shall no longer be using the NEQ6 pier entender which was 8" high and 5" diameter.  Before I got the EQ8 I was pretty convinced that this was going to be taller than the NEQ6 but it turns out that it's actually 30-40mm shorter.  I haven't yet checked but I have a strong feeling that I'm going to lose a significant amount of sky view due to the lower mounting of my scopes.

I have therefore been thinking about how I might increase my effective pier height.  Ideally I'd like a nice solid steel tube of something like 180-200mm diameter with an owl hole.  So I have been thinking about practical alternatives that I could construct myself.  I should say that I'm not in favour of long pieces of threaded rod to extend the gap between plates to 4" or 6" or more, even if they're 16mm diameter or even 20mm if I could find such rods.

Normally an owl hole type would be a cylindrical tube but why not a square section?  I can make a square section tube from flat plates fastened together at the edges with angle and nuts and bolts.  That would be quite rigid.

Here is a screenshot from a SketchUp drawing showing the principle. 

post-13131-0-50275900-1382732506_thumb.p

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Gina

Gina

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How about just making the pier bigger with additional concrete? or is that not doable?

It's basically a question of how to join it to the present concrete.

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wxsatuser

wxsatuser

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Replacing my NEQ6 mount with the new EQ8 has meant that I shall no longer be using the NEQ6 pier entender which was 8" high and 5" diameter.  Before I got the EQ8 I was pretty convinced that this was going to be taller than the NEQ6 but it turns out that it's actually 30-40mm shorter.  I haven't yet checked but I have a strong feeling that I'm going to lose a significant amount of sky view due to the lower mounting of my scopes.

I have therefore been thinking about how I might increase my effective pier height.  Ideally I'd like a nice solid steel tube of something like 180-200mm diameter with an owl hole.  So I have been thinking about practical alternatives that I could construct myself.  I should say that I'm not in favour of long pieces of threaded rod to extend the gap between plates to 4" or 6" or more, even if they're 16mm diameter or even 20mm if I could find such rods.

Normally an owl hole type would be a cylindrical tube but why not a square section?  I can make a square section tube from flat plates fastened together at the edges with angle and nuts and bolts.  That would be quite rigid.

Here is a screenshot from a SketchUp drawing showing the principle. 

attachicon.gifPier Extension 01.PNG

I still favour four rods, it's easy and solid.

Got mine, 16mm ones from ebay, ordered nuts and washers at the same time.

I know some will say it ain't good enough but once bolted up tight I cannot get mine to vibrate or flex.

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Gina

Gina

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I still favour four rods, it's easy and solid.

Got mine, 16mm ones from ebay, ordered nuts and washers at the same time.

I know some will say it ain't good enough but once bolted up tight I cannot get mine to vibrate or flex.

Well, I could try that and see how it goes - thank you for your reply (and link) :)

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Gina

Gina

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How about just making the pier bigger with additional concrete? or is that not doable?

I've had an idea about that.  I could get some stud connectors and extend the threaded rod in the concrete.  Then I could take some more of the cardboard mailing tube I used to build the pier (I still have it) and cast some more pier on the top.  I know it's not recommended to have a join in the pier but with the rods connecting and continuing up I think it should work.

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Gina

Gina

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Well...  The pier needs to be at least 4" (100mm) higher.  First off I propose to just use studding which will have an unsupported height of 6" (150mm) to give this minimum increase in height.  Thinking of M16 as I can get M16 countersunk screws, plus stud connectors and nuts.  I already have plenty of washers :D

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wxsatuser

wxsatuser

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I've had an idea about that.  I could get some stud connectors and extend the threaded rod in the concrete.  Then I could take some more of the cardboard mailing tube I used to build the pier (I still have it) and cast some more pier on the top.  I know it's not recommended to have a join in the pier but with the rods connecting and continuing up I think it should work.

Extend your rods, roughen and clean the old surface.

Your mix will need to be quite wet, much wetter than normal, plus soak the old concrete to stop the water being pulled out

of the new mix........it might be a good idea to use a slightly smaller aggregate if you can.

There is no guarantee it will be as strong as one pour, in fact it won't be, but in this case it's not holding up to much.

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Gina

Gina

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Extend your rods, roughen and clean the old surface.

Your mix will need to be quite wet, much wetter than normal, plus soak the old concrete to stop the water being pulled out

of the new mix........it might be a good idea to use a slightly smaller aggregate if you can.

There is no guarantee it will be as strong as one pour, in fact it won't be, but in this case it's not holding up to much.

Thank you :)  Yes, that was pretty much what I had in mind.  I know you need to wet the old concrete as well as clean it well.  I can go through the ballast and remove the larger stones - I've done that before for finer mixes :)

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JamesF

JamesF

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Should you wish to go for threaded rods Gina, you can get fairly big stuff pretty easily.  I bought some 22mm rod from the local builders' merchants for bolting the frame supporting the childrens' tree house to the trees.

James

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Davey-T

Davey-T

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We do have a welder - somewhere, but I don't like welding.

Come on Gina you're our shining star of DIY, in fact I think of you as some kind of DIY superhero complete with costume, surely a bit of welding can't defeat you :)

Dave

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Gina

Gina

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Come on Gina you're our shining star of DIY, in fact I think of you as some kind of DIY superhero complete with costume, surely a bit of welding can't defeat you :)

Dave

Maybe not :D 

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Gina

Gina

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Quick drying cement might be an idea :)  And yes, I've heard of adding PVA adhesive to the mix - but how much?

I might take a tour of the builders merchants locally and see what I can find.  One thing that occurs to me is the flue damper for a wood burning stove - ready made owl's nest :D

Actually, with the EQ8 I've found that even with the centre bolt done up tight I can still adjust the azimuth for PA then it's fixed with the M8 bolts at the side.  So no need for access to the centre bolt and a plain tube/pipe would do.

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Gina

Gina

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I made a mistake on the size of the nuts and bolts used to hold the two steel discs together - they're M14 not M16.  The studding in the pier concrete is also 14mm.  So the simplest way to raise the top plate would be to use M14 studding with nuts either side of each plate.  I'm going to try this and see how stable it is.  I already have spring washers and a number of nuts and have ordered a pack of 5 x 300mm x M14 BZP studding including 10 nuts and washers.  I'll probably use just four but I could drill some new holes and use 5 studs (avoiding the area occupied by the AZ knobs).  http://www.ebay.co.uk/itm/190913342309?var=490189225617

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Gina

Gina

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I think the aluminium will collapses under the tension, Gas pipe might be better that's close to 5/8" internal diameter.....the pile of washers are going to be stable, just a bit untidy but that don't matter to much..... :)

It is 1/4" thick (6mm) and 57mm OD but you could be right...

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