Pier ideas

[jambouk]

Do piers like this one on the Widescreen Centre website have a solid plate at the bottom or is there a hole?

https://www.widescreen-centre.co.uk/AA-PIER-32.html
 

There is an existing metal pole anchored into a submerged concrete block, and I wonder if a pier like this could be slotted over the pole and concrete poured inside the pier to bond it to metal pole. The pole is probably 6” in diameter and at least 1.5m high but could be shortened.

What do you think?

[Stuart1971]

2 minutes ago, jambouk said:

Do piers like this one on the Widescreen Centre website have a solid plate at the bottom or is there a hole?

https://www.widescreen-centre.co.uk/AA-PIER-32.html
 

There is an existing metal pole anchored into a submerged concrete block, and I wonder if a pier like this could be slotted over the pole and concrete poured inside the pier to bond it to metal pole. The pole is probably 6” in diameter and at least 1.5m high but could be shortened.

What do you think?

Mine is similar to that one, and it does have a hole in the bottom, but no where near 6” diameter, probably about 3” at most....

[Craney]

3 hours ago, jambouk said:

I wonder if a pier like this could be slotted over the pole and concrete poured inside the pier to bond it to metal pole.

...eek !!

It would undoubtedly make a very stable unit, but pouring concrete into one of these piers does seem a bit excessive... unless you want to moor the QEII to it.

My first question would be... are you sure that 'unseen' concrete block is suitably big enough ??..... this pier ( with or without concrete) with a mount and scope on the top is going to provide a large turning force on the concrete-soil interface.  You cannot risk any slight shifting of the rig from its 'fixed' position during slews etc.... it would make the project a bit futile.

I've always seen the advantage of these piers is that they are sturdy and robust with a fair amount of mass, but movable if circumstances change, leaving a residual 'foot-print' of only 4 bolt threads exposed.   (... and by movable, that could be in the vertical direction as well, either a lifting or a sinking of the base plate ).

Your idea of filling with concrete is permanent in the extreme with no chance of selling the pier on at a later date if you wish to...... and it would be a right royal faff to remove if you had to.

Personally, (  if you are sure that block is big enough) , I would chisel and angle grind the metal pole to below the block surface.  Then use ground anchor bolts to secure the pier into the concrete block.  This gives you flexibility for change and some form of graceful recovery should you make a mistake     slight miscalculation 🤔

Sean.

 

 

 

[inFINNity Deck]

9 hours ago, jambouk said:

... I wonder if a pier like this could be slotted over the pole and concrete poured inside the pier to bond it to metal pole. The pole is probably 6” in diameter ...

If you would do that you probably end up with a stability that is equal to the 6" pole. The pier should be fastened to the floor using the bolts around the circumference, fastening in the centre would not add much stability.

Here are some pictures of my pier's maiden voyage and its landing place shortly before touchdown:

The pier is 3.4 metres high and has a baseplate of 80 centimetres in diameter, which is fastened to the concrete floor using 16 M12 threaded anchors. They all have a nut and washer below and above the pier's base-plate and were finally shortened and finished with cap nuts. Recently I did some stability tests which showed the pier is rock solid, no measurable movement.

Nicolàs

 

[tooth_dr]

@Adam J you’ll need a crane for one like this 😉

[Stuart1971]

1 hour ago, inFINNity Deck said:

If you would do that you probably end up with a stability that is equal to the 6" pole. The pier should be fastened to the floor using the bolts around the circumference, fastening in the centre would not add much stability.

Here are some pictures of my pier's maiden voyage and its landing place shortly before touchdown:

The pier is 3.4 metres high and has a baseplate of 80 centimetres in diameter, which is fastened to the concrete floor using 16 M12 threaded anchors. They all have a nut and washer below and above the pier's base-plate and were finally shortened and finished with cap nuts. Recently I did some stability tests which showed the pier is rock solid, no measurable movement.

Nicolàs

 

Why have the nuts and washers under the pier...? As it does not need to be exactly level so no need, you may as well have had it sit solid on the floor... 👍

[Adam J]

6 hours ago, Stuart1971 said:

Why have the nuts and washers under the pier...? As it does not need to be exactly level so no need, you may as well have had it sit solid on the floor... 👍

Somehow I don't think they are going to lift it back off to remove them lol. 

[tomato]

Bolting direct to the floor is good provided your concrete floor is as smooth as your base flange, otherwise you can get some point contacts. 
 

My Altair pier was bolted down onto 8 machined steel jacks,  this was a lot better than bolting it direct to the floor.

[inFINNity Deck]

10 hours ago, Stuart1971 said:

Why have the nuts and washers under the pier...? As it does not need to be exactly level so no need, you may as well have had it sit solid on the floor... 👍

The whole idea behind this is to avoid stress in the pier and the anchors. If indeed the surface on which the pier stands is uneven a lot of stress is created when bolting down the pier and what basically happens is that the pier tries to pull the bolts out of the floor. Having the pier 'floating' above the floor reduces the stress to a minimum. So what I did is first level the pier, then turn up the lower nuts until they were all flush with the baseplate and then tighten the upper nuts to hold the pier. In this way there is only stress between the nuts and in the section of thread between them. The idea was not mine but I saw it mentioned in a brochure of the Euro EMC Star Observatory Pier (see p.2).

I know levelling up the topside of the pier is not a requirement, but it sure is beneficial to the polar alignment. If the topside of the pier is at an angle any change in azimuth will result in a change in elevation, so each azimuthal change requires a change in altitude. Having the top plate near to level avoids this.

Nicolàs

PS: no I am not going to remove the washers... 😉