Builing a pier on a patio

[steviemac500]

I'm hoping to start a pier build soon. I want to attach it directly to my patio rather than dig down through the slabs. Can this be done, has anyone any experience doing this they could share with me? All help would be greatly appreciated.

TIA,

Steve

[RayD]

It can be done of course as it's not much different to having a tripod there, but as with a tripod if you move around on the patio you are very likely to see the vibrations in any images.  Also as slabs are normally just laid rather than built in, you may see a little movement occasionally.

[D4N]

Paving slabs tend to move, your PA might not last very long.

The pier may also wobble if they aren't stable enough.

[Owmuchonomy]

Yes, the main point of setting up a pier is to isolate it completely from the ground around the base.  If you don't then it is highly likely that the PA will move as Dan says and you will get vibrations in your scope/images.

[Davey-T]

Mines bolted to the patio but there is 150mm of concrete under the slabs, not been any problem so far.

Dave

 

[Owmuchonomy]

Just now, Davey-T said:

Mines bolted to the patio but there is 150mm of concrete under the slabs, not been any problem so far.

Dave

 

What a lovely set up Dave!  What height above ground is your pier top?

[Tim]

Hi Steve,

Might be able to help. What slabs do you have, and what are they laid on?

Tim

[Davey-T]

6 minutes ago, Owmuchonomy said:

What a lovely set up Dave!  What height above ground is your pier top?

1150mm Chris, I don't find the fact that it's not isolated from the surrounding slabs a problem as I don't go near it while imaging.

Dave

[Owmuchonomy]

Thanks Dave, that makes sense.  I made sure my obsy floor is completely isolated from the pier base.

[steviemac500]

2 hours ago, Tim said:

Hi Steve,

Might be able to help. What slabs do you have, and what are they laid on?

Tim

Hi,they are laid on a concrete base and are around 40mm thick. The slabs themselves are 300 x 300. 

[Davey-T]

What are you planning on making your pier from ?

Dave

[Tim]

3 hours ago, steviemac500 said:

Hi,they are laid on a concrete base and are around 40mm thick. The slabs themselves are 300 x 300. 

Are they concrete slabs?

2 hours ago, Davey-T said:

What are you planning on making your pier from ?

Dave

Key question

A pier can be a really good lever, and wants a solid fixing that simply will not move. You may be able to drill a 2 or 3" hole with a diamond core drill down through and well below your slab base level. Into these holes you could set some threaded bar into strong liquid concrete, and eventually fasten the pier to that.

If it was me I would bite the bullet and remove say 4 slabs, excavate a decent size hole, fill with concrete and attach your pier to that. A lot of work,  but nicer than picking up the pieces of a broken mount and telescope

[steviemac500]

Thanks for the replies. Could I not bolt the pier directly to the patio if I welded a base to it?

[RayD]

14 minutes ago, steviemac500 said:

Thanks for the replies. Could I not bolt the pier directly to the patio if I welded a base to it?

Absolutely, all that anyone is saying is that you may (could) see some movement as the slabs will be only laid, so not really keyed to anything to  actually hold them down, so the mount will have the tendency to be trying to pull them up, but if you are only imaging and it's not a massive rig you are using then you should be ok.

As Dave noted, so long as you don't walk around the mount whilst actually capturing images then vibration won't be an issue, but if you do, then you will almost certainly see that in your images unless you move ninja style.

It could be worth a try anyway as it would only be drilling a few holes, and if it doesn't provide a suitable base, then look at possible digging a little hole.

[Davey-T]

I made mine with three legs with 2 bolts in each leg, I had the mount and scope running on it before I bolted it down to get it polar aligned.

Dave

 

[steviemac500]

11 hours ago, RayD said:

Absolutely, all that anyone is saying is that you may (could) see some movement as the slabs will be only laid, so not really keyed to anything to  actually hold them down, so the mount will have the tendency to be trying to pull them up, but if you are only imaging and it's not a massive rig you are using then you should be ok.

As Dave noted, so long as you don't walk around the mount whilst actually capturing images then vibration won't be an issue, but if you do, then you will almost certainly see that in your images unless you move ninja style.

It could be worth a try anyway as it would only be drilling a few holes, and if it doesn't provide a suitable base, then look at possible digging a little hole.

I should have said that the slabs are fixed in place with concrete rather than just layed down which I guess should make a difference?

[RayD]

Just now, steviemac500 said:

I should have said that the slabs are fixed in place with concrete rather than just layed down which I guess should make a difference?

Yes it could do.  Well worth having a go as it's only drilling a few holes.  As Dave notes, he has the same thing with no problems so could well turn out absolutely fine 

[Shelster1973]

On ‎03‎/‎01‎/‎2017 at 08:07, steviemac500 said:

I should have said that the slabs are fixed in place with concrete rather than just layed down which I guess should make a difference?

As RayD has said, this shoudl make a difference.  How deep is the concrete that the slabs are sitting in?

Drilling through the slabs and into this base, will spread out any forces and also provide a stable base.  A couple of the expanding concrete anchors or even go down the line of drilling a hole and then using a resin / threaded rod combo to fix it down ( I personally would do the second) and all should be good.

As others have said, you will get some disturbance as you walk away from and too your pier, but this can easily be overcome by adding a small timing gap at the start of your imaging run...or levitating your way to and from the pier.

HTH

[RayD]

1 hour ago, Shelster1973 said:

or levitating your way to and from the pier

My beloved is convinced I can levitate in  the mornings when I'm getting ready for work and she's in bed.  Apparently me walking in socks is akin to a herd of elephants so levitation is something I'm trying to find a college course on 

[SonnyE]

Having worked with Seismology recorders and seeing their bases, and talking with the techs, I've learned that everything moves. Because the Earth is constantly moving and vibrating. Their recorders shown the traffic a mile away from the actual pier the sensors for the recorders were mounted to. It was quite an eye opening experience.

So I wasn't surprised to see my own movements recorded in my camera during imaging. So when all is set and ready, I will usually retire to my inside computer to do my image gathering with the least amount of "traffic" around my equipment. I also try to be "Larry Light-foot" if I do go out to twiddle or fiddle. (My kingdom for a stepper focuser)

My tripod/mount typically stays put, it's toes firmly ensconced into divots to make sure it remains where it is from day to day. But during my alignment I try to always remember to do an All Star Polar Alignment as a part of my procedure to fine tune my polar alignment as need be (Typically a very fine adjustment). So any creepage from temperature swings or vibrations gets a chance to be corrected before I start my actual imaging. And if/when I set up a pier of my own I would most likely continue my A.S.P.A. just to be sure I've done my part to do my best setting up.

But the point being, piers wiggle and piers giggle. Because the Earth does.

[Davey-T]

8 minutes ago, SonnyE said:

Having worked with Seismology recorders and seeing their bases, and talking with the techs, I've learned that everything moves. Because the Earth is constantly moving and vibrating. Their recorders shown the traffic a mile away from the actual pier the sensors for the recorders were mounted to. It was quite an eye opening experience.

So I wasn't surprised to see my own movements recorded in my camera during imaging. So when all is set and ready, I will usually retire to my inside computer to do my image gathering with the least amount of "traffic" around my equipment. I also try to be "Larry Light-foot" if I do go out to twiddle or fiddle. (My kingdom for a stepper focuser)

My tripod/mount typically stays put, it's toes firmly ensconced into divots to make sure it remains where it is from day to day. But during my alignment I try to always remember to do an All Star Polar Alignment as a part of my procedure to fine tune my polar alignment as need be (Typically a very fine adjustment). So any creepage from temperature swings or vibrations gets a chance to be corrected before I start my actual imaging. And if/when I set up a pier of my own I would most likely continue my A.S.P.A. just to be sure I've done my part to do my best setting up.

But the point being, piers wiggle and piers giggle. Because the Earth does.

Reminded me of my youth when I used to go to work with my dad "helping" wire up Land Rovers for oil exploration, loads of seismographic sensors like tin cans they laid out across the desert then set of explosions to map the underground with pen recorders.

Back to the pier thing my obs'y pier is buried in concrete and bolted down but if I set it to videoing Jupiter and then walk away about a dozen feet and jump up and down Jupiter bounces around like a rubber ball (on the PC  screen not in the sky ) 

Dave

[david maitland]

Still get movement with this if I walk around it, though  I would suggest this is definitely the way to go, in my humble opinion.