Pier Question - How to dampen more

[Radar]

The pier in my obs is cemented down into the ground. The obs is on 60cm stilts. The pier and obs are completely independent of each other.

The pier is very heavy and stable, though I noticed that when i'm using a barlow with my imaging source camera, if I bump my foot against the observatory floor, the image on the screen moves a bit, then steadies out.

My question is, is there a way to dampen that kind of vibration out?

Even though the pier is already in, I'm wondering if I can do something else to improve the system.

Cheers

Ray

[hpcoolahan]

Yep ,, dont stomp your foot on the ground :itsme!: :biggrin: :wink:

Hay Ray ,is your metal pier hollow or have you filled it with sand to dampen vibrations.

Its like a resonance or reverb inside the pier that transfers to the mount.

I have to fill mine with sand yet, for the same reasons.

Cheers
Patrick

[Radar]

Hi Pat, that's an awesome idea. I didn't fill it with sand. It was so heavy I didn't think I'd need to. It's quite stable, but if I can improve on the design I will.

Ta

Ray


Yep ,, dont stomp your foot on the ground :itsme!: :biggrin: :wink:

Hay Ray ,is your metal pier hollow or have you filled it with sand to dampen vibrations.

Its like a resonance or reverb inside the pier that transfers to the mount.

I have to fill mine with sand yet, for the same reasons.

Cheers
Patrick

[Dragon Man]

That was my only suggestion, Ray. Fill it with sand :smile:

It works for everyone else that does it.

[rogerg]

Agreed, sand reduced the vibrations significantly in my pier. Made the thing a bugger to move when I relocated my observatory though :smile:

[Radar]

What about making the sand wet or damp prior to putting it in the pier?

(Increasing it's weight).

Ray

[hpcoolahan]

RUST RUST RUST
COROSION COROSION COROSION

Not a good idea i think mate.

The airspace should help with the dampening effect anyway mate.
Just my 2 cents.

Oh, dont get beach sand,,,salt (see above) lol

Clear Skies
Patrick

[h0ughy]

What about making the sand wet or damp prior to putting it in the pier?

(Increasing it's weight).

Ray Not a smart idea Ray, rust and additional moisture in the observatory. you could always have stiffeners added to the side of the pier.

[timthelder]

How about sand.....:biggrin:

But seriously, the only other thing I can think of is to wrap the pier with insulation material.(To stop the 'ring'.) We sell something in refrigeration that would be ideal. It's comes in a 3mx2m, soft rubber sheet, about 13mm, 1/2" thick. Also excellent for padding when making a scope/tripod case.(or anything cheap to deaden sound vibration.)

[Radar]

We sell something in refrigeration that would be ideal. It's comes in a 3mx2m, soft rubber sheet, about 13mm, 1/2" thick. Also excellent for padding when making a scope/tripod case.(or anything cheap to deaden sound vibration.)

That's an interesting idea Tim. Any idea what it's called?

Ray

[timthelder]

Here's the link from my work's product catalog...

http://tinyurl.com/5gdkld

Insul-sheet/sheet insulation, cost US, is about $14. There is also other brand's that makes the same thing under the names, RBX industries, Carmacell, Armaflex, Rubatex. Being this is a refrigeration installation product, surely there is a supply-house over there that carries it, or something similiar.

[GS-Rob]

.............. The pier and obs are completely independent of each other............. if I bump my foot against the observatory floor, the image on the screen moves a bit, then steadies out.
Cheers
Ray
Some thing is not right there Ray
I've a steel pier and a suspended floor as well NO vibrations what so ever
http://www.grampianstars.com.au/observatory.htm
my pier is 4ft deep in about 3 yards of cement sort of a wedge shape.
the floor is hardwood. never had any vibes and is not filled either.

IMO something is touching your pier, footings etc :frown:

[Radar]

Some thing is not right there Ray
I've a steel pier and a suspended floor as well NO vibrations what so ever
http://www.grampianstars.com.au/observatory.htm
my pier is 4ft deep in about 3 yards of cement sort of a wedge shape.
the floor is hardwood. never had any vibes and is not filled either.

IMO something is touching your pier, footings etc :frown:

Thanks Rob. I've taken a look at your setup. What I notice is different is that the feet for your observatory run right around the outside. Whereas I have a line of them through the centre.

http://www.myastrospace.com/forums/attachment.php?attachmentid=1549&d=1202197270

I might take a saw to some of those centre feet and see what happens. I'll reinforce the centre beams first with another cross beam. I should have seen this.

Cheers

Ray

P.S Nice website, I'll stick it on our links page if you want.

[Tenacious Del]

I might take a saw to some of those centre feet and see what happens. I'll reinforce the centre beams first with another cross beam. I should have seen this.


cut them off mate.

[Radar]

This Saturday I am cutting the top of my pier off. Lengthening the tube and then putting the plate back on top. Whilst doing this I was going to fill the pier with sand to help damped any vibrations.

A friend of mine has recommended using lead shot (little lead beads) to fill the pier with. He recommends lead shot because the lead doesn't slide easily against lead, and also the weight of this lead is much more than the sand. He says this would do heaps better at dampening vibrations than sand.

Anyone have any input on this?

Cheers

Ray

[timthelder]

COST!!!!!

Lead isn't cheap...sand is. I think your idea about adding a couple of double joist under the floor and removing a couple of center piers is a good idea. A little carpet on the floor probably wouldn't hurt either. This along with dampening the metal tube should surely be enough..

Just my OP, cheers:smile:

[hpcoolahan]

Hey buddy.
I'm with Tim on this one , sand is tried and proven (and a lot cheeper):wink:

Just make sure you dry it well and get sand well away from the coast, no salt content to start rusting the pier from the inside :biggrin:

Cheers
Patrick

[GS-Rob]

G'day Ray
Let us know how the cut and extend goes! :woot:
This is what I would do-
IMO Run some conduit data and power down the core
seal the bottom with a blob of concrete
then fill with a builders sand, which is pretty good nice and fine & no salt, can buy in 10Kg and 20Kg bags,
and an oil mixture (used vegie oil is OK mix to a paste like wet cement)
there wont be any sand crystals bouncing around inside them


This Saturday I am cutting the top of my pier off. Lengthening the tube and then putting the plate back on top. Whilst doing this I was going to fill the pier with sand to help damped any vibrations.

Cheers

Ray

[Paramount]

Hi Ray
You have three options for filling the pier---sand, gravel or lead shot. Sand is probably the best choice as it is the most environmently friendly and also the cheepest. The best stuff to use is builders sand as there is no salt (which may cause corrosion). The sand must be as dry as possible and if you can put a tough plastic lining bag in the pier first and then fill the bag. If you can and have access to a big oven you should try and dry the sand as much as possible first as wet or damp sand will encourage corrosion as well as mould.
This is something that was always recommended in HI-FI circles for dampening resonances in loudspeaker stands, etc. Sand is also the deadest of the three materials as far as resonance is concerned
Best wishes
Gordon

[Radar]

Guys thanks for all that info. I will be using sand.

Now here comes another thing. My mate here who runs a steel works factory - I was showing him the pier and the extension tube and he suggested getting one of his workers to come round and insert a bit of tube that is slightly narrower, so that I can have a pier which is extendable. He says it can be good quality (no movement) and very well done.

The question is, is this feasible or gonna be too much hassle? Any feedback on if this is worthwhile is welcome. Also any design plans and ideas for it are also welcome. I have no idea about this stuff, I appreciate any feedback.

Ray

[timthelder]

The question is, is this feasible or gonna be too much hassle?


Feasible, yes,. Practical, no. This put's you right back to square one with the dampening problem. You will have a section of tube that you can't dampen due to it requiring to be movable, including part of the existing pier to allow the movement.

My OP, I would'nt...

Cheers:smile:

[GS-Rob]

Guys thanks for all that info. I will be using sand.
Now .......insert a bit of tube that is slightly narrower, so that I can have a pier which is extendable. He says it can be good quality (no movement) and very well done. .......
Ray

G'day Ray
I like it !
not for extending pier height though.
I'm going tho do this for the top plate
will make it real easy for the azimuth adjustment <----->

[Radar]

Thanks guys, more to think about.

I told my lead shot mate that sand would be better, so he suggested that I use dry cement powder to put into the pier. He said do this with some silica gel bags (which he has) to keep it dry, but he said that because the concrete powder is so fine it weighs much more than sand and would dampen down any vibrations much more than sand could. Again comments and suggestions welcome.

Ray