How to decouple scope form ground vibrations ?

Dear All,

My quest for a permanently mounted scope continues. I have an LX200GPS 10"
and find that the set up and tear down every time I want to observe is a
real pain.

I want a permanent observatory - even a small one. However, I live close to
a busy road that has quite a few heavy trucks passing by at all times of day
or night - and this tends to vibrate the ground nearby. not much, but enough
to be a pain. It's perfect for visual and fine for planetary webcam stuff as
I can just remove the frames that are affected by vibration before
processing, but for deep sky imaging, it's less than ideal.

So - my question is, how can one build a permanent pier or mount, but
decouple the peir from the vibrations of the local terrain ?

I had thought about digging a hole for a pier foundation, making it oversize
and then lining it with 4 inches of high density Rockwool before pouring
the concrete footings, but am not sure how this might work.

Does anyone have any ideas or pointers for how to mount a scope to minimise
vibrations from the ground itself ? To be honest, the tripod works quite
well right now as it seems to absorb some of the vibration anyway. The
other thing in my favour is that there is far less traffic at night anyway,
but every now and then a big truck goes past.....

I once saw an artical about a building in Japan that because of the old
glass and other things on display, they didn't want the building to shake,
not only during an earthquake but also due to the traffic going by.
The main thing is the building is on springs that are incased in formrubber
pads, now you'd not need the size they used, which was massive, and you'd
not need the springs in the pads, But, if your place for the scope is on a
wooden plateform, it could be mounted on good car springs (like the ones in
older Caddys) and buy some form pads to place under it too. The big springs
would take up any hard shakes and the form the other stuff, or you might use
heavey duty auto/truck shocks too.


--
The Lone Sidewalk Astronomer of Rosamond

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"adm" wrote in message
...
Dear All,

My quest for a permanently mounted scope continues. I have an LX200GPS 10"
and find that the set up and tear down every time I want to observe is a
real pain.

I want a permanent observatory - even a small one. However, I live close
to a busy road that has quite a few heavy trucks passing by at all times
of day or night - and this tends to vibrate the ground nearby. not much,
but enough to be a pain. It's perfect for visual and fine for planetary
webcam stuff as I can just remove the frames that are affected by
vibration before processing, but for deep sky imaging, it's less than
ideal.

So - my question is, how can one build a permanent pier or mount, but
decouple the peir from the vibrations of the local terrain ?

I had thought about digging a hole for a pier foundation, making it
oversize and then lining it with 4 inches of high density Rockwool before
pouring the concrete footings, but am not sure how this might work.

Does anyone have any ideas or pointers for how to mount a scope to
minimise vibrations from the ground itself ? To be honest, the tripod
works quite well right now as it seems to absorb some of the vibration
anyway. The other thing in my favour is that there is far less traffic at
night anyway, but every now and then a big truck goes past.....

adm wrote:
Dear All,

My quest for a permanently mounted scope continues. I have an LX200GPS 10"
and find that the set up and tear down every time I want to observe is a
real pain.

I want a permanent observatory - even a small one. However, I live close to
a busy road that has quite a few heavy trucks passing by at all times of day
or night - and this tends to vibrate the ground nearby. not much, but enough
to be a pain. It's perfect for visual and fine for planetary webcam stuff as
I can just remove the frames that are affected by vibration before
processing, but for deep sky imaging, it's less than ideal.

So - my question is, how can one build a permanent pier or mount, but
decouple the peir from the vibrations of the local terrain ?

I had thought about digging a hole for a pier foundation, making it oversize
and then lining it with 4 inches of high density Rockwool before pouring
the concrete footings, but am not sure how this might work.

Does anyone have any ideas or pointers for how to mount a scope to minimise
vibrations from the ground itself ? To be honest, the tripod works quite
well right now as it seems to absorb some of the vibration anyway. The
other thing in my favour is that there is far less traffic at night anyway,
but every now and then a big truck goes past.....

Vibration suppression pads or increase the stiffness of the tripod by
joining the end tips with stiffeners (C-section steel bars will do)
and/or both. The trick here is to decouple the frequency response of
the tripod/mount from that of the ground. For serious astrophotography
you'll want you kit's response in the 100 Hz range or above with as
little amplitude as possible, as usually ground trasmitted frequencies
are in the 10s Hz range. For a permanently mounted mount on a pier you
would need to use large rubber grommets between the pier and the
equatorial wedge plus tying the upper part of the tripod to the ground
by preloaded steel cables (you'd need to have concrete foundations for
that) in 3 different positions at 120deg apart.

Hope it helps

Andrea T.

"adm" wrote ...
(snip)
Does anyone have any ideas or pointers for how to mount a scope to
minimise vibrations from the ground itself ? To be honest, the tripod
works quite well right now as it seems to absorb some of the vibration
anyway. The other thing in my favour is that there is far less traffic at
night anyway, but every now and then a big truck goes past.....

What kind of "deep sky imaging" are you planning of doing? Digital imaging,
with a DSLR for instance, is done with many short exposures stacked with
software so the occasional truck should not totally ruin a shot. I suppose
it all depends on how often "occasional" actually is.

--
Richard Amirault N1JDU Boston,
MA, USA
n1jdu.org "Go Fly A Kite"

adm wrote:
snip
Does anyone have any ideas or pointers for how to mount a scope to minimise
vibrations from the ground itself ?

These may help.

http://www.mapug-astronomy.net/pages...rod.html#piers

http://www.mapug-astronomy.net/Astro...ermantPier.htm

- Canopus56

The only thing that you can do if you persist in living around where such
vibrations are common is to make a huge weight and put it on springs so that
the high frequencies are damped. There will always be low frequency
vibrations but if you get the frequency into the cycles per minute, you ca
autoguide them away.
Also, you don't want to walk on this suspension system or your weight will
affect the pointing accuracy.

--
Why do penguins walk so far to get to their nesting grounds?

adm wrote:
Dear All,

My quest for a permanently mounted scope continues. I have an LX200GPS 10"
and find that the set up and tear down every time I want to observe is a
real pain.

I want a permanent observatory - even a small one. However, I live close to
a busy road that has quite a few heavy trucks passing by at all times of day
or night - and this tends to vibrate the ground nearby. not much, but enough
to be a pain. It's perfect for visual and fine for planetary webcam stuff as
I can just remove the frames that are affected by vibration before
processing, but for deep sky imaging, it's less than ideal.

So - my question is, how can one build a permanent pier or mount, but
decouple the peir from the vibrations of the local terrain ?

I had thought about digging a hole for a pier foundation, making it oversize
and then lining it with 4 inches of high density Rockwool before pouring
the concrete footings, but am not sure how this might work.

Does anyone have any ideas or pointers for how to mount a scope to minimise
vibrations from the ground itself ? To be honest, the tripod works quite
well right now as it seems to absorb some of the vibration anyway. The
other thing in my favour is that there is far less traffic at night anyway,
but every now and then a big truck goes past.....

What about vibration pads?
http://www.telescope.com/shopping/pr...&iProductID=55

"adm" wrote in message
...
I had thought about digging a hole for a pier foundation, making it
oversize
and then lining it with 4 inches of high density Rockwool before pouring
the concrete footings, but am not sure how this might work.

I've heard that sand is very good for preventing the transmission of
vibrations.

I (currently) intend to place my pier in a cubic metre of concrete, with
about 2 inches of sand below and around it.

Regards


Donal
--

Move to the desert

"Donal" wrote in message
...

"adm" wrote in message
...
I had thought about digging a hole for a pier foundation, making it
oversize
and then lining it with 4 inches of high density Rockwool before pouring
the concrete footings, but am not sure how this might work.

I've heard that sand is very good for preventing the transmission of
vibrations.

I (currently) intend to place my pier in a cubic metre of concrete, with
about 2 inches of sand below and around it.

Regards


Donal
--

Donal wrote:
I've heard that sand is very good for preventing the transmission of
vibrations.
I (currently) intend to place my pier in a cubic metre of concrete, with
about 2 inches of sand below and around it.

What I got out of the mapug plans was that also filling the vertical
pier tube with concrete also aided in dampening vibrations. That
sounds little drastic to me. Maybe also filling the pier tube with
sand would also absorb vibrations. - Canopus56