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Old 11-12-2011, 04:17 PM
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My new pier is taking shape

Well, it is happening, finally ..
The pier is designed to fit inside 2.3m Sirius dome, carrying my 10" Newtonian on EQ6 mount.

The fit will be pretty tight, only ~6cm clearance between the tube and the dome (to achieve this, the pier needs to be offset by 109mm from the centre of the dome).

However, the dome is planned for my future observatory in Seymour.. For now I will have this pier temporarily mounted on concrete slab here in Mt Waverley in the open, until I retire and finally move to the new residence... Looking forward to this

The concrete slab is still to be built.
I plan to cast the holes for 20mm dinabolts with plastic tubing (arranged in place by wooden template), to avoid drilling into concrete... not sure if anyone did this before.
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Last edited by bojan; 11-12-2011 at 04:43 PM.
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Old 11-12-2011, 07:04 PM
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Good one bojan ! Congrats on the positive step forwards.

Interesting approach for the dynabolts .. avoiding drilling the concrete, that is.

Gee I love the drawings that drawing package of yours produces ... (seen drawings from you before). What application do you use ?

Cheers
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Old 11-12-2011, 07:04 PM
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Bojan
Nice work mate. Love the chunky top plate and supports. Are they threaded at the bottom with a bolt at the top to lock them?
Cheers
Stephen
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Old 11-12-2011, 07:41 PM
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Craig, it's Autocad...
Stephen, yep, there are M12 bolts between two plates.
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Old 11-12-2011, 08:03 PM
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Craig, it's Autocad...
Thanks .. must be something to do with being in the hands of 'a master'.

Cheers
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Old 11-12-2011, 08:06 PM
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Thanks .. must be something to do with being in the hands of 'a master'.

Cheers
Just an amateur, mate.. But trying the best I can
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Old 11-12-2011, 08:37 PM
Damian Couzoff (Damian)
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Looks great bojan.I am going to weld up my own pier out of schedule 80-6 inch diameter galvanised pipe.It will be pretty much identical to the bintel aussie made meade pier,without the hefty price tag though, of $1000,just for the pier.I am going to put my CPC 1100 on it,and build a sliding roof observatory,it will be located in the dark skys of central victoria,50 kms out of bendigo,vic.In the meantime,l have to deal with light polluted melbourne.regards damian
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Old 11-12-2011, 08:52 PM
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Yes, this price is pretty ridiculous.. I spent more money on bolts and accessories than on the pier itself (well, to be honest, a friend gave me this steel pipe because he didn't need it).
I was actually contemplating the concrete pier (it is cheaper in principle) but this pipe turned up so... and since I intend to move to Seymour anyway.. the concrete slab only is easier to remove (from sight by simply growing a grass over it )
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Old 12-01-2013, 12:47 PM
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Recently there was some new development around my pier..

During a walk through local Bunnings store, this water tank caught my eye.. right price and right size for pier + EQ6 (possibly with counterweight).
I bought it and place it over the pier (already mounted on concrete slab in the front yard), and checked next morning, only to be stunned by a quantity of condensed water - it was dripping from everywhere. Excellent for production of clear water, but definitely not very good for protection of mount and optics from elements..
I decided to try to elevate the canister a bit, to isolate it from ground and to allow ventilation, in hope that condensation will be reduced or even eliminated.
The construction on which I plan to mount the water tank could be as well used as a table for laptop and accessories.
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Last edited by bojan; 12-01-2013 at 06:47 PM.
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Old 14-01-2013, 01:45 PM
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Some sort of locking mechanism is going to be fit here...
Probably rubber bonnet locks.
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Last edited by bojan; 14-01-2013 at 09:26 PM.
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  #11  
Old 17-01-2013, 09:29 AM
Poita (Peter)
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I find with leaving my mount outside I have to wrap in in some thick towels first before putting my bin on top of it.
I have also put a disc close to the top of the pier (about 5/6 the way up) to mount the bin onto. If it goes anywhere near the ground, condensation builds up.
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Old 17-01-2013, 09:37 AM
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Quote:
Originally Posted by Poita View Post
I find with leaving my mount outside I have to wrap in in some thick towels first before putting my bin on top of it.
I have also put a disc close to the top of the pier (about 5/6 the way up) to mount the bin onto. If it goes anywhere near the ground, condensation builds up.
Yep.. it's much better now that I elevated the tank from ground.
This morning was pretty good but still some condensation on (colder) metal parts.
I was thinking about plastic bag wrapped over the mount, to reduce the amount of humid air around from where the water could condense.
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Old 17-01-2013, 11:29 AM
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Quote:
Originally Posted by bojan View Post
Yep.. it's much better now that I elevated the tank from ground.
This morning was pretty good but still some condensation on (colder) metal parts.
I was thinking about plastic bag wrapped over the mount, to reduce the amount of humid air around from where the water could condense.
Unless there is some dessicant in the plastic bag, I found I just got condensation inside the bag.
The combo of a thick towel and a vent in my bin and raising the platform about 3ft off the ground seemed to solve it.

I can leave the mount head attached and outside 24/7.
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Old 17-01-2013, 11:33 AM
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Hi,
would it help at all if the bin was lined with insulating material like the ones they use under roofs?
I'm guessing the primary reason for condensation is because the insides are a lot cooler than ambient, a bit like condensation outside a glass of cold water?
Also, is it a good idea to leave the counterweights on without the scope?
this might sound silly, but would the weight be sufficient to bend the bar ever so slightly if kept in the same position for weeks?
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Old 17-01-2013, 11:54 AM
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The main reason for condensation in the beginning was (IMO) the fact that metal parts cooled down over night, and then in the morning, sun heated the tank from outside and the convection of warm air started, sucking the moisture from soil, which was then deposited on colder parts (pier)
Now that the tank is elevated (insulated) from soil, the situation is much better, but there is still enough moisture in the air (trapped inside the tank after observation session) that can condense on colder metal parts.

Towel wrapped around may be a good idea, it may absorb the condensed moisture.. I will try it.
The insulation on inner side of the tank may also help.. but it's not easy to place it, as the tank is rather long (deep)

As for the counterweight, I don't have enough room to keep it on anyway.. but I don't think it's presence can cause permanent bending of the shaft - all those forces (~10Nm) are well below the necessary treshold to cause non-elastic deformation in steel shaft.
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Old 22-01-2013, 04:57 PM
pjphilli (Peter)
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Hi Bojan
Owing to a bad back I have left my scopes on the mount outside
for a year or so now. From experience I have found that the following
procedures keep the gear perfectly dry as if it was stored inside:
1. After the imaging session I first drape a large dry towel over the scopes to absorb any stray rising moisture that may be present.
2. I then cover the all the gear with a large (240litre) bin black plastic bag
and gather the bottom of the bag near the base of the pier and fix it
closed with an octopus tie to stop rising moisture.
3. As the plastic bag is thin and thus fragile in the wind I then cover
the lot with a large bag made out of a shower curtain (which is only semi waterproof) and also tie this around the pier base.
4. I usually find that there is dew on the scopes etc after a night session
so the next day I take the above covers off and dry out the gear and
the towel in the sun and cover it up again as above. If rain is threatened
I spend a bit of time after the imaging session drying off the scopes
and mount with a hair dryer before covering up. I then give it an airing
as above when the sun next appears.
Hope this makes sense.
Cheers Peter
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Old 22-01-2013, 05:28 PM
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Quote:
Originally Posted by bojan View Post
The main reason for condensation in the beginning was (IMO) the fact that metal parts cooled down over night, and then in the morning, sun heated the tank from outside and the convection of warm air started, sucking the moisture from soil, which was then deposited on colder parts (pier)
Hi Bojan,
so if the heating of the tank can be prevented, both by painting the tank white and insulating it, would the issue reduce?
how about if the container was made air tight by adding a rubber seal between the pier and the raised base and a rubber lip where the container sits?
After an all nighter, you'd really want a quick method of packing up.
I was going to do a similar thing, but leave the mount on and build a small sort of wooden shed around the mount and pier that can be locked with the PC/power adaptors. So just remove the OTA after a session.
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Old 22-01-2013, 07:07 PM
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Quote:
Originally Posted by alistairsam View Post
...
so if the heating of the tank can be prevented, both by painting the tank white and insulating it, would the issue reduce?
how about if the container was made air tight by adding a rubber seal between the pier and the raised base and a rubber lip where the container sits?....
Possibly, if my theory is correct.
But, I think the best approach to problem solution is to minimise the cause - in this case the proximity to ground moisture. Then the heating of the enclosure (and circulation of air inside) should actually reduce the condensation.

It's is quite logical - if there is no moisture in the air (around mount), there will be nothing to condense on it when temperature drops (and relative humidity increases).

I did this little project with exactly this in mind - to get inside only the optics and some electronics and keep outside the mount, so I don't have to align every time (which IMHO is waste of time, unless one has to do it).

Peter's procedure is also very helpful, I also check the situation next morning and ventilate the setup properly.
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Old 23-01-2013, 08:19 AM
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There is always hunidity in the air, nothing you can do to mitigate that. If you seal the mount inside a plastic bag it will corrode in some way. Ventilation is the way to go for sure. Dry it off as much as is practical then seal against ingress of bugs and nasties, breathable bottom cover, and allow circulation to dry it out.
Keeping the ground moisture away is the correct procdure. Are you placing a sealed base around the mount ?. Pavers or similar ?
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Old 23-01-2013, 08:37 AM
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Quote:
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...
Keeping the ground moisture away is the correct procdure. Are you placing a sealed base around the mount ?. Pavers or similar ?
At the moment, no - just what you see on images above - round table is the first barrier, it fits into the can rim with ~1cm clearance - and there is enough space left for ventilation in the middle (due to the pier ribs), this may be closed in the future if needed.

There is one more detail:
The top of the pier is machined such that the mount fits on it with very small tolerance. I also fixed one of the screws for azimuth adjustment after drift-alignment (with counter-nut) so I can remove the mount if needed (by loosening the other screw) and put it back on the pier without disrupting the alignment (this was tested couple of times and the alignment accuracy was preserved well enough).

Last edited by bojan; 23-01-2013 at 09:32 AM.
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