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JamesF

JamesF's observatory build

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Not much happening over the last couple of days, but I have completed finished laying the carpet tiles so that's another thing off the list :)  I think the most important thing to get done now is the support posts for the roof rails.  I'll try to remember to stop by the local sawmill tomorrow on the way to go swimming to see what they can offer in the way of posts.  I ought to think about some sort of stops on the rails so the roof can't roll off completely (the roof can't roll off in the closed direction, but there's nothing other than common sense that stops it happening in the opening direction at the moment).  I don't imagine anything particularly clever is required.  And I should start getting back to some of the jobs that still need doing but just haven't been that high a priority so far, such as cladding the northern gable.

I was hoping to take some star trail shots over the house from the observatory this evening, but it seems the clouds do not wish to play ball, at least for the moment, so instead I am configuring up an old laptop to dual boot Linux and Win7 so I can leave it in the observatory for the time being.  I'm going around the Windows "there are updates; install them; reboot; ooh, there are more updates we didn't tell you about last time" loop at the moment :)

James

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Just had a try at the same solution for the HEQ5 alt-az pin as Alex, but no dice.  Even cut down to 25mm, which is probably as short as it can go, the rod connector still fouls the inside of the mount casting.  I think there must just be a bit of variation between the castings such that it works for Alex and not for me.  Hey ho.  I think I can lock the threaded rod in position by itself, so I'll file some flats and just use that for the time being.  If I'm bored some time next century perhaps I'll find a bit of steel or brass and turn something neater.

James

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Happy birthday to you, happy birthday to you, happy birthday dear observatory, happy birthday to you!

Yes indeed.  One year ago this weekend I started work on the observatory.  So, with a little clear sky forecast tonight I went out with the intention of having a bit of a play with the DSLR.  Sadly reality didn't match up to the forecast and what was supposed to be five or so hours of clear sky from 10pm turned out to be barely an hour of intermitted clear sky from just after midnight.  On the positive side, I caught two ISS passes when it suddenly popped out from behind the clouds, so it's not all bad news.

On the construction front, today I spent some time fitting a vent into the northern gable and then putting the cladding on that end, so that's another two jobs ticked off the list.  I'm still pondering over fitting a vent on the southern end, too.  I suspect I'll end up doing so though perhaps not immediately.

I also collected a couple of posts from  the local sawmill to support the ends of the roof rails.  My wife had already disappeared off with the Skoda to take our daughter somewhere so I had to fit them in the Fiesta which was a bit of a giggle.  Now I just need to dig a couple of holes to fill with concrete and set the feet for the posts into the concrete.  I might get the holes sorted and then wait for the builder to have the mixer going before doing the concrete.  I can't imagine I need more than half a mix and it seems a bit wasteful to start up the mixer just for that.

James

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7 hours ago, JamesF said:

I can't imagine I need more than half a mix and it seems a bit wasteful to start up the mixer just for that.

And not have to clean it out yourself :thumbsup:

Dave

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1 hour ago, Davey-T said:

And not have to clean it out yourself :thumbsup:

Dave

The thought had never crossed my mind... :D

James

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6 hours ago, JamesF said:

The thought had never crossed my mind... :D

James

Many years ago, to manage mixing smaller amounts of cement or concrete. I got a mixing tray from Wickes. Been brilliant, but of course it means basically having to turn the stuff over by hand. The good bit is it keeps the ground underneath clean. It also works well if placed under the cement mixer to catch any spills.

https://www.wickes.co.uk/Wickes-Heavy-Duty-Tuffspot-Mixing-Tray---Black/p/543009

They do say a bit of hard work never did any harm, but I am not so sure...

Gordon.

 

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A wheelbarrow and a rake never did me any harm when it came to mixing concrete.  :thumbsup:

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32 minutes ago, Rusted said:

A wheelbarrow and a rake never did me any harm when it came to mixing concrete.  :thumbsup:

A rake?? Never thought about using a rake, always used a spade.. I assume it works well?

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12 hours ago, Bukko said:

A rake?? Never thought about using a rake, always used a spade.. I assume it works well?

Wonderfully well! Almost effortless because no wet lifting is involved.
Improved mix from the rake tines reaching right to the bottom of the dry, then wet ingredients.
After half a century of using a spade and making a mess on the ground I felt liberated.
The mix is always contained and ready to be transported around the site without further lifting, loading or mess.
No more dragging heavy and sloppy buckets around and then having several items to clean including your clothes and Wellies.
No more judging how much water to add into a fragile crater ready to burst its contents across the patio or lawn.
Add a little water at a time and just keep on mixing. Ideal for post holes.
I am only charging £100 for a single [one day only] license for private users of the idea.  :biggrin:

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One word, Postcrete…  sooo much easier.

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19 hours ago, Rusted said:

A wheelbarrow and a rake never did me any harm when it came to mixing concrete.  :thumbsup:

always mix in a wheelbarrow. Less mess and you can move it around easily too 🙂

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The builder returned today having been working in France for a couple of weeks or so.  I mentioned to him about sticking a load in his mixer when he was next using it and he was quite happy.  And then at the end of the day he said to me "Just dig the holes ready for Thursday and I'll mix the concrete and pour it, no bother".  So it looks like I'd best get the spade out tomorrow then :)

James

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I forgot to mention, the builder also brought the motors for the stair lifts.  When I briefly inspected them in the workshop this evening it appears that they both have a reasonably hefty motor and perhaps some sort of bevelled gears in a gearbox to turn the drive through a right angle.  The units are covered in microswitches too, which might well come in handy if I can salvage them.  I'll try to remember to take some photos tomorrow.

James

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The motor/seat units for the stair lifts.  This is the "lighter" one that uses a gear train cut from laminated plate (the gear here is the same construction):

obsy-build-106.jpg

I think the limit switches on that one (along the bottom edge of the frame) are probably beyond recovery on this one.  This is the other unit:

obsy-build-107.jpg

obsy-build-108.jpg

The switches on this one definitely look like they're ok.

For what I want, the motors may be a bit over the top.  Whilst the weight of the seat unit and a person may not be that far off the weight of my roof, the lift also has to, err, "lift" :) whereas mine just has to roll.  On the other hand, perhaps having the motor and gear unit all together means I may have a few more options for mounting it.

James

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Good progress and well done with the builder.

If the motors are wired to include limit switches, then it might be good to get new ones and fit to the roof to make sure the roof stops at the end of the travel. Nothing wrong with adding the safety stop, especially if the motor and gearbox is oversized, it might damage the structure if allowed to go too far...

The motor assembly also looks a bit exposed, so do you have somewhere protected from the weather to mount it/them?

Keep up the good work,

Gordon.

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I'd probably mount it at the top of the scope room side of the internal wall, above the height of the bottom of the gables.  That way there should be no chance of water getting onto it directly.  Or I could mount it lower down in a waterproof enclosure with a belt drive to the pinion at the required height.  It's a bit of a project in itself though and I'm only even considering it because the builder happened to have this stuff lying about in his scrap heap, so very much something for the backburner.  I'll return to it once I've got everything else fully into use and probably caught up with a few other domestic jobs too.  For the time being I think I just need to make sure I don't paint myself into a corner when I plan the electrics.

James

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The limit switches look like ordinary microswitches which are cheap enough to buy anyway.  OTOH you might as well use those if alright.

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Well (an appropriate opener, given the circumstances), despite the persistent rain I've been out this evening to dig the holes for the concrete to locate the support posts for the rails.  It turned out to be both easier and harder than I anticipated.  Harder because the ground was a mixture of soil and stone that was quite hard to get through and despite the fact that it has rained almost all day the ground is packed so hard that it hasn't really penetrated more than a few millimetres.  Easier because when I eventually reached about nine inches deep I found solid rock, so could stop there.  Hopefully tomorrow I can get the concrete in and then fit the posts at the weekend.

James

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It's been a fairly quiet week on the construction front.  Work, amongst other things, has interfered a bit, and I've actually been trying to use the observatory which might have been a touch more successful had the Met Office actually managed to forecast the weather :)

The feet for the rail support posts are concreted into place now.  I'm just waiting for the concrete to cure a bit before I start messing about with the posts themselves.  That may be a job for tomorrow.  Meanwhile there are certainly other things I can be getting on with.

In honesty the failure of suitable weather to arrive probably isn't a big loss.  I've been using the dob for so long now that I'm struggling to remember how everything works with the NEQ6 anyhow :D

James

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Today I have been dodging the rain to get the support posts for the rails in place.  I'm pleased to say that's now done.  I've also fitted some stops so the roof can't roll off the ends of the rails when it's opened.  I've had to stop now as I have a swimming club committee meeting shortly.

Whilst I'm far from finished, this does mean that everything on my "must be done before the observatory is usable" list is now checked off.  I have cables trailing all over the place and so on until such time as I get the electrics sorted, but fundamentally I don't think there's anything other than the weather that should stop me making use of it now.

I think electrics (and networking etc.) now has to be the priority.  Yet again I'm dithering over whether I should take a 12V/13.8V feed (or perhaps more than one) from the warm room to each pier and split it there for the various bits of kit that need it, or have 240V at each pier (which I may need anyhow) and drop it down to 12V at the pier.  I want to avoid a situation where the 12V supply can potentially be a single point of failure, but having less "stuff" at the pier would also be good.  I'm wondering if I could have some sort of set-up where the 12V supply actually comes from a battery in the warm room that is effectively always on charge from the mains, so if the 12V mains supply dies then there's sufficient power in the battery to keep everything going for the night.  Or least the next 30 minutes, given the way the weather is behaving here at the moment...

James

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12 minutes ago, JamesF said:

I'm wondering if I could have some sort of set-up where the 12V supply actually comes from a battery in the warm room that is effectively always on charge from the mains, so if the 12V mains supply dies then there's sufficient power in the battery to keep everything going for the night.  Or least the next 30 minutes, given the way the weather is behaving here at the moment...

James

That is exactly what I have.

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Is actually just that simple, Gina?  Connecting a 13.8V supply across a battery and feeding everything onward from there?  Or are there other things that need taking into account?

James

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Posted (edited)

Yep - that's what I do.  Connections go from the battery to a switch and fuse box (with digital current display) then on to the pier head.  I use an ordinary car battery 45AH - you might prefer a more beefy battery depending on load and how long you want to run during a power cut.  I run two +12v (13.8v) lines to the pier - one for the mount and the other for the imaging rig.  A household heavy duty earth bonding cable runs from an earth rod outside the observatory to a connection/groundpoint at the mount and then on to the switch/fuse box where it connects to battery negative terminal.

Proper fusing is essential as the battery is capable of supplying several hundred amps and will fry most cables given the chance.

Edited by Gina

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IF everything runs off a nominal 12v supply, and you've put in cables that are heavy duty, to ensure that there is no drop of voltage\current, then a single central supply maybe ok.

Personally, as good quality mains\5\12\24v supplies are cheap and readily available, I'd run mains power & network to each mount, to ensure that whatever the requirement that basics are available.

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I won't have mains in a damp or wring wet with dew scope room.

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