Ho no, not another 'My Observatory Build' thread

[earth titan]

Moved to the new house about a year or so ago and after making it warm and water tight and doing the jobs SWMBO asked for (kitchen...) I can focus on pleasurable projects.

The old greenhouse has now gone (it was a wreck and a hazard to the kids playing in the garden) and I'm left with a base.

What to do with it?

How about a roll off pent roof obsy?

Site has good visibility to south and west (ivy covered post is coming down) and electrics already in place.

[earth titan]

200mm plastic pipe ordered for pier.

12mm stud etc. ordered and bloke found to make a top plate.

Going to examine the base later today, which I suspect is hardcore, to work out how big to dig the pier hole.

The old man is bringing a breaker over, so should only take a day or so to dig it.

[str0nach]

I'm jealous. I have several large trees overhanging my garden so I have to move the scope around depending on what I want to see- or take it over the fence to the park. I'd love an obsy project!

[Merlin66]

Tom,

what instrument(s) are you going to put in it?

The SCT or the 8"/HEQ5

[earth titan]

Tom,

what instrument(s) are you going to put in it?

The SCT or the 8"/HEQ5

Actually I'm hoping to run all my scopes except the dob, but not at the same time, obviously.

It would be nice to have everything set up all the time but even if it takes 10 minutes to switch them over, this will be a lot less hassle than current.

I'm going to leave the QHY5 and guide scope installed at all times on a side by side saddle, just have to shimmy it along when I swap over. It's the cabling and polar alignment which is the pain which I hope to overcome and allow extended imaging sessions over a couple of nights.

[Viv]

Perfect space for an obsy !!

Keep us posted & remember - lots of pics please .......

[Gina]

Well you have a great starting point - good luck

[earth titan]

Casting the pier....... All in one go, or base first followed ny pier...

If I pour as one unit, will the weight of concrete in the pillar sink down and cause the base to overflow?

[malc-c]

Tom,

The way I did my pier was to drop the pipe into a 750mm x 750mm x 750mm (approx maybe deeper) hole, poured in a small bag of 20mm chippings around it and then poured in a 4:1 mix of concrete until it was level with the ground. I then squared the pipe up and braced it whilst the concrete dried. When it came to the pier itself, this was cut to length once the floor had been installed. I then hamered in some lengths of rebar until they were just below the level where I wanted the concrete to be. Then it was a case of carefully pouring in more 4:1 mix and using rebar as a poker to ensure all the air was out. It took around 1 and a half barrows of mix to fill the pipe.

[Gina]

I poured base and pier in one go but arranged shuttering with a round hole for the pier for the top of the base so the concrete couldn't run out.

[earth titan]

Hi folks.

Ballast and cement bought today. Hole digging tomorrow if weather holds.

Pier top design kind of complete. Looking for comments re suitability.

It will be in 2 parts. A plate and a 20mm thick spacer boss.

Thanks in anticipation.

[malc-c]

Mounting plate looks good, but I would suggest having it machined in one piece of ali.

Mine followed traditional design of a top and bottom plate, but with the mount sunk into the top plate

[Bizibilder]

That pier plate looks OK. My only comment is that with my own (same general dimensions) I found that the azimuth pin fouled the inside of the head casting (It is difficult to position the pin as it is a rough casting on the original tripod head). Easy to fix as I just filed a bit off the "front" of the pin. I suspect each casting may be slightly different so you may not get this problem. For the same reason it would be worth making the "big" hole 60.5mm diameter - just to be sure it fits easily.

[g0ibi]

Have you seen the obsy build in March's copy of Astronomy Now? A good idea I think??

[earth titan]

Mounting plate looks good, but I would suggest having it machined in one piece of ali.

Mine followed traditional design of a top and bottom plate, but with the mount sunk into the top plate

Love the anodising. My wife would approve of the colour....

One piece might be the way to go. I have a tame fabricator on standby, so may have to find a local machinist... The pain is that if I had a lathe, I could knock one up in five minutes......

[earth titan]

After a bit of thinking and head scratching, largely to keep costs down, I've redesigned it...

Why bother with the additional expense, when I have a perfectly good mounting boss already! I already have travel kit, this is something for the obsy, so just whip the mounting boss off the tripod, stick it on the plate and Bobs your aunties live in lover.....

It will need to be secured in place which is simple enough. I can drill, ream and pin it in place, without damaging it once I've got the alignment roughly right. Two pins, one either side of a lug.

[earth titan]

Good weather and a day away from work, means I can get on with the project.

Pier hole dug which was through a good layer of hardcore, so a real swine of a job. Its about 750mm deep and down into the natural ground, which round here is clay. Every time I go near it, it keeps filling up with the surrounding materials so I'm going to have to empty it out before I pour the pier and shutter around it to make it neat for the floor to fit round.

I have driven a lintel down into the ground about 3" and will try to get it in another inch before I cast. This will then form an additional support strut.

As the surrounding ground is hardcore, I have driven some road pins radially into the ground around the pier to anchor everything in place.

[earth titan]

I'm going to pour the pier in two sessions. Firstly I'm going to pour the base with the pier (200mm diameter) in situ with some more road pins driven through the pier tube for support.

I'll then build the obsy walls and floor, then trim to length and cast the pier itself. Otherwise I can see me making a **** up of the length.

Got plenty to play with.

More work when I get back from a work trip to the Lebanon.

[earth titan]

Off for a well earned beer and watch the rugby...

[malc-c]

Looking good Tom...

[earth titan]

Wonderful spell of weather today and pier base was cast. I drilled some 1" holes in the bottom of the tube to allow a bit of muck to flow through in to the base and give a bit of bite.

I'm casting the pier in 2 sessions. The final session when the walls are up and I know how high I can cut it.

I have fixed a treated timber base to the brickwork frame, on which the obsy will be mounted. This base will form the frame to which everything else is fixed, including the floor which will be suspended.

If the weather holds tomorrow, which it should, I'll get the ivy and undergrowth cleared.

Next weekend, it's the walls.....

Beer time..

[kiffy]

handprints are a nice touch, something that wont be seen for many years

[Gina]

Any wet concrete round here usually gets paw prints

[earth titan]

Thanks. Handprints were my daughters (6 years old) idea.

[Gina]

I thought it was something like that