JamesF's observatory build

[JamesF]

Yes, that's basically one of the reasons that I want to use steel in this case.  As I said in the original post, it's not the ideal site and in the future I may wish to set an observatory up elsewhere.  Being able to unbolt the piers and bury everything is desirable, though I admit that I might need a big hole for the tall pad

Actually, if I moved elsewhere I'd probably just take the piers away, fill in the holes in the floor and use it as another shed.  A chap just can't have too many sheds, after all.

James

[Gina]

That's a very good reason for going for steel piers that can be removed from the blocks.  I was in a different situation as my observatory location was already the best I could have on the property.  I could do with a larger telescope room and another pier but that isn't a practicality - I would need a larger roof and I can't see me doing that.  The spirit might be willing but the flesh is weak.  Have to realise I'm getting past building gert big sheds with funny roofs.  I think a new pier would have to have it's own covering of some sort.  Actually, what I'm talking about is a third pier as I already have a second specifically for widefield imaging as I said before.  OK, so I'm greedy ?

Edited June 8, 2018 by Gina

[Astrokev]

4 hours ago, Adam J said:

I seem to recall starting mine at the same time as you. Must me getting close to a year now. ?

Yep, 1 year in July, though I recall you saying your's was "tiny" ?.

In my defence, the weather was pretty shocking in late summer, together with lots of other things going on in my life last year...….

Hopefully making up for it now though ? 

Edited June 8, 2018 by Astrokev

[Astrokev]

2 hours ago, Dr_Ju_ju said:

Like Gina, I've used concrete to fill 2 part, air conditioning ducting 300mm & 150mm. Nothing will move it now, & I pity the next owners who want to remove it as it goes 2m into the ground.

Likewise.

My 280mm concrete filled air-con duct is bedded into a 750mm concrete cube. It ain't goin' nowhere!

[JamesF]

Today I sorted out the shuttering for the last two pads to support the longer sides.  I also did most of the digging for the pier foundations and cut the last two timbers for the outer frame.  Some tidying up may be required for the pier foundations, but the hard work is now done.  Tomorrow I want to get the concrete for the pads done and then I'll see whatever else there's time for.  Actually getting the piers made so I have a template to work from for pouring the foundations has to become a priority, certainly.

 

James

[Astrokev]

Looking good. 

How did you find the quality of the long joists? I had them spread out over half the floor at Wickes to find the straight ones that weren't twisted! I'm OCD when it comes to buying straight timber. I think RayD called it playing giant Jenga. They must love me at Wickes ?

[Gina]

I've done the same at Wickes ?  But for my observatory I used a local timber merchant at about half the price (but still £600 worth).

[Astrokev]

1 hour ago, Gina said:

I've done the same at Wickes ?  But for my observatory I used a local timber merchant at about half the price (but still £600 worth).

I shopped around the area but, to be honest and all things considered, Wickes seemed to be the best. But you're right, the costs rack up. I'm keeping a complete list of costs for everything that goes into the observatory, but beginning to wish I hadn't started this - it's getting quite scary ?. Good job the build has taken a long time to get to this point, to spread the cost!

[Davey-T]

Building material prices have shot up in the last few years, once they were so cheap we didn't really bother calculating them properly now it all needs careful pricing as one oversight can really eat into the profit.

Dave

[Gina]

I probably spent a couple of grand on my observatory but that's nothing compared with everything else astro and it was well worth it   I didn't add everything up - there were so many odds and ends, there must have been thousands of items and all those little things add up to an enormous amount!!

Edited June 10, 2018 by Gina

[Gina]

5 minutes ago, Davey-T said:

Building material prices have shot up in the last few years, once they were so cheap we didn't really bother calculating them properly now it all needs careful pricing as one oversight can really eat into the profit.

Dave

Profit???  What profit?  Nothing I do now makes a profit!  ?

[Davey-T]

6 minutes ago, Gina said:

Profit???  What profit?  Nothing I do now makes a profit!  ?

I do on very rare occasions get dragged out of retirement and get involved but usually only as unpaid labour now 

Dave

[Astrokev]

1 hour ago, Gina said:

I probably spent a couple of grand on my observatory but that's nothing compared with everything else astro and it was well worth it   I didn't add everything up - there were so many odds and ends, there must have been thousands of items and all those little things add up to an enormous amount!!

You're right there. In order of total cost to date: 1st=Timber. 2nd=EPDM. 3rd=V track and wheels. 4th=small metal brackets.  BRACKETS! Who would have thought it!

I'm obsessive-compulsive when it comes to lists n things. I've got so many spreadsheets and pivot tables related to my astro stuff and obsy it worries me sometimes. Being a retired scientist probably explains it!

Ignoring the pier, actual building costs are currently around £1700. I don't expect much change out of £2500 when it's finished. But as you say Gina - it'll be well worth it!!

Edited June 10, 2018 by Astrokev

[JamesF]

Some of my timber is a bit bowed or twisted, certainly.  I didn't get to choose as it was all delivered by the local builder's merchant.  We have quite a good relationship with them anyhow, so if I felt any of it was too bad they'd deal with it.

As it is I'll clamp the outer pairs of timbers together and then put some hefty screws in to hold them together.  Fixing the remainder of the floor joists in should finish off straightening them up and noggings between the joists should keep them from twisting so by the time I'm done I think it will be ok.

James

[Peter Drew]

On 08/06/2018 at 15:39, JamesF said:

Quotes for making the piers have come in at about £200 each.  Whilst that's significantly cheaper than some of the commercially produced ones, it still seems an awful lot.

As I'm kind of persuading myself to bite the bullet and weld up a frame for the roof I'm also therefore tempted to have a go at welding the piers myself.  I reckon I can buy the steel ready-cut for about £50 per pier.  I'd need to drill the holes and cut out an "owl's nest" (which might be the trickier part though I guess I could cut a rectangle out by drilling out the corners and then applying the angle grinder to join the dots).  It may not be the prettiest thing ever, but would save a fair bit of cash.

James

Meade 8" SCT on the famous "Todmorden" pier. Less than £20, couple of hours work and "solid as a block".   ?

[Gina]

How deep is the concrete block with the gravel round it?

[JamesF]

Got the middle pads done today, but that was the limit of my achievements on the observatory.  I did also lay some paving slabs and patch up part of the patio that is breaking up, so it's still been a busy day.

This evening or tomorrow I shall probably order the bits for the pier.

I can see how Peter's pier would work.  I'm guessing each of the blocks must be a little over 200mm square (they look pretty much the same width as the SCT sitting on them) and perhaps around 430mm tall.  Properly fixed that's going to be quite solid.  In an obsy it could be clad with ply for a less "functional" look :)

James

[Davey-T]

I made my obs'y pier out of 200mm square steel tube then discovered I needed more height to image low over the side walls so cut it near the base and inserted 4 lengths of 75mm steel angle and made it telescopic with an electric ram that raises it 300mm.

Dave

[Gina]

I have similar concrete blocks with holes in a couple of walls here.  I would say they're 18" long and 9" square um... that's about 450mm x 225mm x 225mm so you're pretty much correct.

[JamesF]

I find myself tempted by a "Todmorden pier" now I've done a bit more reading, especially if I could find a suitable adhesive for the blocks as well as bolting them together.  It achieves my goal of being removable which is good.  I want about 900mm above floor height for the top of the pier, so I'd have to bring the foundation very close to the underside of the floor, or get the disc cutter out and use two and a half blocks instead.  I reckon that would get me close to a total pier height of 1200mm which was what I was planning in the first place.  Given a suitable length of threaded rod I could even embed it in the foundation and run it all the way up through all of the blocks to tie them all together.

And if it didn't work out I could always unbolt them and mount a normal steel pier held in place using more rod with resin anchors.

Doing a quick search suggests the actual dimensions of the blocks are 215mm x 440mm and they weigh about 25kg each.

I shall ponder on this overnight.

James

[JamesF]

It also strikes me that such a pier is easy to fix things on (conduit for wiring, for example, or power distribution kit).

James

[SnakeyJ]

9 hours ago, JamesF said:

I find myself tempted by a "Todmorden pier" now I've done a bit more reading, especially if I could find a suitable adhesive for the blocks as well as bolting them together.  It achieves my goal of being removable which is good.  I want about 900mm above floor height for the top of the pier, so I'd have to bring the foundation very close to the underside of the floor, or get the disc cutter out and use two and a half blocks instead.  I reckon that would get me close to a total pier height of 1200mm which was what I was planning in the first place.  Given a suitable length of threaded rod I could even embed it in the foundation and run it all the way up through all of the blocks to tie them all together.

And if it didn't work out I could always unbolt them and mount a normal steel pier held in place using more rod with resin anchors.

Doing a quick search suggests the actual dimensions of the blocks are 215mm x 440mm and they weigh about 25kg each.

I shall ponder on this overnight.

James

I'm pretty sure that any of the waterproof foaming gap filling adhesives would do a good job with concrete block, as it's such a large and pourous area to join (gorilla glue?).   Otherwise a tube of masonry/fixing epoxy resin should give a bomb proof bond.

 

I've bolted my piers down on 16mm rebar - galvanised as I'm sure this will still outlive me!  When I moved out of the last house I bolted the roll off roof down, took away the runners, removed the pier and ground the bolts off with an angle grinder.    The shed conversion took 2-3 hours, or about 1/50th of the observatory build time and the new owner was very pleased with the posh shed!

[JamesF]

Still seems like a good idea to try this out after some thought.  I don't think I'll go for the rod through the entire stack of blocks though as it will be tricky to align the holes properly.  I'll go for a bolt or threaded rod through each mating face with a steel plate either side to spread the load.

James

[JamesF]

I've just rediscovered a thread by @MattGoo with details for his Todmorden pier build.  I even commented on it at the time, but three years later had forgotten in.  Looks as though he might be using four threaded rods for each join, of smaller diameter than I was planning.

https://stargazerslounge.com/topic/251161-mattgoos-block-pier/

Using more than one rod/bolt for each join could be tempting.

James

[Davey-T]

Ready made plates here but you end up with a few spares 

Dave

https://www.screwfix.com/p/sabrefix-m10-square-plate-washers-galvanised-50mm-x-50mm-50-pack/9891h