Astrokev

Thanks Bizibilder - I hope so!

Thanks for your advice about securing the forms for the blocks. Definitely a good idea. After taking the last picture above, I did actually do this, as best as I could. The 2 forms on the grass were secured as you suggested (you can just see the timber posts on the upper left form). Here is a close up of the lower left form which shows the securing posts more clearly. These were screwed to the form after hammering them into the ground.

The 2 forms nearest the fence are sitting on a heavy-duty concrete path, so hammering posts into the ground wasn't possible. For these, I've used bricks to support each side, as shown in the second picture. Hopefully this will be secure enough.

I tried my best to get each form level, and level with each other. This proved more difficult than I expected. The orange line I'd used had sagged slightly over the last week, so I couldn't rely on this, so had to resort to using the only straight piece of long timber I could find (most of the timber used to make my base template had warped quite badly in the 90 degree heat last week!). It was all a bit Heath-Robinson, but hopefully the blocks will be aligned with each other and level enough - I guess I'll have to wait till the concrete is set to find out!

Kev

Shuttering for the 4 corner foundation blocks are finished. Today I start to mix some concrete!

I need to give some more thought to my pier. I'm once again nervous that my 280mm air con tube will be too wide at the top and may foul my scope as it turns past the zenith. I think I've got a few weeks before I'll be ready to install the pier tube, so a bit of time to think this through with a bit of modelling!

Today I started to make the shuttering for the foundation blocks. Size is 550 x 550mm. I plan to make the blocks ~ 200mm deep, with the top edge around 120mm above ground level (the ground is a bit uneven, so the height will vary a bit), so I've had to dig a few centimetres into the ground. I hope this will help provide a firm foothold and prevent lateral movement if they are accidentally knocked.

Weather rather hot, so the parasol provided a little protection from the sun!

4 hours ago, michaelmorris said:

No such thing as overkill when it comes to telescope piers. 

You're right there! My worry is that you do what you think will be good enough (WxDxH) but, if the pier then moves after you've finished, it's nigh on impossible to rectify !

Thanks Julian for the picture and further explanation. Your pier looks fantastic. It's interesting you comment about the risk of the OTA hitting the 280mm pier - I've been similarly anxious about this. I managed to pick up both 280mm and 150mm lengths of ducting from my last employer for free and they've been sitting in the corner of the shed for the last 6 years waiting for me to start this build project!

I've done lots of drawings and SketchUp mock-ups to try and convince myself the OTA will not foul the pier. I think it will be OK, but as stated above, it would be really difficult to correct if I'm proven wrong. Based on your own design, I may revisit using the 150mm tube aswell as the 280. And there was me thinking I'd finalised the design!

Thanks to all for your thoughts and comments.

Kev

Hi Julian

Thanks for your reply. Can I ask how far you sank the tube into the ground, and did you embed it in a concrete block and, if so, how big this was?  I'd love to see a picture if you have one?

Why did you put a 150mm tube inside the 280mm one?  I'm thinking of putting a length of drainpipe down the centre of my duct tube, to run cables, rather than have them trailing everywhere.

There is a concrete path crossing the point where I need to put the pier block. If I put the main base footings in first, I'm worried that breaking up the path (which is only 4-5 inches thick) may cause ground vibration, so I've decided to break up the path before I do the main obsy footings - see image. I've decided to make the hole bigger than the 500mm square I'd originally planned (the wooden batons mark the position of the original 500mm). Still not sure how big to make it, although I'm thinking depth of the concrete block is probably more important than width, as this will help prevent movement of the pier due to torque.

Kev

After a few false starts, the Build has finally started!

I posted a few designs and questions in a topic last year -  Astrokev's Observatory Build - Take 2

In summary, my observatory will be a roll-off roof design, with a small warm-room, very similar to YesYes's build of a few years ago, and also inspired by Gina and Malc-c, amongst others. I've constructed a 3D design in SketchUp (isn't SketchUp wonderful?).

Progress so far -

Ground cleared. The wooden frame in the image measures 3500 x 2300 mm. I made this to help me visualise the size of the obsy, and to help me find the best place to site it. The garden fence runs N-S, with the existing shed due North. The view West will therefore be pretty hopeless, but the view N, S, and E is not too bad. Once I'd chosen the site, I levelled the frame and used this as a guide to mark out the edges with pegs and nylon line. This proved a pain to both line it up along the top edges of the frame whilst also keeping it taught! Once done, I dropped the frame to the ground and slid it out, leaving the orange line marking the periphery.

Next job is to dig footings in the corners and in the middle of the long walls and make concrete blocks to support the base, using shuttering. Not sure how deep to make these yet - I'm thinking around 150 mm deep and maybe 4-500 wide/long.

I've marked out the position and size of the hole for the pier as I drafted it in SketchUp (~500 mm cube). As shown, the pier will be a concrete filled air-con tube (280 mm diameter. The tube needs cutting down before I sink it in the concrete). Now that I've actually marked it out on the ground, I'm not sure the concrete block is big enough. What do folks think?  The air-con tube is quite hefty and I'm worried that this will act as a good lever which might move the concrete block in the ground. Should I make the block bigger?

In case you're wondering, the ladders etc are an effort to keep my dog out of the site until I can get the base finished. Having spent ages trying to get the orange line in the right place, I don't want the dog tripping over it in the dark and ruining my hard work!

I hope you'll follow this topic, as I feel sure I'll be needing lots of help and inspiration along the way...!

Thanks for looking - Kevin

Looking good Tony. Hope the weather doesn't slow the build.

I'm sure your roof will be fine!

Obsy design ain't easy. If I had a pound for every idea I've binned for my own obsy designs, I could retire tomorrow.

malc,

if i came over as defensive i apologise but i felt it the only way to get my point across.

i'm not offended and i hope no-one else is.

Not offended, but a little surprised at the, as malc delicately put it, 'defensive' response! Having just quickly checked, I appreciate you've never requested opinions of others, but as a number of us have said, in a public forum folks will offer opinions, thoughts, comments. Isn't this why we post these interesting threads that we all love to follow and engage with? Maybe you just want to use the forum as a shop window to show what you've done, without engaging.

Regarding your answer above - "then why oh why oh why does near enough every single build thread have everyones floor frames built onto partially supported bases not onto 100% supporting walls".

A valid and true point, but I can't remember seeing too many builds that were a mix of the 2 approaches, which was the point that was being made. Both methods work fine, and mixing the 2 will work fine, it just seemed an unusual way of doing it, which was the point I was making. No big deal.

Looking forward to seeing the rest of your build.

Hi Tony

Like you, the rest of us are avid build-watchers (and some are avid builders - I'm still gearing up to start my own build this year ), so I'm sure we are all very aware of the range of designs, and the ups and downs, of the whole process. Not sure who's build you are specifically referring to but I, and everyone else, probably followed this post-by-post like you.

Your latest pics show an effective and alternative way of constructing a base, which has been used by some others to produce an excellent end result. The choice is therefore yours; a choice that is influenced by many factors, and often includes a degree of compromise along the way. There are many ways to skin a cat, as they say, and such is the case with obsy design.

My personal reason for trying to offer constructive criticism was that your design seemed to be a mix of 2 methods, either of which would work on their own, but I couldn't (and can't) understand why you chose to mix the two!

As you've pointed out, this forum is a great place to share ideas, to learn from others, and to continue to build on our collective experience. It's also a place to take on board and consider thoughts and points of view that may be different to our own. These thoughts are offerred with the best intent - ie. to help you end up with a great observatory, and are not public floggings!

May I suggest you read (if you haven't already) Gina's build thread (I should book a day off work first!). Her design changed many, many times based on discussions that lasted for over 2000 posts, and it was fantastic to see the thoughts and evolution of her obsy develop. The end result was a great observatory that she's very happy with.

Finally, and back to your own build, I personally wouldn't consider knocking the walls down and starting again with design #2. You've put too much work in for that. I'd either just build a 4th block wall, or stick with your original plan. This will work as I've said, it's just a different way of doing things.

Looking forward to seeing the rest of the build.

Oh - and a question - your height limit of 2.5m. I presume this is based on building regs? With such a heavy ground slope, where are you measuring the height from, ie. the high or low end?? Just curious.

Kev

Yep, me too. May work, but just seems an awkward and illogical way of designing your base. Sorry! Still time to consider redesign though

its deceiving in the photo malc but there will be enough room to get behind. my rear wall wont be that close.

if i get the time i'll have a play with that sketchup and see if i can draw it up.

That's fine, but if it's not that close, coming back to Malc's original question - how will you support the joists at the back of the observatory?!

i knew i was missing something

i'll be removing that stump , which is roughly in the centre,then dig out a bit more and fill with concrete then laying 4" block flat to build a pier/support. my floor frame will be 6x2 so probably wont need much supporting anyway but i'm putting one there.

I think malc meant support for the floor joists on the 4th wall, not in the centre where your pier will be. Are you planning to screw a wall plate to the existing wall, as suggested by dmahon ?

well i say 12 x 6 but its more like 12.5, 2m width, by the time i allow for the frame it'll be about 1850 so inside it'll be just over 6 feet.

As they say, it's not the size that matters - it's what you do with it that counts! 12 x 6 sounds fine to me Tony, and I'm sure will give you a great observatory. Good luck with your build and look forward to seeing plenty of pics.

Very nice Malc, although I'm a little disturbed by the line of tiles above the bed. You're not thinking of installing a shower are you?!

Also intrigued by the colour scheme - is this your feminine side coming out?!

Looks great Malcolm. You should feel very proud of the end result. One of the better builds I've seen so far.

Ah,.... it all becomes clear!

Looks fantastic Malcolm. When I get round to building my own observatory, if it turns out half as good as yours I'll be well chuffed!

I sense some sarcasm...

Only friendly tongue-in-cheek....

Gina, I'm just wondering what your thread post count will be when you finally cut the ribbon on your observatory's official opening day

2000, 3000, 4000........? In fact, you may need your very own server.

Looks fabulous.

Great design Darren. Looking forward to seeing it come to life.

Neat idea. It will transform your life! And ain't Sketchup great?

Yep, Sketchup is wonderful to help visualise ideas. I still need to get my head around animations though!

Seriously - they're fine.

Looking great Malcolm. Like the green, the same colour as my old DIY scope tubes! To be picky though, the walls do clash a bit with the floor; "blue and green should never be seen....", but I suppose your not planning on wearing it, so let's not quibble, eh! ;-)