North Kent Roll Off Roof Build

[Graeme]

Every imaging session starts with me carrying my CGX mount and tripod out of the garage, putting on the counterweights, fixing the telescope onto the mount, laying out the 12 volt and USB cables and connecting everything together. This takes at least 40 minutes and at the end of the session, in the early hours of the morning, everything has to be disconnected, dismantled and put away. The time is coming and it's probably not that far away when I will need to separate the mount from the tripod in order to lift them!

We have all heard this story before! So it's time for me to build a permanent setup. After a lot of research I have decided to build a back garden Roll off Roof Observatory. I've been off work for a few months so I've had time to read lots of roll off roof forum threads and think about a design. The initial plan was to build on this patio and use my CGX mount tripod.

 

But then a concrete pier seemed like a good idea. So the adjacent border was cleared and the location moved to include a good place to dig a 600mm x 600mm x 600mm hole in the ground for the pier base. 

 

The first half of the dig was quite easy. The second 300mm was heavy clay.

 

Next step, rebar and shuttering!

Regards

Graeme

 

[carastro]

OMG how have you put up with setting up and down every time.  I dud it for a few months when l first started and very soon realised l needed a way of permanently leaving it set up.  
 

Looking forward to watching your build.
 

Carole 

[Graeme]

It's a massive pain and I only tend to set up when there's a definite clear skies all night so the partials get missed. And my maximum exposure has only ever been 3 hours, so looking forward to multi-night captures of the same target.

 

 

[adyj1]

Good luck with the build! 👍 

[Swoop1]

Once again, my back is twinging after flashbacks having seen your pier base hole.

Very tidy excavation BTW👍

[Graeme]

1 hour ago, adyj1 said:

Good luck with the build! 👍 

Cheers Adyj1

I'm looking forward to it!

[Graeme]

49 minutes ago, Swoop1 said:

Once again, my back is twinging after flashbacks having seen your pier base hole.

Very tidy excavation BTW👍

Thanks Swoop1

Your pier base thread excavation tidiness was one of my inspirations!

My excavation is not quite so tidy now, I left the fence post spike so as to not disturb the ground too much. But I've pulled it out now because it was in the way of the shuttering.

 

 

[Graeme]

Ground levelled some more. Redundant brickwork removed and old tree stump dug out. There was only 8" of that thing sticking out of the ground, I didn't realise it was so big! Had to pull it with a ratchet strap looped around the concrete fence post. The hose pipe feeds a tap at the end of the garden, It might be wise to take that out!

Rebar sections assembled, if the rain holds off tomorrow I'm hoping to get the shuttering finished. Then I just need the brake disk delivered and we will be ready for the concrete pour. Thought I might work out the pier height again before I cut the pipe and pour the concrete, that needs to be right!

[GrumpiusMaximus]

I know that clay soil very well.  Grew up in North Kent (and only moved to East Kent) and it's a bloody nightmare.

Really looking forward to seeing the results.  Love these builds.

[newbie alert]

What size is your dug hole... I'm in Ashford so not a great distance from you... I remember doing my little scope house and I guarantee it's the best thing you can do, already setup and ready to roll

[newbie alert]

[Graeme]

51 minutes ago, newbie alert said:

What size is your dug hole... I'm in Ashford so not a great distance from you... I remember doing my little scope house and I guarantee it's the best thing you can do, already setup and ready to roll

600mm cube. It seems to be the going rate. Your excvation looks massive! Is it finished?

[newbie alert]

1 hour ago, Graeme said:

600mm cube. It seems to be the going rate. Your excvation looks massive! Is it finished?

Im just under a cubic meter, it went down 1.3m as I have a 2m length water duct pipe as a pier... Really enjoyed pouring the concrete as it was the first time I'd used a cement mixer

Yeah it's finished, really pleased with it

 

[Graeme]

Moving on slowly! Excavations done. Shuttering done for the pier, The pipe is just to check the rebar for size, the actual pipe will be 1100mm tall. I'll be picking up the shuttering timber for the trench for the concrete under the side next to the fence on the way home from work tomorrow. Then all the concrete can be poured in one go. 

 

[Graeme]

The brake disc arrived. Big thanks to my neighbour Tony for his drill stand! Three M16 threaded rod lengths fitted and ready to drop into the concrete in the pier. £90 for the Baader mount adapter, £2 for the brake disc from ebay! They come in pairs, so if anyone needs a brake disc, the other one is going for the price of the postage!

 

Edited January 22, 2023 by Graeme

[Peter Reader]

Great build! How much to post the brake disk to Oxford?

[Graeme]

1 hour ago, Peter Reader said:

Great build! How much to post the brake disk to Oxford?

Thanks Peter, it's going a bit slow in this cold weather! But I'm enjoying the build.

Dunno the price of postage, together they were £5.88 for the pair. I'll weigh the spare one and find out.

[Graeme]

On 22/01/2023 at 17:20, Peter Reader said:

How much to post the brake disk to Oxford?

Well it's 300mm x 300mm x 75mm and weighs 5kg. Royal Mail want £4.35 for the postage.

Let me know if you want it and I'll PM you.

 

[Peter Reader]

I'll pass this time but thank you for checking

[Graeme]

Shuttering is all finished, pipework is nearly there, I need one more 135° to kick the internet/camera/alarm pipe back to the shuttering. The pier support is looking a bit Heath Robinson! But the spirit level is happy with it. The blue tape is holding the pipe for the 12V and USB to the mount. 

As well as the 10mm rebar there's a 1m length of M25 threaded rod from the bottom of the block to the top of the pier. I'll make up a wood former for the 3 x M16 studs when the concrete gets poured. My good friend Tony is coming Wednesday with his concrete mixer and vibrating poker. 

[Graeme]

The concrete pour went well today. We filled the base cube and vibrated out all the air bubbles. 

 

Base cube filled, pier pipe filled and brake disc studs inserted. There wasn't time to wait for midday to line up the shadow of the studs with due north! But we lined up a string line to the marker I put in a couple of weeks ago.

 

Job done! We filled in the trench along the fence line which will be the support for the back of the observatory. Apparently I have to wait a week for the concrete to cure before I can put the mount on top of the pier. The jet wash came out to clean up the patio block work. I'll be putting the Baader mount adapter on the brake disc, putting that on the studs and levelling up this weekend. Then I can finish the pipework back to the garage and start thinking about the observatory build!

 

Massive thanks to my good friend Tony for some excellent concreting work today.

 

 

[Graeme]

And here it is with the shuttering struck.

Looks like we didn't use the poker on the rear section! But the cube and pier are as solid as a rock.

Going to start laying bricks tomorrow. I'll pug up the holes in the concrete with the mortar!

This is definitely the most accurate spirit level I have ever used!

I need to get an M6 tap to fix the bolts that came with the Baader adapter to the brake disc.

 

 

[newbie alert]

1 hour ago, Graeme said:

And here it is with the shuttering struck.

Looks like we didn't use the poker on the rear section! But the cube and pier are as solid as a rock.

Going to start laying bricks tomorrow. I'll pug up the holes in the concrete with the mortar!

This is definitely the most accurate spirit level I have ever used!

I need to get an M6 tap to fix the bolts that came with the Baader adapter to the brake disc.

 

 

Looking good so far 

[Graeme]

Phase one civil works is now finished. (After I've had a bit of a clean up!) Next stage is the wood work which I'm hoping to get on with this week end.

 

[Graeme]

Well there was a bit more concreting to do to hold the base section to prevent lateral movement and uplift. There's now a bag of ballast at two opposite corners. Now I need to take up the base section to lay the damp course before I start on building the timber frame. The 4"x4" corner uprights and the 4"x2" for the top section have been stained and are ready to go. 

 

Edited March 5, 2023 by Graeme