IMT3b – Page 4 – IMT3b Observatory

IMT3b – Build Part VI

13th March 2021

So continuing my writeup of progress on the dome build. With the pier block complete, now it was time to make the former for the base and start the concreting. The former was made from 5mm ply that I purchased from Homebase as they cut large sheets on site which is very hand for transport. When home I then cut the material further and then secured the strips together with some scrap wood I found.

With some rebar stakes found in the flow borders I kept the wood former in place. Again I cut a hole in the wood seen to the right of the photo above for the electrical pipe. The height of the block above the ground can be clearly seen.

With the ability to meet 1 person outside, one of my friends came over to help. I had already prepared some days earlier the wood former which was looking good. I noticed that to get the depth required the height of the observatory base to the North was significantly less than to the South due to the slope of my land. So I needed more ballast.

Travis Perkins was the cheapest for ballast locally and had delivered before. The driveway is rather tight at the property, however the drive did his usual finesse and reversed up first time. He then set about manipulating the fantastically well engineered crane are to move the bag to the rear of the vehicle without hitting my lamppost 🙂 Well done Mr TP Driver.

In hindsight I should have made the overall depth much less including that of the pier. I could drive a car on the base or build a house it was so thick, This in part was because we decided not to dig any further into the chalk for the pier block and instead have the block higher to make sure it was still thick enough.

Again the level of the wood was checked across the former to the pier block to make sure the level was correct. By 8:40am we had poured our first load and the long process began.

It was clear after around 5 pours that this was going to take some time and a lot of ballast! After 2 hours it was obvious that we did not have enough ballast and the empty bag stopped us progressing any further. It would be another week before we would have another opportunity to complete the base.

Later that night I found some rebar in the garden and Luke and I hammered it into the concrete to give the next pour in a weeks time something to anchor too Carpet and plastic was used to separate the pier block from the observatory slab.

IMT3b – Build Part V

21st February 2021

It’s been slow going since January. Lots of cold weather, rain and broken ribs had stopped me in my tracks from concreting the pier block. However on 21st February I finally had warm enough weather and a lot of help from Luke to start pouring.

We placed some flint in the bottom of the hole to help reduce the amount of concrete needed and to push up against the chalk. We then started measuring the cement and ballast out. We used Bob’s notes from our last concreting party which was 6 x 10kg buckets of ballast to 2 x 6kg buckets of cement. The water we used a bucket with a marker pen line on and then heaved it into the cement mixer.

The first slump test was perfect. The first pour looked good too. 2 hours in and we were 2/3rds done and nearly up to the downpipes that is to be used for cabling.

Before we started I made sure the wood former was level all the way around. This makes it super easy when pouring concrete, so as long as you pour to the top of the former it will be level as we proved on the final pour.

We then took 3 pieces of rebar that were lying around the garden and placed them where the pier would go. We performed a test fit of the pier housing, some air-conditioning duck so make sure the pier was central to the block. I must at this point thank Ian Piper who’s idea it had been to put the concrete pier in. At a cost of around £50 for the material this would be far cheaper than the £1,000 pier I purchased in the past and the £500 not so great pier I purchased from Pulsar Observatories.

After just over 3.5 hours we had finished and that included the final brushing over the concrete to make it smooth. Thanks Ian for the pier suggestions, Bob for the mixer, Mark for the enthusiasm, Luke for the help, Nigel for the base design and of course Helen for putting up with me and my hobby. A good start, next stop was to concrete the dome base.

IMT3b – Build Part IV

1st January 2021

So the cable is installed in the trench visible here before I laid the ethernet.

It runs all the way across the garden to the observatory very neatly.

When it reaches the observatory, enough cable is left to feed through there pipe later and the end is terminated in an outside socket. This will be later daisy chained to several internal plug to the observatory and the outside power fixed to a new brick pier that I will build.

The next job was running the ethernet from the house. I purchased Cat6E as I also wanted to run cable to several places around the house that would require PoE (Power over Ethernet) which allows one to fix an access point without the need for an additional power supply. I started by preparing one end of the cable to be spliced and crimped given I had not done this for a few decades. I purchased the crimping and test equipment online and it seems to have worked well.

Then I laid out the wires in the correct colour format. The tricky part is getting all the wires to stay flat after twisting round each other to get them in the right order. Then to make matters worse you cut them short to much the connector on and the cables self align in slots.

Cat6e Wiring Diagram - Train Wiring Diagram - gsxr7500.deco-doe5.decorresine.it — Cat6E

The final end looks like this.

Out of interest I have posted here the access point I purchased that is PoE, I simply love it, although nothing to do with the observatory per say apart from going into the kitchen in this instance at the same time as running the cable to the observatory.

The AP does require a switch or hub or router that supports PoE, unfortunately none of the hubs that come from the major broadband suppliers ship any so I purchased the TP-Link switch that does.

To conclude this part here is the single Cat6E cable going into the AP.

So then I set about running the cable from the observatory site across the garden with an RJ45 connector ready and waiting under the tarpaulin at the vegetable patch.

Ethernet CAT6E cable installed long with power.

I then terminated the first leg of the cables journey in the woodshed where the power is connected (I plane to spur a connection to the planned Summerhouse from here in the Spring) and setup my laptop in the vegetable patch to test the connection which worked!

Before I get to the final piece of ethernet running from the woodshed to the workshop, I wanted to run the large length of cable from the workshop to the Snug. I am fortunate that a BT cable had been run back in the 90’s to the workshop when it was used as a business office. Given I had no need for a landline in the workshop I decided to use the BT cable to pull through the ethernet down the length of the underground pipe between the workshop and the house, again I am very lucky it was there!

I started to feed the cable through along with a new piece of rope I found in another duct! But I quickly found a break in the pipe located under the steps leading into the workshop.

After hours of pulling and pulling back the other way, then more pulling, my daughters boyfriend Luke (small mercies for Lockdown he currently lives with us) retrieves the ethernet cable taped to the BT cable some 100ft away.

This is the BT connection rats nest at the back of the house who’s cable I repurposed then removed, next to a bunch of electric connection boxes for outside stuff!

The saga for ethernet does not stop there, but nearly! We pulled through the rest of the cable and tacked it up the wall on the right and then along to the door where we spend hours drilling and hunting for the cable in the loft………..

Darkness falls as we finally pull the cable through into the house and into the Snug.

Ethernet cable into the loft and the house.

Here is the tight loft space where the cable runs through.

The final leg was dropping the cable into the Snug where the fibre terminates in the house from the loft. It snakes it’s way around the perimeter of the house inside the loft (I have a chalet bungalow) which took about 2 hours!

Main ethernet connection to observatory!

Fortunately I have the most understanding wife in the world who is very supportive to have her husband spend hours in the loft with a cable.

IMT3b – Build Part III

22nd December 2020

So with the site prepared I had one last check of the levels as the ground slopes away to the right thus meaning I needed to adjust the former for the central block. The dome segments can be seen resting in the background. I also used a large bag of stones to hold the former in place.

Next I cut a hole in the former for the pipework that will take the electric cable and ethernet from the house. I used some old downpipes and kitchen waste pipe I found lying around in the garden.

Here is a closer shot of the pipework that shows a 90 degree angle that all be flush with the finished floor.

Now I had to prepare a trench for the cable running from the observatory to one of the sheds across the garden. So GingerGeek and I set about digging 6″ down where the cables would lay, eventually to be covered by a slabbed path. The digging took hours, hitting rubble including glass in the ground and offending chunks of flint.

About 70 feet trench across part of the garden

Down to the left as the ground slopes away and towards the observatory location, we dug the trench round the corner. The cable would have to run under large rotes and as we found out a large sleeper buried in the ground across the opening to the vegetable patch.

Turning around standing with your back to the vegetable patch where the observatory will be sited, you can see the trench running off towards some outbuildings/sheds and a planted area that I would have to tackle next as GingerGeek had to go do some chores at home.

So it took almost as much time digging this section out as it did getting across the expanse of lawn. Routes from the Sycamore (left) and countless plants made this hard work. I then managed to get to the trellis separating the planting from the 3 sheds on this side of the garden, which I would need to go under.

Around the other side of the trellis it was very cosy to work in the tight space, old wood still awaiting collection by the previous owner meant digging was difficult, also the land raises up quite a bit this side so I had to dig the trench deeper. The hole I managed to create is shown by the red arrow. Again lots of building rubble had to be removed and I landed up on my hands and knees in the trench digging with a trowel.

So I had made it to the shed. Now it was dark and I had to wait another month before Steve the electrician would be able to fit me in. When he arrived and the armoured cable was laid and fed under all the roots, he made the connection in the existing fusebox in the shed.

Then it ran down the wall and out through a hole that was serving the existing power feed from the workshop. The woodshed is in a dire state and needs replacing, but will serve as a hub for equipment until such time I get around to it.

Next I will share where the power and ethernet cable runs and how I installed.

IMT3b – Build Part II

2nd December 2020

So now the work begins. How to turn a vegetable patch into an observatory. The first thing any good person does when moving into a house is perform a harvest! So we set about harvesting and found some rather large parsnips (which we have been having every Sunday lunchtime since) 🙂

Once done, we removed the edging boards and marked out the dome diameter using the stakes we found in the garden.

Once done I left Luke to dig the rest of the dome base out with a little help from my daughter and as you can see digging in a vegetable patch is rather easier to start with than hard ground due to years of using the land.

Dome base dug out….but what about the pier hole?

Okay, so that’s the dome base which is a nice 6″ deep. Next, which was a slightly bit more problematic was to dig out the pier base through chalk to a depth of 65cm x 1m wide. Yes I know I am mixing my scales but that is because I can 🙂

I then had to wait several weeks for the weather to improve before I could start creating the former for the hole.

I must add at this point, that despite building and installing many domes before, I sought out the experience as one should, of another astronomer and friend, Nigel, who sent me a well prepared document of contracting a concrete base, that I have used as extra guidance on this dome build.

View from above with locally sourced (in my ground) flint to be used as sub base

Next up will be more preparation for the foundations and connecting the electric and ethernet from the house some 100m away the way I have to run the cables!

IMT3b – Build Part I

21st November 2020

So after the shortest time in a house, I have now moved to a much better astronomy home, surrounded by fields and forests, ancient woodland and with some of the darkest skies in the North Hampshire Downs. I am fortunate in my location, however less fortunate that the build of this observatory, unlike my other observatories is happening in the middle of a pandemic of Covid-19. This as you will see makes it extremely hard when you can’t have astronomer friends over to help with the preparation and installation.

The move started to with the dismantling of IMT3 and in the final days at the previous house we dismantled the dome, at least at the time I could have some friends over to the garden to help with Mil Dave, Alan and Shane lending a much needed hand.

So on a quick dismantling, which was much quicker than constructing the astronomers put the dome segments on the lawn 🙂

However as I found that night when a storm front came through, which caused me and my daughters boyfriend to get up after midnight to secure the dome segments in a more wind resistance piece of the premises.

The following day Luke has had his first angle grinding lesson to take out the remains of the bolts and plugs which to be honest I think he really enjoyed.

Then the moving day came and I put all the important scientific astronomy equipment in my old Landy to make sure it got there safely.

whilst the rest of the observatory went in a further truck kindly supplied for free by our removal company who are the best removal company ever! Thanks Camberley Removals!

By mid November, some 4 months after we accepted an offer on the house I landed up with my new more astro friendly observing location surrounded by fields.

Next up is removal of the local vegetation and preparing the ground for concreting.

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