Mini/micro patio

Associate
Joined
11 Dec 2020
Posts
6
When most people think of a patio or a driveway, they are looking at an area of 10’s or 100’s of square metres. I want to make three mini/micro patios. I should explain, I’ve not completely “lost the plot”, rather, I’m trying to improve on what I have, lawn or patio.

I have a telescope the has a mount/tripod that weighs about 60 kg. The tripod has three pointed feet which can be placed on the lawn, on a patio, on a driveway etc. It is also possible to remove the tripod and replace it with a pier that’s concreted into the ground. It turns out that the best position is in the middle of my back lawn and “local planning restrictions” aka SHMBO is not keen/convinced about a pier.

I have tried comparing the use of the scope on the patio and the lawn. On the patio, the vibration from someone moving can be “seen” as it seems the patio may not be laid most effectively. On the grass, there is little vibration, but the legs of the tripod will eventually settle/sink in, and the alignment at the start, starts to shift e.g. 1mm up/down is a "big deal" on a leg.

I have three pavers 160mm x 160mm x 50mm (about the size of a small NUC/mini PC?). The issue is how to fix them firmly on my lawn. Originally, I was going to put a large patio slab under each paver. I now realize that this would be a bad idea as walking nearby will cause the slap to shift/vibrate and maybe just the MOT is better, especially if I slightly increase the size of the pavers (260mm x 240mm), to spread the load and increase stability. The paving slab adds very little and contributes to transmitting vibration.

What would be a reasonable depth of MOT and/or sharp sand/mortar to put underneath, to create the most stable setup? I thought maybe covering an area that overlaps a paver by a couple of inches. The scope is connected/controlled/processed by computer, so “seen” is in the context of "images" that are either accepted or rejected.
 
Associate
OP
Joined
11 Dec 2020
Posts
6
I found out that MOT is the secret to getting things to bed-in. If it works for a driveway then it can work well for isolated pavers too.
 
Soldato
Joined
14 Jan 2018
Posts
11,135
Location
Hampshire
You'll still get vibrations if you walk near the scope. The ideal is a pier with a solid foundation that is isolated from the floor around it like you see in observatories.
 
Permabanned
Joined
22 Oct 2018
Posts
2,455
I have not a clue but what I would do is fill a four inch waste pipe with concrete, dig a hole 6" deeper than the pipe is long, fill it with mot to a depth of 6" then place the pipe in and fill the rest of the hole with mot until there is enough room left for a bit of soil and grass and the pipe is about level with the grass. That way the concrete filled pipe is completely isolated by the mot. The concrete pipe forms the foundation for anything you need on top. If you need bigger than the pipe then you can sort some other way of doing this, perhaps filling the hole with mot, digging a hole in the mot then use a bin liner in the mot to place concrete in. You just need a barrier inbetween the concrete pour and the mot to stop the concrete getting in to the mot and spoiling the isolation.
 
Associate
OP
Joined
11 Dec 2020
Posts
6
You'll still get vibrations if you walk near the scope. The ideal is a pier with a solid foundation that is isolated from the floor around it, as you see in observatories.
Yes, they use heavy slabs e.g. 60cm x 100cm x 100cm was recommended for a steel pier, with a 15cm (5cm above the ground and 10cm below the ground) slab recommended for an observatory base.

A simple pier using two upended hollow blocks can be successful, but also requires a reasonable slab e.g. 40cm x 60cm x 60cm. For these, the isolation is the ground surrounding it.

The lawn in a garden is quite effective at isolating vibration and it dampens a tripod. It can be the exact opposite of a patio that transmits vibration and doesn't stop ringing in the legs.

Where the ground isn't quite so good, is preventing the legs from shifting and sinking in. One solution that is often used, is to carry some wooden squares/tiles.

One interesting idea used upended flower pots, filled with concrete, "planted" in the lawn. The drainage holes provide registration for the tripod legs and the same spot can be relied upon. All that is seen is three small bases with the drainage holes level with the grass.
 
Associate
OP
Joined
11 Dec 2020
Posts
6
I have not a clue but what I would do is fill a four inch waste pipe with concrete, dig a hole 6" deeper than the pipe is long, fill it with mot to a depth of 6" then place the pipe in and fill the rest of the hole with mot until there is enough room left for a bit of soil and grass and the pipe is about level with the grass. That way the concrete filled pipe is completely isolated by the mot. The concrete pipe forms the foundation for anything you need on top. If you need bigger than the pipe then you can sort some other way of doing this, perhaps filling the hole with mot, digging a hole in the mot then use a bin liner in the mot to place concrete in. You just need a barrier inbetween the concrete pour and the mot to stop the concrete getting in to the mot and spoiling the isolation.
Yes, concrete will be "next on the list" and MOT is a good material to level things and provide stability.

For now, I'm going to stick with the three pavers 160mm x 160mm x 50mm, and MOT to provide a firm base. The surrounding lawn will hold the pavers, but not too firmly. So not entirely different to someone turning up with a tripod and some wooden pads to spread the weight!
 
Permabanned
Joined
22 Oct 2018
Posts
2,455
Yes, concrete will be "next on the list" and MOT is a good material to level things and provide stability.

For now, I'm going to stick with the three pavers 160mm x 160mm x 50mm, and MOT to provide a firm base. The surrounding lawn will hold the pavers, but not too firmly. So not entirely different to someone turning up with a tripod and some wooden pads to spread the weight!

Yes. I remember my "optical days". Or an optical bench to be precise. Basically a giant slab of rock to "resist" vibrations which was isolated from the planet by a floating air system. Not very practical for the back garden but it's basically what you need too. I can't think of a cheap material to replace the air flotation system other than mot that is garden proof.
 
Associate
OP
Joined
11 Dec 2020
Posts
6
Maybe a long shot, but how about the rubber tiles you can get for playgrounds?
I have seen them 500mm x 500mm x 50mm
https://www.dflectrubber.co.uk/product/dflect-500/

actually thinking about it, rubber may help with ground vibration but as its not completely solid will probably introduce its own vibration
Rubber is used for isolation. A tripod can need damping and rubber isolation pads are sometimes used, so if you had a tripod on a patio and walked nearby, some vibration would get through to the tripod and the rubber absorbs and dissipates the energy.

A lawn and the ground underneath also provides isolation so it isn’t necessary to isolate the ground under a tripod from the area around it e.g. no need for anything too fancy - no barrier required.

My 3 pavers are deliberately quite small 160 x 160. Big enough to spread the weight of a tripod spike and so providing a stable and flat footing especially as they will each be on a bed of MOT.

I’m just unsure if there is any value on using mortar around it to anchor it down. The edge of the lawn will restrain it and so there probably isn’t much point in using mortar. A spike is over the middle of the paver so it presses directly down. The small area means that nobody gets to stand on the edge and disturb it.

The second issue was electrics. I do have an RCD but I still want to keep electric sockets and dew to a minimum. I’m using a dry box and avoiding having it plugged into an extension reel socket. The boxes can be used to put sockets away from a damp environment and I do have a couple of sockets inside. The box is however filled with other “stuff”, 3 PSU and a wireless extender. The dry box has a cable entering and the other end has a plug that is in a waterproof housing on the side of the house. Key feature is no plug/socket near the scope.
 
Top Bottom