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My home made DIY Stevenson screen
As part of my larger weather station project, I’m also building little extras to go with it, or add onto it and increase the functionality of the weather station. One of the components which is useful is a Stevenson screen. I could easily buy a Stevenson screen, however the ones for sale on websites are actually miniscule in size (about 1.5″ internally and 10cm high).
Here are some examples on Amazon of different Stevenson screens.
I personally tihnk my Stevenson screen is nicely balanced, it’s a good height. There’s plenty of room internally to work with and it’s constructed solidly. I can also customise it how I want. I’ve built in a dome to enable me to have a star/sky camera for Astrology and viewing the nightsky, and I also plan on fitting solar panels to use with the battery backup module. However, this project is custom built to my Stevenson screen though, so it suits me because it was priced similarly to the below, and customisable to suit my needs
Whilst you don’t fit many sensors, I still wanted something not only beefy in size, but plenty of room internally to work with. I have boulder like hands, so need something room that doesn’t cut up my hands when I’m working. Commerical screens are also more expensive, and the cheaper ones are also small. So figure I’d build something for a similar price.
What materials did I use to make my Stevenson screen?
I purchased the following materials for my home DIY Stevenson screen for my weather station project
- 7 x 8.25″ Recycled Plastic Plates from Asda (£9.45) normal price £2.25, on sale for £1.35
- 1 x 1 Metre M8 Threaded Rods from Toolstation (£2.80)
- 1 x 3M 15mm Plastic Tube from Toolstation (£5.78)
- M8 nuts and M8 washers from Toolstation (£5.74)
- 1 x 10 pack of M8 dome nuts from Toolstation (£2.79)
- 4″ Acryllic Glass CCTV Dome from eBay (£5.24)
This made up the basic items I needed to make my own Stevenson screen for my project
How much did it cost to build the Stevenson screen?
The total price it cost me to build my Stevenson screen, excluding any left over parts or tools I had to buy was £31.80
This price will be different if you need to buy tools. The amount I spent was higher because this was a project and I needed tools and wasn’t sure what I would need as my designs were constantly changing. Alternatively if you have the time you could substitute tools for doing all manually (drilling holes and manually cutting with saw for example) rather than using a hole saw. You realistically could built this with nothing more than a Drill + Bits, Pliers and a Hacksaw.
Construction of the DIY Stevenson Screen
The design I wanted was in my head for the Stevenson screen, it was going to white as recommended to maintain a stable temperature. It would be spaced out and constructed on the cheap. I used plastic plates for this, and bought a couple of materials for the construction. I then used hole cutters to make up space internally within the plates as a working area, drilling holes for mounting the spacers and threaded rod.
This is how I made my own Stevenson screen to the form I wanted it to resemble (the final form is how I pictured it) I actually have a drawing somewhere
I don’t think you will be able to find these anymore, but these were the plates that I purchased from Asda with their barcode number if it helps anyone finding them and Asda have any more in stock. My final design was meant to use 12 plates with a smaller gap in between. Designs change however, I had to adapt it when there was only 7 more plates left in stock, so I purchased them all and changed the design to have larer gaps in between.
The plates themselves aren’t perfectly level of lign up properly, so there is always going to be a margin of error when drilling them
The best solution I could come up with was to put the plates inside a box to get some sort of alignment to them. As the plates weren’t all perfectly straight to start with I worked with the best method possible to lining them all up. I actually used a larger than normal drill bit, and expanded the holes bigger than needed to provide a bit of “flex” to help align the plates. This worked out well because it give me a little wiggle room to work with.
The top plate was going to be my template for everything else, so I drilled the holes on this first. I know the holes are not equally spaced, it doesn’t bother me. After drilling the holes I wanted for the Skycam plate, I decided to use this as a template for the othre plates. At least so it could be some form of guidance when it came to mounting them. I tried to get the alignment as close as possible, as this is an amateur project however, the end result as long as it’s close enough is more than acceptable. I marked the holes with a marker, then drilled through them on the other plates.
The top plate of the Stevenson screen has a 3″ hole cut into it, this allows me to mount the Acryllic Glass CCTV dome to the plate, so that I can point my Skycam up to records the clouds / stars / night sky. There is a plate without holes under neath this, so that it gives a solid mounting plateform for the camera and to protect the sensors inside
For mounting the Skycam dome, I had to measure how big it was. It’s meant to be 4″ but this is accurate, the actual internal size of the dome is around 97mm, half of this is 48.5mm. I measured 48.mm for the dome, then used a compaass to draw a circle template to cut out. This was the internal size (I actually reduced this down to 45mm (22.5mm per side) for a bit of leeway
I cut out small sections at a time after marketing underneath to get the right size I wanted. The reason I had to do this was to identify the points that I needed to drill holes in. Test fitting the Acryllic Glass CCTV dome over where it would be mounted on the top plate. I need to cut out some more room internally for the camera to be mounted, but this was just a test fit to see how it would all look.
Using the drill and a smaller bit, I drill holes in the Acryllic glass dome where the screws are normally mounted for the CCTV lens
I already had the screws for this as I purchased them previously as I knew they would do great for little projects. I used an screw nut and washer that was long enough to fit through the dome and the plate; but also small enough so that after tightening there would be nothing poking through the other side of it. I have a small toolkit which I used to tighten the nut
After drilling the holes for the plates and CCTV dome I test mounted it underneath with smaller screws from the assortment that I had. I still need to add an o-ring, or silicone sealant after painting it for a weather proof seal, but this will be done at a later date on the Stevenson screen
The rest of the plates inside the Stevenson screen all have 100m holes inside them for storage space for the main equipment and sensor boards, barring the bottom plate and the camera cover plate (plates 2/7)
One problem with a hole saw, and plastic plates is that it makes a LOT of mess. Hoover is heavily recommended when doing this stuff
I then used my Dickie Dyke plastic shears that I purchased from Toolstation, I used these to cut out some equal length spacers made of plastic pipe. These perfectly fit the M8 threaded rod, and I used the edge of the cutters, so that each piece was of a universally similar size. It doesn’t have to be 100% accurate, just close enough when chopping them up.
After I cut them up and when I did my first test mounting, I found the gap between the plates was too high and didn’t create a small enough gap that I wanted for protection. I planned to mount 2 of these between each section to create around a 25mm gapb between the plates, in the end I cut some newer pieces which were about 5mm shorter to produce the end result in the last picture.
These are just to keep the plates evenly spaced out to allow airflow through them.
With regards to a Stevenson screen, there is actually a proper formula which determines the space required between the louvres based on how much airflow that will be going over there. However I didn’t look into this; first I have upside down plates, second this is an amateur project. I don’t care that much to worry about it. It’s a science experiment
After drilling the holes in the plates. I then just had to mount them onto the threaded rods and spacers. The rods giving the structure strenght. Test assembly of my idea when I first thought of it. I don’t have all the rods and spacers in here, so it looks more lopsided than usual. I just wanted to visualise the idea to see if I liked it
I partially assembled the Stevenson screen by putting spacers between the plates and mounting them all on the threaded rod in between them. When I first made it, I wasn’t sure how long I’d need the rods (hence why I brought more in the first place). After I assembled them I had an excess. I then marked these so I knew how much to cut off.
The main problem I had was that I wanted to purchase rigid plates like this, but I wanted them to be white. I had difficulty finding the ones I wanted, so in the end I just purchased them from Asda, and simply plan on scuffing them up dip them in gloss paint and leave them in the shed to dry for a few days. We’re not going for perfection here, I could have left them, but wanted something which resembles a Stevenson screen at least.
The bottom plate of the Stevenson screen doesn’t have any holes in it, I will be installing a 20mm gland at the bottom which gives access to all the cabling and sensors that need to run through to the computing and recordng equipment. This will also carry the 12v Battery backup power source for longer external runtime. The actual bottom plate is what I’m going to be mounting the sensor board to so when removing the bottom plate it instantly removes the weather board for servicing.
The rest of screen doesn’t fall apart, as I fitted M8 nuts over the spacers to retain it’s shape on dismantling it
One of the things you can’t see in the final design, as I changed it a few times. I decided to mount extra nuts onto the Stevenson screen. The main parts of the housing are held together with their own screws, and the top cover for the sky camera dome, and the base plate are held in seperately. This allows me to service it by taking apart to access the inner sensors, and the top camera without the entire thing falling apart.
I didn’t like the look of the threaded rods on show on the top of the Stevenson screen so I changed out this design to use some M8 dome nuts instead. They will be painted white when everything is finally finished, but I wanted to have something which matched the look of it rather than something angular sticking out the top.
What is left to do with my Stevenson screen?
This isn’t the full project I still have a few things I need to do, but I’m documenting it all as I go. Just for others to learn with me.
The next few things I wanted to do with my Stevenson screen that still need to be done yet. As I need to buy the materials as I go
- Paint all parts white (nuts, rods, spacers) and leaving just the dome clear with a silicon seal
- Create mounts for the sensor board. I’m thinking maybe a clamp for the bolt
- Glue the spacers onto the plates
- Get my Hikvision camera (or a camera working) to use with the starcam
- Build a DEW heater for the dome
- Create mounts for the solar panels
Probably a few others I haven’t thought of yet, which I’ll be documenting in my weather station project post.
What equipment is housed inside the screen?
A Stevenson screen is primarily used to protect sensors, which needs access to the elements, but not direct sunlight. These are normally Barometers, and Thermometers.
I will be housing the main circuit board itself in this (if I have room), and a couple of sensors which need access to the outside but protected from the elements. I’d like to cram the system with as much info as possible, then experiment with data logging to a small PC.
Ideally I want to data log the results to a local database, then upload those results to my website via a connection which updates every so often. The data logger PC should have enough room to store approx 1 year of readings (maybe more) for at least 15 sensors taking readings araound once every 30 secs and writing the results to a database or CSV file
This would equate to following readings (as a guesstimate)
- 60 per minute
- 3600 per hour
- 86400 per day
- 31536000 per year (31.56m)
If each reading is a 1KB write, this would create a file around 40gb? in size (I’m still doing off top of my head here so it could be inaccurate), just adjusting on the fly like I wrote below. Plans change, so just adapt.
What should you remember making your own Stevenson screen?
I decided to make note of a couple of things that cropped up in my head when building this design. If you only have a limited number of plates or bowls, the last thing you want to do is screw something up when making your STevenson screen.
Forward plan your design first and recheck it
The build I had planned in mind initially had a CCTV dome for a Skycam at a later date. One thing to consider however was that whilst there needed to be a hole in the plate for the Skycam. The plate underneath had to be blank, as the sensors internally in a Stevenson screen are meantt o be hidden from direct sunlight and also protected from the elements as this is their purpose.
I planned out my design of 7 plates like the following
- PLATE 1 – CCTV Dome (hole inside for Camera)
- PLATE 2 – No hole (protect internals from direct sunlight)
- PLATES 3 to 6 – Larger holes to access internals for sensors
- PLATE 7 – No hole
I considered that if I use the more commerical night sky cameras, I may need more room. I planned on using my Hikvision 1080P CCTV dome camera as this was spare. I will also however need to work out the connection protocols and shutter controls to see if it works. If I use one of the more common cmaeras, I may need more room internally for mounting. Some of them can be up to 15cm long. This is also why I kept one plate free, because I could simply swap them around internally and create a larger gap. I’d loose room for the sensors, but I can easily adapt this since they’re sensor boards and just wires.
Remember to adapt
If your design or plans change, or your required materials change. Adapt it to suit the purpose it’s for.
I hope you enjoyed the article, keep following for more.
