DIY Laser levelling using webcam and laser level

[devmonkey]

80K for a hole in the ground, they must be on drugs. To be honest, I wouldn't pay 11K either, living in Yorkshire we are surrounded by dozens of old Pit sites and brickworks which all had great big clear blue ponds(well not all clear blue.!), which as kids we lived in. most are still there and know nature reserves or fishing ponds so who needs a heated swimming pool... Lol

Everything with swimming pool in its name has a 10x price multiplier. The guy to fitted the liner has a 'swimming pool liner vacuum pump' to suck the plastic liner onto the pool shell, this machine cost him £2k. It was a £60 machine mart dust extractor fan like we use in our workshops with a nice stainless steel pool company badge plate riveted over the 'Clarke' label, unbelievable.

[Clive S]

a 39KW air sourced heat pump which has a COB of about 10-15, you put in 3kw of electricity get out 30kw of heat

I would be interested in the make and model of the air sourced heat pump as I thought that they were only about 3-4 times the input.

[devmonkey]

I would be interested in the make and model of the air sourced heat pump as I thought that they were only about 3-4 times the input.

Here you go,
https://www.heatpumps4pools.com/prod...ol-heat-pumps/

"Excellent COPs – from 5.8 to 15.8 due to Inverter technology"

Depends how hot the air is relative to the water temp, I don't think you can expect the same when you use them to heat your house in the winter as some people are starting to do. Mine is the 27kw single phase one, not 39kw as I originally posted, brain glitch. Once up to temp it just runs at tick over for most of the summer and stops all together on hot days.

[Kitwn]

Here you go,
https://www.heatpumps4pools.com/prod...ol-heat-pumps/

"Excellent COPs – from 5.8 to 15.8 due to Inverter technology"

Depends how hot the air is relative to the water temp, I don't think you can expect the same when you use them to heat your house in the winter as some people are starting to do. Mine is the 27kw single phase one, not 39kw as I originally posted, brain glitch. Once up to temp it just runs at tick over for most of the summer and stops all together on hot days.

Over here it's called 'reverse cycle air conditioning' you can either heat or cool your house depending on the season. Heating is no good when it's so cold the outside unit freezes up but in more temperate climates like most of Australia it works well. If you need air-con for the summer anyway it's a cost effective heating system to install and to run.
OK, back on track

[Clive S]

Here you go,
https://www.heatpumps4pools.com/prod...ol-heat-pumps/

"Excellent COPs – from 5.8 to 15.8 due to Inverter technology"

Thanks for the feedback. But it also states this

"Bear in mind though that there is no international standard for stating COPs and therefore each manufacturer will state the maximum COP obtainable for their units under optimum temperature and humidity conditions. In reality you may not therefore always acheive the COP rating stated."

I have been involved in installing a few heat pumps air source and ground source and I believe that they were in the region of about 3-4 to 1. My next door neighbour has had his gas taken out and put in an air source pump. I am very interested to see the results over time.

[devmonkey]

Back to the job in hand.

I found a rather obvious flaw in my sensor setup for setting my routing jig into plane today. I have the sensor mounted in a nice true cube and this sits on the jig plate. I then alternate its position above the 3 levelling points bringing each up to the correct height with the jack screws. The problem is unless the sensor is positioned in exactly the same location at each point for subsequent rounds of this procedure you will get different readings. This is because the sensor is effectively rotated around the axis of the jack screw and since the plate is not yet planar to the laser the height of the sensor relative to the laser plane changes based on this rotation. This makes it bloody difficult to do, and it is not until the plate is planar with the laser that sensor reads the same height right across the plate.

To put it another way with the sensor sitting on a plate that is not planar with the laser if you rotate the sensor about any point that is not the vertical axis of the sensor chip itself then the reading will change since the height has changed, similarly if you slide the sensor up and down this plate the height reading will change. This means you can trick yourself into thinking the heights are zero'd by moving the sensor, which I noticed I was doing.

There are two options:

1. Machine up a new sensor mount with some mechanism (likely a dowel pin) inline with the vertical axis of the sensor to that can be used to relocate the sensor consistently at 3 points across the plate.
2. Use 3 sensors simultaneously (would need software change) each fixed to the plate for the levelling operation.

[Kitwn]

Thinking out loud, but is there a three-sensor option that works the the other way round? Set up three sensors around the router frame and firmly fix the laser in one position on top of the moving plate. only the plate needs to be moved and adjusted for constant numbers out of the sensors. No trailing wires from the plate to tread on either. This does require the design to allow the laser to stay in place during routing or to be accurately replaced between cuts.

[Kitwn]

As I said, the limiting factor on air-sourced reverse-cycle air con for heating is when the outside temperature is so low that the external heat exchanger freezes. In the UK I would expect you'd need some additional heating system for the coldest parts of the year (September to May in Cumbria if I remember correctly). In Perth (The Australian one rather than the original) we had a few occasions when the heat exchanger froze but but not many. A well insulated house obviously makes a big difference. It's been a while, but I think that unit used 4kW of electricity for the equivalent of 14kW of heating.

[devmonkey]

I have realised something about these sensors. They are colour sensors, and the colour detection is done by layering a grid of colour alternating RGB filters over the individual pixels which are all identical photodiodes (i.e. the pixel is monochrome) in what is called a Bayer pattern. These are laid out to match the human eye's response to colour, with 50% of the pixels green and 25% red and 25% blue. See https://en.wikipedia.org/wiki/Bayer_filter



This isn't ideal as I'm using a red laser. This means only 25% of the pixels are useful and the sensor will be interpolating the values between 'red' pixels.

Anyway someone pointed me towards some super crazy people in astrophotography who 'de-bayer' their very expensive DSLR sensors with a toothpick so the sensor becomes monochrome at its native resolution, effectively scratching off this colour filer layer to expose the raw sensor.
https://stargazerslounge.com/topic/1...-bayer-matrix/

I have just tried this procedure and ruined a webcam sensor (ripped it off the pcb) so I don't recommend it.

EDIT
The first casualty of this miss-adventure, don't think it is still worth £7 !

[Desertboy]

I have realised something about these sensors. They are colour sensors, and the colour detection is done by layering a grid of colour alternating RGB filters over the individual pixels which are all identical photodiodes (i.e. the pixel is monochrome) in what is called a Bayer pattern. These are laid out to match the human eye's response to colour, with 50% of the pixels green and 25% red and 25% blue. See https://en.wikipedia.org/wiki/Bayer_filter



This isn't ideal as I'm using a red laser. This means only 25% of the pixels are useful and the sensor will be interpolating the values between 'red' pixels.

Anyway someone pointed me towards some super crazy people in astrophotography who 'de-bayer' their very expensive DSLR sensors with a toothpick so the sensor becomes monochrome at its native resolution, effectively scratching off this colour filer layer to expose the raw sensor.
https://stargazerslounge.com/topic/1...-bayer-matrix/

I have just tried this procedure and ruined a webcam sensor (ripped it off the pcb) so I don't recommend it.

EDIT
The first casualty of this miss-adventure, don't think it is still worth £7 !

I managed to buy a monochrome webcam years ago, it was expensive over £200 and I had to buy it from China has highly specialised.

It only saw Far Red (Near Infrared) specifically to see phytochrome reactions in plants.