DIY Laser levelling using webcam and laser level

[devmonkey]

Anyone who used to work down a mine will probably remember Belzona, it was a common and came in a sausage shape plastic packet about 12" long with hardener down the side. You cut it down the middle and mixed it straight away, you had about 10mins before it set like concrete. When I was a young mechanic just about every miner's car in yorkshire had some in the sills or chassis used as filler..Lol

It's come along way since then and the current Belzona is amazing stuff, esp the ceramics. I accidentally used some by mistake and while it was only 3mm thick it hate quality jobber drills for breakfast.

Got a question about this Laser setup.? How wide a beam can it throw and still be accurate.? Could it, for instance, cover a 6mtr x 4mtr area.?

So the way to think about it is as a bunch of rays leaving the laser, each will travel in a straight line. If the optics are good then all these rays will also lie in a plane forming a line on whatever vertical surfaces they hit. I haven't tested the straightness at that distance only that it can be focused to a tight beam at around 10m.

One thing you could try with your large surface plate is setup the laser on the plate, take a bunch of readings in a 1m radius with the sensor sat on the plate, this will tell you whether the laser is planar and if not what the error is for each arc segment, i.e. you can calibrate the optics. Then you can project this error as far as you like to whatever you are actually measuring.

The biggest issue will be whatever you mount the laser on will have to be really solid as just 1 arc second of wobble on the mount will be 0.05mm at 10m. One solution to this is using differential measurement like they do with electronic precision levels, setup one or more fixed sensors and use these to offset any error caused by you breathing near the laser ;-)

This is the part of the system I'm really struggling with. With my laser mounted on that piece of box section with sticks out 400mm from the machine, reasonable finger pressure
is sufficient to bend the box section enough to cause a ~10um deflection in the height of the beam at the other end of the machine say 1.5m away.

When looking at this stuff where the sensor is measuring 3um pixels everything looks like it is made of jelly, at least everything in my garage including the 6 inch concrete slab.

What are you planning that is so large?

[driftspin]

Anyone who used to work down a mine will probably remember Belzona, it was a common and came in a sausage shape plastic packet about 12" long with hardener down the side. You cut it down the middle and mixed it straight away, you had about 10mins before it set like concrete. When I was a young mechanic just about every miner's car in yorkshire had some in the sills or chassis used as filler..Lol

It's come along way since then and the current Belzona is amazing stuff, esp the ceramics. I accidentally used some by mistake and while it was only 3mm thick it hate quality jobber drills for breakfast.

Got a question about this Laser setup.? How wide a beam can it throw and still be accurate.? Could it, for instance, cover a 6mtr x 4mtr area.?

Hi Jazz

Well, i think we arrived at the point were the cheap cam +software used as a levelling sensor proved it is very good.

The new problem is the lens you use to spread the laser into a beam....

The projected line can be a non straight because of the deviations caused by the optics used to spread the beam.


Does that summarize it?

I plan to use it to level check Y and X 1 axis at a time in the axial direction where the line is straight. First for vertical then horizontal deviation. maybe the diagonal

After that i will see...

Not sure how to do Z yet.

My laser crosshair only aligns in 1 orientation. +/- 0.8 mm /mtr out of plum
according to factory spec.

So Z could stil be non straight


Grtz Bert.



Verstuurd vanaf mijn SM-A320FL met Tapatalk

[devmonkey]

There is an optical lab a few miles from my house and it has been built into a cave at the base of a rock cliff at the back of a disused quarry, presumably to reduce these problems with flexing buildings and temperature. It is literally behind a steel doorway set into the cliff.

[devmonkey]

Hi Jazz

Well, i think we arrived at the point were the cheap cam +software used as a levelling sensor proved it is very good.

The new problem is the lens you use to spread the laser into a beam....

The projected line can be a non straight because of the deviations caused by the optics used to spread the beam.


Does that summarize it?

I plan to use it to level check Y and X 1 axis at a time in the axial direction where the line is straight. First for vertical then horizontal deviation. maybe the diagonal

After that i will see...

Not sure how to do Z yet.

My laser crosshair only aligns in 1 orientation. +/- 0.8 mm /mtr out of plum
according to factory spec.

So Z could stil be non straight


Grtz Bert.



Verstuurd vanaf mijn SM-A320FL met Tapatalk

Hi Bert,

The optics should be better than that even for a crap laser, usually the quoted accuracy is out of plum as you say, this is error relative to whatever reference the laser is bolted to, i.e. a pendulum usually, this is not usually a measure of how 'straight' the projected line is.

Cheers, Joe

[JAZZCNC]

What are you planning that is so large?

Large double gantry machine for cutting and polishing granite and marble slabs. The two Gantry's will be mounted on linear rails which are basically fixed on top of a high wall on adjustable stainless steel plates. Accuracy to the Micron level isn't required but still needs to be reasonably good for the polishing.

[devmonkey]

Large double gantry machine for cutting and polishing granite and marble slabs. The two Gantry's will be mounted on linear rails which are basically fixed on top of a high wall on adjustable stainless steel plates. Accuracy to the Micron level isn't required but still needs to be reasonably good for the polishing.

Sounds like a proper installation!

I can only suggest you pick up a laser and try it, or even just borrow a rotary laser from a local builder or window fitter.

[JAZZCNC]

Sounds like a proper installation!

I can only suggest you pick up a laser and try it, or even just borrow a rotary laser from a local builder or window fitter.

I know a few machine installers who use lasers for large machines and lathes so I'll probably speak with them when the time comes. It's a long way off yet and could change in design before then so will see.

[m_c]

Sounds like a proper installation!

I can only suggest you pick up a laser and try it, or even just borrow a rotary laser from a local builder or window fitter.

Jazz will need something far more accurate than the cheap rubbish your typical builder will likely have.

My parents neighbour is a highly regarded surveyor, and has many tales to tell about builders and cheap kit. One was a job to do an independent inspection of a private swimming pool, which after being filled with water, had a 4" height difference between ends.
After a bit questioning, it came to light the builder had used a 'precision' laser to do the setting out, as lasers are "accurate" and less hassle than using a basic water level (aka a bit clear hose). Turned out his 'precision' laser was a special from Screwfix that had never been calibrated, but the builder was really pleased with it as it only cost him a couple hundred pound.
As the neighbour highlighted to him, it had just cost him far more than a couple hundred pound, as the whole swimming pool was going to have to be stripped out and redone.

[devmonkey]

Jazz will need something far more accurate than the cheap rubbish your typical builder will likely have.

My parents neighbour is a highly regarded surveyor, and has many tales to tell about builders and cheap kit. One was a job to do an independent inspection of a private swimming pool, which after being filled with water, had a 4" height difference between ends.
After a bit questioning, it came to light the builder had used a 'precision' laser to do the setting out, as lasers are "accurate" and less hassle than using a basic water level (aka a bit clear hose). Turned out his 'precision' laser was a special from Screwfix that had never been calibrated, but the builder was really pleased with it as it only cost him a couple hundred pound.
As the neighbour highlighted to him, it had just cost him far more than a couple hundred pound, as the whole swimming pool was going to have to be stripped out and redone.

LOL, my swimming pool is within 2-3mm when full and I used a cheap dewalt laser when I pumped the concrete for that, your eyeball can tell 4" at the length of the pool. Anyway you are confusing the pendulum laser alignment error with the optical error, quite different things, surveyors only care about the former. Similarly a window fitter, specifically someone who fits bespoke bi-folds will have a laser scanner for scanning the openings as the units are manufactured to fit.



Still would have required some shimming to attach linear rails rather than sandstone ;-)

[JAZZCNC]

Jazz will need something far more accurate than the cheap rubbish your typical builder will likely have.

I agree Moray, my experience of builders laser level hasn't left me blown away either.
If this build happens then I'll look deeper into laser leveling and probably go hire the equipment I need or get one of the guys I now in when setting up the rails.
To be honest the precision doesn't need to be super high because one gantry will be used with Circular saw attached so no great accuracy required at all. The other will be mostly 2D profiling and edge molding using special profile edge tooling and polishing heads. Only making Kitchen countertops so flatness isn't to precision levels and most of the finishing is done by hand. At the moment all of the cutting, shaping, and polishing are done by hand so will be a massive improvement. They just need to save up some penny's or speak nicely to bank manager...Lol