DIY Laser levelling using webcam and laser level

[JAZZCNC]

Quick question have you checked the end float of this trim router.? I've had quite a few of these trim routers and they are not the best-built things so I wouldn't be surprised if it didn't float more than the Um values your chasing.? . .Esp trying to mill steel with it.!

The frame doesn't look that large do you know anyone with a large surface plate could fit it on. If so then I'd suggest you use Metal Repair paste, like Belzona 1111. This is the method I use for machines that will fit on my surface plate. Better than Epoxy and about the same in costs. It can be Drilled and tapped easily and as strong if not stronger than the metal it's bonded onto. Isn't too fussy about temperatures and they even have types that can be used underwater or subzero temperatures. Dry's in hours not weeks.!

https://www.belzona.com/en/products/1000/1111.aspx

[devmonkey]

Quick question have you checked the end float of this trim router.? I've had quite a few of these trim routers and they are not the best-built things so I wouldn't be surprised if it didn't float more than the Um values your chasing.? . .Esp trying to mill steel with it.!

The frame doesn't look that large do you know anyone with a large surface plate could fit it on. If so then I'd suggest you use Metal Repair paste, like Belzona 1111. This is the method I use for machines that will fit on my surface plate. Better than Epoxy and about the same in costs. It can be Drilled and tapped easily and as strong if not stronger than the metal it's bonded onto. Isn't too fussy about temperatures and they even have types that can be used underwater or subzero temperatures. Dry's in hours not weeks.!

https://www.belzona.com/en/products/1000/1111.aspx

Yeh I checked it with a DTI, if there is end play it is less than 10um so hopefully it will be ok. The little router seems quite happy with steel, I only need to take off about 1/4mm. The best approach is to use masking tape to shim the router off the plate by the the thickness of the tape, cut the surface, then remove the tape and re cut, cutting loads on the 'finish' pass are almost nothing as only taking off a tiny amount of material. I've tested this on a bit of scrap flat bar and it leaves a flycut quality finish, shiny.

I did ask my mate who has a precision machining shop if he would be happy to surface mill the whole thing, he said he would but there is a long queue and since it is run like a clean room for doing some specialised parts I don't think he was overly keen me on me dragging in a great lump of dirty steel ! Good idea with taking an impression of a surface plate, I don't know anyone locally with one though other than him.

If I screw up this optical levelling I might go back to him, there will be enough material left for surfacing.

I've fixed the problem of my compressible work bench by removing one frame of reference, laser is now fixed to a lump of box tacked to the frame:


EDIT
That metal repair paste looks fantastic, it is epoxy based as well unlike the polyester rubbish I have here.

[JAZZCNC]

That metal repair paste looks fantastic, it is epoxy based as well unlike the polyester rubbish I have here.

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.?

[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?

[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.

[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]

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