Home made laser level

[micky]

But easy enough to check. Set the laser on each side and see if it points to the same spot on the wall in each case. Then figure out how to align it.

[Robert]

On May 14, 3:38 pm, [e-mail] wrote: cademic.

Actually, Einstein's theory of gravity bending the path of light rays to a detached observer was proven by seeing the "jump" of the light from a distant star as it passed near our sun during an eclipse. The position of the star shifted abruptly as the light ray followed the bend space coordinates caused by the sun's gravitational field...... then shifted back abruptly as the path moved away from the sun. Hence, the light to a distance observer appeared 'bent".....

[harry]

Yes, I've read that somewhere.

[krw]

Actually, no. Gravity bent space itself. You are observing artifacts of that.

[gregz]

Surfaces can release heat and will bend beams by refraction. I have not found a use for a ruler laser, but I do have a self leveling laser from HF. I use it in low light. I've measured beam sag, and I built my elevated deck using that laser. I did try the water hose. It worked ok. Seemed like more work when looking at multiple points at the same time. I also use the dual beam HF laser to set angles and dimensions on basement upgrade.

Greg

[repairs]

If you take a hose and run it from New York to California and fill it with water, it will NOT be level due to the roundness of the earth.

Better yet, try going from the North pole to the South pole. I can guarantee it wont work.

[repairs]

That would have worked in the 20th century or before. But in the 21st century you would be arrested because a mouse, fly, or bird got killed from the gunshot. And the shooter would be charged for being a terrorist, and would have to face the FBI CIA and Dept of Homeland Security. They would search the entire construction site for bombs, and other weapons and explosives. Then a team of psychiatrists would have to evaluate the shooter, and 20 years of mental health care would be required after the prison term. In the meantime, all schools, shopping malls and gas stations within 200 miles would be placed on lockdown for several weeks. Then the NRA would write a lengthy article boasting their presence and state that guns should be used for all construction projects.....

[repairs]

There is no guarantee that the cheap laser levels sold at places like Home Depot or Harbor Fright are accurate either. I bought one of them, it was not accurate and I proved it. It had no adjustment. The next time I tried to use it, it would no longer light up, even with new batteries. I used it as a regular level for a short time, until I found out the level itself was not accurate either. Into the trash it went.

[repairs]

I'll second that!!!!

[John G]

[e-mail] wrote on 16/05/2013 :

And of course you have built things stretching from the North Pole to the South ole that need to be level :-?

Actually you might find the indicated points in a water level at even that distance are at the same distance from the centre of the earth and hence "LEVEL" :-Z

[Robert]

On May 16, 12:45 am, [e-mail] wrote: .....

Yes, there are a few undesirable side effects.

[Robert]

Ok... Gravity bent space, and space bent the light path.....

On the other hand, we all know that heat rising makes the path of light waver, as happens when watching a distant object in the desert or over hot pavement...

Perhaps gravity doesn't actually "bend" space, and it was the hot air from the sun that made the star jump...... Pehaps Einstein was wrong........

[TimR]

Gravity isn't going to bend light or space over the range of a typical construction project.

However heat will. Warm air will definitely refract a laser beam enough to throw your measurements off. It's the reason a laser can't be trusted to get tunnels from each end to meet in the middle.

[krw]

Since the light's path is through space...

Refraction.

Perhaps but I'd like to have is record of predictions. I'd buy a PowerBall ticket.