Hello, Do you use laser levels and worry about accuracy. I mean on any given day it could be out of calibration and your work at say 40 feet away is not gonna be right. I just tested mine tonite against a sight level and at 58 each way feet its off by almost an inch. I will be resetting a lot of form panels tomorrow. But I just can't see the value in keeping a tool that could be wrong any time. Other than having it calibrated every other month whats a fella to do? tonyg
None of my lasers cost more than $300 and the accuracy is fine. If the laser won't hold its calibration and you're worried about the accuracy day to day buy a new one. Other than that, if you handle a quality laser with care and check it against a water level every couple of weeks or so, it's unlikely that you'll have problems. If greater than usual accuracy is required, or greater distances involved, I still go with a water level, particularly for things such as formwork.
i say a laser should be accurate to 1/4" in 50 feet or whatever the manufacturer says or it is defective and not worth a damn. if possible, i periodically check forms or whatever with my 6 foot level to see if my laser is working. somehow i trust a bubble i can see more than an unseen internal mechanism, especially since i once had a Robotoolz laser that started drooping. wound up with a foundation wall with a corner that was an inch low as a result. never trusted it after that. sent it back to the company and they just sent it back to me without doing anything to it.
some levels can/should be calibrated on occasion. How often depends on how the unit was treated in storage and transport. If it is a cheap one with no calibration, you would probably need a new one. By the way, I've tried 4 cheaper self leveling ones last year, and none was accurate enough. On the other hand I have a manual torpedo style ( ten bucks) that is extremely accurate. You just have to try them out against a water level.
Let me tell you about my water level that didn't read level.
To aid seeing the water, I mixed some anti-freeze with it before I poured it into the tubing. I didn't have enough water to fill the tubing so I mixed up some more and filled the tubing. The first time I used it, I was showing my daughter how it worked. In the process of showing her, I noticed that it was reading true. When holding the 2 ends together, the water in one end was higher than the water in the other end. It took me a while to figure it out. When I mixed the second batch of water/anti-freeze, I used more anti-freeze than the first batch. Part of the water was heavier than the other part.
And you know the sight (dumpy) level is more accurate because ... ?
The more meaningful check is to simply gauge it against itself. I was accustomed to accuracy of a 16th inch (or better) over about 300 ft.
Your manual should have a description of the process, but simply put, set the unit at one end of a range, mark grade on a post at each end (one next to you, one at the far end)
Reset with the unit turned 180. Don't even think of tryin to keep the unit on either of the previous grades ... I'd move the tripod around to ensure a bit of a difference in elevation. But do those same marks again.
Compare the distance of each pair of marks, and you have the error. ( Actually, you find double the error, as this shows the difference as ½ above true level, and ½ below true grade.
It seemed logical to me to repeat this test at each quadrant. I recall at some point discovering some sort of 'conical' error, where the whole unit was casting with a slight cone shape ... so shallow that it was of no consequence to our work, again in the order of a sixteenth at 300 ft.
I knew how to fix one unit ... never ever touched those screws ... good enough is better than out of service.
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