Laser Level, Auto Level

From DIYinfo.org

1 Auto Level
2 Laser Level.
3 Checking a Laser Level or Builder's Auto or Dumpy Level For True
4 Author

[edit] Auto Level

The type of builder's auto level like the one shown at the right has for years a builder's main tool for setting out foundations, concrete slabs etc.

It is a small telescope usually mounted on a tripod, that is set up to read level (horizontal) only. No vertical movement. It needs two men to use, one to read the level and one to hold the staff. The staff being an extending aluminium extrusion with graduations on the face. The staff could also be as simple as a piece of timber that the guy holding it puts pencil marks onto it at the instructions of the guy reading the level.

These levels are quite often called Dumpy Levels, but the auto level is a different beast. The original dumpy level has two long spirit bubbles at right angles to each other, and these had to be checked and adjusted with each swing of the instrument in a new direction. Very rarely seen now, but like many things the name lingers on.

The modern Laser or Auto level has a single circular bubble that is used to set it up. It only has to be set roughly into it's position and the instrument takes care of any finer adjustments. That's why they are called "Auto", so don't spend ages setting it perfectly in the center. Near enough is good enough.

The modern auto level is cheap, quick to set up, easy to use and extremely accurate.

Here's a trick to setting up any of these type of levels with the three knurled knobs for setting the thing level. * Place the thumb and forefinger of each hand on each of two of the knobs.

Turn each thumb either towards or away from each other.

The bubble will move in the direction of the left thumb. Every time. Just like magic:-)

With an auto level, keep your hands off it apart from a light touch to adjust it.
Don't lean on it! Don't rest a had on it while taking a reading. This is a sure sign of newbie.
Set up to one side so that you can level the job with the least amount of swinging around or changing position.
Set up out of the way of working machinery. Backhoes and the like.
Try to set up with your back to the sun, otherwise keep your hat handy to shade the lens.

[edit] Laser Level.

They are getting cheaper all the time and entering the DIY arena. Not only for leveling, but will also read verticals. They are a one man operation, set it up in a safe corner and walk around with a staff and mark the levels. A must for all builders, concretors, ceiling fixers.

In the DIY field I have seen a friend with a really cheap one use it to level and plumb the kitchen cupboards that he made himself.

Above is a shot of a laser level in use. The guys have it set up level and it was spinning when I took the photo. They are using it to get their levels for the top of the sand bed, which will be the bottom of the concrete footing. The guy on the top. from time to time will pass the staff (the white thing leaning on the pile of sand) down to his mate in the trench. When the staff is at the right height, the receiver on the staff (the crosspiece just behind the tripod leg) will give a series of beeps.

I hired a laser level a couple of years ago to set out a complex curved roof, and it was ideal as it sat on the top of the blockwork wall without a tripod. I had previously tried my auto level on the scaffold but the vibration made it impossible to read.

[edit] Checking a Laser Level or Builder's Auto or Dumpy Level For True

If you are hiring one of these instruments, if you are any way like me, you may want to check the thing for accuracy. hire gear is prone to mistreatment.

Here's how to do it.

This method will work with a laser level or any other sort of optical level.

If you are using an auto (dumpy) level you will need an assistant to hold the staff. You won't need one if you have a laser level as you set it up and take the readings yourself, but the principle is the same.

Find a clear stretch of open ground and mark on it two fixed points that are minimum of 100 meters apart. If I am on the street I put chalk marks on the concrete kerb, otherwise I put down a couple of bricks to rest the staff on. You must be able to find the same exact spot for the staff at least twice.

Set up the level so that you will be able to do the readings without swinging the level hardly at all, as in the top example, then take the two readings, first at "A" and then at "B". Subtract the height at "B" from the height at "A". Let's say in this case the difference is 132mm.

Move and set up the level again between points "A" and "B". Take the two readings again, this time you will have to swing the instrument through 180 of so degrees. Measure the difference between the two readings again. It should be the same as before, in our example it is 132mm.

If the difference varies, say by 10mm then your level is out 5mm in 100 metres. Don't get too critical and worry about a couple of millimetres, you can very rarely achieve that accuracy in the actual construction work anyway. You just need to satisfy yourself that the level is not a mile out.

This way gives a worst case measurement. From almost no movement of the level to a full 180 turn of the level to get the readings. You very rarely swing the level so much in actual work.