Cheap and Accurate Long Distance Laser Level

Intro: Cheap and Accurate Long Distance Laser Level

Overview and Parts

If you have to buy a laser pointer at a flea market, you might have to spend a dollar or two, but the rest of the materials are scrap. I happen to have one in the junk drawer when I was building a shed and figured out how to do this. What matters here is the technique and a little patience. You are making a way to hang the laser pointer so that it spins around, sweeping across your corner stakes. Once you have that, gravity takes care of the rest!

You'll need

- a working laser pointer, preferably the cheap, small kind.
- a piece of 2x2 about 24" long,
- a few feet of string or twine,
- a drill and bit capable of about a 0.5" hole in the 2x2, and
- some means to hang the assembled level at a height near the ground.

STEP 1: Prepare the Level Body

Drill a hole near the end of the 24 inch 2x2 for the string. Drill a slightly tapered hole near the other end for the laser pointer of a size so that the pointer fits in it. Most of these little laser pointers all come from the same factory and are about .5" diameter. This hole should be as perpendicular as you can get it, but it doesn't have to be perfect. What has to be just right is that when the laser pointer is pressed into the hole it holds it snugly while depressing the switch to turn it on. This may take a few tries. To make the hole slightly tapered, just drill it, then move the running drill around slowly to ream out the hole a little bigger on one end. Take your time and keep testing the pointer for fit. You'll eventually get the right size if your don't hurry. Still, it should only take a few minutes.

STEP 2: Assembly

Tie the string on the string end of the 2x2 so that the 2x2 spins on it without wobbling much, and hang the level roughly near the middle of the work area where you have staked the corners. The bottom of the level should be near the ground but above any obstructions so there is line of sight from the level to the stakes. The level can be hung on anything that allows the level to spin freely while not in the way of line of sight from the level to the stakes. A shovel stuck very firmly into the ground at an angle works, or even another stake pounded in at an angle. Then tie the string onto the handle. In this picture I used an awesome 1950's era Altas Sound microphone boom stand because it was laying around. Woohoo.

It's important that whatever it hangs from does not move while doing the next step, so make
it pretty solid and avoid bumping it. If it moves your have to redo the next step for all the stakes.

STEP 3: Spin It and Mark Relative Level

This usually works best in low light or even darkness, but once you insert the laser pointer into the tapered hole in the body and spin it, it will wobble some, but the laser dot will keep sweeping across the stake at higher and lower places. Mark the highest and lowest spots. You may want to do this a few times to be confident of getting a consistent pair of marks. Bisect the marks - measure the distance and then mark half the distance between them. That is your relative level mark. It's actual distance from grade doesn't matter.  What matters is that it will be level with the relative level mark on all the other stakes.

Repeat this for each stake.

STEP 4: Measure to Line

Wherever you want your level line, just measure the same distance up or down from the relative
level mark on each stake and mark that, then tie there and you are ready to dig.

You just made your own laser level for about a buck!  BTW, if you have doubts about the accuracy of this rig, run a test and compare it to  a fancy rented one.  It's pretty close, good enough for a backyard pool or shed.  If you are building a house or skyscraper or Hoover Dam, go ahead and rent the fancy level.  :^)

Comments

[mjhilger]

While I like your concept, the laser must be perpendicular to the wood to be accurage. If it is dead in the center of your markings, you are correrct, it will not matter. But if the stakes you intend on marking are much different distances from the laser, it could make a big difference. Lets say the alignment is off by 1 degree, at 10' your off sin (1) * 120 = 2.09 inches; but at 100' your off sin (1) * 1200 = 20.9 inches.
Great idea, but care must be taken to align the laser properly to be accurate over long distances.

[hitman1689]

it actually wouldn't matter how crooked it is because once you spin it you'll get a straight line. If it's angled up down left right it doesn't matter because that dimension won't be changing during rotation which is all that matters for a level line. Now if the whole jig bounces around or sways while it's spinning there's your problem. As long as it's balanced it should be fine

[HaPPI]

Great point (no pun intended) mj, the hole for the laser pointer should be very much perpendicular to the long axis of the 2x2, so best to use a drill press to make that .5" hole. If the sweep of the laser is conical instead of planar, then place ment in the center of, equi-distant from, the corners is critical. This is very doable if the foundation is rectangular. I used a drill press when I was making mine because I happen to have a small bench unit handy. Thanks!

The test for level for me came as an inconvenient HEAVY rain shortly after setting my footer blocks, and the water filled the trench to the top of the block. I was rather pleased with myself that the water was within a small fraction of an inch of the top of the block all around - dead level. One rank of block went on top of those, then the shed framing on that and Bob's your uncle.

[mjhilger]

Part of the reason for my comment is the cheap laser modules I buy are not parallel to their housings. I'm sorry, I should have pointed that out in my original comment. I buy more powerful modules off ebay for < $10, but find that the housing axis and laser axis are not aligned. I would caution anyone to verify the alignment before committing height markings. Drilling the hole in the wood perfectly perpendicular certainly insures the laser housing is in correctly, but not necessarily the light.
All, in all, fantastic use for the laser at an affordable price. Perhaps you could add a battery powered motor to rotate the string at a low rate, 30 - 60 RPM to provide the spin automatically.
Great idea HaPPI!!

[gserrano701]

So simple, I love it. I'll try it this weekend.