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!
- 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.
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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. :^)