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I need to drill 2 holes in a concrete wall, about 1.5m apart and I need the line between them to be as horizontal as possible.

I have a level, not that big, and few other basic tools.

How can I align them properly?

  • To be clear, you're drilling the holes in the wall? – Tester101 Apr 16 '15 at 14:05
  • Yes, in the wall. – Arkaitz Jimenez Apr 16 '15 at 14:19
  • Which of the following is most important to this project: 1) holes are "level" (line between holes is perpendicular to gravity), 2) holes are parallel to the floor, or 3) holes are parallel to the ceiling? If the answer is 2 or 3, then the easiest solution is to measure from the floor (or ceiling) for each hole. – mbeckish Apr 16 '15 at 18:03
  • mbeckish, gravity is the factor, I need to hang something heavy and needs to be as balanced as possible. – Arkaitz Jimenez Apr 16 '15 at 19:14
7
  • Borrow a laser level
  • Borrow a 4 foot mason's level
  • Don't use a level -- use a plumb bob and HS geometry

Make a plumb bob by hanging a heavy and centered weight from a chalk line and snap it in the center of your desired holes.drawing. Now pick a point on the wall that will be your left hole and two points on your chalked line. Use a wire and measure the distance from the hole to the upper point on your chalk line. Draw an arc on the opposite side of the wall. Repeat for the lower point on your chalk line; where they intersect is the location of your other hole.

  • 1
    Ah, so that's how you build a perfect pyramid the size of a football field. – Mazura Apr 17 '15 at 13:52
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If you have a shorter level than the distance between two hole positions you can find yourself a piece of wood that is say 2 meters long that can be seen to be nice and straight.

Hold this length of wood up against the wall in a horizontal position and set your level atop it. The wood can then be repositioned till the level shows a "level" position on its bubble. The wood piece effectively extends your level and should work very well unless the level is one of those really cheap short 5cm to 10cm jobs.

Once the wood piece is positioned properly you can draw a line along the top and have a good level reference. You can pre-mark two positions on the wood piece that are 1.5 meters apart so that you can know just where to draw short marks instead of having to mark a huge line across your wall.

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    There's a reason they don't make levels out of wood... It ain't ever straight. Get yourself a longer level, or a metal straightedge. – Tester101 Apr 16 '15 at 14:46
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    Not true @Tester101. My best levels, even my six foot one, are made out of wood with brass inlay corner edges in them. Not cheap but nice and straight. A big part is all about the type of wood that they are made out of. – Michael Karas Apr 16 '15 at 14:50
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    Just because you own a level that is made of wood doesn't nullify the point I believe @Tester101 is trying to make: grabbing some random 2x4 that looks straight is not a substitute for a proper level. Granted, it might be "close enough" depending on exact needs, but you can't rely on it like you can with a real level/straightedge. – gregmac Apr 21 '15 at 22:40
  • @gregmac - I want to call your comment a bunch of bullocks but I stop at this and point out that it is totally possible to sight in a piece wood as being straight. Any good carpenter can attest to that. My comment to @ Tester101 was to counter that there are some very nice levels made of wood. I happen to own three of them of various lengths. – Michael Karas Apr 22 '15 at 2:27
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Water levels and long bits of wood are good solutions. Alternately, drill one hole; have a helper run string from there; level from the taut string and mark your next hole. (When marking the second hole, try to account for any wandering that the drill bit did when you drilled the first hole.)

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    Take a punch and punch a divot in the wall for the second hole. This will help keep the bit from wandering. – Chris Cudmore Apr 17 '15 at 13:06
  • There's a device called a string level that clips onto the string; they typically come in a package of two. Use non-stretchy string/wire, and make sure that the other end is securely anchored. – gbronner Apr 22 '15 at 16:19
2

One method to do this if you do not have access to a long level is to use a water level.

Get yourself a length of clear plastic tubing from the hardware or auto parts store. For your application it would be good if this tubing was 5 or 6 meters long. Now hold the two ends of the tubing up in the air with the remainder of the tubing hanging down. (It can be extremely beneficial to have a helper for this process).

Fill up a good portion of the tube with water but keep maybe a quarter or third of a meter of unfilled tubing at each end. The ends of the tubing need to stay open to the atmosphere. The water top in each upraised end of the tube will be level with respect to each other. As long as the two tube tops are held at the approximately same height you can move this around to use as a "level". If it is a little hard to see the water top through the tube because the tubing is not really clear you can mix food coloring into the water to make it easier to see.

Mark the position of where you want one of your holes. Then measure over your 1.5 meters distance from the first mark at an approximate horizontal position and make a vertical tick mark. Now with your helper position one end of the tubing with its water level top matching the first mark and the other one near where the second vertical tick was placed. Once equilibrium is reached and the water level is at the first mark you can make a horizontal tick at the water top across the vertical tick. This will mark two spots that are level with respect to each other.

If it is really hard to estimate the "approximately level" place to mark the vertical tick you can use a string from the first mark and measure over the 1.5 meters and draw an arc instead of the short vertical tick. Then when the water level is brought into position you mark across the arc instead to get the level position for the second hole mark.

2

Simply:

  1. Mark your first hole.
  2. Use your spirit level (assuming its a good one and not a tiny boat level etc) to mark a horizontal line from the first hole out towards the second hole position.
  3. Flip the level around 180 degrees lengthways and continue the line towards the second hole.
  4. Keep flipping the level around each time you need to move until you get to the position you want the second hole.
  5. When drilling be mindful that the 'twist' factor as you start each hole heads in the same direction! It's quite easy to start off with two level marks but end up with two slightly out of level holes.

Kind of a small version of this principle...How to mark a level line around a room

It works because turing the level around each time (in theory) cancels out any inaccuracy in the spirit level.

Of course it requires very careful observation of the bubble, every time, plus careful marking.

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2m piece of string with a 1kg weight in the middle and hanging scale (or Newton measures or other substitute) when the 2 scales read the same the hole is level.

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