Levels are used to accurately determine horizontal, vertical and other angles.
The most common and well known level of all.
- pictured above
- Only one DIYer is known to be unfamiliar with this common tool, Mr Nseowo: BBC Google
Its possible for a knock to misalign the vials, so a spirit level should be tested if dropped.
Spirit levels are available with several vials, enabling reading of various angles close to horizontal, eg 1 degree, 2 degrees etc
See Quality, points to look for
Glass vs Plastic Vials
- rarely scratch
- never cloud
- are breakable
- only work the right way up, as the tube is parallel sided, and is curved slightly
- are much more robust against knocks
- scratch easily
- go cloudy in time
- work any way up, since the tube is barrel tapered instead of curved one way.
A fencing level has 3 vials at right angles to each other to enable fence posts to be installed upright.
A line level has hooks to hang on a string line. It needs to hang in the middle of the line to read right.
Bulls Eye Level
- Indicating vial is round rather than tubular
- Indicates level in 2 axes
An uncommon but versatile level capable of finding all angles.
- Determines all angles
- Easily improvised
- Small, lightweight & compact
- Affected by wind
- Fragile if made from card, robust if made from plastic
- Make one
The Plumb bob is a weight on a string. The weight has a pointed base, and indicates the vertical.
- Affected by wind
- Takes time to settle
- Easily improvised with a large washer
A laser level can project a vertical or horizontal line of light onto the workpiece. This makes level visible without needing a hand to hold the level, and without marking the workpiece.
However this doesn't necessarily make things easier or quicker due to setup time. IME a long spirit level is often quicker to use.
Plumb bob level
Set square with mini plumb bob in it
- Reads horizontal & vertical
- not often seen now
- affected by wind
- Used in building the Egyptian pyramids
A flexible pipe containing water. Wherever the ends of the tube are placed, water at both ends will settle at the same height.
Useful for finding level over a long distance.
May be made by using either clear tubing, or a hosepipe with a short distance of clear tube or a funnel at each end.
A line level is a miniature spirit level that is hooked onto a horizontal line. The level is attached at the centre of the line otherwise large errors are introduced. Uneven line surface can also affect accuracy. Not as accurate as rigid spirit levels.
- Spans long distances
- Indication is distant from where the line ends are being held
This is a 3 vial L-shaped spirit level that determines all 3 axes of level for vertical posts. Used for fencing.
A levelled telescope used with a staff (pole) for transferring a level around a site. Used with 2 people. Simple and very accurate.
Testing a Level
Spirit levels don't always read correctly. To test:
- Place level on a surface that is level or close to level. For precision, adjust or pack the surface so it reads level.
- Turn the level round. It should read the same each way round. If it does, it reads correctly.
If it doesn't indicate the same each way, the vial position can usually be adjusted.
As a temporary measure,
- the correct indication is halfway between the 2 spirit level indications.
- the reading can be corrected by adding duct tape or card to the underside at one end
The same approach is used as with a spirit level, take a reading, turn the card round and read again. Both readings should be identical. If not, the card can have a corner snipped to level it.
A plumb bob will always read level providing the weight is symmetrical and hanging symmetrically. Even if not, the string will always read correctly, though the weight may not. Improvised plumb bobs can need testing, correctly designed ones don't.
There are 2 ways to test plumb bobs.
- Determine vertical level by another accurate means, and compare the plumb bob's reading
- Set the plumb bob weight to slowly rotate without it swinging sideways. This is done by twisting the string so that horizontal swing settles before rotation settles. Once swing has settled, the indication should not move at all with weight rotation.