Level
Levels are used to accurately determine horizontal, vertical and other angles.
Level Types
Spirit Level
The most common and well known level of all.
Only one DIYer is known to be unfamiliar with this common tool, Mr Nseowo:
- http://news.bbc.co.uk/1/hi/england/shropshire/3142762.stm
- http://www.google.com/search?hl=en&lr=&rls=en&hs=JXB&q=nseowo+extension&btnG=Search
It is possible for a knock to misalign the vials, so a spirit level should be tested if dropped.
Spirit levels are also available with several vials, enabling reading of various angles close to horizontal, eg 1 degree, 2 degrees etc
Glass vs Plastic Vials
Glass vials:
- rarely scratch
- never cloud
- are breakable
- only work the right way up, as the tube is parallel sided, and is curved slightly
Plastic vials:
- are much more robust against knocks
- scratch easily
- go cloudy in time
- work any way up, since the tube is tapered instead of curved one way.
Needless to say some folk swear by glass, and some will only buy plastic.
Card Level
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
Plumb Bob
The Plumb bob is a simple weight on a string. The weight has a pointed bottom, and indicates the vertical.
- Affected by wind
- Does not settle instantly
- Easily improvised
Laser Level
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 does not necessarily make things easier or quicker due to setup time. IME a long spirit level is often quicker to use.
Other one
Set square with mini plumb bob in it, I forget the name
- Reads horizontal & vertical
Water Level
This is a flexible tube 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.
Line Level
A line level is a miniature spirit level that is hooked onto a horizontal line. The level must be attached at the centre of the line otherwise considerable errors are introduced. Uneven line surface can also affect accuracy in some cases. For these reasons it is not as accurate as rigid spirit levels.
- Spans long distances
- Accuracy variable
- Indication is generally far from where the line ends are being held
Post Level
This is a 3 vial L-shaped spirit level that determines all 3 axes of level for vertical posts. Used for fencing.
Dumpy Level
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 Level
Spirit levels dont always read correctly. How 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. Meanwhile the correct indication is halfway between the 2 spirit level indications.
Card Level
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.
Plumb Bob
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. Thus improvised plumb bobs are the only ones in need of testing.
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. 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 rotation.