Topic 1 – Establish Elevations with a Builder’s Level
Builder’s levels, transit levels and automatic are used for layout operations using a telescope and tripod to shoot readings with a leveling rod. Elevations can be established using a reference point such as a benchmark. The has an adjustable telescope which is levelled on the tripod using adjustable foot screws. The tripod is equipped with adjustable legs with foot pegs which are pushed into the ground. A tripod ring or frame is used to hold the legs of the tripod when being used on hard surfaces such as concrete or pavement. The scope on a builders level only moves horizontally. A single set up and a benchmark are needed to find the difference in elevation between two points. Larger distances may require multiple sets ups to shoot all locations. A turning point is used when the backsight and foresight cannot from the same set up location.
For more details, review Instruction Sheet (IS) on Brightspace:
CNST 102 (p. 4 – 36)
IS 1.2 Types of Levels
IS 2.2 Handling and Setting Up Builder’s Level
For additional information and terms used for operating the builder’s level refer to Carpentry Chapter 27 – Leveling and Layout Tools.
Review Questions
The telescope of a builder’s level swings:
Horizontally
Vertically
What type of instrument uses a split bubble to level the instrument?
On the tilting level, what type of bubble is used on the base plate?
The telescope that shows the clearest image is one that shows and:
Erect image
Inverted image
Two horizontal crosshairs, in addition to the main one, are seen in some telescopes. What is the name and function of these cross hairs?
Name and define the following abbreviations:
B.M.
L.S.
B.S.
F.S.
I.H.
T.P.
E.L.
When a builder’s level is set up over a hard surface such as concrete, what special consideration must be given?
Give two reasons why backsight and foresight should be approximately equal in distance when setting up an instrument.
What is the “rule of thumb” when adjusting footscrews?
What is meant by the term parallax in relation to the telescope on a builder’s level and how is it corrected?
True or False:
The best material for cleaning the builder’s level is a light oil because rust will not form.
Levelling screws on three point levels may be adjusted individually.
The cross hairs must be adjusted whenever the distance to the target changes significantly.