Acrylic circular Bullseye levels feature 40 arc minute sensitivity and hot stamped lenses. ABS mounting flange available for Bullseye level #360. Using three #4 flat head screws, the flange will attach to any flat surface.
Understanding Level Vial Sensitivity
When considering level vial sensitivity
it is important to know that sensitivity
does not reflect the accuracy of a level vial. A highly sensitive vial can be inaccurate and an accurate vial can have low sensitivity. An accurate level vial will read level when in a level position.
describes how easily the level vial bubble moves when shifted from its level position to an unlevel position. Bubble movement is determined by the surface inside the vial.
is measured in minutes and seconds. Minutes are a fraction of a degree (or angle). There are 60 minutes in one degree. This means that 1/2° is equal to 30 minutes. Sensitivity
is defined as the angle the level needs to rotate to get the bubble to move 1/10th of an inch. For example, for a 20 minute vial the level must tip 20 minutes or 1/3° to move the bubble 1/10th'' or 0.1''. A more sensitive 9 minute level vial only needs to be tipped 9 minutes or 9/60° to move the bubble 1/10th'' or 0.1''.
With a circular level, a 2/3° pitch will yield approximately 1/10'' or 2.5mm bubble movement.
A highly sensitive level vial will allow you to detect very subtle changes, which may or may not be important depending on the type of work you are doing. The real life application is that a highly sensitive vial is not good for use in general carpentry; it would take the carpenter a long time to level or plumb his work. When setting machinery or test surfaces, a highly sensitive vial is necessary to create a more precise level position.