How to calibrate the level error
1. Zero error calibration of horizontal position
After the bubble is stable, read a at one end of the bubble at the horizontal position e, then turn the level ruler 180 degrees, place it on the original position of the plate, and record the reading b at the other end of the bubble according to the side of the first reading, twice Half of the reading difference is the zero error.
2. Zero error calibration of vertical position
Adjust the dividing head so that the end of the horizontal position = bubble is aligned with the long scale line, turn the dividing head 90 degrees, read c at the corresponding end of the vertical position = bubble, and add c to the zero error of the horizontal position is the zero error of the vertical position.
3. Zero error calibration at 45 degree position
Adjust the dividing head so that one end of the bubble at the horizontal position is aligned with the long engraved line, turn the dividing head 45 degrees, read d at the corresponding end of the bubble at the 45 degree position, and add d to the zero position error of the horizontal position to get 45 Zero position error in degrees.
