Two types of calibration for a horizontal ruler
The zero position error of the level (including the zero position error of the horizontal position, the zero position error of the vertical position, and the zero position error of the 450 position) and the division value error are important items for the calibration of the level.
The calibration tool consists of an optical dividing head and a special fixture. During calibration, fix the special fixture in the spindle taper hole of the dividing head, adjust the dividing head to make the plate roughly horizontal, fix the level ruler on the plate, and then calibrate item by item.
Zero position error calibration
1) Zero position error calibration of horizontal position
After the bubble stabilizes, read a at one end of the bubble in a horizontal position. Then, turn the level 180 degrees and place it in the original position of the flat plate. Record the reading b at the other end of the bubble according to one side of the first reading. Half of the difference between the two readings is the zero position error.
2) Zero position error calibration of vertical position
Adjust the dividing head so that one end of the horizontal bubble aligns with the long line. Rotate the dividing head 90 degrees and read c at the corresponding end of the bubble in the vertical position. Adding c to the zero position error in the horizontal position is the zero position error in the vertical position.
3) Zero position error calibration at 45 degrees position
Adjust the dividing head so that one end of the horizontal bubble aligns with the long scale line. Rotate the dividing head 45 degrees and read d at the corresponding end of the bubble at the 45 degree position. Add d to the zero position error at the horizontal position to obtain the zero position error at the 45 degree position.
Calibration of division value error
Rotate the dividing head to align the bubble with the starting line on the left (or right) side of the level bubble, and then change the reading of the dividing head in sequence, each time changing to the nominal dividing value of the calibrated level. After the bubble stabilizes, read b0, b1, b2,... bn at one end of the bubble and calibrate the other side of the level bubble using the same method. The division value error is calculated using the following formula: △ b=1- (bi bi-1). In the formula, △ b is the division value error of the level, and bi bi-1 is the reading of the level.
According to the above methods. The division value error of horizontal position bubbles, vertical position bubbles, and 45 degree position bubbles can be calibrated separately.
