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Field Alignment Section 3

4. Establishing the datums. a. You must take readings from the same position relative to the fixed machine or the moveable machine. Choose the position that is the most comfortable. DO NOT CHANGE THE ORIENTATION ONCE YOU BEGIN TO TAKE READINGS.

b. All dial indicator readings must be taken 90o apart from each other and at the same relative position each time. Either mark the couplings in 80o increments or use a two dimension bubble level with a magnetic pad. The level is the most accurate method.

C. The shafts must be rotated together and readings taken from the same exact locations every time; therefore, if the coupling spacer is removed, the stationary and adjustable machines coupling hubs must be marked in 90o increments.

5. Take the initial set of readings.

a. Zero the dial indicators at the 0o position.

b. Rotate the shafts simultaneously taking readings every 90o, (0o, 90o, 180o, 270o). Record readings on the reverse dial indicator worksheet.

6. Determine d' the initial readings are good.

a. Add top Cr) and bottom (B) together for both planes and the two side readings (S) together for both planes.

b. Take the difference of the two readings. If the difference exceeds 0.002", there is something wrong with the readings. Inspect the set up and make any necessary adjustments.

7. Algebraically zero the side readings. Be consistent on which side you zero; it is usually easier to zero the 90" side.

8. Make dial indicator sag correction on worksheet.

a. Dial indicator sag only effects vertical readings. Since the dial indicator is going to read negative on the bottom, add the sag to the dial indicator reading on the bottom.