Handbook Of Shaft Alignment Episode 3 Part 3 ppsx

7. Using the optical micrometer, measure the positions of the targets at the near and far

ends of the far cylinder in the vertical and sideways directions. Study and perform the

information in Figure 19.22. Record the information.

TOPT OP Top Top

One-half of

the original

horizontal

offset

One-half of

the original

vertical offset

Initial

position of

target

Position of target

after moving

horizontally and

vertically inside

the cylinder

Step 4. Adjust the position of the target inside

the bore of the cylinder by alternately loosening

and tightening the target fixture adjustment

screws at the 12 and 6 o’ clock position to place

the target half the total vertical offset distance

measured in step 3 above. Adjust the position

of the target inside the bore of the cylinder by

alternately loosening and tightening the

adjustment screws at the 3 and 9 o’clock position

to place the target half the total lateral offset

distance measured in step 3 above as shown in

the figure below.

FIGURE 19.19 Step 4 for centering a target in a cylinder.

TOPT OP TOPT OP

Initial

position of

target

Position of target

after the target

was moved

horizontally and

vertically inside the

cylinder

Top Top

Observed position

of target after

adjusting vertical

and lateral tangent

screws on jig

transit

Step 5. Adjust the vertical and lateral

tangent screws on the jig transit to center

the telescope crosshairs in the center of

the bore target as shown in the figure

below.

Step 6. Repeat step 3 though step 5 until their

target stays centered in the telescope

crosshairs through 3608 of rotation.

FIGURE 19.20 Step 5 and step 6 for centering a target in a cylinder.

Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C019 Final Proof page 630 26.9.2006 8:43pm

630 Shaft Alignment Handbook, Third Edition

8. If the targets at the near and far ends of the far cylinder are not coincident (in line) with

the targets at the near and far ends of the near cylinder, position either the near or far

cylinder to bring the bore centers into alignment. Refer to the ‘‘correcting the misalign￾ment’’ procedure below and study Figure 19.23 and Figure 19.24.

19.5 BUCKING IN PROCESS

1. Center the bore targets at both ends of the cylinder as shown in Figure 19.21. Measure

the distance between the bore targets and the distance from the near target to the center

of the jig transit (i.e., where it rotates through its azimuth or Z-axis). Focus on the far

target and using the tangent screws, center the telescope crosshairs on the target. Focus

on the near target and observe its position with respect to the telescope crosshairs. If you

are lucky the near target is centered in the telescope crosshairs.

Use optical micrometer

to measure the offset at

this target

Step 1

Step 2

Step 3

Adjust tangent

screws to zero on

this target Near to far target distance

Near target to

transit distance

Translation distance needed for correction = (Near to far target distance + near target to transit distance)*(offset at near target)

Near to far target distance

New position

Original position

Translate the jig

transit to here

Translation distance

needed for correction

Offset at near target

Rotate the jig transit to

aim at the center of the

far target then focus back

to see if the near target

is also centered

FIGURE 19.21 Bucking in your line of sight to the centerline of the bore of the cylinder.

Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C019 Final Proof page 631 26.9.2006 8:43pm

Bore Alignment 631

OK, so much for dumb luck. The near and far targets are not directly in line with each

other. What you have to do now is translate the entire jig transit in the sideways

direction and rotate the jig transit through its azimuth (Z) axis to align the vertical

crosshairs of the telescope with the vertical paired lines on the near target. Similarly, you

have to raise or lower the jig transit in the vertical direction using the precision lift

mechanism and plunge (i.e., pitch) the jig transit through its pivoting (X) axis to align the

vertical crosshairs of the telescope with the horizontal paired lines on the near target. Now

there are two ways to do this: trial and error and mathematics. Both work, mathematics

just happens to be slightly faster but requires a little bit of number crunching.

Plug the scale target reading at the near target and the distances into the formula to

obtain the necessary translation distances.

2. Translate (i.e., move) the entire jig transit in the sideways direction to the amount you

calculated in the equation. You can either use the rotary indicator wheel on the

translation table where the scope is mounted or you can focus the scope on the near

target, set the optical micrometer to the desired lateral translation distance (assuming it

is under 100 mils), and begin translating the scope until the crosshairs line up on the near

target’s horizontal and vertical paired lines.

Raise (or lower) the entire jig transit in the vertical direction the amount you

calculated in the equation by adjusting the vertical lift mechanism. You can focus the

28 mils to the right

18 mils high

34 mils to the left

52 mils high

Telescope crosshairs are

bucked into the bore

centerline of the near

cylinder when these

measurement were taken

Near target in

far cylinder

Far target in

far cylinder

FIGURE 19.22 Measuring the amount of misalignment of the near and far targets in the far cylinder.

Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C019 Final Proof page 632 26.9.2006 8:43pm

632 Shaft Alignment Handbook, Third Edition