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newSchoolWorks.com › VoTechWorks › Manufacturing & Marine › Industrial Maintenance › Mechanical Drives: Belts, Chains, Gears, and Couplings › Lesson 9
MFG-INDU16-02 · Lesson 9 · 19 clock hours · lab

Shaft Alignment with Dial Indicators and Laser Tools

Objective. Students will perform a two-indicator rim-and-face alignment on a coupled pump-motor trainer and achieve alignment within 0.002-inch total indicator reading (TIR) in both planes before re-energizing.

⚠ Pending professional review

This lesson, its worked examples and its practice questions has not yet been verified by a licensed engineer or certified journey-level tradesperson or by a certification or approval body. It is a study draft and may contain errors. Do not use it as instructions for work on a job site or on live equipment. Always follow your instructor, your supervising professional, and current official references and regulations.

VoTechWorks program approval and accreditation are still in progress. Credentials are issued only by the certifying bodies named in each program, after their own exams.

Why Shaft Alignment Matters

When a motor drives a pump through a mechanical coupling, both shafts must rotate on the same centerline. If they do not, the coupling, bearings, and seals absorb the difference on every revolution. Even a few thousandths of an inch of misalignment causes vibration, premature bearing failure, seal leaks, and coupling wear. Precision alignment extends equipment life, reduces energy consumption, and prevents unplanned downtime — all priorities in manufacturing and marine maintenance.

Two types of misalignment exist and almost always appear together:

The acceptance standard for most industrial rotating equipment is ≤ 0.002-inch total indicator reading (TIR) in both the vertical and horizontal planes. Always confirm the acceptable tolerance in the equipment manufacturer's documentation before starting work.

Lockout/Tagout Before You Touch Anything

Shaft alignment work is performed on equipment that could start. Follow OSHA lockout/tagout (LOTO) procedures before mounting any indicator bracket or touching the coupling:

1. Identify all energy sources (electrical, pneumatic, hydraulic).

2. Notify affected personnel.

3. Isolate the energy source at the disconnect.

4. Apply your personal lock and tag.

5. Release or restrain stored energy (capacitors, springs, pressure).

6. Verify zero energy — attempt a start at the control.

Wear safety glasses throughout. Wear gloves when handling shims; edges are sharp. Never reach across a rotating shaft, even during a check run with the coupling guard temporarily removed — replace the guard before re-energizing.

Rim-and-Face Alignment with Dial Indicators

The rim-and-face method uses two dial indicators mounted on a bracket attached to one shaft half of the coupling. One indicator tip contacts the rim (outer diameter) of the opposite coupling half to measure offset. The second indicator tip contacts the face (flat end) of the opposite coupling half to measure angular misalignment.

Mounting and Zeroing

1. Attach the magnetic bracket to the shaft or coupling hub of the stationary machine (usually the motor is moved; the pump is the fixed machine).

2. Position the rim indicator so its tip contacts the coupling OD at 12 o'clock, perpendicular to the surface. Preload the indicator about half a revolution, then zero it.

3. Position the face indicator tip on the coupling face at the same radius, perpendicular to the face. Preload and zero.

4. Confirm neither indicator loses contact through the full 360° rotation before recording data.

Recording Clock-Position Readings

Rotate the shaft to each clock position and record both indicators without changing direction to eliminate backlash error. Standard positions are 12, 3, 6, and 9 o'clock. Enter readings on the alignment record sheet, using a sign convention (positive = indicator compressed, negative = indicator extended) that you apply consistently.

Rim (offset) check: The sum of opposite readings should equal zero within a small tolerance (0 + 6 o'clock, 3 + 9 o'clock). A large deviation indicates bracket sag — correct this before proceeding.

Face (angular) check: The difference between 12 and 6 o'clock readings gives the total angular TIR in the vertical plane. The difference between 3 and 9 o'clock gives it in the horizontal plane.

Making Corrections

Vertical corrections are made by adding or removing precision shims under the motor feet. Horizontal corrections are made by moving the motor sideways using the jack bolts. Work vertical before horizontal. After every adjustment, re-snug all four hold-down bolts in a cross pattern and re-check both indicators. Repeat until both TIR values are ≤ 0.002 inch.

Laser Alignment Tools

A two-head laser aligner places one emitter-receiver unit on each shaft. Each unit sends a laser beam to the detector on the opposite unit. The system calculates offset and angle automatically and displays live corrections in thousandths of an inch. Advantages over dial indicators include compensation for bracket sag (built in), simultaneous vertical and horizontal display, and automatic calculation of shim changes at each foot.

The correction procedure is the same: shims for vertical, side movement for horizontal. Tolerances are identical — the tool changes; the standard does not. Always verify the laser system is zeroed and the detector is within its measurement range before trusting a reading.

Completing the Job

Once both planes are within tolerance, record the final readings on the alignment log, torque all hold-down bolts to specification, reinstall the coupling guard, and remove your LOTO devices in reverse order of application. A final vibration check after a short run confirms the alignment is good under operating conditions.

Key terms8

Total Indicator Reading (TIR)The full range of movement a dial indicator records over one complete rotation — from the most negative to the most positive reading. Used to quantify misalignment.
Angular misalignmentA condition in which the centerlines of two coupled shafts intersect at an angle rather than coinciding along a straight line.
Offset (parallel) misalignmentA condition in which two shaft centerlines are parallel but displaced from each other, either vertically or horizontally or both.
Rim-and-face methodA dial indicator alignment technique that uses one indicator on the coupling outer diameter (rim) to measure offset and a second indicator on the coupling end face to measure angular misalignment.
ShimA thin, precision-thickness metal plate inserted under machine feet to raise the machine and correct vertical misalignment.
Bracket sagThe downward deflection of a dial indicator bracket under its own weight as the shaft is rotated, which introduces a false reading that must be measured and subtracted from alignment data.
Lockout/Tagout (LOTO)An OSHA-required procedure that isolates all energy sources and applies personal locks and tags to prevent equipment from being energized while maintenance work is in progress.
Two-head laser alignerA shaft alignment system in which electronic emitter-detector units are clamped to each shaft; the system calculates offset and angular misalignment from the laser beam positions and displays corrections directly.

Worked examples4

1. Rim indicator readings at the four clock positions are: 12 o'clock = 0.000 in, 3 o'clock = +0.006 in, 6 o'clock = −0.004 in, 9 o'clock = −0.006 in. What is the vertical offset TIR, and does it pass the 0.002-inch acceptance criterion?
  1. Identify the 12 and 6 o'clock readings: 12 = 0.000 in, 6 = −0.004 in.
  2. Calculate vertical TIR = |reading at 12| + |reading at 6| when they are opposite in sign, or subtract if same sign. Here they are opposite: TIR (vertical) = |0.000 − (−0.004)| = 0.004 in.
  3. Compare to acceptance criterion: 0.004 in > 0.002 in.
Answer: Vertical offset TIR = 0.004 in. This does NOT pass; shim correction is required.
2. Face indicator readings are: 12 o'clock = 0.000 in, 6 o'clock = +0.003 in. The face indicator is contacting the coupling face at a radius of 3.00 inches from the shaft centerline, and the motor hold-down bolts are 8.00 inches and 16.00 inches from the coupling face. How much shim must be added or removed at the near feet (8 in) and far feet (16 in) to correct vertical angular misalignment?
  1. Determine angular TIR: reading at 6 o'clock − reading at 12 o'clock = 0.003 − 0.000 = 0.003 in over a diameter of 2 × 3.00 = 6.00 in.
  2. Calculate the angle as a slope: slope = TIR ÷ diameter = 0.003 ÷ 6.00 = 0.0005 in/in.
  3. Shim change at near feet (8.00 in from face): correction = slope × distance = 0.0005 × 8.00 = 0.004 in.
  4. Shim change at far feet (16.00 in from face): correction = 0.0005 × 16.00 = 0.008 in.
  5. Because the 6 o'clock face reading is positive (gap opens at bottom), the motor is high at the coupling end — remove shims at near feet by 0.004 in and far feet by 0.008 in, or add shims so the far end rises more; determine direction from the sign convention used in the setup.
Answer: Remove 0.004 in of shim at the near motor feet and 0.008 in at the far motor feet to correct the vertical angular misalignment.
3. After a shim correction, rim readings are: 12 = 0.000 in, 3 = +0.001 in, 6 = −0.001 in, 9 = −0.001 in. Does the alignment pass in both planes?
  1. Vertical offset TIR = |12 reading − 6 reading| = |0.000 − (−0.001)| = 0.001 in.
  2. Horizontal offset TIR = |3 reading − 9 reading| = |+0.001 − (−0.001)| = 0.002 in.
  3. Compare each to the 0.002-inch criterion: vertical 0.001 in ≤ 0.002 in ✓; horizontal 0.002 in ≤ 0.002 in ✓.
Answer: Both planes pass: vertical TIR = 0.001 in, horizontal TIR = 0.002 in — both are within the 0.002-inch acceptance criterion.
4. A technician measures bracket sag by mounting the indicator bracket, zeroing it at 12 o'clock, rotating to 6 o'clock without any machine contact — using a separate reference — and reads −0.003 in. The actual rim readings with the machine are: 12 = 0.000, 6 = −0.007 in. What is the corrected 6 o'clock rim reading after accounting for sag?
  1. Sag correction at 6 o'clock = −0.003 in (the bracket droops that much under its own weight).
  2. Corrected 6 o'clock reading = raw reading − sag = −0.007 − (−0.003) = −0.007 + 0.003 = −0.004 in.
  3. Use −0.004 in as the true 6 o'clock rim reading in all subsequent calculations.
Answer: The corrected 6 o'clock rim reading is −0.004 in.

The math in this lesson2

Learners combine signed rim indicator readings at clock positions to find vertical and horizontal offset.
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Brush up in the math halls at newSchoolWorks.com:
In class: Instructor demonstration of dial indicator setup on the coupling alignment trainer: mounting the indicator bracket, zeroing the instrument, rotating the shaft through 360°, and recording clock-position readings on a standard alignment record sheet. · Student pairs perform rim-and-face alignment: record TIR readings at 12, 3, 6, and 9 o'clock positions; calculate required shim changes using the indicator readings and a four-bolt motor base; add or remove shims; re-check until within spec. · Introduction to laser alignment tool: instructor demonstrates the same trainer using a two-head laser aligner; students compare laser readings to indicator readings and record both sets of results on their alignment log.
Materials: Pump-motor alignment trainer with deliberately introduced misalignment, magnetic dial indicator stands, dial indicators (0.001-inch resolution), feeler gauges, shim assortment, laser shaft alignment system (two-head), alignment record sheets, PPE: safety glasses, gloves
Check: Final TIR reading recorded on alignment sheet; both angular and offset must be ≤0.002-inch TIR to pass; instructor measures independently to verify; LOTO compliance observed throughout.

Practice check8

Answer each question, then check it. Nothing is recorded; this is your own practice.

NCCER Industrial Maintenance – Mechanical Systems
1. What is the maximum allowable total indicator reading (TIR) in each plane for the alignment to pass in this lab?
NCCER Industrial Maintenance – Mechanical Systems
2. Which type of misalignment is indicated when the face indicator readings differ between the 12 o'clock and 6 o'clock positions?
NCCER Industrial Maintenance – Mechanical Systems
3. A technician records rim indicator readings of 0.000 in at 12 o'clock and −0.006 in at 6 o'clock. What is the vertical offset TIR?
NCCER Industrial Maintenance – Mechanical Systems
4. Which correction method is used to fix vertical misalignment on a motor mounted on a four-bolt base?
MSSC CPT – Safety
5. What must be done before mounting a dial indicator bracket on the coupling for an alignment check?
NCCER Industrial Maintenance – Mechanical Systems
6. Bracket sag causes an error in dial indicator alignment readings. How does sag affect the reading at the 6 o'clock position?
NCCER Industrial Maintenance – Mechanical Systems
7. A laser alignment system is used on the same trainer after the dial indicator alignment is complete. A student finds the laser readings differ slightly from the indicator readings. What is the most likely explanation?
MSSC CPT – Safety
8. After completing an alignment job and achieving the required TIR, what is the correct next step before re-energizing the motor?
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