NCCER Millwright cheat sheet

OSHA general industry rules are in 29 CFR 1910; construction rules are in 29 CFR 1926. Machine guarding is 1910.212 and lockout/tagout is 1910.147.

Permit-required confined space entry requires oxygen between 19.5% and 23.5% by volume, with atmospheric testing before entry and monitoring during the entry.

Fall protection is required at 4 ft in general industry and at 6 ft in construction; guardrails, safety nets, and personal fall arrest systems all satisfy the requirement.

Hearing protection is required when the 8-hour time-weighted average exposure reaches 85 dBA; 90 dBA is the permissible exposure limit for an 8-hour shift.

Extinguisher classes: A ordinary combustibles, B flammable liquids and gases, C energized electrical equipment, D combustible metals, K cooking oils and fats.

Hierarchy of controls, most to least effective: elimination, substitution, engineering controls, administrative controls, then personal protective equipment.

Lockout/tagout verification requires attempting a normal startup after isolation and testing for zero voltage or zero stored pressure at the point of work.

A 50 lb single-person lifting guideline is common practice; heavier or awkward loads call for a two-person lift or a mechanical aid.

Torque (ft-lb) = force (lb) x lever length (ft); 100 lb applied 2 ft from the fastener produces 200 ft-lb.

An inch micrometer reads to 0.001 in (25 thimble divisions across a 0.025 in barrel graduation); a metric micrometer reads to 0.01 mm.

A dial caliper typically resolves 0.001 in; a vernier caliper resolves 0.001 in with a 25-division vernier, or 0.02 mm on metric scales.

Crowfoot or adapter at 90 degrees to the torque wrench handle: no correction needed. In line with the handle: setting = desired torque x L / (L + E), where L is wrench length and E is adapter length.

Never use a torque wrench to break fasteners loose and never add a cheater bar; both overload the beam or spring and destroy calibration.

Bench grinder: keep the tool rest within 1/8 in of the wheel face and the tongue guard within 1/4 in, and ring-test a new wheel before mounting.

Hydraulic torque wrenches and torque multipliers are used where required torque exceeds roughly 1,000 ft-lb or where clearance prevents a hand wrench.

A file cuts on the forward stroke only; the handle must be firmly seated and the file is never used without one.

Third-angle projection places the top view above the front view and the right side view to the right; first-angle projection places the top view below the front view.

Line conventions: visible edges are thick continuous, hidden edges are dashed, centerlines are long-short-long, phantom lines are chain, and cutting planes are heavy chain with arrows.

Scale 1/4 in = 1 ft is a ratio of 1:48; 1/8 in = 1 ft is 1:96; 3/8 in = 1 ft is 1:32; 1 in = 1 ft is 1:12.

The title block carries the drawing number, part number, scale, revision level, material, and approval signatures.

Isometric drawings show three axes 120 degrees apart, drawn 30 degrees from horizontal with no foreshortening; they are standard for piping and spool layout.

A P&ID uses ISA instrument symbols and tag numbers to show process flow and control loops rather than physical location or elevation.

A GD&T feature control frame reads left to right: geometric characteristic symbol, tolerance zone, then datum references in order of precedence.

A datum is a theoretically exact plane, axis, or point from which dimensions are measured; layout work is always started from the datum.

1 mil = 0.001 in = 0.0254 mm; 0.001 mm = 0.0394 mil.

The standard reference temperature for dimensional measurement is 68 degrees F (20 degrees C); steel expands about 6.5 x 10^-6 in/in per degree F.

Sine bar: sin of the set angle = gage block stack height divided by the roll center distance (commonly 5 in or 10 in).

TIR (total indicated runout) is the full sweep of a dial indicator over one revolution; on a round part it equals twice the eccentricity.

Bore measurement uses a telescoping or snap gage locked to size, then read with an outside micrometer; rock the gage to find the true diameter.

A precision machine level reads in thousandths of an inch per foot; 0.0005 in/ft corresponds to about 0.005 in over a 10 in span.

Feeler gages measure clearance by trial: the thickest blade that enters with light drag is the reading, and blades are never forced.

Calibration is verified against a known standard (gage blocks or a setting ring) at the same temperature as the work being measured.

The working load limit (WLL) is the maximum load a sling or hardware item may carry; a sling with a missing or illegible tag is removed from service.

Symmetric two-leg lift: tension per leg = load / (2 x cos of angle from vertical). At 30 degrees from vertical (60 from horizontal) each leg carries 0.577 x load.

Per-leg share of load by angle from horizontal: 90 degrees = 0.500, 60 degrees = 0.577, 45 degrees = 0.707, 30 degrees = 1.000 times the load.

Sling load angle factor = sling length / vertical lift height; multiply each leg's share of the load by this factor to get actual tension.

Hooks must have a functioning latch, be loaded in the saddle rather than the tip, and never be side-loaded beyond the manufacturer's rating.

Shackle screw pins must be fully seated and moused where vibration is present; the load should bear on the bow, not on the pin threads.

The hook must sit directly above the load's center of gravity; otherwise the load tilts and leg tensions become unequal and unpredictable.

Wire rope sling removal criteria include 10 broken wires in one rope lay concentrated in one strand, or 5 broken wires in one strand in one lay, plus kinking or severe corrosion.

Soft foot is checked by mounting a dial indicator on each foot and loosening bolts one at a time; the limit is typically 0.002 in (0.05 mm).

Place shims directly beneath the foot, use pre-cut stainless steel shims, and limit stacks to about four; many thin shims compress and lose bolt preload.

Grout fills the gap between baseplate and foundation, transfers load, and damps vibration; it is poured after rough alignment and cured before final bolt torque.

Anchor bolts are torqued or tensioned to a specified value or stretch; a random part-turn past snug is not a substitute for the specified torque.

Pipe strain is checked with a dial indicator on the shaft or coupling while flange bolts are loosened; movement above 0.002 in requires piping correction.

Rough alignment with a straightedge and feeler gage precedes precision alignment, and final alignment follows grouting and pipe connection.

Thermal growth makes a running machine rise and move toward its thrust end, so cold alignment offsets must compensate for measured or published growth.

The baseplate must be level within the manufacturer's tolerance and the foundation bolts properly tensioned before precision alignment begins.

Two misalignment components: parallel (offset between shaft centerlines) and angular (gap change across the coupling face, expressed in mils per inch of diameter).

Rim-and-face shim correction: change in shim thickness = (face reading / coupling diameter) x distance from coupling to the foot being corrected.

The reverse dial indicator method reads from both shafts to cancel bracket sag; sag itself is measured with a rigid bar and subtracted from readings.

Typical acceptance tolerances are 0.002 in or less offset and 0.0005 in/in angularity, but the coupling or machine manufacturer's specification always governs.

Vertical misalignment is corrected with shims under the feet; horizontal misalignment is corrected with jacking bolts or lateral repositioning of the machine.

Laser alignment systems compute offset and angularity in two planes at once and display live shim and horizontal move values.

Rotate both shafts together during readings so that coupling hub and shaft runout cancel rather than appearing as misalignment.

Gear and grid couplings tolerate more misalignment than disc or diaphragm types; elastomer jaw couplings damp vibration but carry lower torque.

Bore code: the last two digits of a bearing designation times 5 give the bore in mm (05 = 25 mm, 10 = 50 mm); 00 = 10 mm, 01 = 12 mm, 02 = 15 mm, 03 = 17 mm.

A rotating inner ring requires an interference fit on the shaft; a stationary inner ring may use a transition or loose fit.

Do not heat sealed or pre-greased bearings above about 250 degrees F (120 degrees C); induction heaters are preferred over open flame.

Grease fill is about 30 to 50 percent of free space in the bearing and housing; overfilling churns grease, raises temperature, and shortens life.

A lip seal's spring-loaded lip faces the lubricant it retains; a second lip, facing outward, excludes external contamination.

ISO viscosity grades are measured at 40 degrees C; ISO VG 32, 46, and 68 are common machine oils, chosen by speed and load.

Roughly 40 percent of bearing failures are lubrication-related, with contamination, misalignment, and overload accounting for most of the remainder.

Mechanical seal faces must run flat and clean with a fluid film between them; dry running destroys the faces in seconds.

P = F / A, so cylinder force = pressure x effective piston area; retraction force uses piston area minus rod cross-sectional area.

Flow Q = area x velocity; doubling actuator speed requires double the flow at the same pressure.

Hydraulic systems commonly run 1,000 to 3,000 psi while plant air is 80 to 120 psi, so a pneumatic cylinder needs far more area for the same force.

The relief valve limits system pressure and protects the pump; it is set at or below component ratings and is never used as a flow-control device.

Accumulators are precharged with dry nitrogen; oxygen or compressed air can form an explosive mixture with hydraulic oil.

An FRL unit filters, regulates, and lubricates compressed air; the lubricator is installed last so oil mist reaches the using device.

ISO 4406 cleanliness codes report particle counts per milliliter at 4, 6, and 14 micrometers; most hydraulic components need 18/16/13 or cleaner.

Entrained air causes spongy actuator response, foaming, and overheating; bleed at high points and cycle slowly at low pressure until motion is smooth.

Predictive maintenance is condition-based (vibration, thermography, oil analysis, ultrasound); preventive maintenance is calendar- or runtime-based.

Bathtub curve: infant mortality from defects, a random constant-rate period, then a rising wear-out region that scheduled replacement targets.

Vibration signatures: a 1x RPM peak indicates unbalance, a 2x RPM peak indicates misalignment or a bent shaft, and high-frequency broadband energy indicates bearing distress.

Thermography finds loose electrical connections, overloaded circuits, and failing bearings as hot spots while equipment runs under normal load.

Oil analysis reports viscosity, water content, particle counts, and wear metals such as iron, copper, chromium, and lead.

Ultrasonic monitoring locates compressed air and steam leaks and detects early bearing distress before it appears in vibration data.

FMEA prioritizes failure modes by severity, occurrence, and detection so maintenance effort goes to the highest-risk items.

Failure coding on every work order lets the CMMS trend repeat failures, and root cause tools such as 5 Whys or fishbone diagrams prevent recurrence.