Red Seal Machinist cheat sheet

WHMIS 2015 (GHS-aligned) uses pictograms, signal words, and 16-section Safety Data Sheets; the SDS must be accessible in the work area before a controlled product is used.

Lockout applies to stored energy as well as electrical: gravity (raised machine heads), hydraulic/pneumatic pressure, springs, and thermal energy must be bled or blocked before work begins.

Machine guarding rule: a guard must prevent access to the point of operation and must not be removable without a tool; interlocks must stop motion before a body part can reach the hazard.

Personal protective equipment hierarchy: engineering controls and administrative controls come first; PPE (safety glasses with side shields, safety footwear, hearing protection) is the last line of defence.

Compressed air for cleaning must be regulated to 30 psi (207 kPa) or less with a safety nozzle; never use air to clean skin or clothing.

Housekeeping and fire: oily rags go in a self-closing metal container; Class B (flammable liquid) fires need foam, CO2, or dry chemical - never water.

Chip and coolant hazards: use a brush or hook to clear chips (never bare hands or air), and treat used metalworking fluids as a dermatitis and mist-inhalation hazard.

Manual handling: keep loads close to the body, lift with the legs, and use a hoist or two-person lift for anything above the safe single-person limit set by the employer's policy.

Emergency response: know the location of the nearest eyewash station, first-aid kit, fire extinguisher, and emergency stop before starting any machine.

Sine bar angle: sin θ = (difference in gauge-block stack height) ÷ (sine bar centre distance); for a 5 in sine bar, a 1.000 in stack gives θ = 11.537°.

Taper and angle: taper per inch = (large diameter − small diameter) ÷ length; included angle = 2 × arctan[(D − d) ÷ 2L].

Right-triangle layout: use the 3-4-5 relationship (and multiples) to square a layout; hypotenuse = √(a² + b²).

Speeds and feeds: RPM = (cutting speed in ft/min × 12) ÷ (π × diameter in inches), simplified as RPM ≈ (4 × SFM) ÷ diameter for inch work.

Feed rate for milling = feed per tooth × number of teeth × RPM; for turning, feed is per revolution and is read directly from the machine.

Tap drill size (inch) ≈ major diameter − 1 ÷ threads per inch; metric tap drill ≈ major diameter − pitch.

Bolt-circle coordinates: X = R cos θ, Y = R sin θ, measured from the circle centre, with θ referenced to the chosen zero axis.

Allowance and tolerance: allowance is the intentional difference between mating part sizes; tolerance is the total permissible variation (upper limit − lower limit).

Layout datum rule: establish one datum edge or surface and reference every dimension from it; avoid stacking dimensions from multiple edges.

Files cut on the forward stroke only; pressure is applied going forward and released on the return to preserve the teeth and produce a flat surface.

File numbering: single-cut files are for finishing and sharpening; double-cut files remove material faster; the coarsest grade is rough, the finest is smooth.

A file card (stiff-bristle brush) cleans pins from the file teeth; chalk or file lubricant reduces pinning on soft metals.

Hacksaw blade selection: 14–18 teeth per inch for thick sections and soft metals, 24–32 TPI for thin wall tube, sheet, and hard materials; at least three teeth must be in contact with the work.

Hacksaw technique: cut on the forward stroke, use light pressure and full blade length, and relieve pressure on the return stroke to avoid blade breakage.

Chisels and punches: use a soft-faced or brass hammer on hardened punches; mushroomed heads must be ground off before the tool is used again.

Wrenches: use the correct size and pull (never push) an adjustable wrench; a box-end or socket is preferred where access allows because it grips all flats.

Scribes and dividers: a scribed line is more accurate than a pencil line but creates a stress riser on highly stressed parts, so layout dye plus a fine scriber is preferred for precision work.

Screwdriver selection: the blade must fill the slot width and thickness; a loose fit cams out and damages the fastener and the tool.

Micrometer reading: main sleeve value + thimble reading × least count; a 0–1 in micrometer with a 0.025 in sleeve and 25-division thimble has a least count of 0.001 in.

Vernier scale reading: main scale value + (matching vernier line × least count); a 0.001 in vernier caliper has 25 divisions on the vernier and a least count of 0.001 in.

Zero check every instrument before use: close a micrometer on its anvil or use a setting standard; close caliper jaws and confirm zero on the scale.

Calibration rule: measuring instruments are calibrated against traceable standards at defined intervals and are tagged with calibration status; an out-of-calibration instrument's readings are suspect.

Abbe's principle: the measurement axis should be in line with the scale axis; this is why a micrometer is more accurate than a caliper for the same nominal size.

Temperature effect: steel expands about 6.5 × 10⁻⁶ in/in per °F; measure at 68 °F (20 °C) for inch/metric standards.

Surface plate and height gauge: the plate provides a flat datum; a dial test indicator on a height gauge transfers heights and checks squareness and parallelism.

Gauge blocks: wrung together to build a stack; select blocks from largest to smallest and use the minimum number to reduce accumulated error.

Inspection gauges: go/no-go gauges check limits, not actual size; a plug gauge go end must enter and the no-go end must not enter a hole within tolerance.

Filing flat: use a cross-file then draw-file sequence, check with a straightedge or surface plate, and rotate the work 90° between checks to avoid a crowned surface.

Hacksawing and filing to a scribed line: leave half the line width for finishing and file to the line, not past it.

Hand tapping: use the correct tap drill, start the tap square with a tap guide, and apply cutting fluid; back the tap off a quarter turn periodically to break chips.

Tap drill for a metric thread ≈ major diameter − pitch (e.g., M8 × 1.25 → 6.75 mm drill).

Reaming: drill undersize, then ream to size with a reamer turning in the cutting direction only; never reverse a hand reamer in the hole.

Scraping and hand fitting: blue the mating surface, scrape high spots, and repeat until the contact pattern is uniform; used for flatness and bearing surfaces.

Deburring: remove burrs with a file, scraper, or deburring tool after sawing, drilling, and turning; burrs affect fit, measurement, and safety.

Pinning and dowelling: dowel pins locate parts; ream the dowel hole for an interference fit and drill/ream both parts together to preserve alignment.

Bench vice practice: mount the work as low as possible in the jaws, protect finished surfaces with soft jaws, and never hammer on the vice.

Drill point geometry: a standard twist drill has a 118° included point angle; 135° split point is used for harder materials and reduces walking.

Drill speed: use the same RPM formula as turning (RPM ≈ 4 × SFM ÷ diameter); feed per revolution for a given drill diameter is read from a drill chart or the machine.

Drill point location: use a centre drill or spot drill first to prevent walking; a centre drill is short and rigid and is the standard for starting a hole.

Coolant and chip control: use coolant for deep holes and tough materials; peck drill (retract) to clear chips and prevent packing and drill breakage.

Hole accuracy: drilled holes are rough and oversized; for precision use drill, bore, or drill and ream.

Saw blade selection: band saw blade pitch must keep at least three teeth in the cut; coarse pitch for thick sections, fine pitch for thin wall and hard material.

Band saw break-in: run a new blade at reduced feed and speed for the first cut to seat the teeth; use cutting fluid and correct blade tension.

Abrasive chop saw: use the wheel rated for the machine's RPM and material; never exceed the marked maximum speed and always wear face and hearing protection.

Drill press safety: clamp the work or use a drill vice, never hold it by hand; remove the chuck key before starting the spindle.

Turning speed: RPM ≈ (4 × SFM) ÷ diameter for inch work; use the largest diameter in the cut for the calculation.

Facing and turning: set the tool on centre height; a tool above centre rubs, below centre digs in.

Taper turning: use the compound rest for short tapers, the tailstock set-over for long shallow tapers, and a taper attachment for accurate long tapers.

Threading: the thread depth for a 60° unified thread ≈ 0.6495 × pitch; set the compound at 29–30° for the infeed and engage the half-nut on the same spindle mark each pass.

Four-jaw chuck: adjust each jaw independently and indicate the work true with a dial test indicator; a three-jaw chuck is self-centring but less accurate.

Parting off: use a rigid tool on centre, slow speed, plenty of coolant, and a feed that keeps the chip flowing; a chatter or rub indicates the tool is off centre or too long.

Boring: bore from a drilled hole to correct size and alignment; use a boring bar with minimum overhang and check the bore with a telescoping gauge and micrometer.

Knurling: use a knurl that matches the work diameter, apply pressure slowly with coolant, and never knurl a diameter that must remain a precision fit.

Lathe safety: never leave the chuck key in the chuck, keep the tool post clear, and never reach over a rotating workpiece.

Climb vs conventional milling: climb milling (cutter rotation in the feed direction) gives a better finish on machines with backlash compensation; conventional milling is safer on worn machines.

Milling feed rate = feed per tooth × number of teeth × RPM; the feed per tooth depends on cutter material and workpiece material.

Face milling: the cutter should be centred or slightly offset over the work so the teeth enter and exit cleanly; avoid cutting with the very centre of the cutter.

End milling a slot: use a two-flute cutter for aluminium and chip clearance, and a four-flute cutter for steel and finish; use the correct speed for the cutter diameter.

Squaring a block: face one side, then square the adjacent sides to it using a precision vice or angle plate, and check with a square and dial indicator.

Dividing head: use the index plate and sector arms; for a simple ratio, turns of the crank = 40 ÷ number of divisions.

Backlash: always approach a dimension from the same direction; take up backlash in the table screws before a finish cut.

Milling safety: use the correct arbor and spacers, tighten the drawbar, and never reach into the cutter path; use a brush to clear chips, not hands.

Abrasive wheel marking: the letter sequence gives abrasive type, grit size, grade (hardness), structure, and bond; a harder grade holds the abrasive longer and is used for softer work.

Wheel speed: never exceed the marked maximum RPM; a wheel must be ring-tested and visually inspected before mounting, and blotters must be used under the flanges.

Dressing and truing: dress a wheel to expose sharp grit and true it to restore form; use a diamond dresser with coolant and light passes.

Surface grinding: use a balanced wheel, adequate coolant, and a small depth of cut (typically 0.0005–0.002 in per pass) for finish and to avoid burning.

Workholding: use a magnetic chuck with a minimum number of poles covered; demagnetize the work after grinding to prevent chip attraction.

Grinding burn and cracks: caused by too heavy a cut, wrong wheel grade, or insufficient coolant; inspect for discolouration and use a crack-detection method on critical parts.

Cylindrical grinding: the work rotates against the wheel; use the correct wheel width and traverse, and check for taper with a micrometer at both ends.

Safety: grinding dust and sparks are a fire and respiratory hazard; use local exhaust ventilation and eye and face protection.

Coordinate systems: G54–G59 are work offsets; G90 is absolute and G91 is incremental positioning.

Common G-codes: G00 rapid, G01 linear feed, G02 clockwise arc, G03 counter-clockwise arc, G04 dwell, G28 return to reference, G43 tool length compensation, G81 drilling cycle.

M-codes: M03 spindle on clockwise, M04 counter-clockwise, M05 stop, M06 tool change, M08 coolant on, M09 coolant off, M30 program end and rewind.

Program structure: program number, safe start block (G90 G54 G17 G40 G49 G80), tool call with length and diameter compensation, then cutting moves and a safe retract at the end.

Cutter radius compensation: G41 left, G42 right, G40 cancel; the control offsets the tool path by the tool radius stored in the offset register.

Feed and speed: use constant surface speed (G96) with a maximum spindle limit (G50) for turning; use G97 for direct RPM on milling and drilling.

Tool length offset: set with a tool setter or by touching off on the work; verify by running the first tool above the part before cutting.

Program verification: use single block, feed override, and distance-to-go display for the first run; never run a new program at full rapid with the door open.

CNC safety: keep the door interlock functional, never reach into the enclosure while the spindle is enabled, and clear chips only when the machine is stopped.

Orthographic views: first-angle projection places the top view below the front view; third-angle projection places the top view above the front view - check the projection symbol on the drawing.

Line types: visible lines are thick continuous, hidden lines are dashed, centre lines are long-short dashes, and phantom lines are used for alternate positions.

GD&T symbols: form (straightness, flatness, circularity, cylindricity), orientation (perpendicularity, parallelism, angularity), location (position, concentricity, symmetry), and profile (line, surface).

Feature control frame: reads left to right as geometric symbol, tolerance zone, and datum references; a diameter symbol before the tolerance means a cylindrical zone.

MMC and LMC: maximum material condition (Ⓜ) is the largest pin/smallest hole; least material condition (Ⓛ) is the opposite; a bonus tolerance is available when departing from MMC.

Datum reference frame: three mutually perpendicular planes; the primary datum constrains three degrees of freedom, the secondary two, and the tertiary one.

Position tolerance: a position callout defines a cylindrical zone centred on the true position; the bonus tolerance equals the actual size departure from MMC.

Surface finish: Ra is the arithmetic average roughness; a 63 µin Ra finish is typical for a turned surface and 16 µin Ra for a ground surface.

Title block and revision: confirm the drawing revision, units (inch or metric), and the general tolerance note before machining any feature.