Mechanical

Lubrication

The one curve of tribology: friction across the boundary, mixed and full-film regimes, viscosity as the single property that matters, the lambda ratio that names your regime, bo…

Machine Screws and Nuts

The small end of threaded fastening: machine screw head styles and drive types, the numbered gauge sizes and the formula behind them, why a standard nut is the height it is, and…

Machining Econometrics

The economics of a cut: how machining cost and tooling cost pull against cutting speed, the U-shaped cost-per-part curve, and the optimum tool life for minimum cost and for maxi…

Machining Nonferrous and Nonmetallic Materials

Cutting the materials that are not steel: aluminium and copper at high speed with sharp positive tools, built-up edge and how to beat it, and the special care plastics and compo…

Measuring Instruments and Inspection Methods

Workshop metrology: accuracy, precision and the ten-to-one rule, callipers and micrometers with worked readings, dial indicators and cosine error, gauge-block stacks, the sine b…

Measuring Screw Threads

Reaching the diameter you cannot touch: limit gauging and Taylor's principle, the three-wire method with its geometry derived and an M10×1.5 worked over best and ordinary wires,…

Measuring Units

The SI system for engineers: the seven base units and their constant-based definitions, named derived units resolved to base units, coherence and why consistent units need no co…

Metric Screw Threads

The ISO metric system that fastens the planet: reading the designation, the coarse and fine pitch series, the 6g/6H tolerance scheme, the geometric proof that plating grows a pi…

Metric Threaded Fasteners

The ISO metric thread system: reading a designation like M10 x 1.5, the coarse and fine series, the tensile stress area formula validated against standard sizes, and the propert…

Micromachining

Machining at the scale of microns: the size effect and minimum chip thickness, ploughing versus cutting, the very high spindle speeds tiny tools demand, and the fragility that d…

Milling Cutters

Milling with rotating multi-tooth cutters: the main cutter types, conventional versus climb milling, spindle speed and the feed-per-tooth that sets table feed, material removal …

Nails, Spikes and Wood Screws

Fastening into timber: why nails hold laterally but not in withdrawal, how holding power scales with wood density, penetration rules, the wood screw and the clearance-hole disci…

Nonferrous Alloys

The metals that are not steel: aluminium and its designation system, copper and its brasses and bronzes, the light and specialty metals, electrical conductivity, and how to choo…

O-Rings

The almost-perfect seal: the self-energising principle, squeeze, fill and stretch worked for a standard 3.53 mm section, gland geometry, extrusion and its cures, the elastomer m…

Other Threads

The threads that fit no other page: round and knuckle forms that shrug off dirt, the Edison lamp thread, the worm that is a gear, closure threads that open in one turn, and inte…

Pins and Studs

The fasteners that locate rather than clamp: dowels and the two-pin rule, taper pins and the 1:50 taper, spring and grooved pins that make their own fit, cotter and clevis pins,…

Pipe and Hose Threads

Threads that must not leak: why the name is not the bore, the 1:16 taper arithmetic of NPT and BSPT, the parallel threads that seal on a face instead, the flare fittings that se…

Plain Bearings

The sleeve that outlived every rival: pressure, speed and the PV product worked for a real bush, the hydrodynamic wedge that lets a shaft float on its own oil, Petroff's frictio…

Plastics

Engineering plastics for the mechanical designer: thermoplastics versus thermosets, low density and the float test, low stiffness, high thermal expansion, the common families an…

Mechanical12 Aug 2026 · 3 min read

Plates, Shells, and Cylinders

Pressure containment: thin-cylinder hoop and longitudinal stress, thin spheres, the thin-versus-thick criterion, Lamé thick-cylinder analysis, and uniformly loaded flat circular…

Properties of Wood, Ceramics, Plastics and Metals

How the material classes compare: stiffness, strength, density and their weight-adjusted forms, the surprising result that the common metals share one specific stiffness, and ho…

Reamers

Reaming to finish a drilled hole to size and finish: how a reamer works, the reaming allowance and why it must be small, hand and machine reamers, speeds and feeds, and fluting …

Retaining Rings

The circlip and its relatives: how a sprung ring in a machined groove replaces a shoulder, nut or cover, the external and internal families, and the computation showing the groo…

Rivets and Riveted Joints

The permanent fastener and its arithmetic: proportioning a joint with Unwin's rule, the four ways a riveted joint fails, working a lap and a butt joint through all four checks, …

Rolled Steel, Wire, Sheet Metal and Wire Rope

Stock as a component: hot- and cold-rolled character, the sheet-metal bend worked to its allowance, wire as bottled cold work, wire rope's many-small-wires bargain with the shea…

Screw Machines, Band Saws and Cutting Fluids

Three production essentials: automatic screw machines that turn parts by the thousand, band sawing with the three-tooth rule for pitch selection, and the cutting fluids that coo…

Screw Thread Systems

The helix that runs through all of engineering: thread anatomy, pitch against lead, why every fastening thread is self-locking, the efficiency arithmetic that makes a bolt a del…

Mechanical12 Aug 2026 · 9 min read

Self-Threading Screws

Screws that make their own thread: forming against cutting, the self-drilling point, how much a thread in thin sheet can actually hold, the drive-strip torque window that produc…

Shaft Alignment

The element every other element assumed: offset and angle as four numbers at the coupling, dial readings decoded — TIR halved, sag corrected, soft foot first — the similar-trian…

Mechanical12 Aug 2026 · 3 min read

Shafts

Shaft torsion: the torsion formula and polar moments, converting power to torque, design for shear strength, design for torsional stiffness with the degree-per-metre guideline, …

Sheet Metal Working and Presses

Shaping sheet metal in a press: blanking and piercing and the force they take, bending with its allowance and springback, and deep drawing with its ratio limit — with worked fig…

Simple, Compound, Differential and Block Indexing

The dividing head and its arithmetic: the 40:1 worm heart, simple indexing worked across the plates, the compound trick of two motions, differential indexing with its gear train…

Soldering and Brazing

Joining metals with a molten filler without melting the parts: the soldering-versus-brazing line at 450°C, capillary action and the joint gap, why lap joints carry the load, the…

Splines and Serrations

Splines and serrations as multi-tooth shaft-to-hub connections: straight-sided versus involute splines, why many teeth beat a single key, torque capacity from bearing area, fits…

Springs

Helical spring design: geometry and spring index, rate and deflection, shear stress with the Wahl correction, ends, solid height and buckling guidance, stored energy, and notes …

Spur Gears

Spur gear fundamentals: the involute tooth and why it is used, module and diametral pitch, the pitch, base, addendum and dedendum circles, pressure angle, gear ratio and centre …

Standard Steels

Carbon and alloy steels for engineers: what carbon does, the SAE/AISI four-digit designation system and how to read it, the alloying elements and their effects, the carbon equiv…

Standard Tapers

Machine tool tapers: how a taper is defined, self-holding tapers such as the Morse that grip by friction, self-releasing steep tapers held by a drawbar, the self-locking angle c…

Surface Texture

Surface finish: roughness, waviness and lay, the Ra average and Rz peak measures with computed examples, stylus measurement and cutoffs, typical roughness by process, the N-grad…

Symbols and Abbreviations

Writing measurements correctly: the grammar of SI symbols, case sensitivity, spacing and compound units, the base-unit and prefix symbols, the Greek alphabet as used in engineer…

Mechanical12 Aug 2026 · 9 min read

T-Slots, T-Bolts and T-Nuts

The workholding interface of every machine table: the T-slot family, the strap clamp as a lever and why bolt position doubles or halves the clamping force, and the computation s…

Tapping and Thread Cutting

Cutting the thread by hand and by machine: the taper-plug-bottoming tap set, spiral-point and forming taps, dies and chasers, single-point threading on the lathe, and the consta…

Taps

Cutting internal threads with taps: the tap-drill size and percentage thread engagement, cutting versus forming taps, taper, plug and bottoming taps, flute types for through and…

Thread Grinding

The precision end of thread making: a diamond-dressed wheel carrying the thread's negative, single-rib and multi-rib practice, the tilt-to-the-lead-angle geometry, why hardened …

Thread Milling

The CNC way to a thread: a rotating cutter driven around a helical orbit, the geometry worked for an M20 with a twelve-millimetre tool, the 2.5× feed correction that scraps thre…

Thread Rolling

The thread that is squeezed, not cut: why the blank is exactly the pitch diameter, the machines from flat dies to planetary heads, the fatigue case for rolled roots and grain fl…

Tool Steels

Tool steels for cutting, forming and dies: what sets them apart from structural steel, the AISI letter-grade groups (W, O, A, D, H, M, T), red hardness and wear resistance, and …

Tool Wear and Sharpening

How cutting tools wear and when to regrind: flank and crater wear, the wear mechanisms of abrasion, adhesion and diffusion, the flank-wear limit as a life criterion, the speed–l…