Engineering guides
Practical how-to guides for everyday mechanical calculations — each explains the method to its governing standard, works a numeric example, and links to the calculator that runs it.
Shafts & Bearings
- How to Calculate Bearing L10 Rating Life and Modified Life (ISO 281)How to calculate rolling bearing L10 basic life and modified rating life Lnmh to ISO 281 — the load-life formula, the aISO lubrication factor, and a worked deep-groove ball bearing example.
- Shaft Fatigue Safety Factor — Goodman Criterion and DIN 743 ExplainedHow to calculate a shaft fatigue safety factor: the Goodman criterion, the Kf notch factor, and size and surface corrections — plus what DIN 743 requires and how it differs. Worked von Mises example and a shaft calculator you can run free for 30 minutes, no sign-up.
Power Transmission
- How to Calculate Belt Drive Power, Tension and Pulley SizingCalculate belt drive power, tight-side/slack-side tension, wrap angle and belt length with the Euler–Eytelwein equation — worked example, key formulas and a belt calculator you can run free for 30 minutes, no sign-up.
- How to Calculate Gear Contact and Tooth-Root Bending Stress (ISO 6336)How to calculate gear tooth-root bending stress σF and Hertz contact stress σH to ISO 6336 — the governing formulas, key influence factors, and a worked spur-gear example with safety factors SF and SH.
Actuation & Motion
- Sizing a Pneumatic Rack-and-Pinion Lifting MechanismSize the air cylinder and rack-and-pinion drive of a pneumatic lift: build the lift load from the weight it raises, pick a bore at the operating pressure for a safe thrust margin, and check the pinion force and torque — with a worked example and calculators you can run free for 30 minutes, no sign-up.
- Sizing a Pick-and-Place End Effector: Vacuum Pads vs GripperSize the end effector of a pick-and-place head: choose between vacuum pads and a mechanical gripper, compute the required pad diameter or grip force from the part mass and a safety factor, and check the hold — with a worked example and calculators you can run free for 30 minutes, no sign-up.
- Sizing a Pneumatic Lever or Swing ClampSize a pneumatic clamp: turn the required clamping force into a cylinder bore through the lever ratio, check the worst clamping angle, and confirm the safety factor — with a worked example and calculators you can run free for 30 minutes, no sign-up.
- Sizing a Lead-Screw or Ball-Screw Positioning StageSize the drive of a lead-screw or ball-screw positioning stage: build the friction load, convert it to screw drive torque, and reflect the carriage inertia to the motor shaft for a healthy inertia ratio — with a worked example and calculators you can run free for 30 minutes, no sign-up.
- Sizing a Rotary Index (Dial) Table MotorSize the motor of a rotary index table: sum the rotating inertias, reflect them to the motor shaft through the gearhead, check the inertia ratio, and find the acceleration torque for the index move — with a worked example and a calculator you can run free for 30 minutes, no sign-up.
- Calculating Linear Guide Rated Life and Static SafetyCalculate the rated life of a linear guide (LM guide / linear rail) to ISO 14728-1: nominal life in km and hours from the C/P ratio and the hardness, temperature, contact and load factors, plus the static safety factor — with the 50/100 km basis explained and a worked example.
- Power-Screw and Lead-Screw Torque and EfficiencyRaise/lower torque, efficiency and self-locking for Acme, square and buttress power screws — formulas explained, a worked numeric example, and a lead-screw calculator you can run free for 30 minutes, no sign-up.
Joints & Fasteners
- How to Calculate Bolt Preload and Tightening Torque (VDI 2230)How to calculate bolt preload and tightening torque to VDI 2230 — the torque–preload relationship, why ~90% of torque fights friction, and a worked M12 class 10.9 example. With a bolt calculator you can run free for 30 minutes, no sign-up.
- How to Design a Fillet Weld to EN 1993-1-8 — Directional Method ExplainedHow to check fillet weld strength to EN 1993-1-8 — the directional method, throat stress components σ⊥ τ⊥ τ∥, correlation factor βw, and a worked S355 bending example.
- How to Calculate Press-Fit and Interference-Fit Contact Pressure (Lamé / DIN 7190)How to calculate interference-fit contact pressure using Lamé thick-wall theory (DIN 7190) — hub hoop stress, von Mises burst safety, torque capacity and a worked steel-hub example. With a calculator you can run free for 30 minutes, no sign-up.
Structural & Stress
- Beam Deflection Formulas for Common Load CasesClosed-form beam deflection formulas for simply supported, cantilever and fixed-fixed beams under point loads and UDLs — with a verified worked example and an online calculator you can run free for 30 minutes, no sign-up.
- Column Buckling: Euler vs Johnson — Which Formula to UseHow to choose between the Euler and Johnson buckling formulas, compute the critical load and slenderness, and apply the correct safety factor — with a worked steel column example.
- Compression Spring Design: Spring Rate and Shear Stress (DIN 2089)How to design a helical compression spring — spring rate formula, Wahl-corrected shear stress, allowable τ_zul per DIN 2089 / EN 13906, and a fully worked numeric example. Spring calculator included — free for 30 minutes, no sign-up.
- Goodman vs Soderberg vs Gerber: Mean-Stress Fatigue Correction ExplainedHow to apply the modified Goodman, Soderberg and Gerber mean-stress corrections to a fatigue safety factor — formulas, the Haigh diagram, and a step-by-step worked example for bending with a mean load.
- Mohr's Circle and Principal Stresses — Full Method GuideHow to use Mohr's Circle to find principal stresses, maximum shear stress and the principal angle for any 2D stress state — with Von Mises and Tresca safety factors and a worked numeric example.
Manufacturing & Metrology
Fluid Power & Piping
- Hydraulic Cylinder Force, Speed and Rod Buckling ExplainedHow to calculate hydraulic cylinder extension and retraction force, piston speed, flow rate, and piston rod buckling safety factor — with a fully worked 80 mm bore example.
- How to Calculate Pipe Pressure Drop with the Darcy-Weisbach EquationStep-by-step guide to pipe pressure drop calculation using Darcy-Weisbach and the Colebrook-White friction factor — Reynolds number, flow regime, Moody chart, and a worked DN50 turbulent-flow example.
- How to Calculate Pressure Vessel Wall Thickness and MAWP to ASME VIII UG-27How to calculate pressure vessel minimum wall thickness and MAWP to ASME VIII Div.1 UG-27 — the formula, when thick-wall Lamé applies, and a worked cylindrical shell example. Calculator included — free for 30 minutes, no sign-up.
Pumps, Fans & Thermal
- Heat Exchanger Sizing: LMTD and Effectiveness-NTU MethodsHow to size and rate a heat exchanger using the LMTD method with F-correction and the effectiveness-NTU method — formulas, the F factor explained, and a fully worked counterflow example.
- How to Calculate NPSH and Avoid Cavitation in Pumps (ISO 9906)How to calculate NPSHa, check the cavitation margin and size a pump — the formula, a worked water-pump example, and an NPSH calculator you can run free for 30 minutes, no sign-up. Plus what ISO 9906 actually governs, and what it does not.