GD&T
Tolerance stack-up
Builds a worst-case and statistical stack-up along a defined loop, ranks contributors by share of total variation, and tells you which two tolerances to tighten or which can be opened for cost.
ALL SKILLS · FULL LIBRARY
Engineering skills, written and signed by their authors.
15 skills across 11 disciplines, each vetted by practising engineers. Open a skill to read the full sheet or download the PDF.
Author
Discipline
Showing 15 of 15 skills
GD&T
GD&T callout review
Reviews a drawing's geometric tolerancing for legality and intent: datum precedence, degrees of freedom actually constrained, redundant or missing controls, and whether the callout can be inspected.
FEA
Bolted joint sizing
Sizes and verifies a bolted joint end to end: preload, stiffness ratio, separation and slip margins, fatigue on the alternating share, and a torque spec with the friction assumption written down.
FEA
FEA sanity check
Audits a simulation before anyone trusts it: reaction balance, hand-calc cross-check, singularity screen, convergence, and whether the reported stress is even the right quantity for the criterion.
FEA
Hand calc check
Produces a documented first-principles calc sheet for beams, shafts, buckling, pressure, fits, springs, and bearings: assumptions numbered, units carried, margin reported against a named criterion.
Manufacturing
DFM review for machined parts
Walks a machined part for manufacturability: setup count, internal radii, deep pockets, thin walls, workholding, and the tolerances that quietly force secondary operations and triple the price.
Cost
Supplier quote review
Normalizes supplier quotes to common scope and terms, builds a bottom-up should-cost from material, cycle time, and tooling, and identifies the specific line items worth negotiating.
Materials
Material selection tradeoff
Runs an Ashby-style selection: screens candidates on hard constraints, ranks on the right material index, states the failure mode each finalist is weakest against, and recommends grade and temper.
Quality
DFMEA builder
Facilitates a Design FMEA that teams actually use: function decomposition, physics-of-failure brainstorming, honest severity and occurrence scoring, and verifiable actions in RPN or AIAG-VDA format.
Quality
Root cause and 8D
Drives a disciplined failure investigation: is/is-not problem definition, mechanism-first causal analysis, verified root cause with evidence, and a complete 8D covering technical, escape, and systemic causes.
Testing
Test plan builder
Converts requirements into a verification matrix with pass/fail criteria, statistically based sample sizes with stated confidence, test sequencing, and the gaps where a requirement is untestable as written.
Documentation
ECO writer
Drafts a complete engineering change order: itemized before/after, the interchangeability call, an exhaustive affected-items sweep, stock disposition, and the validation required before release.
Mechanism dynamics
Torque balance of a hinged panel under tilt and base acceleration
You will be able to compute the true worst-case gravity and inertia torque on a hinged panel for a vehicle that is tilted, accelerating, braking and pitching, and explain why the level-ground number is not the design number.
Powertrain integration
Engine mounting and isolation in a shock environment
You will be able to select and place engine mounts so the engine is isolated at idle, survives shock in all six directions, and does not tear its own brackets off.
Nonlinear dynamics
Deciding whether nonlinearity actually matters
You will be able to tell from a test whether a structure is behaving nonlinearly, and know that once it does, the frequency response function on your screen describes nothing.