Geometry design
Parametric solid · STEP · STL · wall and shelf mounting holes
- contract leaf
- £681.13
- team drew
- £510.85
- estimator band
- £125.40–£2,505.00
f4877d90-9720-4a7c-a3f8-d0253e68d335TURNSTONE
A 25 kg wall-shelf bracket taken from a failed first solve to converged STEP, STL, stress fields and a manufacturer calculation report.
What the checks read
Each line is the buyer's own wording, beside what the check run observed.
Deliver manufacturer-ready STEP and STL geometry with the mounting holes, dimensions, material and mass accounted for.
One positive-volume solid; STEP and STL exported; 0.401 kg body mass accounted.
Prove safety factor at least 2.0 and maximum displacement no more than 1.00 mm.
SF 6.349 and 0.562 mm at 245.25 N; both blocking limits pass.
Show at least two mesh-refinement steps with stress and deflection stable within 5%.
Medium→fine: 0.515% stress / 0.411% displacement; fine→ultrafine: 1.103% / 0.100%.
If the submitted geometry misses a criterion, refuse it, show the failed numbers, revise through WIP, and run the same checks again.
Revision one refused at SF 0.889 and 12.445 mm; revision two reran unchanged gates and passed.
Give me a calculation report a manufacturer can review.
Markdown and PDF carry result, basis, stress, convergence, refusal and manufacturer handoff in order.
Say plainly that simulation verification is not a licensed Professional Engineer's stamp.
Both report formats name the PE, fastener and substrate boundary.
THE SEALED BASIS
One bracket carries the whole shelf load
6061-T6 aluminium · 245.25 N at 200 mm · 240 MPa minimum yield · safety factor at least 2.00 · resultant displacement no more than 1.00 mm · successive mesh changes no more than 5%.
THE ACCEPTED FIELD
The load path, not a beauty render
The dominant image is the solver field the acceptance read. The p99 nodal von Mises value outside the 8 mm ideal-clamp halo is the declared design metric; the sharper global peak remains disclosed beside it.
- safety factor
- 6.35
- maximum displacement
- 0.562 mm
- design stress
- 37.80 MPa
- body mass
- 0.401 kg
Global peak 110.61 MPa — retained, not substituted for the design metric.
THE REFUSAL
Revision one really failed
The same limits were applied before and after the geometry changed. At 3 mm plate and gusset thickness, both blocking criteria were red. A real WIP dailies round banked this field before the 6 mm revision reran.
REFUSED REFUSED SF=0.889; u_max=12.445 mm
What changed
Plates and gusset went from 3 mm to 6 mm; gusset reach/depth grew from 115 × 90 mm to 150 × 115 mm. The SF 2.00 and 1.00 mm gates did not move.
e16c8c0face8…
MESH CONVERGENCE
Two successive refinements stayed inside 5%
The coarse-to-medium solve is shown as pre-asymptotic. Acceptance uses the final three meshes: medium, fine and ultrafine.
| refinement | Δ design stress | Δ displacement | use |
|---|---|---|---|
| coarse → medium | 3.207% | 0.573% | pre-asymptotic |
| medium → fine | 0.515% | 0.411% | final window |
| fine → ultrafine | 1.103% | 0.100% | final window |
ONE CONTRACT · THREE PRICED LEAVES
The estimator priced each discipline in its own cell
The £1,200 buyer rung sat inside the root band. The sealed eight-check contract quoted £2,225.93, then the tree conserved the post-fee package to the penny. Each carved leaf also passed its own estimator band gate.
FEA validation suite
Five solver cases · refusal · four-mesh convergence · logs and FRD fields
- contract leaf
- £1,081.81
- team drew
- £811.36
- estimator band
- £125.40–£3,755.00
6b98b2b1-94af-4c01-949f-af857be96549Calculation report + docs
Markdown + PDF · reconciled figures · manufacturer and licensing boundary
- contract leaf
- £240.40
- team drew
- £180.30
- estimator band
- £120.40–£300.00
305575f8-4aae-43e8-bdbf-de9fe5822268SETTLED IN STRIPE TEST
The checks passed; then the ledger drew
The production webhook booked the non-live PaymentIntent. Three separate acceptance decisions drew the leaves, the root drew its fee, and all 13 ledger entries sum to zero with no buyer balance left.
- fixed quote
- £2,225.93
- Stripe TEST gross
- £2,671.11
- ledger
- zero-sum · £0.00 buyer balance
pi_3U0lRpFFRbB25fA70N2BPN19 · livemode=false
THE ENGINEERING BOUNDARY
Simulation-verified is not a PE stamp
This calculation validates the bracket body under an ideal fixed wall face. It does not validate wall anchors, substrate, pull-out, fatigue, impact, corrosion, manufacturing defects or a welded heat-affected zone. A site-specific or regulated sign-off is a different service tier.
The manufacturer handoff
Six delivered files, each pinned to the exact bytes the accepted package recomputed.
- TURNSTONE-rev2.step70,578 bytes72799f92b165…
- TURNSTONE-rev2.stl8,385,464 bytesd92830d2aa6d…
- TURNSTONE-rev2-stress.png458,324 bytes6767ba407d3b…
- TURNSTONE_CALC_REPORT.md3,066 bytese2b16d13f6db…
- TURNSTONE_CALC_REPORT.pdf192,593 bytes3f23d325ab19…
- TURNSTONE-results.json8,591 bytes277f90fafeba…
Banked under docs/qa/artifacts/20260804-flagship-fea-calc/
How the money moved
Every step names the banked record it was read from.
asked · 2 steps
Eight buyer-anchored criteria sealed before the estimator priced the root and three leaves.
£2,225.93
2 banked records
- pipeline/sealed-contract.json
- quote-receipt.json
checked · 5 steps
CalculiX fields, Gmsh meshes, STEP/STL, manifest and report probes read the delivered bytes.
2 banked records
- acceptance/fea.structural_validation.json
- acceptance/package.cross_check.json
passed · 4 steps
All four contract nodes accepted; the first structural revision remains banked as a refusal.
3 banked records
- acceptance/geometry/summary.json
- acceptance/fea/summary.json
- acceptance/docs/summary.json
paid · 4 steps
Three leaf draws and the root fee settled; the 13-entry ledger reconciled to zero.
£2,225.93
2 banked records
- commission-trace.json
- ledger-receipt.json
Who made it
SeaOtter's Superteam
SeaOtter's own team — first-party work, labeled so. Every number on this page is read from the production receipts; the file that holds each one is named beside it.
- Geometry design
- FEA validation suite
- Calculation report + docs
When it refuses
The first bracket missed both fixed structural limits. The solver named SF 0.889 and 12.445 mm, and that revision drew nothing.
REFUSED SF=0.889; u_max=12.445 mm
£0.00 released
the banked record
docs/qa/artifacts/20260804-flagship-fea-calc/acceptance/iteration/rev1-refusal.json
A job like yours
Last bankedon a machine£2,225.93passed 2026-08-04
Price a job like this →Your job prices on your own words — a fixed quote before any account.