Stack by F³ Lab
An offline desktop tool for dimensional tolerance stack-up analysis. You describe an assembly — its materials, parts and toleranced features — draw the dimensional chain directly on your own 2D drawing, and the application computes the resulting assembly dimension by three methods side by side:
- Worst Case — the arithmetic limits: every dimension at its worst extreme simultaneously.
- RSS (root-sum-of-squares) — the classic statistical band.
- Monte Carlo — full statistical simulation with per-dimension distributions, yield and Cp/Cpk estimates.
Thermal expansion is built in: assign materials with CTE values (constant or a nonlinear α(T) curve) and the stack is re-evaluated at your minimum, room and maximum temperatures. GD&T with Ⓜ/Ⓛ bonus, the boundary method, PDF and Excel reports, DXF/DWG import and export.
Everything runs locally. No project data ever leaves your computer.
Windows 10/11, 64-bit. Version 1.0.0.
Overview
A floating fastener assembly: two plates, two bolts, and the clearance that decides whether they go together. The replay shows the Calculations sheet at work — the drawing, the requirement, sixteen contributors drawn tip-to-tail, each given its feature from the list with a click, the grid filling as you go, and the result at three temperatures.
| NO. | PART | FEATURE ID | NAME | TYPE | F. SIZE | F. TOL+ | F. TOL− | GEO TOL | +/− | /2 | CONTRIB. | TOL. ± |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | BLT | BLT-001 | BOLT DIA | ↔ | 10.00000 | — | — | — | − | ☐ | −10.00000 | |
| 2 | PLT1 | PLT1-001 | HOLE DIA | ↔ | 10.50000 | 0.20000 | −0.20000 | — | + | ☑ | 5.25000 | 0.10000 |
| 3 | PLT1 | PLT1-002 | HOLE POSITION | ⌖ | — | — | — | 0.30000 | + | ☑ | 0.00000 | 0.15000 |
| 4 | PLT1 | PLT1-005 | ← PLT1-001 | Ⓜ | — | — | — | 0.40000 | + | ☑ | 0.00000 | 0.20000 |
| 5 | PLT1 | PLT1-003 | BOLT PATTERN | ▭ | 60.00000 | — | — | — | + | ☐ | 60.00000 | |
| 6 | PLT1 | PLT1-002 | HOLE POSITION | ⌖ | — | — | — | 0.30000 | + | ☑ | 0.00000 | 0.15000 |
| 7 | PLT1 | PLT1-005 | ← PLT1-001 | Ⓜ | — | — | — | 0.40000 | + | ☑ | 0.00000 | 0.20000 |
| 8 | PLT1 | PLT1-001 | HOLE DIA | ↔ | 10.50000 | 0.20000 | −0.20000 | — | + | ☑ | 5.25000 | 0.10000 |
| 9 | BLT | BLT-001 | BOLT DIA | ↔ | 10.00000 | — | — | — | − | ☐ | −10.00000 | |
| 10 | PLT1 | PLT1-001 | HOLE DIA | ↔ | 10.50000 | 0.20000 | −0.20000 | — | + | ☑ | 5.25000 | 0.10000 |
| 11 | PLT1 | PLT1-002 | HOLE POSITION | ⌖ | — | — | — | 0.30000 | + | ☑ | 0.00000 | 0.15000 |
| 12 | PLT1 | PLT1-005 | ← PLT1-001 | Ⓜ | — | — | — | 0.40000 | + | ☑ | 0.00000 | 0.20000 |
| 13 | PLT1 | PLT1-003 | BOLT PATTERN | ▭ | 60.00000 | — | — | — | − | ☐ | −60.00000 | |
| 14 | PLT1 | PLT1-002 | HOLE POSITION | ⌖ | — | — | — | 0.30000 | + | ☑ | 0.00000 | 0.15000 |
| 15 | PLT1 | PLT1-005 | ← PLT1-001 | Ⓜ | — | — | — | 0.40000 | + | ☑ | 0.00000 | 0.20000 |
| 16 | PLT1 | PLT1-001 | HOLE DIA | ↔ | 10.50000 | 0.20000 | −0.20000 | — | + | ☑ | 5.25000 | 0.10000 |
| MIN | NOMINAL | MAX | |
|---|---|---|---|
| WORST CASE | −0.01468 | 0.98377 | 2.78098 |
| MONTE CARLO | 0.44198 | 1.52555 |
| MIN | NOMINAL | MAX | |
|---|---|---|---|
| WORST CASE | 0.00000 | 1.00000 | 2.80000 |
| MONTE CARLO | 0.45738 | 1.54262 |
| MIN | NOMINAL | MAX | |
|---|---|---|---|
| WORST CASE | 0.05414 | 1.05979 | 2.86996 |
| MONTE CARLO | 0.51410 | 1.60548 |
Download
The installer will appear here with the first release. Until then: support@f3lab.tools. Windows 10/11, 64‑bit. The application runs with a license file, Free or Pro; both are bound to one computer and activated offline by importing the file in Help → About → License.
Editions
- Free
- No charge. Register with your name, e‑mail and the machine code and the file is issued at once. Every feature, a “not for commercial use” watermark on the sheet and on every report, at most 20 chains per project.
- Pro
- 590 zł net per year. Every feature, no watermark, no chain limit, reports that carry your name or your company’s. After the purchase you send the machine code, the file arrives by e‑mail. A renewal starts where the previous license ends.
Buy Pro. VAT is added according to your country.
Who made it
Stack is written by a mechanical engineer: fifteen years of dimensional engineering at one of the largest aerospace companies — tolerance analysis, GD&T and product definition for parts that have to be built, measured and accepted — and an ASME GDTP Senior certification (Y14.5). The calculations are the ones done by hand for years, checked against published examples.
Consulting
The hard part is rarely the arithmetic. It is the product definition: datums that do not match how the part is fixtured, tolerances that cannot be measured, requirements nobody wrote down. Two kinds of help are available, by the hour or per problem:
- Solving a dimensional problem with Stack — the chain, the method, the verdict, and what to change.
- Product definition that makes analysis possible — datum schemes, tolerance allocation, drawing review to ISO GPS or ASME Y14.5, so the stack-up can be run at all.
Write with a drawing or a description of the problem: support@f3lab.tools.