Fits, tolerances and materials: engineering answers with a source sheet
Ask in plain words, for example “What fit for a bearing on a 20 mm shaft?”. The AI assistant EDi Engineer Reference is told to look in the EDi Brain rules, calculate and make a PDF and CSV sheet with a table of numbers. Its screen and answers are in Bulgarian.
Part of Ultra, 39 EUR a month, with 1500 credits each month.
- A sheet with the answerPDF, and the numbers in CSV
- Fits above 3 up to 180 mmH7 with g6, h6, k6 or p6
- Checked calculationin the calculation sheet, up to 20 steps
- Dimension sketcha part with up to 12 holes
What a mechanical engineering AI assistant is
A mechanical engineering AI assistant answers a design or manufacturing question with numbers you can trace. EDi Engineer Reference on EduFacturing covers fits and tolerances, materials and design-for-manufacturing limits, and gives you a sheet with the numbers in a table.
The assistant is told to look in the rules before it answers, but code does not force it: any tool call counts for that check, including the sheet itself.
Part of Ultra: one question costs 5 credits, and 1500 credits a month cover 300 questions if you spend none on other assistants (the wallet is shared).
What you get: a sheet, a fit table, a calculation, a sketch
Gives a sheet with the answer
A PDF with the short answer, a table of numbers and sources, traps and what to check yourself (the assistant fills in the sections; some may be missing), and a CSV with the table. A guide, not a replacement for the standard.
Calculates a shaft-hole fit
A diameter above 3 up to 180 mm and a fit such as H7/g6: limits of hole and shaft, smallest and largest clearance or interference, as PDF and CSV, from the rules tables (ISO 286). The type in the PDF is wrong for H7/h6 and for H7/p6 up to Ø18 mm: it says “transition”.
Builds a calculation sheet
For a calculation the assistant is told to make a sheet: steps with expression and result, and a Check column in which code recalculates the expression.
Draws a dimension sketch
A rectangular part with up to 12 holes and dimensions, as SVG. A diagram, not a standard drawing.
When to ask: a fit, a hole, a material
It suits you when you need one checked number or a choice, not a whole textbook.
A fit for a bearing or a shaft
The screen’s example: a fit for a bearing on a 20 mm shaft.
A bolt hole in a part for 3D printing
A medium-series size plus a correction for FDM.
A material or a wall for printing
The screen’s examples: PETG nozzle, FDM wall.
A calculation for documentation
A calculation sheet with recalculated steps.
Where the numbers come from and how they are calculated
Rule first, calculation next. Code checks the sheet and works out fits.
Looks in the rules
The assistant is told: by area (mechanics, materials, DFAM, electronics, physics) in the EDi Brain rules and in the catalogues.
Calculates in code
The sheet is recalculated (up to 20 steps), a fit comes from a table, a sketch is drawn from the dimensions.
Builds the sheet
The sheet is a required result, unless the assistant replies with only a question.
| Applies to | Formula | Meaning |
|---|---|---|
| Hole and shaft limits | size = nominal + deviation / 1000 | the deviation is in µm from the table; Ø18 falls in the 10 to 18 band, not 18 to 30 |
| Clearance and interference | min = hole lower − shaft upper; max = hole upper − shaft lower | min above 0: clearance; max below 0: interference; otherwise “transition”. At exactly 0 (H7/h6; H7/p6 up to Ø18 mm) that is wrong: by the EDi Brain rules H7/h6 is a clearance fit and H7/p6 an interference fit |
| Example: Ø20 mm, H7/g6 | hole 20.000 to 20.021 mm; shaft 19.980 to 19.993 mm | clearance from 0.007 to 0.041 mm: a clearance fit |
Numbers sit in a table with a source column
A number sits in a table with a source
If the assistant gives no source, code writes “by Edufacturing rules core”: check what matters. For a fit the PDF cites the standard.
A fit comes from a table
The instructions forbid micrometre values from memory; there is no table for other classes.
The sheet is recalculated
Code recalculates each step’s expression and marks a row for checking when the difference is over 1 percent.
The sheet is a guide: a number for a product people will use is checked against the standard. There is a fit table only for H7 with g6, h6, k6 and p6 and diameters above 3 up to 180 mm. The fit type is wrong for H7/h6 and for H7/p6 up to Ø18 mm: the PDF says “transition”.
The assistant is told not to solve coursework or homework outright and not to write standard numbers in the answer. It takes text only, up to 4000 characters. The sketch is a diagram.
Answers are written by AI and may contain mistakes. The screen, answers and files are in Bulgarian, also to an English question; the screenshot shows the Bulgarian screen.
Questions about fits, bolt holes and reference sheets
What fit for a bearing on a shaft?
It depends on the load and on which ring turns. The assistant has a table for H7 with g6, h6, k6 and p6 (above 3 up to 180 mm) and is told to use it for a fit question; there is no table for other classes.
How to calculate clearance between shaft and hole?
Hole lower limit minus shaft upper limit is the minimum clearance; hole upper minus shaft lower is the maximum. Example: Ø20 mm, H7/g6, 0.007 to 0.041 mm. Negative means interference.
What size hole for an M4 bolt?
4.5 mm, medium series: that is in the assistant’s instructions and in the EDi Brain rules. For a part printed in FDM add 0.2 mm, because holes come out smaller. Also: M3 3.4, M5 5.5, M6 6.6, M8 9.0, M10 11.0 mm.
Does it answer in English?
No. The screen and answers are in Bulgarian, as its instructions require. In our test on 10.10.2026 with another assistant, an English question also got a Bulgarian answer.
How much does a question cost?
Ultra is 39 EUR a month with 1500 credits. One question is 5 credits: 300 questions a month if you spend none on other assistants (the wallet is shared). A question outside engineering is usually declined without credits; a model checks it and can err.
The mechanical engineering AI assistant is part of Ultra
Ultra costs 39 EUR a month: everything in Pro (45 tools), the EDi assistants and 1500 credits each month. Every run of an assistant spends credits.
In the Idea & selection group:
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Check the number before you draw the part
Part of Ultra, 39 EUR a month, with 1500 credits each month.