Engineering calculators
The numbers a drawing takes for granted — computed from the standard rather than hunted for in a photographed table.
Available calculators
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We read the drawing before we talk about price. These calculators are that same language, out in the open.
ISO 286 limits and fits calculator
Limit deviations, maximum and minimum size and the resulting fit for any combination of nominal size, fundamental deviation and tolerance grade.
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Metal hardness converter
Vickers, Brinell, Rockwell C, B and A, Knoop and approximate tensile strength, per ASTM E140, with every limit stated.
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Surface roughness converter
Ra, Rz, Rq and the N grades against each other, in micrometres and microinches — with the SPI and VDI 3400 mould finishes placed on the same scale.
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ISO 2768 general tolerances calculator
Which tolerance governs a dimension that carries none of its own — lengths, broken edges, angles, form and position, in all seven tolerance classes.
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These calculators reproduce the published values of the standard they name, for orientation while a drawing is being written. They say nothing about which tolerances a manufacturing partner actually holds — that belongs in the quotation and the control plan, not in a table.