The drawing says 50.000 +0.200 / -0.000.
The machine needs 50.100.
TechRef does that math, converts it into every unit, and records what you measure. Built for the everyday questions on the shop floor.
WHY THE CENTER VALUE MATTERS
The center of an asymmetric tolerance is not the nominal size. TechRef calculates the true center and the full band, so you get it right in one setup.
Input: 50.000 +0.200 / -0.000
Center: 50.100
Range: 50.000 – 50.200
mm 50.1000 (50.0000 – 50.2000)
in 1.9724 ( 1.9686 – 1.9763)
TOLERANCES FROM THE STANDARD (TechRef Pro)
Pick an ISO 2768 class (f, m, c, v) or an ISO 286 fit (hole H7, shafts g6 to p6), and TechRef looks up the deviations for your size. Pick a shaft to see how it fits an H7 hole: clearance, transition or interference. Use ISO, JIS, EN, DIN or BS names; only standards officially identical to ISO are listed.
TABLES AND CALCULATORS
• Tolerance tables (TechRef Pro): ISO 2768 and ISO 286 (H7, g6 to p6, fits with H7), up to 500 mm
• Tap drill charts (TechRef Pro): Metric, Unified and Whitworth, with minor diameter limits. Sizes that could not be verified are left out
• Drill size charts: number, letter and fractional drills in inches and mm
• Cutting speed and feed: spindle speed, cutting speed and feed rate, in mm and m/min or inch and SFM. Formulas only
RECORD WHAT YOU MEASURE
Add measured values to any point in a sheet. Each entry updates the count, mean, max, min, range, standard deviation, deviation from target, out-of-tolerance count, Cp and Cpk.
Drawing: 25.000 ±0.100
Measured: 25.02 / 25.05 / 24.98 / 25.12 / 25.03
Mean: 25.040 (+0.040 from target)
Out of tolerance: 1 / 5
The target is the tolerance center, so you see which way to adjust. Drawing in mm, measuring in inches? Record in your own unit. Free, and not counted toward the save limit.
INSPECTION SHEETS AND CSV
Create a sheet per part with points, each with its own dimension and tolerance. Export CSV per point or per measured value.
13 CATEGORIES, 100+ UNITS
Length, pressure, torque, force, temperature and more. Show only the units you use, from mm and inch to bar, psi, kgf/cm², N·m and lbf·ft. Factors come from exact definitions, never rounded approximations.
SAFE-SIDE ROUNDING
Bands are rounded inward, so a part inside the band on screen is inside it for real.
10 LANGUAGES
English, Japanese, German, French, Italian, Spanish, Portuguese, Korean, Simplified Chinese and Traditional Chinese. Follows your device, or choose in Settings.
FREE, AND TechRef Pro
Conversions, manual tolerances, drill charts, the cutting calculator, Sheets, measured values and CSV export are free. Saving dimensions has a limited number of free saves, then once per hour. TechRef Pro, a one-time purchase, removes the limit and unlocks tap drill charts, tolerance tables and tolerances from the standard. No subscription.
EVERYTHING STAYS ON YOUR DEVICE
No server, fully offline. No ads, no tracking, no analytics, no account.
ALSO
History with search, labels and memos · 1 to 6 decimal places · How to Use · Dynamic Type · Light and dark · iPhone and iPad
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