Specification answers you can use on the drawing.
Reference charts, working calculators and downloadable files for tolerances, surface finish, threads, fits and machining parameters. Get the number first; read the engineering logic when you need it.
From your input to a usable specification.
Choose a task, enter your values, inspect the reference table and download the same data. No separate journey through a long article.
ISO 2768 tolerance lookup
Enter a basic size and select the tolerance class invoked by the drawing.
Surface roughness converter
Convert Ra and check whether the value belongs to the preferred series.
Metric thread reference
Use the table for coarse pitch and tap-drill selection. No calculation is needed for this reference.
H7/g6 fit reference
Read the hole and shaft limits directly. Fit selection depends on function, material and assembly conditions.
Cutting speed to spindle speed
A starting calculation for milling parameters. Validate against the tool and machine.
ISO 2768-1 general tolerances
| Basic size range (mm) | f — fine | m — medium | c — coarse | v — very coarse |
|---|---|---|---|---|
| 0.5 to 3 | ±0.05 | ±0.1 | ±0.2 | — |
| over 3 to 6 | ±0.05 | ±0.1 | ±0.3 | ±0.5 |
| over 6 to 30 | ±0.1 | ±0.2 | ±0.5 | ±1.0 |
| over 30 to 120 | ±0.15 | ±0.3 | ±0.8 | ±1.5 |
| over 120 to 400 | ±0.2 | ±0.5 | ±1.2 | ±2.5 |
| over 400 to 1000 | ±0.3 | ±0.8 | ±2.0 | ±4.0 |
| over 1000 to 2000 | ±0.5 | ±1.2 | ±3.0 | ±6.0 |
| over 2000 to 4000 | — | ±2.0 | ±4.0 | ±8.0 |
| Ra (µm) | Typical processes | What it looks like | Where it belongs |
|---|---|---|---|
| 0.025 | Lapping, superfinishing | Mirror, no visible pattern | Gauge blocks, sealing faces, optical seats |
| 0.4 | Fine grinding, polishing | Mirror with slight haze | Hydraulic cylinders, seal faces, shafts |
| 0.8 | Fine grinding, precision turning | Bright, reflective | Bearing seats, spindle journals |
| 1.6 | Precision turning and milling, fine grinding | Bright, faint tool marks | Precision mating faces, sliding surfaces |
| 3.2 — our default | Standard turning and milling | Smooth, matte-bright | General machined parts, most brackets and plates |
| 6.3 | Rough turning, milling, drilling | Visible, even tool marks | Non-critical faces, clearance, internal corners |
| 12.5 | Rough machining, sawing | Coarse, obvious marks | Clearance surfaces, weld prep |
| 25 | As-cast or as-forged, rough saw | Very coarse, irregular | Non-functional surfaces, bases |
| Thread | Coarse pitch (mm) | Tap drill (mm) | Pitch dia. (mm) | Typical use |
|---|---|---|---|---|
| M3 | 0.5 | 2.5 | 2.675 | Small electronics, instrument covers |
| M4 | 0.7 | 3.3 | 3.545 | Sensor mounts, small brackets |
| M5 | 0.8 | 4.2 | 4.480 | General light fastening |
| M6 | 1.0 | 5.0 | 5.350 | The default metric fastener |
| M8 | 1.25 | 6.8 | 7.188 | Structural brackets, fixtures |
| M10 | 1.5 | 8.5 | 9.026 | Machine frames, mounting plates |
| M12 | 1.75 | 10.2 | 10.863 | Heavy brackets, bases |
| M16 | 2.0 | 14.0 | 14.701 | Structural joints |
| M20 | 2.5 | 17.5 | 18.376 | Heavy structural, lifting points |
| Basic size range (mm) | Hole | Hole deviation (µm) | Shaft | Shaft deviation (µm) | Clearance min / max (µm) | Assembly |
|---|---|---|---|---|---|---|
| over 3 to 6 | H7 | +0 / +12 | g6 | -4 / -12 | 4 / 24 | Sliding — hand push, light lubrication |
| over 6 to 10 | H7 | +0 / +15 | g6 | -5 / -14 | 5 / 29 | Sliding — hand push, light lubrication |
| over 10 to 18 | H7 | +0 / +18 | g6 | -6 / -17 | 6 / 35 | Sliding — hand push, light lubrication |
| over 18 to 30 | H7 | +0 / +21 | g6 | -7 / -20 | 7 / 41 | Sliding — hand push, light lubrication |
| over 30 to 50 | H7 | +0 / +25 | g6 | -9 / -25 | 9 / 50 | Sliding — hand push, light lubrication |
| over 50 to 80 | H7 | +0 / +30 | g6 | -10 / -29 | 10 / 59 | Sliding — hand push, light lubrication |
| over 80 to 120 | H7 | +0 / +35 | g6 | -12 / -34 | 12 / 69 | Sliding — hand push, light lubrication |
| over 120 to 180 | H7 | +0 / +40 | g6 | -14 / -39 | 14 / 79 | Sliding — hand push, light lubrication |
| Work material | HSS (SFM) | Carbide (SFM) | Feed per tooth (mm) | Notes |
|---|---|---|---|---|
| Aluminium 6061 | 300–500 | 1,000–2,000 | 0.10–0.30 | High rake, polished flutes, no coolant needed |
| Aluminium 7075 | 250–400 | 800–1,500 | 0.10–0.25 | Rigidity matters more than speed |
| Carbon steel 1018 | 90–110 | 300–450 | 0.05–0.15 | Flood coolant, watch chip evacuation |
| Alloy steel 4140 | 60–80 | 200–350 | 0.05–0.15 | Reduce further if hardened or pre-hard |
| Stainless 304 | 40–60 | 150–250 | 0.05–0.12 | Never dwell — keep the feed up to stay under the work-hardened skin |
| Stainless 316L | 35–55 | 130–220 | 0.05–0.12 | Gummy and work-hardening; sharp edges are essential |
| Tool steel P20 | 50–70 | 180–300 | 0.05–0.12 | Pre-hardened; treat like 4140 at the harder end |
| Titanium Ti-6Al-4V | 25–40 | 100–180 | 0.05–0.10 | Lots of coolant, sharp edges, never rub |
| Brass C360 | 200–400 | 600–1,000 | 0.10–0.25 | Free-cutting; ideal for high volume |
| Copper C110 | 150–250 | 500–800 | 0.08–0.20 | Sticky — sharp tools and generous rake |
| Grey cast iron | 80–120 | 300–500 | 0.10–0.25 | Dry or air-blast; avoid coolant on dust |
| POM, PEEK, nylon | 300–600 | 800–1,500 | 0.10–0.30 | Sharp, polished flutes; control heat to avoid melting |
Reference only; confirm the drawing, standard edition and production requirements. Read the connected source guide ↗
Heat Sink Size Calculator
Turn a heat load and temperature limit into a starting geometry. Set the available length, fin height and surface emissivity, then compare passive heat sink concepts before detailing the part.
For vertical, open-air natural convection and radiation with a full-base heat source. Preliminary sizing; export the concept and validate the actual thermal design.
Browse by what you want to use.
Charts, tools, files and guides are first-class assets. Each appears once, with a clear action and no article-archive filler.
Heat Sink Size Calculator
Estimate passive heat sink width, clear fin spacing and fin count. Compare concepts and export a sizing report.
ISO 2768 general tolerances
Look up linear deviations by size range and tolerance class, then export the same table.
Surface roughness converter
Convert Ra from micrometres to micro-inches and identify the preferred N grade.
Metric threads & tap drill
Coarse pitch, tap drill and pitch diameter for the sizes used on engineering drawings.
Hole-basis limits & fits
Compare clearance, transition and interference fits on the ISO 286 hole basis, including H7/g6.
Spindle speed & feed rate
Turn cutter diameter and cutting speed into rpm, feed per revolution and feed per minute.
ISO 2768 table — CSV
A reusable spreadsheet file generated from the exact table shown in this resource center.
Production cycle time in CNC machining
The formulas and production logic behind machining-time estimates, with a direct path to cutting tools.
Sheet metal cost estimation — PDF
An existing downloadable reference covering sheet-metal fabrication cost estimation approaches.
Material certification explained
Understand data sheets, material certificates, chemical composition and mechanical-property evidence.
Read the reasoning without losing the answer.
Long-form content is curated around the workbench, not listed by publication date. Every guide has a direct route back to a table or tool.
ISO 2768: a guide to standard tolerancing
Understand the four classes and which dimensions the standard does not cover.
Surface roughness: everything you need to know
How Ra is measured, what the numbers mean and how to specify them.
SFM in machining
Surface feet per minute and how cutting speed becomes a spindle speed.
A reference is only useful if its basis is visible.
Each asset should carry its standard, source, review state and limits. Production content requires engineering and quality approval before release.
General tolerances
Linear dimensions, size ranges and tolerance classes remain attached to the result.
Surface and thread references
Terminology and series stay connected to their source guides and intended use.
No silent engineering promises
This demo reuses published reference data. New values, PDFs and XLSX files need formal review.
Found a questionable value? The production version should provide a correction route and record the asset revision rather than silently replacing the number.
Keep the specification connected to the part.
Send your drawing for a review of geometry, material, critical features and production requirements. If you are unsure which value to call out, talk to an engineer first.