The independent, practitioner-built reference for WebSocket technology. Protocol internals, production patterns, scaling guides, and honest protocol comparisons with real code.
Resources
From HTTP upgrade to binary frames — the complete picture.
Hands-on guides from first connection to production scale.
Not everything needs a WebSocket. Pick the right tool.
Real-world patterns for common WebSocket applications.
Explore the full guide library — implementation patterns, framework integrations, and more.
Browse all guidesInteractive Tools
Test WebSocket connections in real time. Send messages and see them echoed back instantly — no signup, no setup.
Try it nowAnswer a few questions about your use case and get a protocol recommendation.
Find your protocolHow it works
One request, one response. Connection closes. Every interaction has overhead.
Server streams to client only. Great for push — can't send back.
Full-duplex, persistent. Both sides send whenever they want.
The lowercase letters in ISO 2768-1 define four classes of tolerances: f (fine), m (medium), c (coarse), and v (very coarse) [1, 5]. Below is the standardized chart for the designation, which is the most widely adopted standard across mechanical engineering [1]. Linear Dimensions Tolerance Chart (Class m)
| Feature | Tolerance Class | Key Values | | :--- | :--- | :--- | | Linear dimensions (0.5–4000mm) | m | ±0.1mm up to 6mm, ±0.2mm up to 30mm, ±0.3mm up to 120mm, ±0.5mm up to 400mm | | Radii and chamfers (0.5–6mm+) | m | ±0.2mm up to 3mm, ±0.5mm up to 6mm, ±1.0mm over 6mm | | Angular dimensions (0–400+ mm) | m | ±1° up to 10mm, ±0°30′ up to 50mm, ±0°20′ up to 120mm | | Straightness/Flatness | H | 0.02mm up to 10mm, 0.05mm up to 30mm, 0.1mm up to 100mm | | Perpendicularity | H | 0.2mm up to 100mm, 0.4mm up to 300mm | | Symmetry | H | 0.5mm for up to 3000mm | | Circular run-out | H | 0.1mm |
What are you planning to use? (CNC milling, sheet metal, injection molding?) What is the primary function or material of the component?
The “mH” designation pulls from both parts. iso 2768-mh tolerance chart
Ranges from 0.02 mm for lengths up to 10 mm, up to 0.5 mm for lengths over 1000 mm.
The "H" class defines strict limits for form and position, such as how straight or perpendicular a feature must be. Straightness and Flatness Range of Nominal Length (mm) Tolerance (mm) Over 10 to 30 Over 30 to 100 Over 100 to 300 Over 300 to 1,000 Over 1,000 to 3,000
This public link is valid for 7 days and shares a thread, including any personal information you added. This link or copies made by others cannot be deleted. If you share with third parties, their policies apply. Can’t copy the link right now. Try again later. The lowercase letters in ISO 2768-1 define four
Dimensions on drawing:
"ISO 2768-mh allows anything to be sloppy." Reality: A 0.2mm deviation on a 6mm shaft is a 3.3% error. For general machinery, that is acceptable. For a wristwatch, it is a disaster. The standard is not "sloppy"; it is "economical."
| Nominal Dimension Range (mm) | Permissible Deviation for Class 'm' (mm) | | :--- | :--- | | 0.5 up to 3 | ± 0.1 | | >3 up to 6 | ± 0.1 | | >6 up to 30 | ± 0.2 | | >30 up to 120 | ± 0.3 | | >120 up to 400 | ± 0.5 | | >400 up to 1000 | ± 0.8 | | >1000 up to 2000 | ± 1.2 | | >2000 up to 4000 | ± 2.0 | (CNC milling, sheet metal, injection molding
| Nominal Dimension (mm) | Tolerance (mm) | | --- | --- | | 0 - 6 | ±0.05 | | 6 - 30 | ±0.1 | | 30 - 120 | ±0.2 | | 120 - 400 | ±0.3 | | 400 - 1000 | ±0.5 | | 1000 - 2000 | ±0.8 | | 2000 - 4000 | ±1.2 |
For the most complex geometries or critical applications, it is always best to consult the official ISO documents (ISO 2768-1:1989 and ISO 2768-2:1989) and coordinate with your manufacturing partner to ensure that the specified tolerances are appropriate for the production process.
Below are complete tolerance tables per ISO 2768-1 (m class for linear dimensions) and ISO 2768-2 (H class for geometrical tolerances).